Increase the capacity of a 2x12v battery setup

look at Redarc or ctec products for multi battery options as a cheaper option 1 of the prianha products may work. Look up their sites via your search engine and phone the companies I have found them all to be extremely helpful when discussing your needs and requirements.
on a good point Redarc talked me out of my needs and talked me into a cheaper option requirements which suited me better technically and money wise.

Redarc and Piranah products are both Australian I am not sure about Ctek.

Regards
M

What's the aH capacity of each battery?

What's the voltage of your panels and the effective charge of the batteries?

All the amph have to be exactly the same, if you mix them you will only have the equivalent of the lowest one, so this means the highest amph battery will never charge to 100% so it will fail (not - might - WILL) and that in turn will kill the other one too!

Same can be said for mixing old ones with new ones it will work but the new one is going to have a short life.
Only real long term solution is the expensive one.

As with solar panels if you mix different watt panels you will never have higher than the lowest one in the string, ultimately means you can screw up your solar panels - Doh!
Nigel

Starter batteries are not deep cycle; they provide short-term high power output.

That'd be your prob IMO but I'm no expert.

Well I've done some more googling, and a few websites list the "XV27MF" battery as a Deep Cycle 95aH battery. Maybe these are deep cycle batteries? And it is possible to add a new/different one in parallel with minimal fuss?

Dave,

The XV27MF is a combination Cranking/ Deep-cycle battery of about 100 Ampere Hours capacity. Batteries of this type are a compromise and never as good as the correct type for each duty, cranking or deep-cycle. Nevertheless, they are not too bad if maintained properly.

You say that these batteries are only 2 months old, so if that is true (did you buy them?) and they are being correctly charged then they should be capable of supplying your fairly modest needs as you do not mention a fridge load.

If the batteries are OK then I would be suspecting your solar charging system. The 5-9 amps you quote represents 20-36 ah contribution to the battery if available for say 4 hours, providing perhaps 16-29 ah battery output. This is possibly not enough for your needs.

If the bottleneck is your solar system then adding further batteries will not solve the problem and in fact would possibly make it worse. I would suggest having the existing batteries tested by a battery supply retailer, although unless he is of repute he may condemn them in order to secure a sale. The best way by far is to separately charge these batteries fully with a quality multi-stage charger then connect a known load such as a 50w 12v lamp (auto or domestic halogen) and observe the discharge time to reach 12.2 volts which is considered 50% "state-of-charge" and as low as you should be discharging. 50w draws about 4 amps so a perfect 100ah battery should be providing about 12 hours to consume 50% of its 100ah. In reality, the battery will not be perfect and so will last for more like 10 hours.

If the batteries are reasonable then you will need to consider the solar charging system. Bear in mind that batteries are like your bank account......you can only draw as much as you have put in. Getting further bank accounts will not help if your deposits are inadequate for your withdrawals! LOL

Hi Dave,

looking at your loads of two lappies, the two batteries are able to power for 90 minutes, that's about 15~20Ah all up.
Add 20% for inverter and p/s inefficiencies and you're looking at a measly 25Ah juice from two batteries which should provide 190Ah (if they're specced 95Ah each).

Three possibilities for this low Ah output:
batteries not fully charged (very likely), battery capacity permanently reduced by chronic undercharging (quite likely), or a combination of 1 and 2.

What you can do:
Use a quality solar regulator, or a mains powered 3 stage charger to try and bring the batteries up to their maximum remaining capacity.
It may take several days of 'cycling' the batteries.

As Al has already mentioned, the amount of solar mightn't be enough to do this for you, so you have to either invest in a proper 3 stage charger, or have someone baby the batteries for you.
A load test with a known load is also a good way of finding out about the remaining battery capacity.

If the capacity can't be recovered to higher than say 90% (85Ah per battery) don't wire them in parallel with a new deep cycle battery (you mightn't need a new one if you get to this stage anyway).
Reason for this is the open circuit voltages of the weak batteries are lower due to their more dilute electrolyte which in turn can partially discharge the new deep cycle battery, leading to accelerated ageing of the new one.

For a good quality/best value for money deep cycle battery, ideally suited for your loads, and a good quality true MPPT solar regulator with expert battery/solar advice thrown in for free, look in the profile of Battery Value Pty Ltd. We ship all over Australia most economically.

cheers, Peter

Hi guys, i looked at all the options and the associated prices and it really gets expensive and i would add "complicated" so i looked at some of the "systems" that have been around for years in trucks and busses and have stood the test of time and went out and brought 2 N70Z's, Centrys at a good price, made a secure mount in the tray, set them up with the "charge" link to the main battery with a 200amp soliniod that simply clicks in with ign on and out with ign off and it works really well, i run the engle and other stuff off it and it all is isolated from the main starting batt when ign is off so dont matter if it goes flat and charges with ign on and motor running, if i have it parked up for more than a few weeks i connect a chatger to them and that is as technical as it gets ........... in 2 years time yes they will be stuffed but for under $300 i can simply buy 2 new batts ...
Works for me..
Oh and i got it all from Isa :O)
Cheers
Joe

Dave,

If you're set on buying more gear in the Isa, there won't be a lot of places that will have what you might need.

TJM & Atlas Superstore(they got Batts, panels & chargers) are in Simpson St, at each end of the block facing Maccas.

Autobarn has some deep cycle batteries, and 3 way chargers(I got a 16 amp Projecta there, that does Calcium as well)

Supercheap is just up Marian St about 150 metres from A'barn. Isa Auto Supplies are also in Marian St, next to BP, & Muffler Shop. There's also Dave Clancy Electrical, in Cook Crescent, who I think has some panels, if you want to go that way.

Blackwoods are over in Traders Way. on north side. They've ususlly got everything, except that one part you really want. Sorry, Mr Balckwood.

Good thing with the Isa, being a mining town, if they haven't got something, it can be up overnight, depending on what it is.

And go & see George at Bearing Service, as he sells lots of other stuff, like chargers & tools, oh, & batteries too.

No affiliation etc etc

Hooroo,
Bob.

Well!

Hopped into Autobarn, Supercheap, TJM and finally Atlas. The battery fella at Atlas is amazing :) highly recommend going there if you need anything camping/electrical.

He jumped in the van with a multimeter and found the charge coming out of the "solar controller" was a bit lower than what it should have been. He wanted me to remove all the dials and make sure none of them were causing issues, so back to the caravan park I went and got in with the screwdriver.

2 minutes in I found the problem (and started to smell it as well) - melty!



back to atlas and left with a new solar controller (7amp as opposed to the previous 20amp - not sure if that will slow charge down?)

It's wired in now and I'm going to leave it charging the batteries tomorrow - I'll test the batteries tomorrow night and see how long it'll run the inverter for.

Next purchase will be a 3 phase charger to make sure the batteries are up to scratch between powered caravan site visits.

Thanks for all the recommendations and advice, I learnt a lot :)
Looks like we'll be skipping the new solar panel and battery purchase if this fixes the problem.



Cheers!!
Dave
travelaroundthecountry.com