# Battery Charging



## MBrady (Apr 15, 2010)

I have my traler with dual batteries in my garage. what is the best way to maintain the battery between uses. Should I get a disconnect switch to eliminate the battery from draining? Plug the trailer in and leave it plugged in? Or once a week plug it in over night? so far I have been plugging it in once a week just to keep the batteries charged. Not sure if this is the best thing to do. Any feedback would be greatly appreciated. I'm a fairly new member, and this site has been great for a new trailer owner


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## ED_RN (Jun 25, 2006)

Any of your ideas will work. With the cut off switch the propane alarm won't drain the battery over time. I usually plug mine in for a day every week or two, the batteries are almost 4 years old and still hold a charge. If you decide to leave it plugged in just make sure you check the water level in batteries regularly.


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## maddog (Dec 16, 2009)

MBrady said:


> I have my traler with dual batteries in my garage. what is the best way to maintain the battery between uses. Should I get a disconnect switch to eliminate the battery from draining? Plug the trailer in and leave it plugged in? Or once a week plug it in over night? so far I have been plugging it in once a week just to keep the batteries charged. Not sure if this is the best thing to do. Any feedback would be greatly appreciated. I'm a fairly new member, and this site has been great for a new trailer owner


For years I have left mine plugged in all season with no battery issues. And in the winter would pull the battery and use a maintainer. In 9 years of owning my last TT I replaced 1 battery at around 4years old.


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## hautevue (Mar 8, 2009)

Winter storage: if the garage is not heated, take the batteries out and bring them into the basement or some non-freezing area. Put the charger on them about every 3 - 4 weeks. Always check the water level, and I recommend buying a battery hydrometer--that's the float thingy that gives you the specific gravity (and therefore the charge level) of the fluid. They cost maybe $5 at Trak Auto and other auto supply stores. That will tell you how often you need to top off the battery charge. I have to do it about every 3 - 4 weeks, and so I run each batt (I have two 12 volt batteries) on the charger for about 6 - 8 hours.

Summer: I recommend a battery cutoff switch (see elsewhere on this site for these things and how to install). This will prevent the propane detector, the CO detector, a smoke detector, and the Jensen radio from draining your batteries over about 2 weeks. Those devices are all hard-wired into the 12volt system and there is no switch to kill them. So you have to be able to cut off the ground line to stop the drain.

During summer non-use, I suggest charging the batts with a regular battery charger rather than depend on the TT power converter to do it. "Normal" power converters supplied into most TTs are simple chargers, and are not "three stage" ones that taper off the charge when the battery is fully charged. Thus they can overcharge the batts and run them low on fluid. They work fine when towing, camping, and general usage, but if you leave the TT hooked to shore power in your garage for 3 - 4 weeks between trips, you run the risk of running the fluid out, etc.

Check the battery fluid level periodically, and wear goggles to protect your eyes; when you put that screwdriver under the plastic cap and flip it off, you can get a spritz of battery acid. Bad for your corneas! [grin!]


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## Up State NY Camper (Apr 7, 2010)

I have another battery question. If dry camping, and you use your vehicle to charge your battery? Some tech's said yes, some said no. I would assume the answer is yes, but how efficient is it? Obviously I don't have a camping generator yet.

Also I noticed some of you upgraded to two 6v batteries vs one 12v or two 12vs. I have the old battery from my old RV and it's a 12 volt. Can I use both? How? Is using two 12 volts at the same time like using 24 volts or should they be on a switch? Are two 6 volts better than two 12? Thanks for your DC expertise!


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## rdvholtwood (Sep 18, 2008)

MBrady said:


> I have my traler with dual batteries in my garage. what is the best way to maintain the battery between uses. Should I get a disconnect switch to eliminate the battery from draining? Plug the trailer in and leave it plugged in? Or once a week plug it in over night? so far I have been plugging it in once a week just to keep the batteries charged. Not sure if this is the best thing to do. Any feedback would be greatly appreciated. I'm a fairly new member, and this site has been great for a new trailer owner


If it's during the season, I don't do anything. After the winter season, I put the battery on a slow charge to bring it back up to capacity.

I know your supposed to keep it on trickle charge over the winter, but, I haven't and probably should.


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## hautevue (Mar 8, 2009)

Up State NY Camper said:


> I have another battery question. If dry camping, and you use your vehicle to charge your battery? Some tech's said yes, some said no. I would assume the answer is yes, but how efficient is it? Obviously I don't have a camping generator yet.
> 
> Also I noticed some of you upgraded to two 6v batteries vs one 12v or two 12vs. I have the old battery from my old RV and it's a 12 volt. Can I use both? How? Is using two 12 volts at the same time like using 24 volts or should they be on a switch? Are two 6 volts better than two 12? Thanks for your DC expertise!


You can upgrade from one 12v battery to either two 12v or two 6 volt.

Two 12's: you wire the batts in parallel to keep the voltage at 12 v. If the batts are labeled A and B: wire from A minus to B minus. Go from either A minus or B minus to ground (or into your battery cutoff switch and then go to ground). Connect a cable between A plus and B plus. Wire the black wire of the TT (the Hot or plus) to A plus or B plus, whichever is the easiest and shortest cable.

Two 6's: wire the batts in series to end up with 12 volts to the TT. If the batts are labeled A and B: wire from A minus to B plus. Wire from B minus to ground (or into your battery cutoff switch and then go to ground). Wire the black wire of the TT (the Hot or plus) to A plus.

There are several good drawings and photos of both setups here on the site.

Since I have two 12s, I won't comment on the two six volt setup, but those who use that love it. I've dry-camped for 4 days in Glacier Nat Park and we were getting to the end of battery power after 3 1/2 days. And the heat came on at night--it was in the 40s over night in July, and we had no generator to help. But I'm not a user of the two sixes setup so someone else can contribute info on that.


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