My partner's Micra SE (2006) has had starting/electrical issues for a while now. Multiple mechanics have diagnosed bad batteries and replaced with the problem returning within days/weeks of the replacement.
The starting issue manifests as either a repeated rapid clicking or a very slow, laboured revolving noise and no start either way. Can be started by jump starting the car.
The other electrical issues have come/gone however the one that remains is no reverse lights. Bulbs have been replaced, they don't work even brand new.
My belief is that it's an electrical issue overall (most likely a drain leaving the battery too low to start the car although the car can be put into accessory mode for considerable time even at this point with no issues). I've tested the voltage across the battery at various points and it's as such:
- Car Off for some time: ~10.2-11.5v
- Car just turned off: ~12.9v*
- Car on at idle: ~14.4v
- Car revving to 2-2.5k rpm: ~14.4-14.5v
The car can be restarted fine if just turned off, however leaving for even a few minutes it won't start. If I keep the multimeter connected after turning the car off, I can see the voltage drop by 0.01v every few seconds though I haven't seen at what point this stops (if at all). Also, with the car off, the rear right reverse light appears to be pulling anything from 1-6v constantly (checked by inserting the multimeter probes into the plug that connects the rear lights).
I've checked 2 of 3 fuse boxes (the third under the front left headlight is a pain to access so I haven't done that yet) and all fuses seem fine.
I'm far from a mechanic and only have a rudimentary understanding of electrics. Just want to confirm if my thinking is correct and where the next places to look would be?