Hi all,

I'm seeking some ideas about a very 'interesting' issue I've been having with my 1999 S70. It started about 6 months ago. Almost every day, within the first 5 minutes of starting the car in the morning, the battery light will start flashing every 5 seconds. The fan will cut out while the light is on, then start up again. This continues for a few minutes until other electrical functions start to cut out as well - radio, wipers, until most of the warning lights come on, the car goes into an idling state where the accelerator is unresponsive, and I have to pull off the road. Over the next few minutes, the car idles until it gets rough and gives a little lurch (like it is about to stall completely), then magically comes back to life, at which point everything works fine and I happily drive away. It occurs regularly, but only once a day, and usually first thing in the morning.

I have checked the battery with a multimeter while this is happening, and noticed that the voltage drops continuously while this is occurring. I've had it into multiple shops, and they can't seem to agree what the problem is. One stated the alternator was bad, one stated it was an electrical drain somewhere, and one stated it was a door light staying on. None have fixed it. The alternator was replaced about 8 months ago, but it has been tested and is allegedly ok.

Any help appreciated!

 

I'd have to think it would be a pretty big battery drain to drop the system voltage when the engine was running... How old is the battery? if its over 4-5 years it may be time to replace. Otherwise, inspect the battery cables including to the starter, alternator and ground strap, then check the connectors and terminals. Next I'd look at the ground connections to the alternator. Seems possible when the alternator was replaced, one of those wires/connectors could have been compromised.

 

Thanks for your reply. The battery was replaced less than a month ago as part of ongoing investigations - I should have mentioned that! Nevertheless it still wouldn't explain the odd "reboot" that the charging system seems to undergo. I will check out the cables as you have suggested.

 

if you see any swelling under the insulation or any melting, that's a sign of corrosion which in turn adds resistance to the cable (messing with the voltage and voltage sensing). If you see any of that, it'd be advised to replace the cable and the terminals.