trickle

I am not using the SL enough at present and need to use a trickle charger which connects to battery + and body earth however the boot of the SL does not offer an obvious earth - can anyone who has dione this advise the best spot for the earth wire please

After having experienced some problems with the battery going flat while not using the car for a few days (more like 2 weeks), I decided I've had enough of calling out MB (twice so far). Anyway, bought a "proper" MB branded trickle charger from local dealer who told me "just plug it in and you...

Maplin a selling a trickle charger that sits on the dash and plugs into the cig lighter. My question is this.....do they work? I'm thinking getting it for my SL which sometimes sits about for a while.....thanks folks.