Brand new member. First question: I use two 6 volt 232Ah batteries in my RV. I run them in series. I want to purchase a battery maintainer. I see that some of the maintainers say that they are recommended for up to a certain Ah (often for up to a 120Ah battery). Someone told me that, for my purposes (mostly winter storage or attaching it for the weeks that I don't use the RV) even the 120Ah maintainer would be fine (he said it would merely take longer to fully top it up). Is that correct? I need a maintainer but I want to make sure that it will FULLY maintain my batteries to the full 232Ah.

Best procedure is to fully charge the batteries with your RV's converter or a charger. The maintainer can then be used to float the batteries.

I hook a marine multi stage charger directly to my battery.bumpy

I would not get in a position where it needs to be "topped up" unless you boondock. If you are storing it where you have access to AC to use the maintainter while the batteries are still in the trailer, just get a dog bone to convert the RV shore power plug down to a standard 110 house plug and keep the trailer plugged in all the time, than in the warm season it is always full and being maintained by the built in converter/charger in the trailer. For winter take the batteries out of the trailer, Canadian winters will crack them and permanently damage them. Store the batteries on a maintainer in an above freezing location for the winter.

westend wrote:Best procedure is to fully charge the batteries with your RV's converter or a charger. The maintainer can then be used to float the batteries.This.Get a name brand fully automatic charger of at least 2 amp capacity.If they are anywhere near to a full charge, it should be able to top them up.Leaving the RV plugged in is an option but the onboard systems often are not good enough for really long term use like that. You could just plug the RV in for a couple of days every month though.

I leave my batteries on a "really working" SMART MODE CONVERTER/CHARGER unit in my trailer all the time when sitting at home. These working smart mode unit really take care of your batteries for you.I would become very knowledgeable how your batteries work and watch and maintain them. The batteries is your trailer life-line and will last many years if properly maintained. If your Trailer on-board converter/charger is the single mode type unit that only puts out 13.6VDC then this will require you to keep an constant watch on your battery fluids as 13.6VDC will tend to boil out battery fluids over time. Once the battery fluid level drops below the cell cores then the battery will start building crud on them and eventually short between the cores. When this happens it is usually game over for the battery.Also keep in mind that a fully charged battery will do quite well when completely disconnected at one of the battery terminals when in storage mode. They will hold their charge for very long periods of time even in the winter months. Here again you would want to monitor them and put back on charge occasionally to keep them topped off.Parasitic drains from installed trailer appliances and devices electronics boards left connected to your trailer battery setup can drain your batteries rather quickly sometimes in just a few days time. You need to be mindful of what parasitic drains you have in your trailer. The big rule of thumb for me was to never let my batteries drop below their 50% charge state which is pretty close to only 12.0VDC. When camping off the power grid my number one priority is watch my battery DC VOLTAGE with an inside mounted monitor digital meter setup. It takes planning to know what you operate when camping off the power grid and the game plan is to make it until the next morning with what you have and then recharge the batteries back up to at least their 90% charge state each so you can do this all over again for the next day/night run off the batteries. You just can't show up at the off road camp sites and expect it all to work for you... It usually gets dark on you around 10PM at night when you first do this haha...Camping in your back yard has a lot of merit sometimes learning how things work battery wise.We enjoy our many camping trips off the power grid over the years the best...Just some of my thoughts here...Roy Ken

Battery maintainer help | Good Sam Community

27 Replies

acowhite
Explorer
Aug 19, 2015
Tecmate just informed me that the float voltage is 13.6v.
MEXICOWANDERER
Explorer
Aug 18, 2015
They never answered a question about what voltage they float at. Fascinating.
acowhite
Explorer
Aug 18, 2015
Thanks everyone. I decided to purchase the Optimate 5 Voltmatic. I'll keep the trailer plugged in during the camping season and, once the batteries are removed for winter, will keep them attached to the Optimate. Should be ok.
MEXICOWANDERER
Explorer
Aug 18, 2015
750 -800 ma wall wart just like Westend above describes is perfect for a 100-amp hour battery and not even in the ballpark with two 100-amp batteries. This size wall wart is common as can be and you can get one cheap at allelectronics.com or MPJA.com

These things work continuously for years and years and don't break. For flooded batteries only. A 400-ma may be enough for an AGM battery but thorough testing of final voltage float is essential. For cold weather hibernation a one amp 15 volt model may fit the bill. But for max life a top charge every 2-3 months is recommended for a flooded battery.
westend
Explorer
Aug 18, 2015
What I use for my small inventory of loose 12V batteries is a stand-alone shop charger and then tend them on a 12V (nominal) wall wart with two alligator clips. The wallwart has a no load output of 750 ma at 15VDC. When first connected to battery the charge voltage lowers to the batteries existing voltage. I monitor the voltage rise until it attains 14V, usually a period of several days. I then, disconnect the wallwart and connect it to the next battery. This regimen is repeated a few times a year to keep the batteries top charged. I should also be doing an equalizing process but that more often gets skipped when dealing with these castoffs. I use these batteries in my lawn equipment and for emergency pump use at the house.
randallb
Explorer
Aug 18, 2015
A Battery Tender Jr @ .75A (about $20) will do the job just fine. Anything more for storage is just overkill. I would pull in to the big garage, turn off the battery disconnects and plug in the hardwired BT Jrs (2). The longest it ever took for them to go in to float mode was 2 days. Our HR had 2 large 12V (Group 31?) chassis and 2 6V (GC-2) batteries for the house. You want to charge a battery slowly for max life. We abuse them enough when we are "camping" and run them through repeated drain/recharge cycles.
MEXICOWANDERER
Explorer
Aug 15, 2015
I do not like ads for
"PLUGGER-IN AND LETTER RIP" chargers, tenders, or other energy sources.

ZERO numbers except "FOUR AMPS OUTPUT!" Buying blind.

"HERE! BUY THIS HERE BATTERY! IT'S PERFECT FOR YOUR R.V.! CONNECT THE CABLES AND GO!" Full color picture of the battery - a red headed man, blonde wife, two dark headed children all standing around their RV showing 118 teeth. numbers? What numbers except for C.C.A.

I've been sucker-punched enough in my life buying stuff whose ads screech FANTASTIC! UNBELIEVABLE, SIX STAGE CHARGING, NEVER GETS DULL, JUST READ READER COMMENTS BELOW! Then along came LED chips and I had to learn how to send questions to the manufacturer to prevent being defrauded there. FIND AN LED FIXTURE AD that lists milliamps required @ 12-volts. Then you've found a responsible company.

I do not need atomic LASER clock accuracy. But neither do I need an overhyped watch that tells high and low tide, phases of the moon and loses 4-minutes a day.
wa8yxm
Explorer III
Aug 15, 2015
You can get larger battery minders.. They make them in assorted sizes.

Shop a batteries Plus store to find the model you want and then go online to see if you can find a better deal and make a decision. B+ has an assortment in stock most of the time.
Vulcan_Rider
Explorer
Aug 15, 2015
acowhite wrote:
Vulcan Rider
The Optimate 5 Voltmatic is about $65USD (I am in Canada).
CHARGING AMPS : 4A (6V) / 2.8A (12V)

I think that would be a good choice.

But.....you had better wait until at least one of the "professional experts" on here gives it their blessing. ;)

So....here's the thing.....maybe an analogy would help with the explanation:
You ask what time it is.
One answer from a professional in the "time field" tells you in some detail how to build a clock.
Another answer refers you to a Stephen Hawking book on time relativity and how it relates to the history of the universe.
I tell you it is 8:39 AM, Eastern Standard time.

Also I forgot to mention that it is not necessary to remove batteries from your RV in the winter time IF you have access to power where it is parked. A fully charged battery doesn't freeze until about -70 F and moderate cold actually tends to extend their life.

You should visit your RV about once a month though to check various things, like looking for water leaks and rodent incursion and checking the water level in the batteries and casually observing that the tires haven't gone flat.

K.I.S.S. :B
acowhite
Explorer
Aug 15, 2015
Vulcan Rider
The Optimate 5 Voltmatic is about $65USD (I am in Canada).
CHARGING AMPS : 4A (6V) / 2.8A (12V)