Best Battery Maintainers for RVs: Brand Picks, Sizing, and Dual Bank Tips

[Scottro]

Anyone out there have a recommendation for a battery maintainer/tender?
We just took our coach out for the weekend, but it had previously been sitting for nine months with nothing maintaining the batteries. They were OK, but the chassis batteries were getting fairly low, the chassis batteries are lead acid.
My thoughts were that I would go down to the storage and move the tender back-and-forth from chassis batteries to house batteries every 4 to 6 weeks when we aren’t using it. Thanks for any advice or info you may have.
Scott Orlando

 

[jymbee]

Anyone out there have a recommendation for a battery maintainer/tender?
We just took our coach out for the weekend, but it had previously been sitting for nine months with nothing maintaining the batteries. They were OK, but the chassis batteries were getting fairly low, the chassis batteries are lead acid.
My thoughts were that I would go down to the storage and move the tender back-and-forth from chassis batteries to house batteries every 4 to 6 weeks when we aren’t using it. Thanks for any advice or info you may have.
Scott Orlando

I bought a couple of these NOCO models. Haven't used them extensively yet but seem ok:

https://tinyurl.com/m9xryzt8

 

[gwinger]

I use the Deltran Battery Tenders on my motorcycle and trailer batteries.
I have the Battery Tender Plus 1.25 amp.
They also make 3, 4, and 5 amp models.
All are "Smart" chargers that monitor the voltage and turn off when charged.
Come back on if needed.

 

[Gary RV_Wizard]

Most all of the lead-acid battery maintainer/chargers these days are "smart" and "3-stage". Even the Cen-tech models from Harbor freight. They will all do the job nicely and not overcharge or "boil" them. But they should be sized properly for the battery bank amp-hours (or CCA rating). A 1A model is enough for a single battery up to around 115AH (or a CCA of 650), but almost any multiple battery configuration will total 170AH or more and will benefit from a larger model, say 1.5A-3A. Same for the twin starting batteries on most diesels or the 750 CCA singles used on big gas engines. If your battery bank totals 400 AH or more, I suggest a 5A model. Some sources use 1A per 100AH as a rule of thumb for battery maintainers. I wouldn't argue against that.

There's no danger from a too-small charger, though. It may not keep the batteries up to 100%, but it will still keep them alive.

 

[Mark_K5LXP]

Nothing says you can't combine the banks for one tender to maintain.

Mark B.
Albuquerque, NM

 

[Isaac-1]

I would stick with reliable brands like NOCO, or Deltran as in my experience they tend to last, unlike some of the lesser known brands which in my experience may die for no obvious reason at random.

 

[DonTom]

I would stick with reliable brands like NOCO, or Deltran as in my experience they tend to last, unlike some of the lesser known brands which in my experience may die for no obvious reason at random.

I use them on 7 of my ICE vehicles--various brands-- over many years, so far I have only had one crap out.

IMO, they are all about the same, just decide how many amps you want to maintain at. While I tend to use smaller current ones on smaller batteries, I don't think that makes much difference as once the battery is fully charged, they don't stay on as long if they are a higher amperage before they go off. They usually turn off at around 13.4 volts. A few tenths below that and they are on again.

-Don- Douglas, AZ

 

[Wasillaguy]

My trickle charger is a single 100w solar panel permanently mounted on the roof with controller wired directly to the house batteries (not cut off by the dc cutoff switch).
Has worked great for us. Of course wouldn't work for covered storage.
Start batt just has a disconnect, but that has worked well. We leave the RV untended for 5 months in summer storage.

 

[Scottro]

Thanks for the advice and recommendations from everyone.
Mark, you mentioned combining the banks together to use just one tender, that makes sense that that would be the way to go. Is there anything in particular I need to do to be able to charge the chassis and house batteries at the same time?

 

[Rene T]

I see that NOCO has a 4 amp maintainer for two banks. 2 amps for each bank or battery

 

[DonTom]

I see that NOCO has a 4 amp maintainer for two banks. 2 amps for each bank or battery

This Class A has a Go-Power controller with two such outputs.

I added a Victron DC2DCC to charge up my added 300AH lith system.

The way this RV works is if any battery is being charged, by solar or anything else, all three systems charge. But the DC2DCC will only charge my added 300AH lith battery after all the stock batteries are charged up as I have it adjusted to to turn on at 13 volts.

-Don- Douglas, AZ

 

[Lou Schneider]

My trickle charger is a single 100w solar panel permanently mounted on the roof with controller wired directly to the house batteries (not cut off by the dc cutoff switch).
Has worked great for us. Of course wouldn't work for covered storage.
Start batt just has a disconnect, but that has worked well. We leave the RV untended for 5 months in summer storage.

MPPT controllers are getting cheap. I just bought (2) no-name 60 amp MPPT controllers from Amazon for $23 each. I'll see if they're any good when they get here next week.

Edit: They're now selling a 100 amp version for $25. Wow.

https://www.amazon.com/Controller-Battery-Intelligent-Regulator-Display/dp/B0BLVMC2JS

 

[Scottro]

MPPT controllers are getting cheap. I just bought (2) no-name 60 amp MPPT controllers from Amazon for $23 each. I'll see if they're any good when they get here next week.

https://www.amazon.com/Controller-Battery-Intelligent-Regulator-Display/dp/B0BLVMC2JS

Lou, does that particular unit just go from the solar panel to the controller and then charges the battery? You have to have solar panels to use that controller correct?

 

[Lou Schneider]

Lou, does that particular unit just go from the solar panel to the controller and then charges the battery? You have to have solar panels to use that controller correct?

Right - that's the definition of a solar controller. It takes input from a solar panel and conditions it to charge a battery. 60 amps can process up to 720 watts at 12 volts or 1440 watts at 24 volts, both fairly large systems.

Solar panels are also getting cheap - places like Santan Solar and Facebook Marketplace have used panels removed from commercial installations with plenty of life left. Combine two or three of their $45 250 watt panels, a MPPT controller like the one above to convert them to 12 volts and some mounting hardware, wire and fuses and you can make a very capable solar setup for $150-$200 plus shipping if you can't find the panels locally.

 

[DonTom]

They're now selling a 100 amp version for $25. Wow.

The one in your link says "60A".

-Don- Dragoon, AZ

 

[Wasillaguy]

I'm normally not an "early adapter" kind of geek, but I guess I was with MPPT. Pretty sure I paid over $200 for my 1st MPPT controller, back when $200 was still significant.

 

[Lou Schneider]

The one in your link says "60A".

-Don- Dragoon, AZ

I know. That's what I ordered. Scroll down the page a bit for the 100 amp version.

 

[DonTom]

I know. That's what I ordered. Scroll down the page a bit for the 100 amp version.

You must mean this one.

I didn't see any spec for the max solar Voc or max solar voltage input, not even in the PDF manual.

I am not looking for a solar controller, but I wonder if that would work with my three solar panels in series with a Voc total of 73.5 volts.

-Don- Dragoon, AZ

 

[Isaac-1]

A lot of the cheaper MPPT controllers are limited to a VOC of only about 25V, some mid range models have a max VOC of 50V. Anything over that and I would stick with a known brand that prominently advertises the VOC limits such as Victron where most models can handle a VOC of 100V or more.

 

[Lou Schneider]

A lot of the cheaper MPPT controllers are limited to a VOC of only about 25V, some mid range models have a max VOC of 50V. Anything over that and I would stick with a known brand that prominently advertises the VOC limits such as Victron where most models can handle a VOC of 100V or more.

Yeah, when I looked at the user manual for the one I cited the rated solar voltage is 15-23 volts when operating with a 12 volt battery, 30-45 volts when using a 24 volt battery. This suggests the limiting factor is heat dissipation within the unit. If so, it may be fine with some enhanced cooling or operating at half of it's rated current into a 12 volt battery.

I think I'll keep the two I ordered. $46 won't bankrupt me. One will work as I originally intended with 4 older 18 volt panels I want to make into a portable ground mounted system, the other I may just connect to a couple of 36 volt panels and see where the magic smoke comes out.