Trickle Charger

[nine6four]

Morning chaps

I have a 911 (964) that is having a little rest over the festive period. It is parked up in my garage and I find if I don't use it for 2-3 weeks the battery gets pretty low.

A trickle charger seems the answer to my problems but I have no power in the garage. Are there any battery powered trickle chargers on the market (a bit of an Oxymoron I know)?

Many thanks

[LuS1fer]

You can buy solar-powered ones if you can find one with a longish cable.
There is a cable on ebay that connects to the battery and cigarette lighter...