Battery light stays on for the first 10 min of a journey.
Discussion
Mignon said:
Possibly something eventually gets jiggled into contact again after the car has been moving for a while.
Only thing about this is that it appears to be so regular and down to time between journeys etc think its 4 hours max and the light comes back on. Its driving me nuts now!
J3JCV said:
No idea - would that make it work intermittently or not at all?
I'd have thought so, but it's the sort of thing that could be sensitive to thermal heating and just happen to change behaviour when it has got enough heat into it.If it was me, I'd get a couple of ordinary cheap voltmeters and connect one between the ignition switched 12V supply and battery ground, and one to the alternator output and battery ground. These ought to read very similar values while the engine is running. If they don't, and especially if that difference changes when the no-charge lamp goes out, then you've got tangible evidence of the problem and can pursue it from there.
GreenV8S said:
J3JCV said:
No idea - would that make it work intermittently or not at all?
I'd have thought so, but it's the sort of thing that could be sensitive to thermal heating and just happen to change behaviour when it has got enough heat into it.If it was me, I'd get a couple of ordinary cheap voltmeters and connect one between the ignition switched 12V supply and battery ground, and one to the alternator output and battery ground. These ought to read very similar values while the engine is running. If they don't, and especially if that difference changes when the no-charge lamp goes out, then you've got tangible evidence of the problem and can pursue it from there.
With the fault on the vehicle 2 multimeters connected as you have advised will obviously show different voltages, it is the difference in the voltages that are illuminating the bulb
Penelope Stopit said:
With the fault on the vehicle 2 multimeters connected as you have advised will obviously show different voltages, it is the difference in the voltages that are illuminating the bulb
That's correct. And by knowing both voltages, you can now determine which of them is wrong and trace that to the cause of the problem. Penelope Stopit said:
Nope, you don't need 2 multimeters to prove what the warning light is proving
With the fault on the vehicle 2 multimeters connected as you have advised will obviously show different voltages, it is the difference in the voltages that are illuminating the bulb
Fixed that for you. A subtle omission sometimes makes a massive differenceWith the fault on the vehicle 2 multimeters connected as you have advised will obviously show different voltages, it is the difference in the voltages that are illuminating the bulb
GreenV8S said:
That's correct. And by knowing both voltages, you can now determine which of them is wrong and trace that to the cause of the problem.
Yes you've got it, there is no need to use 2 voltmeters, the voltage can be measured throughout the circuit with 1 voltmeter and the results of those measurements will point to what's possibly causing the problemPenelope Stopit said:
there is no need to use 2 voltmeters, the voltage can be measured throughout the circuit with 1 voltmeter and the results of those measurements will point to what's possibly causing the problem
You're right. I was thinking of this as a problem that would need to be diagnosed on the road, as many electrical problems have needed in my past. In that case I am used to preparing whatever instrumentation I need to understand the problem - two voltage readings, for this one. As the OP describes it, this problem will probably show up with the car idling for ten minutes or so from cold so it would be perfectly practical to measure the two voltages separately with a single meter. However the OP does it, those are the two voltages that need to be measured to understand what's causing the lamp to light.Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff