Electrical problem, poor running/not running

Faust · Post by **Faust** » 02 Aug 2019, 15:21

'04 V70 N/A To begin at my beginning. Today as I sat in front of coffee shop with engine running and radio playing, the radio quit. Wouldn't restart so I shut of engine. Engine wouldn't restart. Got a jump locally and started immediately, Ran at 1200 rpm, wouldn't respond to throttle, quit wouldn't restart. Had it towed home. Checked the usual and put charger on battery. If I switch charger to "start" it starts. Runs erratically, slight response to throttle, rpm drops them quits. I notice fuel gauge quits when engine does. Engine will not restart, some solenoid click (or similar). Wait five minutes, engine starts, Runs smoothly, rpms drop and quits. Will not immediately restart, needs five minutes with charger attached. I am a poor electrician, but I seem to be getting 11 volts from battery, without charger attached. Any guesses, would poor battery do this? I should think it would run on the charger.

Faust · Post by **Faust** » 02 Aug 2019, 15:35

Power to radio, air conditioning, etc seems erratic. That may result from inappropriate observation.

Faust · Post by **Faust** » 02 Aug 2019, 17:06

A few more observations. After a few hours to cool, I put in a charged, known good, battery. Starts right up, runs smoothly and normally. Only obvious problem is that alternator light comes on below 1000 rpm. 3-4 minutes later, engine runs roughly, rpms drop and it quits. I seem to have about 6 volts at battery. Apparently no electrical power, not even lights on dash when I turn the key. Hook up charger set to "start". It starts and I disconnect charger. Runs normally for a few minutes then begins to stumble and stops. Once again, about 6 volts at battery. Does this sound like an alternator problem? I have one of those too, but don't want to just "throw parts at it".

Faust · Post by **Faust** » 02 Aug 2019, 17:07

Sorry, can't "pull codes"

Post by **abscate** » 02 Aug 2019, 17:14

How are you measuring that battery voltage?

6 Volts at a 12V battery is beyond dead, so that measurement isn't right.

Weak batteries will cause havoc with these cars - you need a good full charge battery and good cables/grounds to troubleshoot.

Faust · Post by **Faust** » 02 Aug 2019, 17:30

How are you measuring that battery voltage?
Across the poles at the battery with terminals removed. Please note that at these times there is no electricity apparent at the dash, no lights, no starter click, nothing. Time (cooling?) seems a temporary cure.

I will check cables and terminals. However problem wasn't gradual (except for loss of A/C yesterday) so I suspected something more immediate than corrosion. I suppose corrosion could be gradual up to the point where it becomes immediate.

Post by **abscate** » 02 Aug 2019, 17:44

To get a known to be good battery to discharge to 6Volt charge level would involve dissipating about 1 kW hour of heat - that's a lot, like the amount a space heater puts out in one hour. You would notice something burning somewhere.

Faust · Post by **Faust** » 02 Aug 2019, 20:44

abscate wrote: ↑02 Aug 2019, 17:44 To get a known to be good battery to discharge to 6Volt charge level would involve dissipating about 1 kW hour of heat - that's a lot, like the amount a space heater puts out in one hour. You would notice something burning somewhere.

I know what you are saying, but there is a tremendous voltage drop while the engine is running such that the engine stops and there is no power to the gauges.

Faust · Post by **Faust** » 02 Aug 2019, 20:59

I think it significant that the alternator light comes on below an "indicated" 1000 rpm. I have never seen this light come on during operation before. As best memory serves, it seems to come on even when the charger is hooked to the car battery. It also seems significant that that it runs 3-4 minutes then quits (slowly, it doesn't just shut off), then will not start without a cooling interval. This suggests to me that something is heating and cooling, but I cannot imagine what.

greg850r · Post by **greg850r** » 02 Aug 2019, 21:20

Faust wrote: ↑02 Aug 2019, 17:06 A few more observations. After a few hours to cool, I put in a charged, known good, battery. Starts right up, runs smoothly and normally. Only obvious problem is that alternator light comes on below 1000 rpm. 3-4 minutes later, engine runs roughly, rpms drop and it quits. I seem to have about 6 volts at battery. Apparently no electrical power, not even lights on dash when I turn the key. Hook up charger set to "start". It starts and I disconnect charger. Runs normally for a few minutes then begins to stumble and stops. Once again, about 6 volts at battery. Does this sound like an alternator problem? I have one of those too, but don't want to just "throw parts at it".

My first check after this would be to disconnect the battery and check voltage of just the battery to see if it's the same. A hot battery should run 20 min or so in my experience before being dragged down low enough to see problems. If it only lasted 3-4 minutes and the alternator light was lighting I would suspect a short in the alternator.
Edit: make sure your key is turned on when you connect the battery.