We camp with elec hookups 80% of the time, so I've decided to continue to use the group 24 marine battery for those trips as it is more than adequate. I'm also keeping the cheap WFCO converter (as long as it lasts) because it's also adequate when on hookups. Once or twice a year though, we want to be able to dry camp for a 3-4 night stretch. I bought a pair of Trojan T105s and plan to use them only when we dry camp. Then, since we store the camper offsite with no electricity, I plan to remove the T105s when we get back from a trip so I can fully recharge them at home in the garage. The thing I'm wondering is how I should charge them at home. I have a typical car battery charger and I also have a Battery Tender Jr. Let's say I get home and the GC2s are at 50% SOC. Can I just hook them up to the Battery Tender and expect them to receive a full charge? Or should I use the car charger first? Or do I need to buy something better like a VEC1093?Thanks in advance for any advice!

First. Most battery charging hardware is designed for 12 volt batteries these days so put 'em in series and call them a 4-D (that is what they are electrically)Then use a SMART CHARGER that can fully charge 'em to bring 'em up, switch to the Battery Tender 24 hours later. and monitor every couple months to insure it's holding them (It might not, less it is one of the larger models that is a lot of battery for it to tend) re-apply smart charger if needed.

wa8yxm wrote:First. Most battery charging hardware is designed for 12 volt batteries these days so put 'em in series and call them a 4-D (that is what they are electrically) "Most" charging hardware these days is still switchable for 12 or 6 volts.I think the initial bulk charging should be done on each battery by itself. After that, the tender can be used with the two in series.......if both settle back to the same voltage after a bulk charge and a rest.The only way to really know if each cell is charging properly is a specific gravity test but that's probably overkill in most situations.

I use the VEC1093 Equalize to get the 6v pairs to "baseline" (highest it will go) SG as seen with an hydrometer. Then I put them on a Float charger at a voltage suitable for the prevailing average temperature. Every month I give them another shot of Equalize with the VEC to prevent "stratification" then return them to Float.I never have more than two months between camping trips off grid, and that works fine for that. Longer term storage has other "issues" that can come up trying to Float deep cycle batts like 6s vs UPS batts with lower baseline SGs. However, since it seems everything you could do then is wrong :) I would just keep on doing my routine and so what if the batts only last 8 years instead of 10?

Charge them in series, just as they'll be used.A battery tender plus will charge them batteries in series, no problem.Better??,....there ain't nothing better,...the tenders are even temp compensated. And they charge at near 15 volts, then drop to float.....12.9 in hot weather.The Tender JR mite take longer, maybe use a bigger charger first.

Keep 'em all winter at 92% state of charge all winter and your battery store will send tou a free calendar being a frequent customer.FIND OUT!using a hydrometer if your Einstein Charger CAN get the batteries to 100% state of charge. A voltage limited maintainer limited to 13.4 volts might need 361- years to acheive full charge from 92% SOC. Guess if you want to your battery vendor will blow you a kiss.

Best/proper way to charge GC2's at home | Good Sam Community

30 Replies

jake2250
Explorer
Aug 09, 2015
http://www.geniuschargers.com
I use one of these, they are outside in the shed and I monitor the water level, they have stayed out there for over six months at a time on the charger and are always ready to go.

I have the G3500
westend
Explorer
Aug 09, 2015
I'd suggest to bypass all of the anticipated maintenance process and install both 6V's on the RV, along with a solar system to charge them.
I don't like lugging batteries around.

All portable chargers are not the same. You would have to measure charge current, know the parameters, and use a hydrometer to get the most life out of your 6V batteries. My temp compensated solar system does a better job than I can when parked in storage and I monitor electrolyte level and SG a few times each year. It is, basically, hands-off.
RDMueller
Explorer
Aug 09, 2015
Vulcan Rider wrote:

And if you have access to power where the RV is parked, no reason to remove the batteries either.

That is the problem, no power where the rv is stored. So it's either remove the batteries and charge them at home or put solar on the rv.
Vulcan_Rider
Explorer
Aug 09, 2015
RDMueller wrote:
Or is there something portable that will do the job? I'm basically looking for a product recommendation.

You are making this much harder than it IS.

Any name brand fully automatic "tender" type charger will be just fine. Something with a 1.5 or 2 amp (or slightly higher) capacity might be slightly better to bring them up when down. Available at WalMart or any auto parts store or RV dealer.

And if you have access to power where the RV is parked, no reason to remove the batteries either.
RDMueller
Explorer
Aug 09, 2015
Thanks for the replies. I definitely was thinking I'd charge in series just like I use them. The main question is what to charge with. For people who park the rv with shore power, it's easy - ditch the WFCO, install a quality 3 stage converter, plug in when you get home, done.

But, because I want to charge the batteries at home (out of the rv), I'm just not sure what the best way is to charge them. I guess I could buy a quality 3 stage converter and install it in my garage! Or is there something portable that will do the job? I'm basically looking for a product recommendation.

One other possibility I'd consider is solar and then just leave the batteries in the rv for storage. With a proper solar setup installed, is it ok to return from a trip with batteries at, say 50%, and then expect solar to fully recharge the batteries? Storage facility is full sun btw.

Whatever I do, I want to take good care of these batteries so they last!
MEXICOWANDERER
Explorer
Aug 09, 2015
Keep 'em all winter at 92% state of charge all winter and your battery store will send tou a free calendar being a frequent customer.

FIND OUT!

using a hydrometer if your Einstein Charger CAN get the batteries to 100% state of charge. A voltage limited maintainer limited to 13.4 volts might need 361- years to acheive full charge from 92% SOC. Guess if you want to your battery vendor will blow you a kiss.
RJsfishin
Explorer
Aug 09, 2015
Charge them in series, just as they'll be used.
A battery tender plus will charge them batteries in series, no problem.
Better??,....there ain't nothing better,...the tenders are even temp compensated. And they charge at near 15 volts, then drop to float.....12.9 in hot weather.
The Tender JR mite take longer, maybe use a bigger charger first.
BFL13
Explorer II
Aug 08, 2015
I use the VEC1093 Equalize to get the 6v pairs to "baseline" (highest it will go) SG as seen with an hydrometer. Then I put them on a Float charger at a voltage suitable for the prevailing average temperature. Every month I give them another shot of Equalize with the VEC to prevent "stratification" then return them to Float.

I never have more than two months between camping trips off grid, and that works fine for that. Longer term storage has other "issues" that can come up trying to Float deep cycle batts like 6s vs UPS batts with lower baseline SGs.

However, since it seems everything you could do then is wrong :) I would just keep on doing my routine and so what if the batts only last 8 years instead of 10?
Vulcan_Rider
Explorer
Aug 08, 2015
wa8yxm wrote:
First. Most battery charging hardware is designed for 12 volt batteries these days so put 'em in series and call them a 4-D (that is what they are electrically)

"Most" charging hardware these days is still switchable for 12 or 6 volts.

I think the initial bulk charging should be done on each battery by itself. After that, the tender can be used with the two in series.......if both settle back to the same voltage after a bulk charge and a rest.

The only way to really know if each cell is charging properly is a specific gravity test but that's probably overkill in most situations.
wa8yxm
Explorer III
Aug 08, 2015
First. Most battery charging hardware is designed for 12 volt batteries these days so put 'em in series and call them a 4-D (that is what they are electrically)

Then use a SMART CHARGER that can fully charge 'em to bring 'em up, switch to the Battery Tender 24 hours later. and monitor every couple months to insure it's holding them (It might not, less it is one of the larger models that is a lot of battery for it to tend) re-apply smart charger if needed.

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Best/proper way to charge GC2's at home

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