charging woes part IV 'The Wrath of Tim'

[tim eh?]

I had the same problem last week on my wifes 89 535I. The battery was new, and could charge with charger, but wouldn't go to 14 volts with the car running, and would drain back down to 11.5. Thought it was the altenator, but the altenator only has 500 miles on it. Just had the starter replaced 100 miles ago. Turns out it was a broken 3 wire black connector below the starter, mounted on a bracket attached to the engine. This must kick the altenator, on, cause once I hooked it up 14 volts.

i'm very interested in this... i looked around but i think mine is mounted differently... something like the connecter here?

[tim eh?]

I admit the battery is small - but it is listed as stock, and I only have an m20 with no wacky extras. And it used to work really well.

The battery I swapped in was a 550A/hr but pretty new. I got the same results. I will try to find a bigger battery to borrow.

I'll try and upgrade, I have a feeling it will be a hassle, I went there already once.

Not sure if I want to pull the starter apart today



it would be kind of funny if all this was just a dead battery.

[tim eh?]

What're the liquid levels like in the internal battery cells? Pop the caps and have a look in each cell to see how much liquid is in there.

[...]
The battery should spin the starter from 12.5 like a rocket... I'd start eyeing up the starter.
Try cranking the car over and seeing what voltage the battery drops to while cranking.

I find it interesting from your original post that the battery appears to be losing charge while just sat still outside and out of the car.

at 12.5 it does spin like a rocket... 12.0 not so much I would assume that is normal.
from obc#9 it drops to about 10.5 when cranking.

I am leaving the battery out a bit longer I think will test the voltage drop for a bit. Case is translucent... fluid levels good i think... i tilted it a bit for this photo.