Draining battery!
Moderator: martauto
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RegTourist
- E30 Zone Newbie
- Posts: 52
- Joined: Sat Nov 28, 2009 11:00 pm
Hi guys I've just got hold of a 325 touring with factory fitted alarm.Problem is that when activated it drains the battery badly....any ideas why this is and any solution?
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votivequagmire
- E30 Zone Regular
- Posts: 428
- Joined: Wed May 24, 2006 11:00 pm
- Location: Swansea, South Wales.
Is the battery ok? Have you had it tested? Maybe it's a couple of cells down?
If the battery is fine then it sounds like you have an earth leakage.
If you've just acquired the vehicle then you will know very little about it's past.
Is there a reason that it was available? Electrical faults are notoriously difficult to diagnose very often. It could simply be a connection problem. Although the following does not guarantee to fix the fault you have, it would enable you to remove certain things from the equation. And although there's a lot of text, the work itself shouldn't take more than an hour to complete.
Remove the Earth clamp lead from the battery first , check both the post and the inside face of the clamp for corrosion and / or dirt deposits and clean as necessary, I find fine to medium sandpaper works ok, obviously there are tools which you can buy for this but unnecessary expense I think.
While the Earth is off, remove the positive clamp and check also in the same way.
Once you're happy that they're clean enough, I'd move around the engine compartment finding all the earth connections and cleaning them up in the same way.
There should be a major Earth next to the battery on top of the suspension turret. I'd also check that the alternator is Earthed correctly and that the positive feeds that are connected at the rear are also clean and free from corrosion. And finally I'd make sure the positive feeds to the starter motor are also clean and all bolts are tight.
Once you're happy with these connections, reconnect the Positive clamp to the battery first and tighten with spanner, also making sure any auxiliary feeds from it are also clean and tight, for instance the feed to the fusebox.
Then reconnect the earth and tighten.
Start the car and check the charging voltage is high enough.
Then switch off and check the battery for any voltage drop, then engage the alarm and test the battery again for a voltage drop. Of course it is possible that there is a connection problem with the alarm system itself but that will take a bit more investigating and time.
Let me know how you get on.
If the battery is fine then it sounds like you have an earth leakage.
If you've just acquired the vehicle then you will know very little about it's past.
Is there a reason that it was available? Electrical faults are notoriously difficult to diagnose very often. It could simply be a connection problem. Although the following does not guarantee to fix the fault you have, it would enable you to remove certain things from the equation. And although there's a lot of text, the work itself shouldn't take more than an hour to complete.
Remove the Earth clamp lead from the battery first , check both the post and the inside face of the clamp for corrosion and / or dirt deposits and clean as necessary, I find fine to medium sandpaper works ok, obviously there are tools which you can buy for this but unnecessary expense I think.
While the Earth is off, remove the positive clamp and check also in the same way.
Once you're happy that they're clean enough, I'd move around the engine compartment finding all the earth connections and cleaning them up in the same way.
There should be a major Earth next to the battery on top of the suspension turret. I'd also check that the alternator is Earthed correctly and that the positive feeds that are connected at the rear are also clean and free from corrosion. And finally I'd make sure the positive feeds to the starter motor are also clean and all bolts are tight.
Once you're happy with these connections, reconnect the Positive clamp to the battery first and tighten with spanner, also making sure any auxiliary feeds from it are also clean and tight, for instance the feed to the fusebox.
Then reconnect the earth and tighten.
Start the car and check the charging voltage is high enough.
Then switch off and check the battery for any voltage drop, then engage the alarm and test the battery again for a voltage drop. Of course it is possible that there is a connection problem with the alarm system itself but that will take a bit more investigating and time.
Let me know how you get on.
'88 325i M20, could've done with a sunroof.
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RegTourist
- E30 Zone Newbie
- Posts: 52
- Joined: Sat Nov 28, 2009 11:00 pm
Thanks for that will get on to it today!!
I recommend you buy a clamp meter.
Then look in under the bonnet and measure all big cables for any drain, when you find check if it goes to the fusebox, if it does then start plugging one fuse at the time until the drain stop, then find out what that fuse goes to, then come back here ;)
Then look in under the bonnet and measure all big cables for any drain, when you find check if it goes to the fusebox, if it does then start plugging one fuse at the time until the drain stop, then find out what that fuse goes to, then come back here ;)