Topping up battery with Solar panel

[kez]

Hi All,

Due to illness and running down towards winter our motorhome is not going to see much action until next year. It’s stored on a secure site without any electrical support. Each winter we have to bring it home to top up the engine battery to keep the alarm working. Alston’s has previously drained the battery.
Thinking of buying a small solar panel, possibly from Halfords, that I can lay on the dash and which will just supply enough power to keep the engine battery alive whilst onsite.

Any recommendations for panel size, would it work etc. Any advice appreciated please.

 

[autorouter]

I've had some success with even a 2.5W panel, which was attached by suckers inside the windscreen. It was facing south with no shading. It just about kept the starter battery topped up. I had a similar one for the leisure battery, but that wasn't good enough, it slowly lost charge. If I had to do it again, I'd go for the a much bigger one, 10W or even 20W.

These small panels don't have a solar controller module, and don't need them, there's not much chance of overcharging a big battery with a small panel like that. Over about 20W a controller is needed.

The trouble is, different motorhomes have widely different background battery drain. Even what looks like the same model might have different alarms and accessories fitted. But it's worth a try if you're in a spot that gets the winter sun.

I'm presuming there's no solar on the roof, charging the leisure battery.

 

[GMLS]

If you can afford it, as a better long term investment, I'd be thinking of getting at least 100w of solar on the roof maybe with a battery master to transfer charge from leisure to vehicle battery