Battery drain

[martyyn 2]

So I think Ive found out when my battery is draining but I cant really find anything on the web.

My battery has been fine the last couple of weeks but today again it was dead when I tried to start it. Now each time this has happened it been when Ive left the keys in the ignition to either clean it or load it up or something.

It doesnt need to be too long either as today was only enough time for me to clean all the wheels.

Has anyone heard anything about the key being left in the ignition draining the battery or have any ideas on what it could be?

[*Glenn* 854]

How old is the battery ?

Is it the correct battery ? Should be a calcium Din 65 or 85

Check battery charge rate as well

Do all your fan speeds settings on the heater work...fan speed resistor blocks can discharge batteries when they are faulty.

There is a procedure for checking battery discharge that can be quite complicated without the right gear. You need either GT1 or 2 multimeters to do this.

Edited December 21, 2008 by *Glenn*

[kiwi535 538]

i have got a multimeter Martyn

[mr E34 11]

To measure quiescent current (background drain)i.e. current drain when vehicle in shut down mode, disconnect +ve terminal from battery & set your digital meter to AMPS DC, put the positive multimeter lead on the +ve battery terminal & the -ve multimeter lead to the +ve cable that was connected to the battery....the reading should come up like 0.2 as an example....this means it is drawing 200ma...which is 1 fifth of an AMP, if it read 0.1 that is 100ma.It shouldn't draw much current at all.

I don't know what most cars draw on standby,will vary considerably..someone will have a rough idea.

edit. your battery must be on the way out unless it just needs a good long charge.

Edited December 21, 2008 by mr E34

[*Glenn* 854]

To measure quiescent current (background drain)i.e. current drain when vehicle in shut down mode, disconnect +ve terminal from battery & set your digital meter to AMPS DC, put the positive multimeter lead on the +ve battery terminal & the -ve multimeter lead to the +ve cable that was connected to the battery....the reading should come up like 0.2 as an example....this means it is drawing 200ma...which is 1 fifth of an AMP, if it read 0.1 that is 100ma.It shouldn't draw much current at all.

I don't know what most cars draw on standby,will vary considerably..someone will have a rough idea.

edit. your battery must be on the way out unless it just needs a good long charge.

It should be about 40 milliamps. However most multimeters wont go from amps to milliamps without switching , which will take the ECE's back out of sleep mode. You need to use 2 meters and wait at least half an hour for the ECU's to shut down to check it. Use the two meters in paralell. Have one on amps and when it drops switch the 2nd one to milliamps and disconnect the first without breaking the circuit. Or use GT1