Been a while since I've posted anything, but I've been lurking and learning the whole while
Anyways, we've started our power system build so it's ready by the time we "hit the road". I've just managed to find some time to document what we have so far, and thought I'd give a little back to the community by way of sharing it.
http://dm-touring.com/let-there-be-light - have an appropriate amount of fun
Cheers,
Mattt (and Dee).
Brenda and Alan said
09:08 PM Feb 11, 2016
Matt the big power user as I see it will be your desk top computer, can you give us an estimate of the power draw you expect when using at an average capacity. As an aside we chew through an average of 40 Ah at 12V per 24 hours winter touring in a 17.5 Ft Van. We use 22 " Kogan TV with DVD (about 4 Hours), radio/CD player, led lighting, electric blankets on low or diesel heater (depending on ambient temp.) plus the usual laptop and phone charging and other small 12V appliances. We have 360 Watts of solar only to maintain charge in a 200Ah LiFePo4 12V battery and have not had to resort to other means of charging even in the southern states. I can give you the power consumption figures for the various items we use if it will help in your planningAlan
madaboutled said
10:39 PM Feb 11, 2016
Hey Matt, from what I read you're way too light on battery & solar with everything you intend running. Look at everything you have and try to run as much as possible direct from 12v. I understand using the PC over a laptop, but have a look at the PC's power supply you'll probably find it's 240v AC down to 12v DC, so you might be able to make (or have made) an adapter to run it direct from 12v. Yeh get a bigger LED Screen although going back to one screen takes some getting used to (ex graphic artist).
You can get 12v chargers & power supplies for any portable device like laptops & phones etc... far better direct on the batteries running 12 volt upto 19-22v than 12v upto 240v AC then back down to 19-22v DC.
Have a look at Bitdeals for their Pure Sine Wave Inverters, I have a 1500w/3000w Peak inverter that we use from time to time and has been great. Just remember Inverters should be used for emergency only cause they'll drain a battery bank in no time flat!. In 12 months I probably used my inverter less than 4 times and for no longer than 20 minutes each time.
The wires coming from your solar controller look pretty light to me, and the solar controller..... I've seen a few similar to that used as a boomerang (um... stick! cause when thrown, they didn't come back). A good controller will have an LED readout showing you some helpful readings with out the need of relying on a multimeter. Mine records Amps into the batteries over 3 days which is handy cause I've got a fair idea what my daily usage is. The heart of your solar system is the controller, so best to have a really good one. The trick is getting one that's a true MPPT controller, some say they are but they're not.
Using 240v cable for 12v is not good no matter how you want to sugar coat it, 240 volt cable is designed for Alternating current (AC). Voltage drop in a DC system can only be overcome by using the correct thickness of DC cable allowing for distance & power and going thicker than the recommended is better again. Mixing Batteries.... Sorry I don't agree with your theory, but it's your money... time will tell.
Anyway good luck on your travels.
Steve.
-- Edited by madaboutled on Thursday 11th of February 2016 10:40:27 PM
Mattt said
01:37 AM Feb 12, 2016
Brenda and Alan wrote:Matt the big power user as I see it will be your desk top computer, can you give us an estimate of the power draw you expect when using at an average capacity. As an aside we chew through an average of 40 Ah at 12V per 24 hours winter touring in a 17.5 Ft Van. We use 22 " Kogan TV with DVD (about 4 Hours), radio/CD player, led lighting, electric blankets on low or diesel heater (depending on ambient temp.) plus the usual laptop and phone charging and other small 12V appliances. We have 360 Watts of solar only to maintain charge in a 200Ah LiFePo4 12V battery and have not had to resort to other means of charging even in the southern states. I can give you the power consumption figures for the various items we use if it will help in your planningAlan
Hey Alan,
Yeah, my main workstation PC is definitely the biggest concern - partly because it's absolutely central to my ( / our) living, and partly because it's gonna be a major power chewer which needs to run for big hours. I'm afraid I have no "real life" figures to provide in terms of what kinda power it uses. The best I have is that it currently has a decent quality 550w (240v, obviously) power supply which has never had any issues. I'm looking for reliable (and easy
I think that the PC, aircon and fridge will be the major concerns.
The ultimate goal (in this instance, by "ultimate" I mean "soon") is to go lithium for storage. I just needed to make a start and be able to afford / justify the initial spend. So AGM it is for now...
I'd love and appreciate to hear your real-life stats - the more data we have to work with, the less wasted money and dramas we'll need to deal with
Cheers,
Mattt.
Mattt said
02:36 AM Feb 12, 2016
madaboutled wrote:
Hey Matt, from what I read you're way too light on battery & solar with everything you intend running. Look at everything you have and try to run as much as possible direct from 12v. I understand using the PC over a laptop, but have a look at the PC's power supply you'll probably find it's 240v AC down to 12v DC, so you might be able to make (or have made) an adapter to run it direct from 12v. Yeh get a bigger LED Screen although going back to one screen takes some getting used to (ex graphic artist).
You can get 12v chargers & power supplies for any portable device like laptops & phones etc... far better direct on the batteries running 12 volt upto 19-22v than 12v upto 240v AC then back down to 19-22v DC.
Have a look at Bitdeals for their Pure Sine Wave Inverters, I have a 1500w/3000w Peak inverter that we use from time to time and has been great. Just remember Inverters should be used for emergency only cause they'll drain a battery bank in no time flat!. In 12 months I probably used my inverter less than 4 times and for no longer than 20 minutes each time.
The wires coming from your solar controller look pretty light to me, and the solar controller..... I've seen a few similar to that used as a boomerang (um... stick! cause when thrown, they didn't come back). A good controller will have an LED readout showing you some helpful readings with out the need of relying on a multimeter. Mine records Amps into the batteries over 3 days which is handy cause I've got a fair idea what my daily usage is. The heart of your solar system is the controller, so best to have a really good one. The trick is getting one that's a true MPPT controller, some say they are but they're not.
Using 240v cable for 12v is not good no matter how you want to sugar coat it, 240 volt cable is designed for Alternating current (AC). Voltage drop in a DC system can only be overcome by using the correct thickness of DC cable allowing for distance & power and going thicker than the recommended is better again. Mixing Batteries.... Sorry I don't agree with your theory, but it's your money... time will tell.
Anyway good luck on your travels.
Steve.
-- Edited by madaboutled on Thursday 11th of February 2016 10:40:27 PM
Hey Steve,
I'll say from the get-go that you obviously didn't read all (or much) of my page - for which I don't blame you a bit. It turned out to be quite a novel...
Anyways, let's go at it in order of your thoughts
No, we have nowhere near enough input or storage. I'm thinking we'll need (at best) 5 x what we have now. And yes - the idea is to run everything we can on "12v native". As you mentioned, it's the most efficient way to go. You're also right about the PC P/S stepping everything down to 12v (there's also a 5v rail). PC power supplies are readily available which take 12v input, but I think I might be better off designing and knocking up something to suit my specific needs. I'll need to take a bunch of measurements and some more research to ascertain whether I need to refactor the displays (I'm also looking at physical space, of course).
Obviously, we're aiming for as close to "native 12v" as possible. I guess you also missed from my writing (haha - or maybe ranting...) that this is the path we're taking
I'm assuming that the "wires coming from your solar controller" you refer to are the ones coming out of the unit itself. The "controller" is rated for 20a, and those interconnect cables look good for at least 25a. We're not intending to push more than about 15a through it (we're not using it's load / output side), so no issues there.
You said "The heart of your solar system is the controller, so best to have a really good one" - you're absolutely right if you need to rely on it because you don't know how to manage the system yourself. Unfortunately, it's difficult to be certain that the "controller" you choose is really any good at all. Most are not. And you're again right that a lot of the "controllers" claim to be MPPT when they're absolutely not.
I meant for my writings to imply that using 240v cabling for longer-length interconnects was absolutely insufficient for 12v systems. I just needed to save some $$$. Thus far, it's all been (almost completely) good. By the way, though, it's got little to do with the difference between AC and DC current profiles - it's more to do with the fact that lower voltages don't travel as well over longer distances via thinner cables. You also said "going thicker than the recommended is better again". You're wrong on two different levels - you don't need to go thicker than actual spec, and "recommendations" are rarely based on actual facts, but rather on opinion. I feel like I didn't word that very well (thanks a lot, red wine...), but it probably makes enough sense to most...
Mixing batteries... Haha... I rarely do "theory". I prefer fact. But it's your money... time will tell
Cheers,
Mattt.
Jaahn said
08:20 AM Feb 12, 2016
Hi Matt,
Interesting ! I could say quite a bit but some of it has been said already and some will be said soon !!So I will just make a couple of general comments in the spirit of being constructive.
There are big plans but perhaps some small steps being made. You must not be seduced by cheap wiring or regulator/controllers unless you are prepared to throw them away soon !! or perhaps use them for other lesser uses. The wiring is not sensitive to ac or dc as said but VOLTAGE DROP and overheating. When you only have 12v you cannot afford to loose a few. Big cross section copper is needed and you should read some of the other posts on here to get the good ideas on wire size. Not just opinions either but real facts are presented and by people who are living with it too. Buy a good multi meter and measure the voltage drop in both wires under maximum use, you will be surprised (or not0 !
The list of 240V items is unrealistic. The power required to run some of them is large for each and together would require a large solar/battery home setup that is not achieable in a mobile home IMHO. Some priority is needed here, certainly in the medium term. Using invertors for the 240V is also a source of problems in the losses and voltage drops and the sheer size of wiring to get them to run properly. Not to mention the battery capacity needed. I would say that your disapointment with your current invertors is probably due to voltage loss to their input terminals when using them.
For now good luck, Jaahn
Brenda and Alan said
08:30 AM Feb 12, 2016
Matt I'll post the power usage figures for you tonight. My thoughts on your computer would be to swap the desktop PC for a similar spec laptop and a second battery to get you through the hours of darkness then charge during the day.
Alan
Nomad_Nev said
09:13 AM Feb 12, 2016
Hey Mattt
My wife and i with the 1 year old have been on the road for coming up on 3 months full time now with most of it free camping, I am also in IT so have spent a lot of time looking at the power stuation to be able to run all our stuff.
My biggest concern to date has been batteries, fistly how many Amp Hours they hold, what i draw, how long i can go on pure batteries, then how to re-fill them.
We have 2x deep cycle batteries, a 100amp and a 135 amp, giving us 235 total, you shouldnt run them below 25% odd percent so call it 175 Amps usable.
The 40L 12v fridge, dimmable LED strip lights x5 (Put em togehter myself), recharging of all the various tech, water pump... etc, takes about 25 Amp hours a day out of the batteries, and an occationally used 300w inverter for charging the stuff that cant go on 12v. (Excluding laptop - more on this in a bit)
Sooooo, 7 days on batteries
200 watt solar panels with a 20amp reg can put about 70 Amp hours back into the batteries on a great full day in the sun, so nearly 3 days back in for each day sun.
I have a i7 Quad core, 17 inch laptop, with a 70watt 12v charger, and it consumes way too much power, nearly 6 amps, so 10 hours use of the laptop will eat 60 amp hours out of hte battery, add the days use of 25 amps and we talking 85 amps for the day, completly unsustainable.
The 12v charger also fails when the voltage on the batteries is below half due to the battery voltage drop and the loss through the camper wiring to where i plug in, if i connect diretly to the batteries i can run for longer, but eventually the battery voltage gets a bit low and the charger freaks out.
Short answer we are looking into a small generator, having a good look at the quieter generators, as well als looking into a lower spec laptop that wont eat as much power.
-- Edited by Nomad_Nev on Friday 12th of February 2016 09:32:07 AM
Mattt said
11:01 AM Feb 12, 2016
Hi Jaahn,
Haha - funny how everyone wants to tell me that the battery setup will kill kittens on a good day, but aren't quite certain enough to actually pull the trigger :p At the end of the day, let's just say that I wasn't always a software developer
Of course, you're right about (some of) the wiring and the regulator - they're merely stepping stones. The wiring (240v extensions) will be refactored later for reaching 240v sources when needed (hopefully never, all going to plan). The regulator will wind up being gifted to someone else who's starting their own build in due course. It's cheap, almost nasty crap.
As said in the blog, I have measured the drops (one doesn't need a "good" MM - just a digital one) - my office continues to supply under 11v which has thus far precluded me from running a 12v laptop adapter which I'm keen to introduce into the system. Problem is (expressed as a real life scenario for clarity) the 5m of cable between the panel and the regulator cost $40. I need about 15m to get to my office. That makes for $120 worth o' 6mm cable, and 6mm isn't good enough for that run. As this office is temporary (would love to think I won't be working here before 2017), I'm not prepared to trivially drop that kinda cash on it yet.
The "list of 240v items" consists of two things which are non-negotiably (I think I just invented another word :p) 240v - the fridge and the aircon. Of course, a few other items on the list won't be able to be converted in any justifiable way, but they're either sparsely run, low wattage, or both. Oh, and there's the coffee machine but that's somewhat temporary in the scheme of things (the greener we get, the more I think about the pods...). At any rate, you'd be better off trying to warn the folk who are already successfully running domestic (240v) fridges and aircons on their 12v, off-grid systems. And perhaps the multitudes who run entire 240v households from off-grid and grid-tied systems (although most of those are 48v native, which is admittedly a slightly different ball game). For the record, they work (through their usually 3-5kw inverters) because the inverter is usually installed less than a metre from the storage, and their 220-250v (in AU) output is happy(ish) to travel over longer runs of "thinner" cable to get where it needs to go. That's one of the intrinsic premises of the commercial power grids - thousands of volts over vast runs to localised distribution hubs, then down to 110/240v for local distribution. Seems to work okay
I would say that my disappointment with our current inverters is because they are cheap crap. Of course, I've run them straight from the battery bank (okay... so some 20mm of (decent) cabling from them...). They simply don't work as advertised (haha - surprise, surprise).
Cheers,
Mattt.
Mattt said
11:04 AM Feb 12, 2016
Hi again Alan,
Thanks mate - that'll be muchly appreciated
I'll address the PC stuff in my next reply to Nev...
Cheers,
Mattt.
Mattt said
11:35 AM Feb 12, 2016
Hey Nev,
Firstly, thanks for actually managing to make me jealous :p I sometimes think I'm not gonna be able to sustain the wait between now and having been out there for 12 weeks. I don't think I've ever wanted anything so badly (although admittedly probably already have just about everything else I've ever really wanted (in realistic terms), so my gauge on this one might not be terribly accurate). I'm working my ass off for a "drive off" date sometime in 2016...
Yeah, we definitely need a decent monitoring / measuring system. I've thus far held off because I'm starting to develop a plan for building all the "smarts" myself - likely based on an Arduino platform. I wouldn't be the first person to design and build an MPPT regulator from the platform
Mate, are you *really* tapping your batteries to that depth? I totally understand the sometimes large deficit between needs / wants and resources, but you seriously need to grow your storage bank to the point where you're only skimming, say, around 25% of their rated capacity. Otherwise, you'll potentially go somewhat hungry while shopping (repeatedly) for replacement batteries. And don't forget that, should just one battery in a bank suffer a serious failure and go unnoticed for *any* length of time, it'll murder it's kin. Given your current setup, that's a minimum of $500 per replacement...
I hear what you (and others) are saying about the workstaion / PC, but I'm afraid that's not negotiable for me. I may very well not even be able to forego the dual display setup (in fact, I'm almost constantly running the laptop as a "third display" of sorts and am kinda thinking about either larger displays or adding a third...
On the upside, the new Skylake platform is the most energy efficient to date. And I guess I could take the add-on video card out of the equation in favour of the discrete Intel video (which can apparently run three displays, but I'm unsure of the performance), and maybe also the audio card - it was primarily installed for recording muso's, but I rarely do that these days. On the other hand, I'm quite the audiophile and would likely hear the difference in the onboard audio system. Oh - and my RAM usage *never* goes over 30% of the 16gb installed, so maybe it's prudent to pull half of it, although that'll be a bugger as I don't think the board can do dual channel with a single module :-/
Obviously, I'll need to measure the thing's appetite in due course and formulate a plan based on the results. There are certainly plenty of 12v-input power supplies available, or I could of course just build my own. Internally, there are only three power rails anyways and the largest is 12v...
Cheers,
Mattt.
oldtrack123 said
11:53 AM Feb 12, 2016
HI
Without getting into a long discussion on voltage drop ,AC & DC, Domestic OFF grid systems etc
Although not really sure why you are posting since you seem to believe you know all the answers
Some points about cables used in TRANSPORTABLE Structures.
The normal 240V cables are not considered flexible enough to withstand vibration & movement & the Standards require they SHALL be multi strand, as defined in the relevant Standards, not just 3<7strand
All the 240V SHALL comply to relevant Aus Standards!
The same applies to EXTRA low voltage DC, although not covered by any standards, best practice again is to use real multi strand cable i.e Auto cable!!
Of course all voltage drop calcs should be based on cable cross sectional area, bearing in mind most 12V equipment requires 12V Min for effective operation!
Most designed for Automotive use can stand up to 15V
.
Mattt said
12:53 PM Feb 12, 2016
G'day,
Haha - if I had anywhere near even *half* of the answers, I'd not be chained to my desk on this glorious day in one of our many versions of paradise
But the reason I'm posting is deviously hidden in the third sentence of my first post - "I've just managed to find some time to document what we have so far, and thought I'd give a little back to the community by way of sharing it.".
Firstly, as I've repeatedly stated, the 240v-rated cable runs currently in use in our build are TEMPORARY. They are not permanent. They are not part of the final design (other than to perhaps source 240v feeds for recharging purposes in the likely case that I don't, after all, have "all the answers"). With that said, I must say it's been interesting to measure and observe the characteristics of said cabling being used "out of spec". But then, I'm a tragic geek :p
Unfortunately, you didn't specify what a "normal" 240v cable actually is. The stuff I'm (currently, temporarily, non-permanently, not married to, etc) running is very flexible multi-core. I haven't measured how many strands or any dimensional data because I simply don't care. Clearly, it's not up to the task - and yet it's done the job very nicely for us for a few weeks now. And it was dirt cheap. And it was already here, unused.
You also failed to mention what "auto cable" is, which would have been somewhat important given that there's no such specific thing.
Any device designed for use in the kind of system we're discussing *needs* to be able to handle up to somewhere around 15v, as that kinda voltage (well, over 14v) is regularly fed to them (notwithstanding voltage drops) while charging. Most such devices can also handle down to 10-11v for similar (although inverse) reasons. In fact, *everything* in my office has been running faultlessly at under 11v (under nominal load), with the sole exception of a ~12v input / 15-24v output laptop inverter I have which demands a minimum of 11v in...
Cheers,
Mattt.
madaboutled said
01:09 PM Feb 12, 2016
Hey Matt,
Appoligies for trying to help..... won't happen again!.
Steve.
Jaahn said
01:26 PM Feb 12, 2016
madaboutled wrote:
Hey Matt,
Appoligies for trying to help..... won't happen again!.
Steve.
Hmmm yes gives that sort of feel !
A comment to finish on. "one doesn't need a "good" MM - just a digital one" ?? but cheap multimeters are like " our current inverters because they are cheap crap. .... They simply don't work as advertised (haha - surprise, surprise)". Just a pointer from me generally!
I wish you luck
Jaahn
-- Edited by Jaahn on Friday 12th of February 2016 01:26:54 PM
Mattt said
01:27 PM Feb 12, 2016
Steve,
Ouch - you've clearly read me in a way I absolutely did not intend to come across...
Like most others (I'd guess), I'm here primarily to soak up as much good quality info as I possibly can. Secondarily, some like-minded conversation is rarely a bad thing. And bonus points for the possibility of meeting some decent folk
I work in an industry where there are many self-proclaimed "experts" who "shoot from the hip". While I'm more than just a little happy to share my (extremely) hard-earned knowledge in my areas of expertise / interest, I don't have a lot of time to sugar coat stuff or beat around the bush. As such, I guess I regularly come across as being fairly blunt. And often arrogant. I humbly and thoroughly apologise if that's anything like the impression I've given you. I'm truly here to share (which is very much a two-way street by it's very nature).
The thing here for me / us is that, while I have perhaps oodles of knowledge about these types of system, I have zero practical experience in building or using them. You, on the other hand, are apparently living with and relying on it. That kind of real-life knowledge is priceless.
Again, I'm very sorry if I've offended you (or anyone else here). Happy to owe you a beer in return any time we're in the same area
Cheers,
Mattt.
Mattt said
01:31 PM Feb 12, 2016
Jaahn,
For brevity, please see my reply to Steve moments ago
I absolutely see (and fundamentally agree with) your point about the DMM. I guess I'm working on the assumption that even the cheapest of them shouldn't have any real dramas accurately reporting something as simple as <15v to just a couple of decimal places.
I do miss my trusty Fluke, but the ^*($%$@ who nicked it probably doesn't
240V TPS Cable for general house wiring normally has only 7 strands.
Mattt said
01:38 PM Feb 12, 2016
Hey Troopy,
Thanks mate - I never was a 240v / AC guy...
Is my thinking that maybe running dual cables (I have other unused 240v extension cables in the garage / workshop) and thus doubling the number of strands (speaking ideally, of course) back to my office would vastly improve the voltage drop situation I'm currently seeing?
Cheers,
Mattt.
03_Troopy said
02:11 PM Feb 12, 2016
MatttAndDee wrote:
Hey Troopy,
Thanks mate - I never was a 240v / AC guy...
Is my thinking that maybe running dual cables (I have other unused 240v extension cables in the garage / workshop) and thus doubling the number of strands (speaking ideally, of course) back to my office would vastly improve the voltage drop situation I'm currently seeing?
Cheers,
Mattt.
Hi Matt, the big difference is flexibility. 240V domestic house cable (7 strand type) is meant to be fixed installed and not moved or be exposed to vibration. Auto cable, on the other hand is meant to be flexible and be able to withstand vibrations, and is made up of many more strands of finer wire, which is what Oldtrack123 was pointing out. 240V extension cables are much more flexible and again have a higher strand count than the "normal house wire" and may suffice providing the current isn't so high and the run not too long. When calculating cable run, you need to take into consideration the return path. ie a 5M run will have 5M pos, and 5M neg return, so overall circuit length is 10M.
Yes doubling up on the wiring will effectively double the cross sectional area, but it can get messy.
Extension leads:
10A lead - 1.0mm˛ conductors - voltage drop over 10M at 12.5VDC @ 5A = 886mV or 7.1% ie too high
10A or 15A lead - 1.5mm˛ conductors - voltage drop over 10M at 12.5VDC @ 5A = 590mV or 4.7% ie too high
15A lead - 2.5mm˛ conductors - voltage drop over 10M at 12.5VDC @ 5A = 354mV or 2.8% just scrapes in
The problem though, is knowing the conductor size in the cable. Heavy Duty 15A cable usually refers to the cable having heavy duty insulation, and not the larger 2.5mm˛ conductor size.
Edit: sorry I referred to the wrong person above. now corrected. My apologies Oldtrack123.
-- Edited by 03_Troopy on Friday 12th of February 2016 02:59:52 PM
Mattt said
03:24 PM Feb 12, 2016
Troopy,
Very, very cool stuff (copied and pasted into the relevaant e-note) - many thanks
Will introduce another 240v extension cable when I can find the time (haha - now it's playing on my mind, I bet I find the time sometime today / tonight :p). Hopefully, that'll see me through the next little while until I loosen the requisite orifice and ante up for some appropriate cable. Of course, I'll be able to re-use it in the bus later, so it's not like it's money wasted - just that there are several better things to spend it on presently (like a decent controller / regulator).
Cheers,
Mattt.
Nomad_Nev said
05:46 PM Feb 12, 2016
Yep i hear you on the discharge cycle of the batteries, normaly we try to keep them topped up but sometimes the weather and shopping requirements combine to mean we can get the panels out without the batteries getting low.
I have to say, keeping the power levels up is not as easy as you would think.
I gave the car a go for charging the batteries, but the car i have automatically changes the alternator power as it sees fit, bottom line it would take a lot of petrol for the car to make a dent.
I think the only real solution is to have a generator, we will use solar most of the time and when we are camped in the shade or the weather doesnt play a long, let the generator run for a few hours every second or third day to top up the batteries.
A 1000kva 60db generator will comefortably power a 30Amp charger,(using about 400 of the 1000 watts) so 90 amp hours into the batteries in 3 hours, with leftover power to charge stuff and run 240v stuff at the same time.
I hear you on the requirements, i just dont see how you will get enough amps a day back into the batteries, your setup will eat through them i suspect, in terms of cost per amp i think a generator will be a lot more cost effective than using the bus to recharge
I have done a fair bit of playing with Arduino's, mainly around distance measurement using infra red, sound, lazer etc. they are good fun.
Brenda and Alan said
07:46 PM Feb 12, 2016
Matt here is the current draw list for the gear in our van but as we run LiFePo4 batteries do the arithmetic using 13V not 12V. This may be of some use in your planning even though you will have your own power use priorities. I suggest you look at the posts by "Plendo" concerning his power set up as he planned to use lots of 240V stuff of his system.
Alan
3way fridge on 12v heating element RM2350 13 A
Waeco 35Lt fridge /freezer as a freezer 3.6A
LED replacements for 10Watt QI reading lights 0.19A
original 12v flouro lights 0.70A
range hood light 1.7A (car indicator globe -- rarely used)
range hood fan 0.6A
shower/toilet fan 1.7A
water pump (Shurflo) with one tap open 4.9A
Sony car radio playing MP3 0.8A
TV on standby 0.5A
TV only on 2.0A Varies a little around this figure
TV playing DVD 3.8A as above
VAST decoder on standby 0.5A ( omited to measure running)
Diesel heater fan speed 1 0.84A
Diesel heater fan speed 2 1.1A
Diesel heater fan speed 3 1.8A
Diesel heater fan speed 4 (full) 2.6A
1000W PSW inverter on standby 0.6A
running twin electric blankets on 1 3.1A
running twin electric blankets on 2 4.9A
running twin electric blankets on 3 9.5A
running ASUS laptop 2.5-4.0A (depends on state of charge of battery)
03_Troopy said
08:01 AM Feb 13, 2016
Hi Alan, your Sony stereo draw seems conservative. You must be playing quite softly with only 2 speakers. I have blown 5A fuses while testing Kenwood, which is a mechless MP3 player and radio, when I fitted it. But I tested it with AC DC and 4 speakers turned up about midway. The greater the volume and number of speakers, will mean a higher current draw. Your Sony most likely has a 10A fuse fitted in the back of it, so I'd expect it would easily draw 5A in similar situations to mine.
Nomad_Nev said
09:14 AM Feb 13, 2016
Nice breakdown thanks Alan,
Interesting figures on the inverter and electric blankets, I figure we will be lookinginto them come winter so it is good to be able to figure the numbers in
oldtrack123 said
02:40 PM Feb 13, 2016
MatttAndDee wrote:
Troopy,
Very, very cool stuff (copied and pasted into the relevaant e-note) - many thanks
Will introduce another 240v extension cable when I can find the time (haha - now it's playing on my mind, I bet I find the time sometime today / tonight :p). Hopefully, that'll see me through the next little while until I loosen the requisite orifice and ante up for some appropriate cable. Of course, I'll be able to re-use it in the bus later, so it's not like it's money wasted - just that there are several better things to spend it on presently (like a decent controller / regulator).
Cheers,
Mattt.
Just another point when paralleling cables , it is essential that the resistance of each leg is the same including all connections ,If the combined cables are being used near their MAX combined current rating
.Also be aware that normal 'extension' lead cable is not acceptable for FIXED 240V wiring
Such use does not comply to Aus Standards.
Aus-Kiwi said
11:10 PM Feb 14, 2016
One has to wander how 240v copes in this situation being single or 7 strand ? If it's saddled or in conduit the flex is minimal .. Yet 12v a "safe" voltage is multi strand .. Funny thing is service wires are 7 strand, hard drawn and they blow around in the wind all day .. Ahhh elect. Rules ..
Hey all,
Been a while since I've posted anything, but I've been lurking and learning the whole while
Anyways, we've started our power system build so it's ready by the time we "hit the road". I've just managed to find some time to document what we have so far, and thought I'd give a little back to the community by way of sharing it.
http://dm-touring.com/let-there-be-light - have an appropriate amount of fun
Cheers,
Mattt (and Dee).
Hey Matt, from what I read you're way too light on battery & solar with everything you intend running. Look at everything you have and try to run as much as possible direct from 12v. I understand using the PC over a laptop, but have a look at the PC's power supply you'll probably find it's 240v AC down to 12v DC, so you might be able to make (or have made) an adapter to run it direct from 12v. Yeh get a bigger LED Screen although going back to one screen takes some getting used to (ex graphic artist).
You can get 12v chargers & power supplies for any portable device like laptops & phones etc... far better direct on the batteries running 12 volt upto 19-22v than 12v upto 240v AC then back down to 19-22v DC.
Have a look at Bitdeals for their Pure Sine Wave Inverters, I have a 1500w/3000w Peak inverter that we use from time to time and has been great. Just remember Inverters should be used for emergency only cause they'll drain a battery bank in no time flat!. In 12 months I probably used my inverter less than 4 times and for no longer than 20 minutes each time.
The wires coming from your solar controller look pretty light to me, and the solar controller..... I've seen a few similar to that used as a boomerang (um... stick! cause when thrown, they didn't come back). A good controller will have an LED readout showing you some helpful readings with out the need of relying on a multimeter. Mine records Amps into the batteries over 3 days which is handy cause I've got a fair idea what my daily usage is. The heart of your solar system is the controller, so best to have a really good one. The trick is getting one that's a true MPPT controller, some say they are but they're not.
Using 240v cable for 12v is not good no matter how you want to sugar coat it, 240 volt cable is designed for Alternating current (AC). Voltage drop in a DC system can only be overcome by using the correct thickness of DC cable allowing for distance & power and going thicker than the recommended is better again. Mixing Batteries.... Sorry I don't agree with your theory, but it's your money... time will tell.
Anyway good luck on your travels.
Steve.
-- Edited by madaboutled on Thursday 11th of February 2016 10:40:27 PM
Hey Alan,
Yeah, my main workstation PC is definitely the biggest concern - partly because it's absolutely central to my ( / our) living, and partly because it's gonna be a major power chewer which needs to run for big hours. I'm afraid I have no "real life" figures to provide in terms of what kinda power it uses. The best I have is that it currently has a decent quality 550w (240v, obviously) power supply which has never had any issues. I'm looking for reliable (and easy
I think that the PC, aircon and fridge will be the major concerns.
The ultimate goal (in this instance, by "ultimate" I mean "soon") is to go lithium for storage. I just needed to make a start and be able to afford / justify the initial spend. So AGM it is for now...
I'd love and appreciate to hear your real-life stats - the more data we have to work with, the less wasted money and dramas we'll need to deal with
Cheers,
Mattt.
Hey Steve,
I'll say from the get-go that you obviously didn't read all (or much) of my page - for which I don't blame you a bit. It turned out to be quite a novel...
Anyways, let's go at it in order of your thoughts
No, we have nowhere near enough input or storage. I'm thinking we'll need (at best) 5 x what we have now. And yes - the idea is to run everything we can on "12v native". As you mentioned, it's the most efficient way to go. You're also right about the PC P/S stepping everything down to 12v (there's also a 5v rail). PC power supplies are readily available which take 12v input, but I think I might be better off designing and knocking up something to suit my specific needs. I'll need to take a bunch of measurements and some more research to ascertain whether I need to refactor the displays (I'm also looking at physical space, of course).
Obviously, we're aiming for as close to "native 12v" as possible. I guess you also missed from my writing (haha - or maybe ranting...) that this is the path we're taking
I'm assuming that the "wires coming from your solar controller" you refer to are the ones coming out of the unit itself. The "controller" is rated for 20a, and those interconnect cables look good for at least 25a. We're not intending to push more than about 15a through it (we're not using it's load / output side), so no issues there.
You said "The heart of your solar system is the controller, so best to have a really good one" - you're absolutely right if you need to rely on it because you don't know how to manage the system yourself. Unfortunately, it's difficult to be certain that the "controller" you choose is really any good at all. Most are not. And you're again right that a lot of the "controllers" claim to be MPPT when they're absolutely not.
I meant for my writings to imply that using 240v cabling for longer-length interconnects was absolutely insufficient for 12v systems. I just needed to save some $$$. Thus far, it's all been (almost completely) good. By the way, though, it's got little to do with the difference between AC and DC current profiles - it's more to do with the fact that lower voltages don't travel as well over longer distances via thinner cables. You also said "going thicker than the recommended is better again". You're wrong on two different levels - you don't need to go thicker than actual spec, and "recommendations" are rarely based on actual facts, but rather on opinion. I feel like I didn't word that very well (thanks a lot, red wine...), but it probably makes enough sense to most...
Mixing batteries... Haha... I rarely do "theory". I prefer fact. But it's your money... time will tell
Cheers,
Mattt.
Hi Matt,
Interesting ! I could say quite a bit but some of it has been said already and some will be said soon !!So I will just make a couple of general comments in the spirit of being constructive.
There are big plans but perhaps some small steps being made. You must not be seduced by cheap wiring or regulator/controllers unless you are prepared to throw them away soon !! or perhaps use them for other lesser uses. The wiring is not sensitive to ac or dc as said but VOLTAGE DROP and overheating. When you only have 12v you cannot afford to loose a few. Big cross section copper is needed and you should read some of the other posts on here to get the good ideas on wire size. Not just opinions either but real facts are presented and by people who are living with it too.
Buy a good multi meter and measure the voltage drop in both wires under maximum use, you will be surprised (or not0 !
The list of 240V items is unrealistic. The power required to run some of them is large for each and together would require a large solar/battery home setup that is not achieable in a mobile home IMHO. Some priority is needed here, certainly in the medium term. Using invertors for the 240V is also a source of problems in the losses and voltage drops and the sheer size of wiring to get them to run properly. Not to mention the battery capacity needed. I would say that your disapointment with your current invertors is probably due to voltage loss to their input terminals when using them.
For now good luck, Jaahn
Matt I'll post the power usage figures for you tonight. My thoughts on your computer would be to swap the desktop PC for a similar spec laptop and a second battery to get you through the hours of darkness then charge during the day.
Alan
Hey Mattt
My wife and i with the 1 year old have been on the road for coming up on 3 months full time now with most of it free camping, I am also in IT so have spent a lot of time looking at the power stuation to be able to run all our stuff.
My biggest concern to date has been batteries, fistly how many Amp Hours they hold, what i draw, how long i can go on pure batteries, then how to re-fill them.
First up, get yourself a "Watt Meter" off ebay, you can wire it in and see exactly how many amps each 12v item is pulling, then you can get a much more accurate number for sizing, this is a temp checker item, dont wire it in permanently,
www.ebay.com/itm/Digital-60V-100A-Battery-Power-Analyzer-Watt-Meter-Balancer-For-DC-RC-Helicopter-/321890071368
For a more permanenet solution get yourself a Amp Meter, with a shunt, that can be wired in permanently to give you a current amps draw for when you on the road.
www.ebay.com/itm/200V-100A-DC-Digital-Voltmeter-Ammeter-LED-Amp-Volt-Meter-Current-Shunt-/310995957137
We have 2x deep cycle batteries, a 100amp and a 135 amp, giving us 235 total, you shouldnt run them below 25% odd percent so call it 175 Amps usable.
The 40L 12v fridge, dimmable LED strip lights x5 (Put em togehter myself), recharging of all the various tech, water pump... etc, takes about 25 Amp hours a day out of the batteries, and an occationally used 300w inverter for charging the stuff that cant go on 12v. (Excluding laptop - more on this in a bit)
Sooooo, 7 days on batteries
200 watt solar panels with a 20amp reg can put about 70 Amp hours back into the batteries on a great full day in the sun, so nearly 3 days back in for each day sun.
I have a i7 Quad core, 17 inch laptop, with a 70watt 12v charger, and it consumes way too much power, nearly 6 amps, so 10 hours use of the laptop will eat 60 amp hours out of hte battery, add the days use of 25 amps and we talking 85 amps for the day, completly unsustainable.
The 12v charger also fails when the voltage on the batteries is below half due to the battery voltage drop and the loss through the camper wiring to where i plug in, if i connect diretly to the batteries i can run for longer, but eventually the battery voltage gets a bit low and the charger freaks out.
Short answer we are looking into a small generator, having a good look at the quieter generators, as well als looking into a lower spec laptop that wont eat as much power.
-- Edited by Nomad_Nev on Friday 12th of February 2016 09:32:07 AM
Hi Jaahn,
Haha - funny how everyone wants to tell me that the battery setup will kill kittens on a good day, but aren't quite certain enough to actually pull the trigger :p At the end of the day, let's just say that I wasn't always a software developer
Of course, you're right about (some of) the wiring and the regulator - they're merely stepping stones. The wiring (240v extensions) will be refactored later for reaching 240v sources when needed (hopefully never, all going to plan). The regulator will wind up being gifted to someone else who's starting their own build in due course. It's cheap, almost nasty crap.
As said in the blog, I have measured the drops (one doesn't need a "good" MM - just a digital one) - my office continues to supply under 11v which has thus far precluded me from running a 12v laptop adapter which I'm keen to introduce into the system. Problem is (expressed as a real life scenario for clarity) the 5m of cable between the panel and the regulator cost $40. I need about 15m to get to my office. That makes for $120 worth o' 6mm cable, and 6mm isn't good enough for that run. As this office is temporary (would love to think I won't be working here before 2017), I'm not prepared to trivially drop that kinda cash on it yet.
The "list of 240v items" consists of two things which are non-negotiably (I think I just invented another word :p) 240v - the fridge and the aircon. Of course, a few other items on the list won't be able to be converted in any justifiable way, but they're either sparsely run, low wattage, or both. Oh, and there's the coffee machine but that's somewhat temporary in the scheme of things (the greener we get, the more I think about the pods...). At any rate, you'd be better off trying to warn the folk who are already successfully running domestic (240v) fridges and aircons on their 12v, off-grid systems. And perhaps the multitudes who run entire 240v households from off-grid and grid-tied systems (although most of those are 48v native, which is admittedly a slightly different ball game). For the record, they work (through their usually 3-5kw inverters) because the inverter is usually installed less than a metre from the storage, and their 220-250v (in AU) output is happy(ish) to travel over longer runs of "thinner" cable to get where it needs to go. That's one of the intrinsic premises of the commercial power grids - thousands of volts over vast runs to localised distribution hubs, then down to 110/240v for local distribution. Seems to work okay
I would say that my disappointment with our current inverters is because they are cheap crap. Of course, I've run them straight from the battery bank (okay... so some 20mm of (decent) cabling from them...). They simply don't work as advertised (haha - surprise, surprise).
Cheers,
Mattt.
Hi again Alan,
Thanks mate - that'll be muchly appreciated
I'll address the PC stuff in my next reply to Nev...
Cheers,
Mattt.
Hey Nev,
Firstly, thanks for actually managing to make me jealous :p I sometimes think I'm not gonna be able to sustain the wait between now and having been out there for 12 weeks. I don't think I've ever wanted anything so badly (although admittedly probably already have just about everything else I've ever really wanted (in realistic terms), so my gauge on this one might not be terribly accurate). I'm working my ass off for a "drive off" date sometime in 2016...
Yeah, we definitely need a decent monitoring / measuring system. I've thus far held off because I'm starting to develop a plan for building all the "smarts" myself - likely based on an Arduino platform. I wouldn't be the first person to design and build an MPPT regulator from the platform
Mate, are you *really* tapping your batteries to that depth? I totally understand the sometimes large deficit between needs / wants and resources, but you seriously need to grow your storage bank to the point where you're only skimming, say, around 25% of their rated capacity. Otherwise, you'll potentially go somewhat hungry while shopping (repeatedly) for replacement batteries. And don't forget that, should just one battery in a bank suffer a serious failure and go unnoticed for *any* length of time, it'll murder it's kin. Given your current setup, that's a minimum of $500 per replacement...
I hear what you (and others) are saying about the workstaion / PC, but I'm afraid that's not negotiable for me. I may very well not even be able to forego the dual display setup (in fact, I'm almost constantly running the laptop as a "third display" of sorts and am kinda thinking about either larger displays or adding a third...
On the upside, the new Skylake platform is the most energy efficient to date. And I guess I could take the add-on video card out of the equation in favour of the discrete Intel video (which can apparently run three displays, but I'm unsure of the performance), and maybe also the audio card - it was primarily installed for recording muso's, but I rarely do that these days. On the other hand, I'm quite the audiophile and would likely hear the difference in the onboard audio system. Oh - and my RAM usage *never* goes over 30% of the 16gb installed, so maybe it's prudent to pull half of it, although that'll be a bugger as I don't think the board can do dual channel with a single module :-/
Obviously, I'll need to measure the thing's appetite in due course and formulate a plan based on the results. There are certainly plenty of 12v-input power supplies available, or I could of course just build my own. Internally, there are only three power rails anyways and the largest is 12v...
Cheers,
Mattt.
HI
Without getting into a long discussion on voltage drop ,AC & DC, Domestic OFF grid systems etc
Although not really sure why you are posting since you seem to believe you know all the answers
Some points about cables used in TRANSPORTABLE Structures.
The normal 240V cables are not considered flexible enough to withstand vibration & movement & the Standards require they SHALL be multi strand, as defined in the relevant Standards, not just 3<7strand
All the 240V SHALL comply to relevant Aus Standards!
The same applies to EXTRA low voltage DC, although not covered by any standards, best practice again is to use real multi strand cable i.e Auto cable!!
Of course all voltage drop calcs should be based on cable cross sectional area, bearing in mind most 12V equipment requires 12V Min for effective operation!
Most designed for Automotive use can stand up to 15V
.
G'day,
Haha - if I had anywhere near even *half* of the answers, I'd not be chained to my desk on this glorious day in one of our many versions of paradise
But the reason I'm posting is deviously hidden in the third sentence of my first post - "I've just managed to find some time to document what we have so far, and thought I'd give a little back to the community by way of sharing it.".
Firstly, as I've repeatedly stated, the 240v-rated cable runs currently in use in our build are TEMPORARY. They are not permanent. They are not part of the final design (other than to perhaps source 240v feeds for recharging purposes in the likely case that I don't, after all, have "all the answers"). With that said, I must say it's been interesting to measure and observe the characteristics of said cabling being used "out of spec". But then, I'm a tragic geek :p
Unfortunately, you didn't specify what a "normal" 240v cable actually is. The stuff I'm (currently, temporarily, non-permanently, not married to, etc) running is very flexible multi-core. I haven't measured how many strands or any dimensional data because I simply don't care. Clearly, it's not up to the task - and yet it's done the job very nicely for us for a few weeks now. And it was dirt cheap. And it was already here, unused.
You also failed to mention what "auto cable" is, which would have been somewhat important given that there's no such specific thing.
Any device designed for use in the kind of system we're discussing *needs* to be able to handle up to somewhere around 15v, as that kinda voltage (well, over 14v) is regularly fed to them (notwithstanding voltage drops) while charging. Most such devices can also handle down to 10-11v for similar (although inverse) reasons. In fact, *everything* in my office has been running faultlessly at under 11v (under nominal load), with the sole exception of a ~12v input / 15-24v output laptop inverter I have which demands a minimum of 11v in...
Cheers,
Mattt.
Hey Matt,
Appoligies for trying to help..... won't happen again!.
Steve.
Hmmm
yes gives that sort of feel !
A comment to finish on. "one doesn't need a "good" MM - just a digital one" ?? but cheap multimeters are like " our current inverters because they are cheap crap. .... They simply don't work as advertised (haha - surprise, surprise)". Just a pointer from me generally!
I wish you luck
Jaahn
-- Edited by Jaahn on Friday 12th of February 2016 01:26:54 PM
Steve,
Ouch - you've clearly read me in a way I absolutely did not intend to come across...
Like most others (I'd guess), I'm here primarily to soak up as much good quality info as I possibly can. Secondarily, some like-minded conversation is rarely a bad thing. And bonus points for the possibility of meeting some decent folk
I work in an industry where there are many self-proclaimed "experts" who "shoot from the hip". While I'm more than just a little happy to share my (extremely) hard-earned knowledge in my areas of expertise / interest, I don't have a lot of time to sugar coat stuff or beat around the bush. As such, I guess I regularly come across as being fairly blunt. And often arrogant. I humbly and thoroughly apologise if that's anything like the impression I've given you. I'm truly here to share (which is very much a two-way street by it's very nature).
The thing here for me / us is that, while I have perhaps oodles of knowledge about these types of system, I have zero practical experience in building or using them. You, on the other hand, are apparently living with and relying on it. That kind of real-life knowledge is priceless.
Again, I'm very sorry if I've offended you (or anyone else here). Happy to owe you a beer in return any time we're in the same area
Cheers,
Mattt.
Jaahn,
For brevity, please see my reply to Steve moments ago
I absolutely see (and fundamentally agree with) your point about the DMM. I guess I'm working on the assumption that even the cheapest of them shouldn't have any real dramas accurately reporting something as simple as <15v to just a couple of decimal places.
I do miss my trusty Fluke, but the ^*($%$@ who nicked it probably doesn't
Cheers,
Mattt.
Automotive Cable
240V TPS Cable for general house wiring normally has only 7 strands.
Hey Troopy,
Thanks mate - I never was a 240v / AC guy...
Is my thinking that maybe running dual cables (I have other unused 240v extension cables in the garage / workshop) and thus doubling the number of strands (speaking ideally, of course) back to my office would vastly improve the voltage drop situation I'm currently seeing?
Cheers,
Mattt.
Hi Matt, the big difference is flexibility. 240V domestic house cable (7 strand type) is meant to be fixed installed and not moved or be exposed to vibration. Auto cable, on the other hand is meant to be flexible and be able to withstand vibrations, and is made up of many more strands of finer wire, which is what Oldtrack123 was pointing out. 240V extension cables are much more flexible and again have a higher strand count than the "normal house wire" and may suffice providing the current isn't so high and the run not too long. When calculating cable run, you need to take into consideration the return path. ie a 5M run will have 5M pos, and 5M neg return, so overall circuit length is 10M.
Yes doubling up on the wiring will effectively double the cross sectional area, but it can get messy.
Extension leads:
10A lead - 1.0mm˛ conductors - voltage drop over 10M at 12.5VDC @ 5A = 886mV or 7.1% ie too high
10A or 15A lead - 1.5mm˛ conductors - voltage drop over 10M at 12.5VDC @ 5A = 590mV or 4.7% ie too high
15A lead - 2.5mm˛ conductors - voltage drop over 10M at 12.5VDC @ 5A = 354mV or 2.8% just scrapes in
The problem though, is knowing the conductor size in the cable. Heavy Duty 15A cable usually refers to the cable having heavy duty insulation, and not the larger 2.5mm˛ conductor size.
Edit: sorry I referred to the wrong person above. now corrected. My apologies Oldtrack123.
-- Edited by 03_Troopy on Friday 12th of February 2016 02:59:52 PM
Troopy,
Very, very cool stuff (copied and pasted into the relevaant e-note) - many thanks
Will introduce another 240v extension cable when I can find the time (haha - now it's playing on my mind, I bet I find the time sometime today / tonight :p). Hopefully, that'll see me through the next little while until I loosen the requisite orifice and ante up for some appropriate cable. Of course, I'll be able to re-use it in the bus later, so it's not like it's money wasted - just that there are several better things to spend it on presently (like a decent controller / regulator).
Cheers,
Mattt.
I have to say, keeping the power levels up is not as easy as you would think.
I gave the car a go for charging the batteries, but the car i have automatically changes the alternator power as it sees fit, bottom line it would take a lot of petrol for the car to make a dent.
I think the only real solution is to have a generator, we will use solar most of the time and when we are camped in the shade or the weather doesnt play a long, let the generator run for a few hours every second or third day to top up the batteries.
A 1000kva 60db generator will comefortably power a 30Amp charger,(using about 400 of the 1000 watts) so 90 amp hours into the batteries in 3 hours, with leftover power to charge stuff and run 240v stuff at the same time.
Pay close attention to the noise made by a gennie, if you are in camp grounds peeps get annoyed with noisy stuff running, the one i have planned is from masters:
www.masters.com.au/product/100550974/tpe-1kva-inverter-generator
I hear you on the requirements, i just dont see how you will get enough amps a day back into the batteries, your setup will eat through them i suspect, in terms of cost per amp i think a generator will be a lot more cost effective than using the bus to recharge
I have done a fair bit of playing with Arduino's, mainly around distance measurement using infra red, sound, lazer etc. they are good fun.
Matt here is the current draw list for the gear in our van but as we run LiFePo4 batteries do the arithmetic using 13V not 12V. This may be of some use in your planning even though you will have your own power use priorities. I suggest you look at the posts by "Plendo" concerning his power set up as he planned to use lots of 240V stuff of his system.
Alan
3way fridge on 12v heating element RM2350 13 A
Waeco 35Lt fridge /freezer as a freezer 3.6A
LED replacements for 10Watt QI reading lights 0.19A
original 12v flouro lights 0.70A
range hood light 1.7A (car indicator globe -- rarely used)
range hood fan 0.6A
shower/toilet fan 1.7A
water pump (Shurflo) with one tap open 4.9A
Sony car radio playing MP3 0.8A
TV on standby 0.5A
TV only on 2.0A Varies a little around this figure
TV playing DVD 3.8A as above
VAST decoder on standby 0.5A ( omited to measure running)
Diesel heater fan speed 1 0.84A
Diesel heater fan speed 2 1.1A
Diesel heater fan speed 3 1.8A
Diesel heater fan speed 4 (full) 2.6A
1000W PSW inverter on standby 0.6A
running twin electric blankets on 1 3.1A
running twin electric blankets on 2 4.9A
running twin electric blankets on 3 9.5A
running ASUS laptop 2.5-4.0A (depends on state of charge of battery)
Interesting figures on the inverter and electric blankets, I figure we will be lookinginto them come winter so it is good to be able to figure the numbers in
Just another point when paralleling cables , it is essential that the resistance of each leg is the same including all connections ,If the combined cables are being used near their MAX combined current rating
.Also be aware that normal 'extension' lead cable is not acceptable for FIXED 240V wiring
Such use does not comply to Aus Standards.