Community Forums

Str8edg · 02-21-2019, 10:18 AM

My folks allow me to store our RV at their place. I don't want to take advantage buy plugging in to their power or installing a 50amp pole for the RV.

So my question, what will be needed or recommended to keep my house and engine battery in top working order in my 2018 Class A FR3? We like to go out every other month or so with our schedules for weekend stints. We do live in sunny SWFL so solar could work if advisable.

Many thanks, Rich

Persistent · 02-21-2019, 10:32 AM

Your requirements pretty much limit you to solar or periodic generator use. There are no other practical solutions.
Keep in mind, you do not need 50 amps or 50 amp connection to maintain house and chassis batteries. Prop the refrig door open and trip all the breakers except the converter/charger and plug in using a 15 or 20 amp outlet and dog bone adapter. You can also pull 12 volt fuses or breakers to disconnect other parasitic loads if necessary.
You can also pay them a small amount each month to ease your conscience. That is a lot cheaper than installing solar.

Str8edg · 02-21-2019, 10:43 AM

Something like this is no good?

https://www.harborfreight.com/15-wat...ger-68692.html

Persistent · 02-21-2019, 11:08 AM

It is cheap. It is also very small. I was imagining a 100 watt solar or more so it could charge the batteries if you decide to dry camp.
A way to know is to find out what the parasitic load is for your RV. I would set the RV up like you are going to store it. Batteries should be fully charged.
Disconnect the negative lead to your battery bank and measure the current draw with an amp meter. You must provide more than that amount to maintain the battery. Or you may have a load center built in that will report the draw.
Even my Kodiak Cub would not work with that. Parasitic load is about .3 amps. That solar will provide a little more than .1 amp. You RV probably has many more devices running standby.
It is cheap enough you could buy it and try it. If you come back in about 2 weeks you should be able to see whether the batteries are still fully charged.
My guess is you need 3 to 6 amps. That would be 36 to 72 watts.

Persistent · 02-21-2019, 11:16 AM

PS:
Full solar is only available for part of a 24 hour day. So you need about three times the solar output as the parasitic draw.
100 amp solar is what many would choose as a standard starter size.

l1v3fr33ord1 · 02-21-2019, 11:29 AM

Rich-

From what I have learned, a healthy battery, fully-charged and disconnected from all loads, should self-discharge less than 5 percent per month. You can disconnect the negative battery cables from both batteries and do just fine.

Three details:

1) They make devices to eliminate the need for a wrench to remove the battery leads. Links to two are here and here.

2) If your coach has a Magnum inverter, read the manual before disconnecting the house battery cable. The manual may require the battery positive cable being removed before the negative.

3) Do not rely on either of the battery disconnect switches to fully disconnect the loads. Depending on your coach's wiring, some loads may bypass the disconnect switches. If that is the case, you can deplete the batteries even with the disconnect switches in the "off" position(s).

Podivin · 02-21-2019, 11:43 AM

I had a boat stored in a marina in St Augustine.
The marina was damaged in the last hurricane and was without power for a few months. I kept one battery bank charged using a cheapie solar panel from Harbor Freight (this was the battery the powered the bilge pumps, so I didn't want to disconnect it, nor did I want it to go dead).
https://www.harborfreight.com/13-Wat...ger-68750.html
That's what I used.

The start batteries I simply disconnected and let them sit. I'd go out every few weeks, hook up the start batteries and fire up the engines. No problem doing that, I'd expect you'd be fine doing the same on the RV. But as mentioned, don't count on the 'salesman switch' to really disconnect the batteries if you choose not to charge them. Do something to physically disconnect the cables, a disconnect switch as linked above is easy to work.

Arch Hoagland · 02-21-2019, 12:18 PM

https://www.amazon.com/WirthCo-20128.../dp/B000CQFWLY

Use for house and engine. You'll be fine.

Mark_K5LXP · 02-21-2019, 12:51 PM

For a belt and suspenders solution you could disconnect the battery *and* connect a solar trickle charger. The power requirement just to keep up with self discharge would be accommodated with a fairly small panel (20-30W). My personal opinion is if it's going to sit longer than I'm comfortable not being able to check on it, the negative lead comes off. This goes for my 4 and 2 wheel vehicles too.

Because the power requirement is so small even if you factor parasitic loads, leaving it plugged in to shore power would consume very little. You could connect up a Kill-A-Watt meter up to it and see but if it used a dollar's worth of electricity between outings I'd be surprised.

Mark B.
Albuquerque, NM

Mudfrog · 02-22-2019, 12:16 AM

Quote:

Originally Posted by Arch Hoagland

https://www.amazon.com/WirthCo-20128.../dp/B000CQFWLY

Use for house and engine. You'll be fine.

I agree. From my own experience, you can go a couple of months, probably more, if you disconnect the batteries. That is, if the batteries are in good health and fully charged when you disconnect them.

Edited to add,,, Parasitic loads would run my chassis battery down within about a two weeks before I started disconnecting it. I installed a disconnect switch which worked well and was easy to use. However, I still found myself forgetting to open the switch at times. I finally ran power out to the motorhome and after doing that, bought one of these to make things fully automatic.

https://www.amazon.com/Woods-50015WD...+outdoor+timer

Thought I'd throw it out there since the OP was worried about electricity usage. I set the timer to come on once a week for 8 hours. This seems to be perfect for keeping all the batteries up without having to disconnect anything.

Winemaker2 · 02-22-2019, 05:10 AM

If you have power available but hesitate to connect a larger load you might consider a trickle charger / maintainer.
I do this when in storage and my storage place waives the fee for using power (just connecting the MH). I've made mine a permanent installation in house & chassis batty locations and have one conveniently located extension cord to plug in.
They draw about 1 +/- amp when operating.
Battys are always fully charged and they like that... no need to try to remember to go charge them.

bobmar · 02-22-2019, 07:18 AM

FWIW, We’ve always just made sure batteries are full charge and disconnected negative cables or disconnect knife switches. No problems on a healthy battery even during Minnesota winters.
Also a similar item- we have a 12v 5000# boat lift with a deep cycle battery on a solar charger. We leave that in location all winter. This battery has been there for 6yrs.
Just sayin’!