12 volt/240 volt inverter?

Santa · Guru

12 volt/240 volt inverter?

valiant81 · Guru

Hi Santa;

I have one of these inverters in my caravan ( 300 Watt model ) and use it just for my Vast satilight box , have used it for just over 12 months and so far so good. A pure sign wave inverter for under $100.00, value for money in my book.

For what you want it for ( charging camera batterys, laptop computer etc ) this size would be all you need.

oldbobsbus · Guru

I have bought a few inverters from Ozplaza and although one of them tossed in the towel they were very good and replaced it once I proved to them it was faulty so Ihave no problem with recommending them as a good ebay seller..

Just be sure to buy a PURE sinewave inverter that is larger than you think you want..

If you think you need the 300w inverter I recommend you buy this one..

www.ebay.com.au/itm/Pure-Sine-Wave-Power-Inverter-600w-1200w-12v-240v-/260901149832

it will do your job with ease and it is very little more for double the power..

I have this one for sale at the moment but it is most likely bigger than you need..

www.ebay.com.au/itm/331048634863

johnnz · Senior Member

I agree with buying a larger capacity inverter, just bear in mind that whilst working an inverter uses power. An electrician explained to me that an inverter draws about .1 of an amp for every 100watts size so a 1200 watt inverter draws about 1.2 amps.

John

oldbobsbus · Guru

johnnz wrote:
I agree with buying a larger capacity inverter, just bear in mind that whilst working an inverter uses power. An electrician explained to me that an inverter draws about .1 of an amp for every 100watts size so a 1200 watt inverter draws about 1.2 amps.
John

As a rule of thumb thats a good way of looking at it John,

The ones above use a little less that but they still use power at idle, if I'm not using my inverter I just turn it off and allow the solar panels to fully charge the batteries in readiness for the next time I want to use it.

I also make sure I mount the inverter in an easily accessible place so i don't have to pull the joint to peices to get to it and also they generate heat so need to breath when in use.

oldbobsbus · Guru

I had an inquiry from one of our members wanting to know if the inverter I have for sale on eBay will run an 800w microwave so I connected it up and plugged our microwave into it which is a 700w output unit that draws 1150w on input (remembering it draws x3 during startup) and it wouldn't do it, it just kept cutting out after about 3 seconds then comes back on after 5 secs..lol.. which goes to show that the overload switch is working..
So if you want to run a microwave you would need atleast 2000w/4000w inverter at least so therefor I would recommend a 2500w/5000w unit to have some capacity up your sleeve.

Santa · Guru

Thanks for the info people.

Bob, your right the unit you have for sale would be far bigger than what I need.

Cloak · Guru

Why don't they just make sine wave batteries and be done with it?

valiant81 · Guru

Hi Santa;

If you only want to run a phone charger or even a lap top computer off your inverter. All that you would need is a small inverter and 300 Watts is a over kill....Why ??? Well my Vast receiver uses 65 Watts of power from the mains ( 240 Volts ) and my phone charger draws 36 Watts and my wifes charger draws 48 Watts and again at 240 Volts.

Now as i have said i have the 300 Watt pure sign wave inverter and purchested it from the same company that you are looking at. This inverter is only used for the Vast receiver that i use in our caravan and only when we ' free camp' as the rest of the caravan runs off of 12 Volts, anyway when i installed the inverter i was able to install a Amp meter so as to measure the curent draw out of my house battery when the inverter is on. The current draw worked out to be 1.1 ~ 1.3 Amps at 12 Volts.

So far so good.

Now my UEC Vast receiver draws 0.3 Amps from the mains ( 240 Volts ) and that works out to be 80 odd Watts. So all of these currents are realy small and i would think that IF you only want to use your inverter for the odd phone charger or even the computer's power supply, then a 300 Watt inverter would be all that you need.

BUT if you want to free camp and use a micro wave oven or other heavy current drawing devises, then by all means get a bigger inverter, but you would also need to up grade your batterys and if you have them, also your solar panels.

oldbobsbus · Guru

Santa, it is good that you got the answer you needed to solve your problem but you need to realize that others have problems as well and use these threads to research their problem.

I personally have had a couple of members contact me regarding their inverter problem and I was able to put them on the right track (and bugga my inverter was also no good to them..lol)
So you can feel proud that you started a thread that not only you got your answer but also others got some info from it..:)

-- Edited by oldbobsbus on Wednesday 30th of October 2013 06:31:18 PM

briche · Guru

In regards to running a microwave 3000 to 5000 watt inverter. You will also need to keep in mind that a inverter of that capacity will need a huge battery back to run it, up into the 1000's of amp hours. In the main, not viable.

briche

brian · Guru

briche wrote:
In regards to running a microwave 3000 to 5000 watt inverter. You will also need to keep in mind that a inverter of that capacity will need a huge battery back to run it, up into the 1000's of amp hours. In the main, not viable.
briche

That's not necessarily so, running a 600w microwave which may actually draw say 1000w for 15 minutes will take only about 20Ah from your battery, or for an hour, about 80Ah.

Remember that the Magnetron is not in operation for the entire time.

Obviously you need enough battery capacity so that voltage depression does not become an issue, and you have to be able to replace that used energy.

I can easily run a 600w microwave for up to an hour on high (I've never tried longer than that) with my 675Ah of flooded batteries, but 400Ah of LiFePo4 batteriies would do the job even better for most stuff that you would expect to microwave, and would recharge more rapidly.

Santa · Guru

Thanks again for the info, I had my question answered early on in the thread.

I have absolutely no intention of running a microwave, simply need to charge PC & phone batteries, not sure how the MW crept into the topic.

Santa · Guru

oldbobsbus wrote:
Santa, it is good that you got the answer you needed to solve your problem but you need to realize that others have problems as well and use these threads to research their problem.

I personally have had a couple of members contact me regarding their inverter problem and I was able to put them on the right track (and bugga my inverter was also no good to them..lol)
So you can feel proud that you started a thread that not only you got your answer but also others got some info from it..:)

-- Edited by oldbobsbus on Wednesday 30th of October 2013 06:31:18 PM

I realise this full well Bob, subjects that stray off topic are difficult to search and eventually become irrelevant to the subject title.

Far more useful to start a dedicated thread pertaining to Inverters and microwaves.

oldbobsbus · Guru

Thanks for the advice Santa..
I will be sure to only answer your questions in future..

landy · Guru

Bob thanks for ringing me and for the time you spent on the phone explaining why I should not buy your inverter . I for one have found the thread very enlightening.
Cheers Landy

_wombat_ · Master (of Mischief)

part quote:

Hi Santa;

If you only want to run a phone charger or even a lap top computer off your inverter. All that you would need is a small inverter and 300 Watts is a over kill....Why ??? Well my Vast receiver uses 65 Watts of power from the mains ( 240 Volts ) and my phone charger draws 36 Watts and my wifes charger draws 48 Watts and again at 240 Volts.

valient81, I also run a 300 pure sinewave for VAST and phone chargers, works well for us over the past 9 years.

Boy have the prices dropped on these inverters.

PS running Analouge and then VAST

-- Edited by _wombat_ on Thursday 31st of October 2013 01:04:04 PM

PeterD · Guru

Santa wrote:
I have absolutely no intention of running a microwave, simply need to charge PC & phone batteries, not sure how the MW crept into the topic.

You can get 12 V chargers for each of those things you mentioned. You are far better off going that way than running an inverter and wasting extra power. As for the MW, you should know how threads drift by now.

UPO · Veteran Member

As always an interesting topic - slightly expanding the original topic so here goes.

Looking at a small dirty inverter - modified sine wave unit - to only run a Sphere washing machine - washing is stated at 200W & spin at 230W. wash cycle is about 45 minutes ( rounded up from the brochure info as we have not yet done a trial home use with the Sphere ) so guess 220W for the 45minites would cover usage.

Battery bank is 1 x 120AH & will soon be 2 x 120AH, solar will stay at 2 x 140W through a Ctek D250s controller.

We have modest 12v requirements - all LED lights & 12v 22" LED TV & a 12v CPAP - I have installed USB charge points for phone & kindles - a cig lighter port for use with a variable voltage laptop charger ex Jaycar ( about $80 some years ago ) - by using the USB & the Jaycar charger ( inverter ) I have no other 240V items we need to power, hence looking at a cheap, modified sine wave inverter just for the Sphere W/M.

I am thinking 600W will be adequate, Dickies or E-bay have at under $100 - my main question is what is the WORST case battery draw likely ? and if used on a good sun day, would it be wise to also support the solar panel input while running the inverter by having the tug on line when washing ? the tug is an 09 Colorago with heavy duty wiring to Anderson plug then to the Ctek.

Thanks for any input

UPO - Richard

brian · Guru

I would suggest that you seriously consider a pure sinewave inverter.

Their costs are so low now that there is little reason to settle for a lesser type.

Many electrical devices incorporate electronics which baulk at modified or other corrupted wave forms with often catastrophic results for the device.

A 600w unit will handle the washing machine satisfactorily.

As for the battery draw:- Take the rated wattage of the device, divide that by 12, and add 2 to the answer (allows for quiescent current of the inverter plus power factor) and you will have the approximate current draw on 12v.

Multiply that figure by the time it runs, ie x3 for 3 hours, x 0.5 for half hour etc, and you will have the amp hours.

Formula:- Ah = runtime in hours*((watts / 12) +2)

The preceding calculations work for almost all devices with the exception of microwaves where the actual wattage draw may be considerably higher than the rated watts of the unit.

Mr B2 · Senior Member

I have a small solar panel, It puts out 12 volt and 6 volts, It designed to plug into all the little accessories to charge them, Ipad,, GPS, Charge small Batteries, Etc,

Its 100 by 200 mm in size, it folds out for the panels to charge, iSun is the name of it,

My 1800 watt invertor ran my M/W, and any thing else I needed to run, Drills, sewing machine, Pumps, watermaker, Electronics, Etc,

380 Watts of solar panels and a wind generator, 400 amp hours of battery, I was totally self sufficient for power, Thats on my Boat, Middle of the Coral Sea,

I bought a new Invertor from China, To replace My drowned Xantrex 1800,

5000 Watt with a 10000 Watt surge, Fully Auto, Pure Sine Wave, $500-00 delivered in my hand,

It runs a 500 watt drill and a 5 inch grinder, both under heavy load at the same time,

My coach will have 400 Watts of solar on the roof, 400 A/H Batterys, Then it will be fully self sufficient for power as well,

UPO · Veteran Member

Thanks Brian - if my maths & understanding are correct the follow will be correct

220w draw / 12 = 18.3 then add 2 = 20.3. Then divide 20.3 by expected run time in hours so 20.3/.75 = 27AH.

For the 2 x 120AH battery bank, is that rate of discharge within the parameters for long battery life ?

Am I correct in thinking that with the solar panels inputting a ( possible / probable / roughly ) 13AH over the same time, the actual drain is about the 14AH level? and that the solar alone will have the battery bank back to float in about a further hour - assuming no further load / drain is applied ?

Or am I on the wrong track here ? As is easy to see, solar, batteries & me do not understand each other very well at all confuse

Thanks

UPO - Richard

brian · Guru

I would say that you have a pretty good handle on it Richard, the figures look right.
Just another little formula that may come in handy.
Percentage of battery capacity used = (Ah consumed/ battery capacity)*100
In your case = (27/240)*100 = 11.25%
Anything less than 50% is OK but less than 30% is excellent for battery longevity.

JayDee · Guru

We have a 300 watt invertor which I am having trouble with the cigarette lighter end connection. I want to replace the unit, but all the ebay inverters seem to have a red and black connection and not the Cigarette lighter connection. I do not want to connect directly to the battery as we have the 12 v connection in the van.
Now we free camp a lot, and use our gennie for washing machine and other small electrical appliance, but not got jug toaster or microwave oven.
Need the invertor to operate our Sat. TV and computer and charging phones etc etc.

Soooo... what is the unit I am looking for, and where could I buy it? Should I look at the 600 sine wave or a lessor one.?

Jay&Dee

oldbobsbus · Guru

You can buy just the ciggy lighter connection end on it's own from Jaycar or similar and fit a new end..

You dont say what the exact problem is but if it is fused in the connector you could maybe put a SLIGHTLY larger fuse in (3amp to 5amp).

Going to a 600w PSW inverter would give you better power availability..

03_troopy · Guru

@ JayDee... A cigarette lighter socket is probably a bit light duty for your 300W inverter. Most are only good for a maximum of roughly 10A, high quality ones about 15A, which is right on the limit for a 300W inverter. You are better off replacing the cigarette lighter socket and plug for a Merit plug, or wiring direct to your 12V source. The cable size for the ciggy socket is way too small as well, so you'll suffer from voltage drop at your inverter input.

Knowledge speaks, but wisdom listens.