M3 Battery maintenance charging necessary?

[curious2]

Hi Guys Im new to this section just purchased a 2010 M3 with fancy dual clutch gear box. I have an AM V8V and they need to be kept on charge if not used for more than three weeks. Official reason is the tracker, radio memory and other electronic wizardry consumes power while car is not being used......this is common to all modern Astons. My question is will I need to leave the M3 on a charger if not used for say a month or more.

Thanks in advance !

[shim]

use a conditioner like CTEK which will charge and then top up.

I would say a good battery would last 4 weeks without problem and without charge

[MarkwG]

Mine's a touch more antique than yours, but still has the Tracker etc issues. I hook it to a CTEK when it's offline, which works fine; it also seems to hold its charge longer, which is a bonus.

[T-bagger]

Hi,
As long as the battery is in a good state of charge when you put the car away, it should be fine for many weeks. All newer BMWs have sophisticated power management systems that allow the many systems in the car to sleep. In fact a standard M3 in it's fully shut down state should only have approx 50-70 milli Amp current drain on the battery. If there is an excessive drain on any of the vehicle systems, not essential to engine start or security, then the car will wake-up and physically disconnect the circuit from the battery. Coupled with the type of battery fitted (absorbant glass mat AGM) which has a very slow linear discharge characteristic, you should be fine.

[curious2]

HI T-Bagger

Thanks for a a very informed response. If i were to leave the car for a few months would it do any harm to the sophisticated electrics if I did connect a CTREK via the cigarette lighter socket.

Thanks !

[shim]

curious2 said:

HI T-Bagger

Thanks for a a very informed response. If i were to leave the car for a few months would it do any harm to the sophisticated electrics if I did connect a CTREK via the cigarette lighter socket.

Thanks !

not sure if you mean charging your car from your cars cigarette lighter.........that may not work...........

otherwise is you have aplug socket try that. CTEK connects either thru the engine bay +/- or to the battery terminals. They even provide a plug in connector.

[T-bagger]

Hi,
I wouldn't recommend charging through the cigar lighter, it could damage the body electronics or one of it's ECUs. However if you charge the car via the underbonnet terminals then that should be fine on trickle charge or equivalent.

[Big Slippy]

Mine has sat for a month during the snow and started as if it had been sitting for a day. No issues.