sudden battery discharge

Mar 13th, 2004, 15:54

I have a Volvo V40 T4 1998 that has done approx 90K.

Four months ago, the battery was completely flat in the morning. I got a new battery and then a month later , the new one was flat aswell. The garage replaced the battery thinking it was faulty.

Four weeks later, the battery was flat again. We replaced the alternator and recharged the battery. 8 weeks later (can you guess where we are going with this?)..... the battery was flat again!!

Each time when the battery has been flat there has been no ignition lights, Central locking etc.

Using a multimeter we have checked the alternator is working and the battery is OK once recharged.

The car runs perfectly between incidents and shows no difficulty starting. It seems that when left overnight now and again there is something draining the battery. Has anyone got any ideas what it could be.

We have tested the battery when the car is locked and the alarm set and there was no significant drop in voltage.

Any help would be very gratefully received.

Stu and Lou

vjck_uk · Mar 13th, 2004, 17:40

You could try taking the earth lead off and putting a test meter in between the lug and the battery and see if there's a current flowing.
To flatten a good battery overnight it must have a discharge equal to about 3 times the sidelight demands.
If there is no discharge when you try it try putting a voltmeter on ther battery when starting,it should not drop below about 10 volts on the starter and should rapidly rise from 12.5 cold to 14(ish) volts when running.

4 forty · Mar 13th, 2004, 19:07

suprised the dealer did not check your system for "earth leakage discharge" which it very much sounds like.

paul

Mar 13th, 2004, 15:54	#1
robbiedog Guest Location:	sudden battery discharge I have a Volvo V40 T4 1998 that has done approx 90K. Four months ago, the battery was completely flat in the morning. I got a new battery and then a month later , the new one was flat aswell. The garage replaced the battery thinking it was faulty. Four weeks later, the battery was flat again. We replaced the alternator and recharged the battery. 8 weeks later (can you guess where we are going with this?)..... the battery was flat again!! Each time when the battery has been flat there has been no ignition lights, Central locking etc. Using a multimeter we have checked the alternator is working and the battery is OK once recharged. The car runs perfectly between incidents and shows no difficulty starting. It seems that when left overnight now and again there is something draining the battery. Has anyone got any ideas what it could be. We have tested the battery when the car is locked and the alarm set and there was no significant drop in voltage. Any help would be very gratefully received. Stu and Lou

Mar 13th, 2004, 17:40	#2
vjck_uk Premier member Last Online: Jul 29th, 2017 15:54 Join Date: Nov 2002 Location: southern edge of birmingham	RE: sudden battery discharge You could try taking the earth lead off and putting a test meter in between the lug and the battery and see if there's a current flowing. To flatten a good battery overnight it must have a discharge equal to about 3 times the sidelight demands. If there is no discharge when you try it try putting a voltmeter on ther battery when starting,it should not drop below about 10 volts on the starter and should rapidly rise from 12.5 cold to 14(ish) volts when running.

Mar 13th, 2004, 19:07	#3
4 forty VOC Member Last Online: Aug 12th, 2015 14:44 Join Date: Dec 2001 Location: sunderland	RE: sudden battery discharge suprised the dealer did not check your system for "earth leakage discharge" which it very much sounds like. paul

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