I'm not even planning to fit an after-market alternator - and I'm taking notes! Thanks to everyone that's contributed to this one.
DS - New alternator with voltage regulator
- Thread starter maxmaniac
- Start date
What a comprehensive response and, like Budge, many readers will be thanking you. However I have a BVM and was obviously not very clear about the problem. The yellow light switches on and off with the ignition, however it does not switch off when the motor is running, nor is there any charge registered on the battery. It looks as though I have connected everything correctly, but I will recheck - just in case.
But why the question about having a starter relay fitted? Is that a potential problem?
Regards
But why the question about having a starter relay fitted? Is that a potential problem?
Regards
Hello, have you had the alternator checked to make sure it works?
An auto-electrician can run it up on a test bed and check the output. Or if you have a DC 100amp moving coil ammeter you can can connect this between the battery +ve and the fat lead from the alternator (i.e. in series) then rev it. You should see 55 amps plus. The usual test meters only go to 10amps, you'll blow the fuse in the meter.
Peter
An auto-electrician can run it up on a test bed and check the output. Or if you have a DC 100amp moving coil ammeter you can can connect this between the battery +ve and the fat lead from the alternator (i.e. in series) then rev it. You should see 55 amps plus. The usual test meters only go to 10amps, you'll blow the fuse in the meter.
Peter
Nuts, I thought I had solved it for you...
I am still concerned it may be wiring, rather than the new alternator. A third dash BVM car should not have the battery mounted starter relay. That means you may have some non-standard wiring. Does the car start with the key or do you have a push button somewhere?
In any event you can perform one more experiment. If you have a volt meter and a piece of wire or test lead, disconnect the Lamp/Exc wire from the spade terminal on the alternator and connect that directly to the battery. This will simulate to the alternator the indicator lamp coming on. Start the engine and observe if the battery voltage goes to something over 14V. If it does, then the alternator is OK and there is something in the wiring. If the battery voltage does not change, then the alternator is defective. If you really want to get fancy, hook a test lamp between the battery and the spade terminal then start the engine. If the light goes out and the battery voltage goes up, then you know the alternator is fine.
I am still concerned it may be wiring, rather than the new alternator. A third dash BVM car should not have the battery mounted starter relay. That means you may have some non-standard wiring. Does the car start with the key or do you have a push button somewhere?
In any event you can perform one more experiment. If you have a volt meter and a piece of wire or test lead, disconnect the Lamp/Exc wire from the spade terminal on the alternator and connect that directly to the battery. This will simulate to the alternator the indicator lamp coming on. Start the engine and observe if the battery voltage goes to something over 14V. If it does, then the alternator is OK and there is something in the wiring. If the battery voltage does not change, then the alternator is defective. If you really want to get fancy, hook a test lamp between the battery and the spade terminal then start the engine. If the light goes out and the battery voltage goes up, then you know the alternator is fine.
John I appreciate your advice that much that I logged in at 21:20 to see if you had responded - knowing the time differential. You did not let me down. I will however wait for the morning to do the suggested tests. Thank you again.
I will update tomorrow.
Regards
Errol
I will update tomorrow.
Regards
Errol
I agree with John, new alternator very much doubt will be the problem but if you have the positive straight out to the battery you will have a charging battery.
Success!!
After performing your simple test I eliminated the alternator as the problem. From the test I deducted that I should get 12v on the exc lead when the key is on - nothing. I then ran direct from the old regulator L lead to the alternator, and hey presto. Clearly some unstable wiring around. Perhaps a new loom is needed, but that is a project for the future.
Thanks to all contributors Annie gets a reprieve.
Regards
Errol
After performing your simple test I eliminated the alternator as the problem. From the test I deducted that I should get 12v on the exc lead when the key is on - nothing. I then ran direct from the old regulator L lead to the alternator, and hey presto. Clearly some unstable wiring around. Perhaps a new loom is needed, but that is a project for the future.
Thanks to all contributors Annie gets a reprieve.
Regards
Errol
Now I am beginning to wonder if a dodgy EXC wire was the source of your problem in the first place. Anyway, glad you got it all sorted out.
How rude of me not to update as I said I would do back in 2018. Now with lockdown and time to spare I was rereading and making notes for future reference.
After all of the wonderful advice given it turned out that the wiring was 100% correct, and the problem was that the alternator needs a "kick start" of about 2500 rpm to get the charge light to go out, and to start charging the battery. After the kick start it charges quite happily at idle, and the light remains off. I have no idea why this is necessary but Badabec did mention in the post that revs might excite the alternator. I am sure it is not correct, but hey I am going to let sleeping dogs lie.
Cheers
After all of the wonderful advice given it turned out that the wiring was 100% correct, and the problem was that the alternator needs a "kick start" of about 2500 rpm to get the charge light to go out, and to start charging the battery. After the kick start it charges quite happily at idle, and the light remains off. I have no idea why this is necessary but Badabec did mention in the post that revs might excite the alternator. I am sure it is not correct, but hey I am going to let sleeping dogs lie.
Cheers
harrisson_citroen
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While on the topic of the yellow light of the alternator being on, I have to report that mine flashes every second or so while running. But solid with ignition only on, battery seems to get charged properly, so not really a problem or is it? Is there a fix?
I know its an old thread now, just thought I would make a suggestion why this is so.
Most likely the pulley on the new aftermarket alternator is a larger diameter and at the normal idle speed is turning slower, hence the need to rev it up to 2500rpm.