Disco I ‘97 -last time out the car ran well with newly installed battery. Then after a week of non use headlights were dim and then the engine cut off while driving. Then doesn’t turn over…hour later I jump start to drive it home …engine needs coaxing to drive 1/4 mile home. Now, on a jump start the engine turns over and revs nicely only to cut out after 2-3 seconds…..I can repeat this process but again engine revs and cuts off.

I’ve been checking alternator, fuses and grounds…still no luck.

Any ideas are much appreciated.

 

Fully charge the battery, try starting it see if it stays running. If it does check the voltage at the battery with it running

 

Sounds like alternator is kaput. If alternator is working well, the voltage at the battery should be 13.8 to 14.4 with engine on. If alternator is bad, voltage will be less. Could be less than 12 volts since the car is running on battery only.

 

Ok ✅. Having jumped the battery from another running vehicle instead of the Halo portable AC booster, the engine now continues to run. The voltage at the battery terminals without the jumper cables is 13.1 volts at idle speed.

The voltage of the battery before starting was 5.2 volts and the battery after running for a while was up to 9.2 volts. Plan on slow charge over night….new battery is suspect but at least the alternator is producing in range (?) and the engine runs and rest of electric system is ok.

So when using the portable Halo booster the charger is electrically switched off as the engine turns over, then w/o enough sustaining battery voltage the engine would just cut off.

 

Fully charged and running - 14.3v at battery terminals…will monitor for a few days. Thanks!!

 

Unless you know how old that alternator is, I’d have a new one on standby.

 

For a good period of time prior to my alternator failing, the battery light on the dash would glow faintly, fading in and out as I drove down the road. It was only noticeable at night. Then the tachometer stopped working, and the alternator was dead (the tach senses pulses from the alternator to gauge engine speed).

Interesting design I understand that battery indicator light bulb on the dash is part of the charging circuit, and if the little bitty bulb fails, the battery will not charge. I have that little bulb in my bag of emergency spares just in case. Haven't needed it yet (knock on wood). I also understand the OEM alternators have brushes that can be simply replaced if worn out.