maximizing battery capacity

[nuckfan]

I have an 8 foot camper with a 100 watt solar panel and charger. Right now I have a group 24 12v battery and would like to increase the amp hr capacity, I was wanting to run two 6v in parallel but I cannot due to the size of the battery box being too small. the opening on it is 14.5" wide by 20" tall and 9" deep. What I would like to know is what type of battery can maximize the amount of amp hours given the limitations I need to deal with.I have looked at Interstate batteries but cannot find one that is not rated in cold cranking amps, as I was informed that this would not be an ideal application for a solar setup.

[Almot]

People with generator and no solar tend to treat their batteries, er... "differenty" :)... I can understand this, given a difficult task of getting it 100% full without having to run darn machine all day and night.

It's not that 255 AH wet battery at 50% "demands" 52A. It can "accept" 52A, but recommended maximum rate is 0.15-02C or 40-50A. Exceeding it will shorten battery life. OTH, charging it at 20A would only result in longer charging time (which you don't want of course).

Keeping it for 2 hours at 14.4V Absorption is also not something curved in stone, this depends on battery and SOC. Majority of solar controllers - especially those with a fixed timer - have 1 hour Absorption stage, as engineers determined this to be sufficient in "most" scenarios.

In any event, 127 AH daily is pretty fat energy budget for a boondocker. With moderate use of microwave you can get by on 80 AH, and without MW - on 30-50 AH.

With planned 150 AH bank, 45 AH daily will put the OP at 70% full in the morning. 200W solar is perfectly capable of delivering that much in summer, even in places like Langley BC. As long as it doesn't rain. 8ft camper sounds like a truck camper - those tend to move around more often than big rigs, and can get some charging while on the road.

[msmith1_wa]

If you are willing to mount a battery to your truck Torklift has brackets for this purpose.

[RoyB]

Keep in mind a typical 120WATT SOLAR PANEL will only produce 5-6AMPS when in HIGH SUN... Two solar panels in parallel will only be 10-12AMPS DC Current.

My battery bank is rated at 255AHs and will demand 52-53AMPS DC CURRENT when 14.4VDC is first applied for boost charge mode. This will start tapering back down to around 8AMPS DC Current with-in 15-30 minutes time or so.. To get my battery bank charged back up from 50% charge to 90% charge I will need to charge them using 14.4VDC for two hours and then 13.6VDC for an additional hour to get the battery bank back up to its 90% charge state.

I have to run my camper shore power connected to my 2kW Generator in order for my on-board converter/charger unit to get this accomplished in a three hour generator run time.

If I had solar panels installed I could run the generator first for one hour to get past the initial high 52-53AMPS DC Current demand and then just use the solar panels after the Battery Bank DC CURRENT DEMAND has tapered back to around 8AMPS DC CURRENT.

In my case I will not use my battery bank again until it is at least back up to its 90% charge state. Otherwise in my case I lose battery performance real quick and this will also do damage to my battery battery bank if I do this as a routine.

[landyacht318]

The trojan J185 is taller and has more capacity than the t-1275 and would 'almost' fit the space listed. It is 14.71" wide.

Dooh! Put a bottle jack on its side and make the battery compartment 0.21" wider 🙂

205Ah though.

The Lifeline GPL-30HT is about the same size and capacity as a T-1275. Note Lifeline when deeply cycled recommends a 20% charge rate, 20amps per 100Ah capacity, so You would need to be able to apply 30+ amps to it when cycled to 50%.

Trojan 'recommends' 10-13% for their flooded batteries

http://www.lifelinebatteries.com/marineflyer.php?id=4

Low charge currents on a deeply cycled AGM will tickle them to death, even 200 watts of solar would be considered tickling this battery

[nuckfan]

I definitely am leaning towards the T1275 now. 150 amp hours will probably double what i'm currently running with.It's too bad i can't make room for two 6v but being an 8' camper kinda limits me in space for batteries also in roof space for solar but i do have plans for at least one more 100w panel which will give me a little more solar production (200W) and help limit the amount of time i run the genny.:)

[Almot]

Two 6V batts like T105 won't fit in 14.5"x9" space.

A single 12V is the way to go, just make sure you can lift it. T1275 weighs 82 pounds.

You want a deep cycle battery. If it doesn't have AH in specs, only cold cranking amps, it's not a deep cycle.

Your solar is marginal though, no matter what battery.

[Chum_lee]

14.5" wide by 20" tall and 9" deep

Hummmmm. Thats kind of an oddball size for a battery compartment. Just a little too small in each dimension to be efficient. My 6 volt deep cycle batteries (232ah) are +-11" tall (plus you need space to service them) so stacking them on your rig is not an option. With a little research, if you want to convert to 6 volt wet cell deep cycle batteries, you could probably find batteries with somewhat less than 232ah capacity. If you could find batteries that were about 8" tall at the fill caps you could run 6 volt deep cycle batteries in series and stack them. It would be a tight fit. Another option would be to find a specialized battery for something like a fork lift, a pallet jack, or some other warehouse type equipment that is much taller than a standard deep cycle battery. Those could be pricey though.

Another option (which I wouldn't recommend) is to use two 12 volt automotive batteries wired in parallel. They would fit, stacked, but only the highest quality batteries would give you minimum life. Marine deep cycle batteries, which are generally not true deep cycle batteries are another option.

AGM batteries can mount in any direction so that might help you.

Any upgrade suggestions from the camper unit manufacturer?

Chum lee

[gbopp]

Have you ever read The 12 Volt Side of Life? Maybe it will have information you can use.

[kellertx5er]

If you do find the space for two 6V batteries, you will want to connect them in series, not parallel, if you want 12V from them.

[Boon_Docker]

Trojan T-1275 (150 AH)

Length 13" x width 7.13" x height 11.13"

[MEXICOWANDERER]

Absorbed glass mat will render more kWh than a flooded L/A battery. They can also tolerate unintentional over-discharging better than a FLA. But brand is important. I find it difficult to fault Concorde's Lifeline. This brand has thicker plates than even a Trojan T105 Golf Car battery.