MK2 Golf Battery Drain

[Mattz]

Hi All,

I have been expoeriencing trouble with battery drain in my golf. It first happened a couple of weeks ago as I was driving the battery light started flickering on and off, after about 10 minutes of this happening the car cut out. I was unable to start the car so tried bump starting and this worked but within 5 minutes the car had cutm out again so got trailered home

I put the battery on charge and started up and took measurements on the battery both on and off. I had 12.4v constantly. I had an alternator already as was planning to replace mine so replaced that the following week. After doing this I took measurements of the battery and had 11.4v so had lost 1v in a week. I then measured the voltage when turned on and still 11.4 but was decreasing! So i revved the engine at 3500 rpm, turned on lights, heater etc and after about 5 minutes the voltage increased to 13v which is great but once turned off it started draining again. I then went out and bought a starter motor and replaced the old one as this was playing up and thought this could be part of the starting issue, which it wasnt.

I have now wireburshed all connections on alternator, starter motor, the earth by the battery and the earth for the engine to gearbox mount and still no change. I am not very good with electrics so this is the limit to my capabilities. I am now out of ideas. Someone please help me sort out this problem. 

Thanks

[weazgti]

Should have around 14 volts when running.

[danny_p]

battery light flickering  means alternator isn't chargeing  usally because it's knackerd. sometimes you can replace brushes or overhaul the reg pack  othertimes they are knackerd.

a battery drain isn't your problem  lack of alternator is

[Mattz]

battery light flickering  means alternator isn't chargeing  usally because it's knackerd. sometimes you can replace brushes or overhaul the reg pack  othertimes they are knackerd.

a battery drain isn't your problem  lack of alternator is

The voltage on the battery decreases once the car is switched off though and the alternator was replaced by a new one from GSF. Is there any way of testing the voltage coming from the alternator?

[danny_p]

usual fault finding rules aply for battery drains

it's ether going to be a small light in the boot or glovebox ( or any other pissy littel bulb )  the radio or the alternator dioeds leacking back.

the battery light is baicly an alternator FAULT tho,  as it's used to excite the alternator windings when the alternaor isn't genorating it draws a littel power to excite the windings whitch brings the light on, once it's been spun by the engine it should be come self sustaning and no longer need exciteing so the light goes out. 

also any DRAIN big enough to remove enough power tostop a car from running and stopit restaring after just been running  is a short circuit and will have let a large quantity of magic smoke out.

charge your battery up,  put multimeter on and start engine see if the volts rise  then turn everything on.

[clipperjay]

A good trick to narrow down the drain is to stick a amp meter on the positive terminal read how many amps you start with. Then start pulling fuses out (CAR OFF) to see if the drain goes down or amps increase. Usually the one you pull is grouped and it might be lights, alarm, stero etc.  Tracking it down makes it easier.
I've always said if you own a golf spending a few quid on a Multi meter it will be your best investment long term!
I use mine all the time even to establish dodge earths for continuity reasons.
Another method is when the car starts turn on all lights and blower fogs the lot and start reading the voltage from the alternator the drain should high light the fault off not supplying enough juice from the alternator and the battery has to do more work.
Dimming of the lights and general tickover would struggle if the alternator can't cope.