From alternator terminal on battery isolator to each of the battery banks, voltage drop should be about .7 VDC and both battery banks reading very close to the same thing (assuming both batteries are reasonably charged to begin with.
Best test is to charge both banks, then start the engine and check voltage at Alternator IN and Battery Bank #1 and Battery Bank #2 OUT.
190 amp alternator is plenty, as is the isolator (if it checks out electrically, as only with deeply discharged batteries and engine RPM at cruising speed will an alternator put out max amps.
And check with the engine at high idle, particularly if batteries not fully charged. Even a 190 amp alternator will be putting out very little at idle.
* This post was
edited 04/01/12 05:01pm by wolfe10 *
wolfe10 wrote: From alternator terminal on battery isolator to each of the battery banks, voltage drop should be about .7 VDC and both battery banks reading very close to the same thing (assuming both batteries are reasonably charged to begin with.
Best test is to charge both banks, then start the engine and check voltage at Alternator IN and Battery Bank #1 and Battery Bank #2 OUT.
190 amp alternator is plenty, as is the isolator (if it checks out electrically, as only with deeply discharged batteries and engine RPM at cruising speed will an alternator put out max amps.
And check with the engine at high idle, particularly if batteries not fully charged. Even a 190 amp alternator will be putting out very little at idle.
It seems like the isolator is defective with such a voltage drop to the main battery, but I will check the readings again with the engine off and see if there is more than a .7 volt difference.
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