>>1978028Those are made for cars parked long term. 5W is fine to trickle charge the thing. If you have a weekend car or need to park at the airport for a couple weeks, it’s not a bad idea.
If you really want to charge the battery, there are plenty of larger 12V panels, especially since tons of solar systems run into 12V batteries for storage. Also worth checking out RV stuff, I’m sure they have a million.
However, if you need a quick charge or boost, drop $75 on a lithium brick jump starter, they’re great. Also you can get small plug-in chargers for $20-$30, either the little 1A trickle chargers for storage, or a 4A or 8A charger that will typically go into a maintenance mode like a trickle charger once the battery is topped off.
