How much solar power to free camp for a week or 2 ?

Mez · Veteran Member

How much solar power to free camp for a week or 2 ?

dragonfly1 · Senior Member

we have 400 watts of solar and 2 120 amp hr batteries and never have any trouble free camping for weeks at a time

Dragonfly1

brickies · Guru

Depend on how much sun there is .

Tony Bev · Guru

Hello Mez

I am not a electric/solar teckie

You have to start off working out how much 12 volt power you require each day
Then you have to make sure that you have enough battery capacity for the power you require
Finally you have to have enough solar to recharge your battery/s during the hours of usable sunlight

Perhaps if you put up what 12 volt appliances you have, and how many hours a day you plan to use them, then the electric/solar teckies can give you a precise answer

As a comparison, the maximum battery power I am likely to use is 60 Amp Hours per day

I have the original (unknown age) 100 AH Gel deep cycle house battery
Plus as a backup a 2012 55 Amp Hour spiral bound AGM hybrid, start/deep cycle house battery
I have the two batteries isolated from each other by 2 x 4 way isolating switches
They are charged (one at a time) by a 300 watt solar panel, or the engine, both going through the same 20 Amp DC/DC battery management unit.

Hope this info is helpful to you

macka17 · Guru

When we started out with Solar. we used to have a 20w panel (the biggest) and car battery. 12v Sharp TV. lights and radio. PLUS a Genny.
Never had a problem.
Last van. 360w panels plus another 80w on ute. 2 x 110a AGM's Lights. TV Movies and 80ltr Waeco
Plus a Genny.

Get the drift.

You can survive comfortably anywhere under whatever or not, sun.
WITH a genny.
Always make one part of your equation.
It comes in for power outages at home. Like a lot have at present. as well as camping.

This van. 1 x 200w panel on van 1 x 85w panel on ute. with 2 x 85a NZ70Z's in tray.
Works fine.
LED's right through van inside and out. 21 in, 12v tv. and 2 terra HDD. with laptop for movies.
and the old genny for Air cond.

Will never run out.

If you run Solar only.
After 40 odd yrs of using it.Unless you ridiculous with volume of panels. And even then.
You WILL run out sometime or other
That's why we ran Wind Genny's on yachts. along with panels and alternator.
and towing Alt's and Genny.

FUEL power is the only Guaranteed full supplier of electricity at present.
These others only supplement it.To whatever levels.

NOBODY lives FULL time, while travelling all over on Solar only.
Guaranteed. Unless you run engine every day or so. (Fuel supplied.)

Even up here in QLD. we don't get NO Cloud days all yr.

macka17 · Guru

PS.

Whatever battery size you have.
Make sure you have the panel capacity to keep them NOT LESS than 12.5v at all times.
if you want batt's to have any life as such.
(12.5v is basically 1\2 empty)

Jaahn · Guru

Hi Mez, smile

Some more thoughts about free camping and solar !

IMHO it depends on what sort of person(s) you are. If you like everything to work just when you want it and have all the mod cons to use then perhaps solar is not for you. But if you put in a decent battery meter and can fit your usage to the available power and when the sun is shining and have the basics then you can get by with what you have now. My suggestion is to get out there and see how you go for a day or two or more and see how you cope. I get by with 140watts just now and will head off anytime if it suits. When the meter says enough at night we turn off the telly and go to bed biggrin

Read the Techies' Corner- Solar Power subforum threads for ideas too.

Jaahn

-- Edited by Jaahn on Friday 30th of September 2016 04:32:41 PM

-- Edited by Jaahn on Friday 30th of September 2016 04:34:36 PM

Mez · Veteran Member

Thank you so much to all for your replies and info , much appreciated Cheers Mez & Christian

-- Edited by Mez on Friday 30th of September 2016 05:12:11 PM

Peter_n_Margaret · Guru

Subject to weight and space, fit as much solar as you can. It has never been cheaper.
Portables are a PITA. Set and forget is better and they won't get pinched.
We don't carry a generator. Heavy, smelly, noisy, anti social, dangerous fuel.......... You have a very good alternator that can produce an enormous amount of power. Choose one of the several methods of using it in an emergency. In 12 years, we have needed to use ours about 3 times, I reckon.

Cheers,
Peter

Aus-Kiwi · Guru

2 stroke genie and park close to Pete and Marg . Lol

TheHeaths · Guru

Mez,

lots of information for you to set up a good system.

We use 2 x 100 Ah batteries, but only have 160 watts of portable solar, as we do not do a lot of free camping, and do not run a lot of items when we do. This keeps us going ok.

I have fitted a volt meter to allow me to check state of charge for batteries. Most guides I have looked at show 12.7v as full, 12.5v as between 80 - 90% charge, and 12.1v - 12.2v as the 50% mark, which is what you should try to limit battery draw to.

Hope this helps.

Aus-Kiwi · Guru

I have Green , Amber and red light on reg . Also shows state of charge in volts. Volts charging from solar . From memory 13.2 is full charged . I find its best to have full charge by about mid day to give some safety on overcast days . I try not to get into red . 12.2 or there abouts . 2 X 100 AH does me too . 2 TVs . Can run microwave ? But use genie when on our own . Having 5kw diesel generator built in is reasonably quiet .. The diesel heater surprisingly hardly uses much battery . My concern in my case is flat battery and not enough to start generator ., although good mornings sun fixes that ! We got cought in weeks overcast, rain in WA .,The sinking feeling when batts go dead !! In overcast days !!

macka17 · Guru

Hence a Genny hey.....
Alternator of any size is no good if battery won't start car.

Pull the string. you have all the power you want. anytime.

If you want any life out of your battery's.
try to get enuff power that you don't drop below 12.5v by morning

12.4/5v is really around 50/55% of holding charge in a battery.
Ask a sparky. Well the marine ones I work with anyway.

The lower you continue going. the less life you'll get out of the battery's.

Over a lot of yrs on solar. keeping the min voltages around the 12.5v
and recharged by around 11.00/11.30 am..
I've averaged 6 to 7 yrs out of a lot of battery's,
in yachts.boats and caravans.
Dropping them lower has always shortened battery life a lot.

Delta18 · Guru

I installed a complete system to our new van. 1000w solar with 10 x 100w slimline panels. They weigh around 1.5kg each including the underlay and brackets. This feeds 400ah LiFePo4 Lithium batteries. Weight of battery is 63kg compared to some 240kg for the equivalent capacity in deep cycle LA batteries. This feeds all gpo's in the van with 240v via a 3000/9000w inverter. Also fitted a Redarc 40amp DC/DC charger from the car. With this we can stay indefinitely even in the cruddy weather we have been experiencing lately. We use almost all 240v appliances, 2400w kettle, 400w toaster, 2000w induction hotplate etc. Heating is via a diesel heater. This is probably an extreme system which is not for everyone but it suits us. Cheers Neil

Aus-Kiwi · Guru

Yes Maka . I let my controler handle the min voltage . It cuts out if too low . I adjust minimum voltage up a little to have reserve to start geni . I can bridge with starter batteries . For some reason at times I have had low battery on BOTH systems !! Just lucky I was in camping ground !! My worry is it happening way out when free camping . I guess a seperate starter battery system for geni ? I can't hand start a 2 cyl 5200 watt diesel Geni . Can't even park on Hill to push start being auto !! Ahh the sophisticated days we live in ! Ahaha funny thing is I enjoy and appreciate the sun now !! Solar at home too .

T1 Terry · Guru

As you already have some solar and battery power, add a portable panel and go out and use it, the best test you can get is to see just how much you use each day and just how much you can put back in. My advice would to buy a 40 amp DC to DC charger in preference to a generator, you already have the alternator in the tug, why not use it. As you only have a 100Ah battery, a drop to 12v from fully charged at a rested 12.8v plus would give you 50Ah useable as long as the load is 5 amps or less, the higher te load over 5 amps the less than 50Ah useable you have and at a compounding rate, a 50 amp load would drop that back to 5 mins, then a further trickle at 5 amps or less till it was dead flat, but the 12v/50% mark will remain true.
Portable solar can be a pain but you already have 1 portable panel and like to park in the shade so the portables pain is the price you must pay, a battery monitor such as the Victron 700 BMV is really a must have if you are being serious about not suffering the flat battery blues, look at the SOC (state of charge) around 3 pm and decide if you need to run the tug and 40 amp DC to DC for 30 mins. By watching the charge rate during that 30 min period you can determine just how much benefit you are getting from the DC to DC charger Vs the SOC and from there you can determine if a top up charge earlier in the day might be a better idea, it is all trial and experience with recharging lead acid batteries.
If you find you need more capacity or the battery you have won't deliver 50Ah without dropping below 12v then have a serious look at swapping over to a lithium battery. You can have all 100Ah of the advertised 100Ah capacity, less than half the weight and it will take in the full 40 amps from the DC to DC plus the solar right up till the 100% SOC point is reached on the Victron 700BMV. All the gear you have now is useable on a well designed lithium control system, no need for new anything, so the cost of 200Ah of AGM batteries is the bench mark for the cost of the 100Ah of lithium, the other benefits are a bonus. One other bonus not often mentioned, you can add to the capacity by reconfiguring the battery pack, cell age is not an issue like it is with lead acid/AGM batteries, you can up grade capacity as required and even take the battery with you when you upgrade to a new rig, they really do last that long.

T1 Terry

macka17 · Guru

I bought my Genny String start for that reason, they sold it both ways.

A 1500 power pack I use when camping/fishing would do that for you and good for a lot of things.
Pushbike tyres. emergancy lighting. starting outboards.Running electric motor on boat.
Will start my D Max easily too.

Aus-Kiwi · Guru

Thing is if your going to run tug motor ? Not much different to geni ? That depends if your staying 2 days at each stop I guess. ?

Peter_n_Margaret · Guru

Aus-Kiwi wrote:
Thing is if your going to run tug motor ? Not much different to geni ? That depends if your staying 2 days at each stop I guess. ?

Running the tug motor would make similar or less noise that a generator it would not use much more fuel and would certainly be less polluting (there are no pollution controls on generators and many are off the planet bad).

In addition, you can produce huge charge currents (my 80A alternator can give battery charge rates of up to 70A) which would require a very large and very expensive battery charger.

Cheers,

Peter

Aus-Kiwi · Guru

Most new cars are 120 amp plus now . Stationary at idle pollution hardly works being on closed loop mode .. My issue is short runs on cold engine plus saving tug alternator for tug !! At idle there's not any chance of full power from alternator . My 6.5 V8 wouldn't be apreciated over my Onan .. Lol

T1 Terry · Guru

30 mins at a high idle will put in 20 Ah via the 40 amp DC to DC no matter if it has a smart alternator or not, hard to do that with a generator and charger without spending a lot more money than the DC to DC charger would cost, then the weight and storage room needs to be considered. As we travel back from Melbourne each free camp spot has a min of 2 generators running for hrs on end, fine for the generator owner but what about everyone else there? The tug running at a fast idle for 30 mins possibly in the morning and again in the afternoon if absolutely necessary would be far less annoying than the generator running for hrs on end trickle charging the battery while it powers the TV. Good batteries that accept a full charge right up till 100% SOC, good solar and portable panels when needed, leave the generator at home

T1 Terry

Peter_n_Margaret · Guru

Aus-Kiwi wrote:
Most new cars are 120 amp plus now . Stationary at idle pollution hardly works being on closed loop mode .. My issue is short runs on cold engine plus saving tug alternator for tug !! At idle there's not any chance of full power from alternator . My 6.5 V8 wouldn't be apreciated over my Onan .. Lol

I set the idle to about 1500rpm. At that speed, the alternator produces close to its maximum output and that is enough load to keep the engine sweet.

100A at (say) 14.2V is more power than you can make available for charging by almost any other means. Why do so few of us make use of that?

Cheers,

Peter

T1 Terry · Guru

Peter_n_Margaret wrote:
Aus-Kiwi wrote:
Most new cars are 120 amp plus now . Stationary at idle pollution hardly works being on closed loop mode .. My issue is short runs on cold engine plus saving tug alternator for tug !! At idle there's not any chance of full power from alternator . My 6.5 V8 wouldn't be apreciated over my Onan .. Lol
I set the idle to about 1500rpm. At that speed, the alternator produces close to its maximum output and that is enough load to keep the engine sweet.
100A at (say) 14.2V is more power than you can make available for charging by almost any other means. Why do so few of us make use of that?

Cheers,
Peter

I guessing because very few have batteries that could accept 100 amps for more than a min or 2 before the internal resistance forces the terminal voltage higher than the alternator regulator voltage, then the 100 amps won't flow from the alternator into the battery. Now consider the newer vehicles with smart alternators... well it is really a smart engine control computer dropping the alternator output voltage, you can get a good charge into any battery type with 14.4v or higher at the battery terminals, but you can't if the voltage drops to around the 13v mark, then it's just a trickle as the house battery voltage will rise above 13v if the charge rate is any faster. You can belt a lot more current (amps) into a very flat 400Ah battery pack for a lot longer than you can into a half charged 100Ah AGM battery

T1 Terry

Peter_n_Margaret · Guru

T1 Terry wrote:
I guessing because very few have batteries that could accept 100 amps for more than a min or 2 before the internal resistance forces the terminal voltage higher than the alternator regulator voltage, then the 100 amps won't flow from the alternator into the battery.

Yep, but the battery will take all it can and that will not be limited by the "charger", so charging time is as fast as it is possible to be, determined by the output voltage of the alternator and the acceptance rate of the particular battery.

So called "smart alternators" clearly need other considerations.

Cheers,

Peter

Aus-Kiwi · Guru

I love suny days !! Bit rare at times this year !! I have motorhome so it's more inclusive . No cable length etcto consider . Solar,reg, batteries are only 4m away at most . Why my views are slightly different .. Everyone has different living standards etc .. I guess if I wanted to improve over mine I would add another 100 AH battery to give better reserve for overcast days . I can cut back a little on usage . But 400 watt , 200 AH seems fine .. I could argue if another separate battery for reserve or emergency ? Would help .. I guess it's the sleep conforyably at night thing ? So many options ..Yet simple .

T1 Terry · Guru

Peter_n_Margaret wrote:
T1 Terry wrote:
I guessing because very few have batteries that could accept 100 amps for more than a min or 2 before the internal resistance forces the terminal voltage higher than the alternator regulator voltage, then the 100 amps won't flow from the alternator into the battery.
Yep, but the battery will take all it can and that will not be limited by the "charger", so charging time is as fast as it is possible to be, determined by the output voltage of the alternator and the acceptance rate of the particular battery.
So called "smart alternators" clearly need other considerations.

Cheers,
Peter

Agreed, the DC to DC charger can be a bottle neck in some instances, but that consistent 14.4v throughout the charging period soon catches up what it may have held back early on in the charging period. If you have an alternator that will maintain 14.4v at the house battery then there is no advantage to having a DC to DC charger, that is a very rare event though.

T1 Terry

Aus-Kiwi · Guru

Terry if your dead set against genies Atleast compare apples with apples . No need to run geni longer than tug motor . In any case it's just to top up if batteries are low or some security to keep them well charged . Maybe charger is too small if genie is required to run too long . Thing is to consider noise etc when buying ? Don't buy too cheap !! I have seperate old fashioned 80 amp Bosch alternator for charging house batteries . Mind you the old 7.5 Fuso emits way more noise than the built in geni .

T1 Terry · Guru

Agreed, if you have a big generator and big mains charger then run it only until you see the charge rate drop off, then turn the generator off..... but people don't do that do they, they just leave it running for hours on end, they won't do that with the tug engine though, they want to switch it off as soon as possible.

The whole thing I'm trying to get at is that the real need for carrying a generator can't be battery charging if using the tugs alternator isn't going to do what you want, if it is only battery charging in an emergency then why carry a generator around when you already have the equipment to do the job

T1 Terry

kezngaz · Senior Member

I bet you wished you'd never asked!!!

Aus-Kiwi · Guru

If you camp up for over two or three days . There's 2 or 3 options . We don't really know your living stds or what Mrs expects ., I tell you one thing . When you think you have everything sorted !! No no no .. Dead batteries is a nightmare !! Maybe exercise bike with 200 Charger ? Lol solar and batteries can be just as heavy as geni . Oh but it's bloody great when it all works !!