Electrics: Battery Drain

[Tulip0852]

Hi folks,

Bit of a battery drain on my 2003 V70
I have taken out the fuse for the alarm and I lock the car with the key in the door and not remotely. I have checked the clove compartment light which goes off when lid is shut, interior lights are off and I have a drain of 1.3 amps resulting in a dead battery in a week or so if not driven. Alternator charges at tick-over 13.6v.
Any suggestions greatly appreciated.

[bongodave]

It's not unkown for batteries to drain through the alternator when a diode fails. If you are sure the battery is fine and there are no obvious reasons why it's draining, I'd be looking at that.

Here's a good link but it would appear you've tried a lot of this.

http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

[timh30]

13.6v from alternator is a bit low. Should be around 14.5v - so that might be worth investigating further.

Interestingly my v70 has suffered flat batteries if not used for a few days to a week (happened again this evening), I've checked for drain with car and systems powered down and only observed around 50ma draw. I've changed the battery a few times and also had a new alternator - but still get the issue. I suspect that some system is powering back up when car has been standing for a while, but tracking this down is easier said than done - need some form of data logger I can leave in place and look at drain over the period of a few days.

By the way, it takes about 15mins for all the systems to go to sleep, up to this point you will get a higher reading - so check after this period.

[100K+]

I used a bit of kit (from Maplins I think) that had a spade fuse connector that you stuck in the fuse board to read the draw through that fuse. Helped me ID the cause of my power loss
However, it also caused a SRS to appear - which needed DICE to remove.


Cheers

Bob

[timh30]

Don't wish to hijack your thread, but it is related and could be useful to other people.

After my flat battery again last night (and the alarm going mad and annoying the neighbours), I left it on charge overnight. Just tested and car started fine - static voltage around 12.6-12.7v, charging voltage 14.6v, I also measured the minimum voltage reading with cranking/starting the car this was 10.2v (if below 9.6v then battery is faulty - need a meter with min/max function for this) - so that all looked good. This was all measured at the fuse box main terminal in the engine bay and ground.

I purchased a clamp ammeter a while back and used this to check the charging currents with the engine running. At the main feed (1) on the image, I am reading 35-40A, but strangely (this time at least) I am reading nothing at cable (2) which I thought was the feed back to the battery (can someone confirm this), and at the battery itself I was reading negligible current flow - so it wasn't being charged!

Now I have performed this test before and measured current at the battery while charging, but clearly it is not doing so at the moment. I guess this is why the car runs fine (as alternator is running all the load), but the battery is not getting properly charged and I'm only getting a few starts from it before it is drained.

I guess I have a high resistance fault somewhere, which allows the battery to trickle charge from the main charger, but not with the high current from the alternator?

Any electrical experts out there offer advice? In the first instance I'll disconnect and clean the main connections at the fuse box and also the battery connection - but beyond that, I'm not sure where to look (maybe the fuse/relay panel in the rear left of the boot?). I'm assuming there aren't any fuses on the battery to engine feed, as firstly the battery does trickle charge ok, and it also needs to take the full cranking amperage (100's of Amps).

[timh30]

Thinking about it, it doesn't make sense that the battery can supply the current to crank the engine, but not to receive it from the alternator.

Maybe the battery was just so full, it didn't need any charge to top backup - although I'd have expected to see a few amps at least providing a 'top up'.

Just trying to think out loud - as I'm a bit stumped ;-)

[chiptivo]

Originally Posted by timh30

Don't wish to hijack your thread, but it is related and could be useful to other people.

After my flat battery again last night (and the alarm going mad and annoying the neighbours), I left it on charge overnight. Just tested and car started fine - static voltage around 12.6-12.7v, charging voltage 14.6v, I also measured the minimum voltage reading with cranking/starting the car this was 10.2v (if below 9.6v then battery is faulty - need a meter with min/max function for this) - so that all looked good. This was all measured at the fuse box main terminal in the engine bay and ground.

I purchased a clamp ammeter a while back and used this to check the charging currents with the engine running. At the main feed (1) on the image, I am reading 35-40A, but strangely (this time at least) I am reading nothing at cable (2) which I thought was the feed back to the battery (can someone confirm this), and at the battery itself I was reading negligible current flow - so it wasn't being charged!

Now I have performed this test before and measured current at the battery while charging, but clearly it is not doing so at the moment. I guess this is why the car runs fine (as alternator is running all the load), but the battery is not getting properly charged and I'm only getting a few starts from it before it is drained.

I guess I have a high resistance fault somewhere, which allows the battery to trickle charge from the main charger, but not with the high current from the alternator?

Any electrical experts out there offer advice? In the first instance I'll disconnect and clean the main connections at the fuse box and also the battery connection - but beyond that, I'm not sure where to look (maybe the fuse/relay panel in the rear left of the boot?). I'm assuming there aren't any fuses on the battery to engine feed, as firstly the battery does trickle charge ok, and it also needs to take the full cranking amperage (100's of Amps).

Take out the fuse for the alarm, (37 or 38 in the dash end).

Very common for the battery leaking and causing a battery drain.

[Jim314]

The location of the alarm fuse in my 2004 V70 is in the fuse panel at the end of the dash (driver side I think), but in some other year models there is a fuse panel under the dash on the driver side and the alarm fuse in those is there.

When I removed the alarm fuse I no longer had a drain that would cause the battery to go flat after a few days parked.

[Dealerbeater]

I have this battery drain problem too. I have had to call AA three times to jump start me and then everything is fine for weeks, I thought I must have left lights on or something, I do have an alarm battery problem but I have removed the fuse ages ago. Today it seems more serious as it was flat this morning and after a run and lunch it was flat again. I intend to try and isolate the cause by using my ammeter and removing fuses when the weather improves. The AA were great and said the battery and alternator were fine.

[steved15]

A garage checked my S80 and found if they removed the gearbox fuse the 0.8 drain stopped but they can't find where the issue is and advise fitting a battery isolator.