Micro charging system needed for micro battery!

[syvictoria]

...Well, perhaps a slight exaggeration!

I have an Odyssey PC1100 Extreme Series Battery which is a mere 45Ah. I seem to recall that they have a c. 12 month self discharge time, but I fear that my little battery may be a culprit of covid/lockdowns and only time will tell when I finally get back to my boat. The battery at present has no means of charging other than by the engine. My house batteries have a 100W solar panel wired directly (via a solar controller).

I'm looking for a super simple (and ideally low cost!) method of keeping the little 45Ah battery charged when we're away from the boat. Could I somehow charge it via the cigar socket off the other batteries, or (my original plan pre-covid) can someone perhaps recommend a decent small solar panel that wouldn't require an additional solar controller (so <4W). When I looked on line a year or so back there seemed to be little on the market to satisfy the latter, but now Amazon seems to show quite a choice!

So, what's the simplest (KISS), most robust, modest cost solution to change my little battery, please? TIA!

 

[syvictoria]

Well, that has to be all but a first - no replies, and it's an electrical question too!

I've since realised that using the cigar lighter socket would be ill advised as that would require the domestic circuit to be left on in our absence. I will therefore just pick a random small solar panel and see how it goes.

 

[Refueler]

Plenty of trickle charge Solar Panels on eBay etc.

Why can you not charge from the existing solar panel ? A suitable splitter that isolates each battery but allows charge ...