Has anybody any experience of using 'maintenance battery chargers' for maintaining battery charge for long term storage of car in a garage over a 4 – 6 month period. Problem is that modern electronics have a slow discharge and battery is totally dead after a couple of months. Used to not be a problem with older technology cars.

Are they safe top be left unattended for such periods?

How about disconnecting the battery instead?

Used to use one on the motorbike (motorbike alarms are a bugger for that) and it did the job. I think it was an optimate III.

Yep, use one on the bike and on one of my cars (neither of which get much use in the winter). It's not an optimate but it's something similar.

If it wasn't for the garage you could get one of the 12 volt solar power trickle chargers you put on your dash etc.

If you disconnect some modern cars i think they can forget things like radio codes etc, my mates beemer 330d needed its key reprogramming when he left it in the ingition and let it go completely flat. We used a trickle charger on our forklift at work and it was fine.

Used an Optimate 3 on a motorbike all winter – would highly recommend one.

CTEK linky

I just bought one of these for the same, fully automatic, reconditioning modes as well. I think the much cheaper 7000 model is adequate too and remembers codes etc, also some good accesories like leads you can leave attached permanently for easy charging.

I have used a Airflow Conditioner since 2002 and cant fault it, if your lucky and your cig lighter is live all the time(works without the ignition being on) you can on a lot of cars just plug it into that and then there is no need to keep popping the bonnet every time you want to use it.

(mine came with both the croc clips or the cig lighter socket)

http://www.airflow-uk.com/index.php?view=product&product=batteryconditioner