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BeenThereB4 · 06-23-2021, 11:59 AM

Since my class A often sits idle for awhile, it becomes necessary (of course) to maintain the state of charge in the batteries.. This one has the typical setup, one chassis battery and two coach batteries, and the electrical panel with battery disconnect switches. I am wanting to permanently install a pair of trickle chargers under the hood so that one of the chargers is on the single (chassis battery) and the second charger is on the two (coach) batteries.. I have had pretty good results in the past using the Battery Tender Jr. type of trickle chargers on some of my (other) vehicles, but never had an occasion to trickle charge a pair of deep cycle batteries connected in parallel.. I am sure many people on this site are maintaining their RV batteries using trickle chargers.. So my question is, will the Battery Tender Jr (0.75 Amps) handle the two big deep cycle coach batteries, or will I need to spend a little extra and purchase a larger output Battery Tender Type of trickle charger (typically between 1 and 3 amps) for the pair of deep cycle batteries ?
Also, would I save any wear and tear on the electrical panel (with the "use" and "store" switches inside) if I were to install a pair of Battery disconnect switches under the hood (which would interrupt the ground cables
for the chassis and coach batteries ? I am told the main electrical disconnect panels do wear out, and I see they are rather expensive... I wonder what steps, if any, can be taken to preserve that panel longer ?
Any helpful advice would be much appreciated.. Thanks Very Much Everyone..

Fiesta48 · 06-24-2021, 07:51 AM

I leave my RVs plugged into 120v 100% of the time. Only pulls 0-2A. Relays are cheaper than batteries. My 41' DP has 8. Probably over $1000. Just remember to check water levels every 3-6 months.

153stars · 06-24-2021, 11:15 AM

You can find a decent dual 20a marine maintainer charger for about $100. It will have enough juice to keep up or recharge a pair of house batts during or after using a few lights going in or doing stuff , tests or repairs on house or chassis and not have to plug in. Not that good maintainers are great but low power maintainer are just that.

Flyer15015 · 06-24-2021, 11:28 AM

B4,
I do the very thing you describe.
One "Battery Tender" for the chassis, and one for the (2) 12 volt deep cycle coach batteries. I do unhook the (-) posts if she is going to set more than a week.
All my "Walmart" batteries are 6+ years old, and have served us well.

Mike in Colorado

Mark_K5LXP · 06-24-2021, 11:48 AM

A good rule of thumb for a maintainer is 1/100th of the capacity. So for a 200Ah house battery a 2A maintainer is about right. .75A is pretty light, it might keep up if the batteries are in good shape and start out at 100% but may not be enough depending on the batteries or environment. I much prefer to use maintainers with the batteries disconnected, then I know for sure they will not get overcharged and if the mains gets disconnected, they will not go flat from phantom loads.

Mark B.
Albuquerque, NM

BeenThereB4 · 06-26-2021, 10:32 AM

Thanks everyone for the great input on this subject. . I opted to order two Battery Tender Jr. Chargers, with the intent being to have them in place under the hood, connected and powered up at all times when my Class A is sitting idle.. One charger on the chassis battery and one on the (pair of) coach batteries.. This way I should be able to maintain an adequate state of charge without any risk of either sulfating or cooking (overcharging) my batteries.. Just need to mark it on the calendar to check the electrolyte level in battery cells (that seems to be a frequently neglected item on the list of "must do" maintenance by many RVers

Much appreciated, have a great day N Be Safe Everyone

astrnmrtom · 06-26-2021, 12:08 PM

I put in disconnect switches also. One thing to note about low amperage maintainers is phantom loads. These can strip some power off the top of your charger leaving less for the batteries. Factory disconnects don't always completely disconnect all power. I discovered that the hard way by coming back to dead batteries despite the use of the factory disconnect. After installing true manual disconnect switches, my batteries always remained in great shape.

BeenThereB4 · 06-27-2021, 09:40 AM

Quote:

Originally Posted by astrnmrtom

I put in disconnect switches also. One thing to note about low amperage maintainers is phantom loads. These can strip some power off the top of your charger leaving less for the batteries. Factory disconnects don't always completely disconnect all power. I discovered that the hard way by coming back to dead batteries despite the use of the factory disconnect. After installing true manual disconnect switches, my batteries always remained in great shape.

Thanks very much, MrTom, isolating the batteries so the phantom loads no longer impose any load will be my next priority, so I will be ordering the manual battery disconnects (I like the "marine" type switches.) For now, just disconnecting my ground cables at the batteries will suffice.
On many vehicles, disconnecting the battery leads also clears any codes from the control modules and such, perhaps that is why the OEMs do not seem to equip the (new) motorhome with manual disconnect ?
In any case, the convenience factor of just flipping the two switches and plugging the battery chargers into shore power all in one move should insure my RV is ready to go at a moment's notice, and I should seldom be inconvenienced by defective batteries .. A "win -win" situation..

Sonic · 06-27-2021, 12:44 PM

I use two BatteryMinders that have full time pulse desulfation.
2 amps on the chassis batteries, and a selectable 2/4/6 on the house batteries.
Both keep float voltage at 13.4 volts as long as the inverter is turned off as well as the two OEM disconnect switches.
Standby power (aka Phantom loads) is not an issue as long as the trickle chargers are properly sized.

BeenThereB4 · 06-28-2021, 10:52 AM

Quote:

Originally Posted by Sonic

I use two BatteryMinders that have full time pulse desulfation.
2 amps on the chassis batteries, and a selectable 2/4/6 on the house batteries.
Both keep float voltage at 13.4 volts as long as the inverter is turned off as well as the two OEM disconnect switches.
Standby power (aka Phantom loads) is not an issue as long as the trickle chargers are properly sized.

Thank You, Sonic.. The Battery Tender Jrs, I ordered put out .75 amps, which is adequate for my single (chassis) battery, but a bit light for the pair of (coach) batteries.. I have another vehicle which is seasonably driven I can use the Batt, Tend. Jr. on, while switching over to another (slightly larger output) charger for my pair of coach batteries (2 amps or so should be adequate) just to maintain state of charge without risking overcharge.. i still plan to add the marine type disconnect switches to interrupt the grounds.. I will be soldering some good copper terminal ends on the existing cables to insure good conductivity..
On another note, maybe I should start a new post inquiring about what brand(s) of Battery Tender Type maintainer/chargers are the most satisfactory, in terms of effectiveness and longevity ? Or perhaps this subject has been addressed previously on this form..
In any case, thanks for all the great advice, everyone, much Appreciated