Additional Batteries

Phill, in very basic terms (and I'm not being condescending here) the 160Ah battery should last 60% longer than the 100Ah one.

Phil,

No problem mixing different amphour rated batteries.....BUT.....

It is very desirable that all batteries be of similar type and in similar condition. Hard to achieve if adding new batteries to existing ones. You will certainly increase your storage, and the new ones "should" add about 160% to your existing capacity. In practice, assuming that they all have the same basic chemistry, it is the tiredest battery that will largely determine the output of the whole battery bank. The same chemistry is very important - mixing for example some calcium style batteries with standard ones will limit the calcium batteries' charging opportunities to those of the others; they will never achieve full charge.

The big question in my mind is why? Do you need more storage, or would more charging capacity better meet your needs? You might find Electricity for Camping a useful read. It discusses how to assess your storage needs and charging options.

Cheers

John

Phill,

You may well find the existing batteries are more than adequate for your needs.
Try them out first to see how long you can draw on the power from the battery bank, while being supported by the solar panels when stationary.

Only if your experience determines that the two existing batteries, plus the solar panel support is not adequate enough, should you need to upgrade to higher capacity batteries. In this case two 160Ah batteries may be better than two 100Ah and two 160Ah batteries as any method of charging them, may also need upgrading.

As well as the electrical side of things, don't forget the extra weight of batteries etc counts in your load allowance. I read somewhere a 100 AH battery weighs about 35 kgs.

Hi Phil

Looking at your existing setup you are close to possibly having what you need.........I will clarify that by comparing our set up to yours and what you already propose to do..

you will have
390 w of charge on the roof once you add the third panel you stated and
already have two of 100 ah batteries
a compressor 220 fridge

we have
390 w of panels (3 x 130)
3 x 100 ah batteries
220 L compressor fridge

our setup is nicely in balance and as a rough guide our 24 hour usage is around the 70-90 ah........obviously dependent on the ambient..and we dont watch TV but we do use a diesel heater for an hour or two in winter .....everything else is all 12v......only on rare occasions have we dropped our SOC to around 65% and only for a day or so at the most

we have an anderson plug on the outside for portable panels....we have them..never needed them and no longer carry them ( our Solar controller is a PL60 and so is designed to handle increased inputs...we can also monitor the in / out and be concious of the SOC of our batteries

So bottom line before you spend unecessary $.....maybe the 390 w you propose and one extra battery...may have you in balance.....subject to extra draw of other electronic appliances you may use compared to the above

Just make sure that whatever you add to the existing system can be handled by the solar controller and the battery charger you have......and if you do add...watch your wiring size.....dont just copy what is there assuming it is the correct size.....voltage drop from undersize cable is the killer of 12 v systems

I reckon one other battery would be more than enough esp with two lots of solar. Can you also charge your van betteries by linking with the car via an Anderson plug? You can just let it idle for 15/20 mins or so on site, perhaps apply a little tickle on the pedal to help it along - doesn't take much running of the car to give them a boost and that's a last resort but easily done but..........you'll be wishing it was raining and no solar power when you see Robin bangin em in for United ;-))

Hello,
Just reading your questions and answers.

Upgrading to 3 or 4 batteries is not as easy as adding more batteries and cables,

Firstly the Batteries Must all be the same age, model, make and usage, The cabling must be all a minimum of 50mm2, the connections from the battery to the chargers and load must be crossed linked between all batteries.

The charger must be capable of charging the batteries from 50% SOC or DOD to full in a minimum of 12 hours, there for the capacity of the battery charger must be 10% minimum of the full capacity of the battery bank that it is trying to charge, regardless of Solar,

There for 400 amp hours of batteries and the charger must be a minimum of 40 amps. If your free camping and running of a generator, i would go up to a 60 amp charger.

There is a rule of thumb, never parallel more that 3 batteries, as the chances of dropping a cell in a battery increases.

You can achieve the same amount of amp hours using 6v batteries in a series parallel system, charging and usage on a typical battery bank using this will have a far less chance of having issues with the battery system failing. IF you had 4 batteries in parallel The chances of failure is high, when it does fail the system will then have to be completely replaced.

The best way to achieve better battery storage is knowing when the batteries are 100%, 75%, 50%, ETC A good quality battery monitor will give you enough info to the guide you with your usage and charging status.

12.8 static voltage is fully charged, 12.5 static voltage is 50% 12.1 static voltage is flat. It is also recommended to only ever drain your batteries to 50%.

Question, Trivia
If you have a portable generator, you plug it into your caravan, motor home or Camper, do you have the same level of protection, from the safety switch as if you where plugged into mains power?? to protect you from electrocution.

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