Hi all. Just started driving my NB MX-5 around again after it’s been off the road for the winter. I’ve been driving it for almost a week absolutely fine until today where I’ve had some strange electrical issues.
As the car is running (idling or while driving), the battery voltage will drop to ~12.5V, then as the voltage starts to drop into 11.xxV (battery light sometimes comes on), the engine starts to labour and the lights will dim. Then suddenly there will be a spike to 15V, then drop back down to ~14.5V. This happened repeatedly at random intervals. The voltage across the battery when the engine is off and the surface charge has dissipated is 12.35V
Revs don’t seem to effect it. I can be idling at 800rpm or cruising around at 3,500rpm and there’s no difference.
I’ve checked my grounds, cleaned them up regardless and there’s been no change.
Here’s a video of it happening at idle.
My battery is about 2 years old and my alternator is about a year old.
I’ve attached a video of it happening at idle.
Any ideas?