Solar while the RV is in Storage

[dufferdj]

Need some guidance for how to use solar while in storage. My solar panels are suppling a daily charge, topping off both my house and chassis batteries. Each night my class A has the charge drawn down due to minor drains . That means that my battery charge will rise and fall daily, if only a small amount. If I shut off the battery disconnects that would prevent this fluctuation. Should I leave my batteries "live" so that they will charge during the day and slightly discharge each night or do I flip the disconnect switches to keep the batteries from either increasing or decreasing their charge. Which method should extend the life span of new batteries, or does it really matter? Thanks for sharing your knowledge and opinions.

[BUB1988]

So while we had our RV in storage we kept it on solar to keep the batteries charged. We have 4 - 12 V batteries, 2 coach and 2 chassis. The solar panel was only 100W and we never had an issue. We live in Florida and it never was in storage for over 6 -8 weeks at time.

[dufferdj]

Thanks to all of you that replied and the many questions and suggestions that have been made. After reviewing your various questions I tried disconnecting the battery bank. Since the solar panels (400W) are wired directly through the Blue Sky Solar Boost 3000i they are keeping the batteries fully charged even though we had a cloudy day today. Since I have the battery bank disconnected ,the draw throughout the night should be minimal. So at this point I believe that this condition should be best for the life of these batteries and the new ones I will be installing soon. Thanks again.

[All_I_could_aff]

If we are talking about maintaining charge while in storage, a couple of cloudy days in a row wouldn’t be anything to worry about with small solar setup. It would be a problem boondocking!

[wolfe10]

I certainly have no problem with shore power plugged in 24/7 with a smart charger or smart inverter charger, but many thousands of motorhomes use solar to maintain battery charge in storage with no ill effects.

If you have access to shore power where you store, excellent. If not, solar is a good "plan B".

[CA_Traveler]

wolfe10 wrote:

RLS7201 wrote:
I see no difference in leaving the solar connected or leaving your coach plugged in all the time. If both are smart charging systems, you're good to go.

Richard

I agree. Assuming solar of sufficient size, snow kept off it, smart controller, etc. Expect that you may have 3-4 cloudy days in a row when sizing the solar panels.

I disagree. Utility power maintains the float charge 24/7 including night unlike solar with constantly changing light.

[wolfe10]

RLS7201 wrote:
I see no difference in leaving the solar connected or leaving your coach plugged in all the time. If both are smart charging systems, you're good to go.

Richard

I agree. Assuming solar of sufficient size, snow kept off it, smart controller, etc. Expect that you may have 3-4 cloudy days in a row when sizing the solar panels.

[RLS7201]

I see no difference in leaving the solar connected or leaving your coach plugged in all the time. If both are smart charging systems, you're good to go.

Richard

[time2roll]

13.0 to 12.1 is a significant drop while connected. Either the battery is not full or they are shot. What is the programmed peak absorption/bulk voltage? How cold is it?

13.0 down to 12.65 while disconnected from the RV seems to be in good shape. Although the batteries could still be weak.

13.0 is a bit low for a float voltage in Winter. Is that the programmed voltage or is that late in the day with minimal solar power drifting down to sunset?

Does the controller support temperature compensation?

For now I would let the batteries set with the disconnect switch remaining in the disconnected (off) position. Need to figure out the programmed voltages before you get new batteries.

How many watts are the panels rated?

[wolfe10]

Again, either of two things could cause this:

Dead batteries-- where even a small draw will discharge them. The batteries are only "storing" a small amount of their design amp-hrs.

Higher amp draw what would take down even a good battery bank.

If you know the batteries are bad, replace and THEN evaluate.

Another option is to use an ammeter to determine draw.

[dufferdj]

Thanks to all for your replies thus far. I know that I need new batteries so I'm trying to figure out what to do so that the new ones will last as long as possible.
At the end of a sunny day after the sun is low in the sky, so that I'm not really getting any more solar gain, my Blue Sky 3000i Solar Boost controller shows 13.0 with the Float and Absorption lights lit up. The next morning before sunrise it was reading 12.1. Nothing was being used in the RV as it was in the storage lot --- no TV. no lights, no heat --- no nothing other than the random draws from the house electronics.
Last night, after a sunny day the controller showed a reading of 13.0 F/Ab. I turned the disconnect switches off on both the house and chassis battery banks. Checked them again this morning prior to sunrise and got a reading on the controller of 12.7/6.
This info seems to tell me that by disconnecting the battery banks, the voltage drops significantly less than when leaving them connected.
Once I install new batteries I'm sure these stats will change. But from what you can see, would I be better off just leaving the batteries connected to the solar panels 24/7, or disconnect the battery bank and just reconnect it one sunny day a week? Which way will extend the life of the new batteries or does it really make a difference ?

[wolfe10]

Yup, for a more considered answer, you will need to tell us how low the voltage goes.

So, what is float voltage at the end of a sunny day? How low in the morning after a couple of cloudy days?

Also, what controller do you have? Quite a range of quality/capabilities.

[CA_Traveler]

time2roll wrote:
Sounds fine to me unless the voltage on the battery is dropping significantly. Depending on conditions you could be a week+ with minimal to no solar.... will that be a concern?

Good suggestion, get a digital voltmeter that will read 2 digits and see what is going on. Like 12.68V.

Better get a AC/DC clamp on meter and check the battery drain. So much better than "minor" drain. Reasonable ones are about $80.

[WAFlowers]

My PV system is direct connected to the batteries and has its own shutoff. Of course, I designed and installed the system myself so YMMV.

[time2roll]

Sounds fine to me unless the voltage on the battery is dropping significantly. Depending on conditions you could be a week+ with minimal to no solar.... will that be a concern?