E86 3.0si Coupe battery draining

S

Stuartll267

Member
 Northamptonshire
My Z4 does not get daily use- sometimes can be a couple of weeks or more between uses. After longer periods of non use >2 weeks the battery will be drained and I’ll be unable to start it without charging the battery. I know there are a number of threads and I’ve tried a number of the suggestions, but still am experiencing the battery drain.

My battery is <2 years old, YUASA Silver. I use an intelligent charger to confirm it is fully charged and once rested (overnight) voltage reading is 12.67 V.
Idle and 2000 rpm charging reads 14.20 V.
I’ve put my amp meter in-line and read 0.21 A when the car is switched off, doors closed and locked - I can peer in through the rear windscreen at my meter in the boot. It takes a few moments for it to reduce from ~3.0 A after interior lights have gone off etc..

Any ideas?
 
Yep, checked that - I can see the light go out before I shut the console. And verified with my amp meter reading, I could see the current draw go up when I opened it and then drop again when it was shut. I did wish it was that straight forward… I also checked the same with the glove box light too.
 
Hello,

Further development…

On starting my Z4 is slow and laboured as the engine turns over; once started everything is absolutely fine- runs like a dream. So my original thinking on this was my battery charge and my battery being drained. I wonder if the starter is actually excessively draining my battery on each start given it is so laboured? And added that we haven’t been very far in the car recently the drain of the laboured start is not being replenished through 20-30 minutes of running.

Per my previous notes the alternator is charging at >14volts.

I’ve read some other posts about cable issues and had a good look over the car and all looks pretty clean and solid.

2007 car with ~68k miles; is it likely to be my starter motor- thinking I need to replace it?
 
Starter motors do go on these cars often without warning . Does sound that yours might benefit from replacement, a simple and inexpensive job. Although your battery isn't old once it drains it never comes fully back so if it's done it a few times might be worth a full check looking at amps as well as voltage.
Also what about boot light, is that staying on when trackle charger running
 
Thanks Mike - I am gonna start with changing the starter motor; like you say given the age it be problematic.

Will advise how I get on, cheers.
 
Starter motor changed - starts perfectly; assume as it did on day 1. I used a remanufactured Bosch motor and followed the instructions on another post on removing and installation without removing the intake manifold which worked out👍.

Will monitor and see how my battery lasts now.
 
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