Leon Mk2 Battery Drain

[Bast008]

So a bit of a strange battery drain issue has risen its ugly head on my Mk2 Seat Leon

A few months ago the alarm would start going off at random times (usually the early hours, so I'm popular with the neighbours). After much research, I decided the issue was probably down to the drivers door lock module, as it seemed responsible for the "open door" light on the dash and interior light coming on. Anywho, replaced that, made sure the battery was fully charged, and all was well....for 3 days, when the alarm went off again.

Unlocked the car, noticed the battery was a bit weak, so topped it up and left the car sat unlocked to save the alarm going off again. I then came back to it 3 or 4 days later and it was completely flat, so charged it up and left it again, unlocked, after a couple of days the battery was noticeably drained.

So took the multimeter to the battery (was new in January). Voltage reads fine, Cold crank sees the Voltage drop momentarily to just under 10v then back up to 14 (so the alternator is working). Measured the circuit to see that the draw sits at about 0.8amp, will drop down to around 0.3 over a few seconds, then ping back up to 0.8. And just continues to do so every 10 seconds or so.

Even when left locked for 30 minutes, the same cycle happens, although it'll sometimes drop down to 0.1 before bouncing back up to 0.8

I've obviously not resolved the cause of the alarm going off, and think its possibly one of the other door lock modules causing that.

Anyone any thoughts as to the cycle its going through?

[E-bmw]

Bast008 said:

So took the multimeter to the battery (was new in January). Voltage reads fine,



Cold crank sees the Voltage drop momentarily to just under 10v then back up to 14 (so the alternator is working). Measured the circuit to see that the draw sits at about 0.8amp, will drop down to around 0.3 over a few seconds, then ping back up to 0.8. And just continues to do so every 10 seconds or so.

Even when left locked for 30 minutes, the same cycle happens, although it'll sometimes drop down to 0.1 before bouncing back up to 0.8

I've obviously not resolved the cause of the alarm going off, and think its possibly one of the other door lock modules causing that.

Anyone any thoughts as to the cycle its going through?

1. Define "fine" - A 12v battery is 6 x 2.1 volts cells in series so should read 12.6v fully charged, as a rule of thumb every 0.1 volt less equates to around 20% charge lost.

2. After going proper flat batteries rarely recover well enough to be used again long term.

3. Having said that it sounds like you may have an excessive drain, is it still the same after 1/2 hour of being locked & left alone?

[Bast008]

Yeah sorry, by fine I meant fully charged, its between 12.6-13 volts. With the charge indicator on top of the battery going Green

And yeah, without a doubt there's an excessive drain

Edited by Bast008 on Thursday 7th May 10:08

[Penelope Stopit]

Disconnect stereo unit, CD stacker if fitted and test again???????????????????????????????????????