AAVP7
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I just finished a body-off resto of my A0 Humvee and did a first test drive today. During the restoration, I swapped the 60 A for a brand new 200 A alternator. The 200 A is wired for dual voltage use, according to the TMs. I also compared and rechecked all the time with my A2 slantback, which has a 200A from the factory.
The new alternator is a Niehoff N1225-1 with a M3135 regulator.
Before the test drive, I had the engine running for about half an hour (for adjusting tranny oil, warming up, etc.). I also checked voltage at the regulator output posts before setting off, and got nice 28.8 and 14.5 volts, respectively. The voltage meter on the dash was at the top of the green. So everything looked fine. About 15 minutes into the drive, however, I noticed the voltage meter had dropped into the middle of yellow. I managed to get home, but again checking at the regulator output posts I got only 24.5 and 12.2 volts, which is exactly battery votage. So no more charging. I cycled the engine to see if the Niehoff overvoltage feature might have tripped, but got the same result.
I then ran all the tests in the Niehoff troubleshooting guide, and got the result that my regulator seems to be shot, but the external wiring and the alternator seem to be OK. I also checked all grounds, connections, etc.. All seem good.
Now my questions:
With the rather low battery voltages (24.5 / 12.2 V), I guess we can rule out that the regulator regards the batteries as "fully charged", and stops charging on purpose, right ?
Can the above voltages be already too low to excite the alternator enough ? I´m charging overnight, so will try with full batteries again.
Is it common for a regulator to fail after less than an hour of operation ? According to other posts, they seem to fail quite often, but right out of the box ?
How do I make sure that there are no external problems that killed the regulator ? The field coil resistance for example is supposed to be between 1.8 to 2.2 ohms according to Niehoff. I measured 2.8 ohms. Can this kill the next regulator ?
I know there are numerous 200 A threads (and I think I read them all). However, the price of new regulators has risen to such ridiculous levels that I thought I better ask a bit around before swapping a new one in just for a try.
Thanks in advance
Arnd
The new alternator is a Niehoff N1225-1 with a M3135 regulator.
Before the test drive, I had the engine running for about half an hour (for adjusting tranny oil, warming up, etc.). I also checked voltage at the regulator output posts before setting off, and got nice 28.8 and 14.5 volts, respectively. The voltage meter on the dash was at the top of the green. So everything looked fine. About 15 minutes into the drive, however, I noticed the voltage meter had dropped into the middle of yellow. I managed to get home, but again checking at the regulator output posts I got only 24.5 and 12.2 volts, which is exactly battery votage. So no more charging. I cycled the engine to see if the Niehoff overvoltage feature might have tripped, but got the same result.
I then ran all the tests in the Niehoff troubleshooting guide, and got the result that my regulator seems to be shot, but the external wiring and the alternator seem to be OK. I also checked all grounds, connections, etc.. All seem good.
Now my questions:
With the rather low battery voltages (24.5 / 12.2 V), I guess we can rule out that the regulator regards the batteries as "fully charged", and stops charging on purpose, right ?
Can the above voltages be already too low to excite the alternator enough ? I´m charging overnight, so will try with full batteries again.
Is it common for a regulator to fail after less than an hour of operation ? According to other posts, they seem to fail quite often, but right out of the box ?
How do I make sure that there are no external problems that killed the regulator ? The field coil resistance for example is supposed to be between 1.8 to 2.2 ohms according to Niehoff. I measured 2.8 ohms. Can this kill the next regulator ?
I know there are numerous 200 A threads (and I think I read them all). However, the price of new regulators has risen to such ridiculous levels that I thought I better ask a bit around before swapping a new one in just for a try.
Thanks in advance
Arnd