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Old 06-27-2016, 07:27 PM   #1
Junior Member
Join Date: Jun 2016
Posts: 4
Figuring it out without manuals

So, I'm troubleshooting my Hehr Powerline alternator running a Powerline 3 terminal isolator that the 3rd terminal is not charging house batteries but goes to a coil. I'm also determining why there's an adjustable negative rectifier wired to the batteries.
The rig is a Roadmaster chassis, '92 Monaco with 8.3 Cummins with MD3060.
Had dead batteries, replaced them, ran an alternator load test through my external battery charger and an alternator fault showed. Luckily I'm at home and it's safely parked outside.
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Karakashian is offline   Reply With Quote
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Old 06-27-2016, 08:22 PM   #2
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Join Date: Jun 2016
Location: Nine Mile Falls WA / Arizona City AZ
Posts: 673
so if you put a volt meter on the terminal from the alternator.... to the battery isolator you should be reading charging voltage... and if you put an amp meter around that cable you should read current charging current.... with that in mind.... you should now be able to read a voltage with the meter from the output terminal to the engine batteries and a second reading at the output terminal to the house batteries... both of these readings should be no more than .2 less than the voltage you read coming into the this device....

In addition if you measure the amperage in the alternator to isolator cable... the sum of the two values.... 1 - from the isolator to the house batteries, and 2 - the value from the isolator to the engine batteries should equal the value of the first test...

The tests above would easily verify that the isolator is functioning as it should.... if not replace it... if so.. find the additional problem...

This device is nothing more than some very large diodes... (one way path for electricity) these diodes allow one alternator to charge 2 systems and the 2 systems can't drain or run electricity to the other system

Hope this helps you understand what's going on
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