Want to add solar battery charger for storage use

[Dan_Diego]

I want to add solar battery maintainer to my attitude toy hauler. I intend to hang solar panel in a trailer window, running cables to the battery. The panel would only be connected when in storage. I am currently using two GC2 6 volt batteries connected in series. I would be grateful for any advice or hardware recommendations.

[HRTKD]

A lead acid battery will discharge about 4% a week.

More info at the Progressive Dynamics web site.

The PD web site was one of the first that came up for me on a Google search. The number they are using is inline with what I've heard from some sources, a little high compared to other sources (5% per month). A LiFePO4 battery will discharge much less when disconnected and may be another option.

My 150 watt solar panel on the roof does a great job of keeping the battery bank charge when the trailer is in storage.

[nayther]

Dan Diego wrote:

Why do you want to keep 12v connected in storage? Just curious

I have and use a battery disconnect switch on my trailer when in storage.

Due to health issues, I was unable to perform any maintenance on my trailer for seven months, last year. In that time, the batteries had run down significantly. That is why I felt compelled to take some action. The easiest thing for me to do was the small solar panel. I will see soon enough if it was a good decision or not.

I am encouraged that you get great life out of the battery by charging before storing and disconnecting cable. Thanks for your advice.

if there is significant drain with the disconnect open then you must have something connected "ahead" of the disconnect, perhaps the breakaway switch or tongue jack? Try disconnecting the ground wire AT the battery.

[Rockinfigs]

yeah i would go big also...I have two 12v lithium batteries connected to 420watt solars...love it especially the lithium batts.

[Dan_Diego]

Why do you want to keep 12v connected in storage? Just curious

I have and use a battery disconnect switch on my trailer when in storage.

Due to health issues, I was unable to perform any maintenance on my trailer for seven months, last year. In that time, the batteries had run down significantly. That is why I felt compelled to take some action. The easiest thing for me to do was the small solar panel. I will see soon enough if it was a good decision or not.

I am encouraged that you get great life out of the battery by charging before storing and disconnecting cable. Thanks for your advice.

[Dirtclods]

Just keep an eye on your battery levels.

[nayther]

Dan Diego wrote:
I do not disagree with your post. My situation is that I do not have access to electrical at my storage yard. I also do not have the ability to keep my trailer in my driveway over night without running afoul of my HOA. The effort to pull my batteries, charge them for a day, then return them to the trailer is significant with recent shoulder problems. For me, this seemed worth the risk.

I would not go to all that trouble. batteries should be fully charged after camping by pulling it home. Once parked in storage with 90% plus SOC disconnect the positive lead and walk away, reconnect when you return. You'll have batteries in nearly the same SOC as when you parked it. BIL has a battery for his boat (standard lead acid group 24 Marine) that is 10+ years old. He disconnects when he parks it and all is good.

Why do you want to keep 12v connected in storage? Just curious

[dedmiston]

jdc1 wrote:
Yep...go big, as dedmiston says. 100-200watts will keep you happy when you're out there in Glamis or Borrego.

We put in 700 watts of panels. You can see the sun get dim when it comes over our roof. I think we even get a little charge from the full moon.

[Dan_Diego]

I do not disagree with your post. My situation is that I do not have access to electrical at my storage yard. I also do not have the ability to keep my trailer in my driveway over night without running afoul of my HOA. The effort to pull my batteries, charge them for a day, then return them to the trailer is significant with recent shoulder problems. For me, this seemed worth the risk.

[pianotuna]

Dan Diego wrote:
Thank you all for the advice. I am not yet committed to the full solar roof option. I was just looking for something to keep the batteries from running down in a period of inactivity.
I opted for a cheap fix. $30 7 watt solar panel from harbor freight. $33 Battery Tender solar regulator. $10 extension cable. When in storage, I put the 14x14 solar panel in the window with the most sun exposure and have it cabled directly to the battery. So far, so good. I will have better feedback when in storage for a period longer than a month.

Return them. Fully charge the battery bank. Disconnect the ground cable. Why waste your money?

[Dan_Diego]

Thank you all for the advice. I am not yet committed to the full solar roof option. I was just looking for something to keep the batteries from running down in a period of inactivity.
I opted for a cheap fix. $30 7 watt solar panel from harbor freight. $33 Battery Tender solar regulator. $10 extension cable. When in storage, I put the 14x14 solar panel in the window with the most sun exposure and have it cabled directly to the battery. So far, so good. I will have better feedback when in storage for a period longer than a month.

[RickLight]

Last winter I used a 5W panel for 300AH of lead acid. It also powered 2 ultrasonic rodent deterrents. We aren't a major winter sun zone.

You don't need to spend mega bucks!

[garym114]

Save your money, charge the batteries fully and disconnect the ground battery cable. Batteries will not lose their charge.

[Lwiddis]

But I say “go appropriate” based on an energy survey of what you use (amp hours) or what you would like to use. Throwing money (solar watts) at a problem (need more power) isn’t the answer.

[pianotuna]

Putting the panel in a window may reduce the power output a LOT.

Far better to permanently mount on the roof.

For 2 golf cart batteries I'd recommend 140 watts (or more).