Add second battery for boondocking or upgrade current battery?

[mcsquish]

We picked up our first “real” travel trailer a year ago and now want to start boondocking. I have a feeling we don’t have enough battery though; it can get rather cool at night. We have already completely killed our existing battery so I want to replace it anyway. My confusion is do I some how upgrade the current battery (it’s a group 24) to something else, or add a second? Then with either choice do I need to get a different charger? My biggest overload is deciding on which deep cycle battery and where to buy it.
Any help would be greatly appreciated and I want to learn as much as I can.

[bikendan]

Well, I would get two 6v golf cart batteries. They are better for dry camping and boondocking, since they are true deep cycle batteries.
I'm guessing that your group 24 is a dual purpose RV/marine battery, which is NOT a true deep cycle battery.
Getting a different charger isn't going to help keep the batteries charged if you don't have solar or a generator.

[mcsquish]

Thank you bikendan.

[pgandw]

I second the Golf cart batteries. I buy mine from Costco (just purchased a set for my new A-frame - Interstate 210AH, $93 each, $15 core charge each). Sam's Club has similar Duracells at a similar price.

Depending on how you manage your battery usage, you can get 2-4 nights out of a pair of GC-2s. Assuming you are not changing battery types (still using flooded batteries), your current converter will charge the new batteries just fine, albeit slightly slower than if the converter capacity and wiring were optimized.

My A-frame will do 4 nights from fully charged GC-2s with 5 hours run time on the heater each night and basic parasitic loads. But anything more will take the batteries down below 50% by the end of the 4th night unless I find a way to recharge. The deeper the discharge, the fewer the number of charge/discharge cycles available before the battery is toast. 50% is considered a decent trade-off between battery life and usable charge. GC-2 manufacturers advertise 800+ cycles if recharged when discharged to 50%. Sears Marine Diehard (12V) advertises 400 cycles.

Maximum charge current is 20-25% of a batteries AH capacity, which equates to max charge current of 50 amps for a pair of GC-2s. However, 50 amps requires 6 gauge (preferably heavier) wire on a short run between the converter and batteries to prevent voltage drop from messing with your converter's brains.

Solar and/or generator are needed to extend your battery endurance beyond the 2-4 days. If using a generator, you need good, properly sized converter and wiring to minimize generator run time. Since I don't carry a generator or solar due to hassles, the recharge time through the converter is not a big deal. But since the stock WFCO converter never goes into trickle mode (13.2V), I am replacing the converter with a Progressive Dynamics PD-4135. The 4135 I installed in my previous A-frame worked as advertised, readily going into bulk, normal, and trickle modes as needed. The 35 amp output was adequate for me.

Hope this helps in your planning
Fred W
2019 Flagstaff T21TBHW A-frame
2008 Hyundai Entourage minivan

[MR.M]

you can get true deep cycle 12 volts batteries with same amp hr as 2 6 volts . trojan sells them get a couple and you will have much more reserve power . IMO

[deepseadan]

Do the 6 volt deep cycle batteries still fit in a group 24 battery box. I can barely fit two of those.

[bikendan]

Originally Posted by deepseadan

Do the 6 volt deep cycle batteries still fit in a group 24 battery box. I can barely fit two of those.

They have the same footprint but are slightly taller.

[TitanMike]

Just upgrading from Group 24 (if that's what you have) to a group 27 or group 29 will give you a 25-30% increase in battery capacity.

I've been a fan of installing 2) 12v true deep cycle batteries rather than 2) 6 volt deep cycle batteries. With the 12 v batteries in parallel you have two batteries, each capable of delivering 12 v power. If one fails you still have one to get by on until you can replace.

If a 6 volt battery in series fails, you have no power.


That said, if I had the room and weight capacity I'd get 4) Deep Cycle 6 volt batteries and wire them in series/parallel for a total capacity in the neighborhood of 400 amp hours.

[Tom48]

Originally Posted by mcsquish

We picked up our first “real” travel trailer a year ago and now want to start boondocking. I have a feeling we don’t have enough battery though; it can get rather cool at night. We have already completely killed our existing battery so I want to replace it anyway. My confusion is do I some how upgrade the current battery (it’s a group 24) to something else, or add a second? Then with either choice do I need to get a different charger? My biggest overload is deciding on which deep cycle battery and where to buy it.
Any help would be greatly appreciated and I want to learn as much as I can.

Yes upgrade. Many tongue mounts will not take two battery boxes unless they are the small footprint Gr24s. If you have height above, get two 6v boxes, about 10 to 12 bucks online. If they fit your rails I would say ANY BRAND NAME GC2 6VOLT batteries. The common size is 220 amp but you can find them with 208 to 235 amp ratings. More is obviously better but around SoCal the most economical deal seems to be Costco Tire dept which has the Interstate 220 amp 6vs for $93 plus a $15 core charge where the are others locally with $30 core charge.

We also have a chain store BATTERIES PLUS and ordering online to pickup at the store is probably our second best cost effectiveness choice here.

Then to remain true to form, I have to suggest you look at solar. Easy to install and makes battery charge nearly a non issue.https://www.windynation.com/Polycrys...631?p=YzE9NDY=

YouTube will teach you all you need to know to install solar.
Most importantly, have fun. (OH, AND NEVER RUN YOUR BATTERIES DEAD.)

[BaltimoreMark]

I am thinking of upgrading to 2 GC2 batteries as recommended. Any idea where I can get a battery box that they will fit in? I have a Surveyor 200mble so they will be on the front frame behind the propane tanks.

[TitanMike]

When in doubt check Amazon

https://smile.amazon.com/Powerhouse-...70_&dpSrc=srch

OR

https://smile.amazon.com/NOCO-HM306B...85QXE6N63F5P9G

[pgandw]

There used to be plastic battery boxes to fit 2 GC-2s length-wise for about $40. I can't find them anymore. By far the current cheaper option is 2 separate GC-2 (tall Group 24s also work) boxes (maybe $15 each). These will fit the rails. If you want a single box for the 2 batteries, it now costs $80+.

You will add 60-80lbs to your tongue weight.

Fred W
2019 Flagstaff T21TBHW A-frame (with dual Costco/Interstate GC-2)
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time

[bikendan]

Originally Posted by BaltimoreMark

I am thinking of upgrading to 2 GC2 batteries as recommended. Any idea where I can get a battery box that they will fit in? I have a Surveyor 200mble so they will be on the front frame behind the propane tanks.

Walmart has them.

[pmsherman]

Originally Posted by TitanMike

.....
I've been a fan of installing 2) 12v true deep cycle batteries rather than 2) 6 volt deep cycle batteries. With the 12 v batteries in parallel you have two batteries, each capable of delivering 12 v power. If one fails you still have one to get by on until you can replace.

If a 6 volt battery in series fails, you have no power.
......
.

While it's true that using two 12V batteries will give you one to use when one of them fails, this really doesn't work well, especially with flooded (wet cell) batteries.

When the first battery fails, almost always a shorted cell, it will immediately draw the remaining good battery down to the same voltage as the dead one. You now have two batteries that will read around 10V. Your problem is determining which battery is still good. The best way is to charge them individually and see which one holds a charge.

If you now replace one battery, you have the situation where one battery is new and the other is used. Not only that, but the used battery had had a full discharge cycle and may have sat at that state for a number of hours before being recharged. This has started sulfication of the plates which further reduces the old "good" battery's capacity.

You'd probably be better off replacing both batteries since, if one failed, the other's failure may not be far in the future. Don't forget that replacement batteries are not difficult to find. They're available at any auto parts store, WalMart, Costco, Sam's club, and other big box discount stores.

The OEM chassis battery in my 2011 Georgetown failed around two hours out from my destination that day. At 8pm, well after the local WM auto department closed, I was able to purchase the replacement and, at the customer service desk, trade in the dead battery instead of paying a core charge.

Phil