Post-hibernation, intermittent battery light

Technical Area Electrics & ICE
1
  1. My model of MX-5 is: 2001 1.6
  2. I’m based near: Glasgow
  3. I’m looking for technical help or recommendations on: intermittent battery light

My first run of the new year had the battery charge light come on, intermittently, after about 10 miles. I had a similar issue last year, took out the ECU to make sure it wasn’t moist, and then reinstalled. Problem disappeared immediately. This year, same procedure, but it hasn’t cured it.

The alt was fully overhauled 2 years ago, the battery is new as of last year.

Any ideas?

2

I would take a look at the alternator brushes - I have seen some cars after long storage with sticky brushes.

Either fit new brushes or clean them out with contact cleaner so they work properly again.

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How long was the car hibernating, and how was the battery stored during that time? Was it on a charger of some form? If the battery went completely flat is make not be able to hold a charge any more.

I know it has been overhauled but have you checked the alternator is working okay? With the engine running and all the lights on the voltage across the battery should be over 14V.

I’m sure others who are more technical than me will be along shortly with more/better advice.

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4

It’s just been since early November. The battery was stored in the car, but disconnected. It cranked and fired no problem. I’ll do a voltage check over the weekend and see what it’s showing.

5

I’ll take a look and see if this is the case.