Car eating batteries

[Bloatbag Stu 0]

Hi.

 

I have an electrical fault with my G60 that I have owned for 16 years. I fully expect that it will need to be looked at by a specialist auto-electrician (particularly in view of my complete ignorance about car matters), but I thought I'd ask here for some insight so that I can at least be somewhat informed about what the problem could be.

 

The problem has manifested itself in the following way;

 

I install a brand new battery in the car. After approximately two weeks, the alarm starts sounding usually in the early hours of the morning, signaling that the battery is in the last throes of life. Sure enough in the morning the is not even enough power to activate the central locking. I call the AA for assistance and one of their operatives checks for any unusual parasitic drain. He can't find any. He checks the health of the alternator and finds that it is kicking out the correct amps consistently. It is. However when he hooks up the battery to his tester the printout tells us that the battery needs replacing. OK, I tell myself that I've been unlucky, and received a dud battery. So the supplier concedes that the battery is defective and they replace it.

 

But the situation repeats itself verbatim. Actually, I've had four new batteries in succession and they've all shown up as defective after about two weeks. So I think that I can rule out a battery problem as the original source of the problem. I've also disconnected the alternator for a couple of days and the battery is still being drained.

 

My worry is that if I have it seen to by an auto-electrician, that I will rack up a hefty bill in labour costs and still be none the wiser.

 

Any Ideas folks?

[Jim 2]

Not sure - I reckon half a day with a good auto electrican wouldn't break the bank, and would surely be cheaper than new batteries every month! Have you tried some diagnosis yourself? Wondering if perhaps it's something coming on only after the car is locked and alarmed rather than something that's draining batteries all the time.

[Chuggs1 10]

Central door locking pump seems to be a common one - not sure if that can be intermittent

[davidwort 0]

with the ignition off connect a (current reading) multimeter in-line with the battery +ve and see what current is being drained, it's going somewhere, then pull fuses until you find the culprit, don't operate the windows/CL etc with the multimeter connected or the current draw will pop it's internal fuse.

my bet is the aftermarket alarm or immobiliser

[g0ldf1ng3r 14]

with the ignition off connect a (current reading) multimeter in-line with the battery +ve and see what current is being drained, it's going somewhere, then pull fuses until you find the culprit, don't operate the windows/CL etc with the multimeter connected or the current draw will pop it's internal fuse.

my bet is the aftermarket alarm or immobiliser

 

now that is a great piece of advice & very pragmatic

[Chuggs1 10]

with the ignition off connect a (current reading) multimeter in-line with the battery +ve and see what current is being drained, it's going somewhere, then pull fuses until you find the culprit, don't operate the windows/CL etc with the multimeter connected or the current draw will pop it's internal fuse.

my bet is the aftermarket alarm or immobiliser

 

Mine was the after market alarm - which had been spliced in to the wrong power - think it should have been taken straight to the battery but they had cut corners and it was draining battery to virtual zero in 2-3 days - all is ok now that has been sorted

[Dox 23]

I presume the car is not being used for 2 weeks at a time?

 

You could try a solar charger clipped to a sun visor if the car sits for several weeks without use?

[easypops 8]

The boot light on mine was the cause of a draining battery, the switch is in the lock mechanism, also glovebox light can be one. Ignition switch not clicking off when key is withdrawn can leave some power on

[Bloatbag Stu 0]

Hello. OP here.

 

Thank you everyone for your thoughts. I'm so car un-savvy that I don't even have a multimeter so I haven't investigated the drain myself, I only know that when the AA came out that the draw on the battery was considered in the normal range. ie just enough to power the alarm. The alarm, incidentally, I had fitted 10 years ago. This problem has only surfaced in the last 6 months.

 

Excuse my ignorance, but if there is an intermittent drain on the battery that has gone undetected when the AA have conducted the tests, how would this explain the ruination of the battery after such a short period of time? The battery(s) don't seem to be able to hold a charge after this two week period. BTW the batteries have all been under warranty so I have inly paid for the original one but you can imagine that I was a bit sheepish when taking the fourth one back.

 

PS on one occasion I made a point of letting the car idle for about an hour, and still the next day there was nothing in the battery so I don't think it can be caused purely through under-use.

 

So to me the problem seems twofold;

 

a) there is something draining power from the battery that has gone undetected, and

b) something in the circuitry is damaging the battery.

[Harrier 1]

I had a similar problem , turned out to be the alarm. Battery used to go flat after a couple of weeks of not using the car. Once the alarm was removed you could leave the car for a month and still it would start no problem

 

You say the alarm is 10 years old, about the time they normally start to fail in my experience

[madmatt 10]

as the others have said alarm would be the first thing id check.a golf i had from nearly new did the same thing charge the battery and after a couple of weeks low power would kick it off charge it and off we go again remove the alarm and perfect.thing to remember is that a couple of weeks is a very lowcurrent drain.

[borarob 0]

are you using the car at all? once you've put a new battery in it will need to be driven a bit as the battery may not have full charge in it.

 

also have you checked your ground? The ground / negative to the battery seems to have been the culprit for my battery drain issues. Once the garage had spotted that and tightened it up properly its been ok...

[MarkR 11]

The original dealer fit alarm caused me loads of problems. Since it has been replaced the battery retains its charge.