Re: 2000 Grand Villa M4000 GV320
Reply #49 –
The tech is correct when he recommends the 48162 isolator, but I think he is incorrect in saying the 48160 isolator has "failed". It didn't fail - it was just improperly paired with the Wilson alternator. The Wilson 90-01-4721 alternator is a clone (or rebuilt) version of a Delco 28Si alternator. The 28Si will not turn on unless it sees 12V on the B+ output terminal. If this model alternator is connected directly to a battery (like when you bypassed the isolator) then it works fine. BUT, when it is connected to the center post on the isolator, it can't see any 12V signal, because the isolator diodes prevent voltage from the battery posts getting to the center post. So, the alternator will not turn on. The solution, in this case, is to use a isolator that includes a separate "ignition terminal". You connect a wire to this terminal that is hot only with ignition switch in ON position. The "ignition terminal" on the isolator supplies the required 12V signal to the isolator alternator post, which will then tell the alternator to turn on.
I can't tell (from my search) if the Wilson 90-01-4721 alternator has a "sense" terminal. If it DOES NOT have a sense terminal, then it will still not work correctly on your coach, even if they replace the isolator with the 48162. If it DOES have a sense terminal, then it will work with the 48162. The sense terminal on the alternator should be connected to a 12V source that that reads CHASSIS battery voltage and is HOT all the time.
If the Wilson alternator does NOT have a "sense" terminal, then I would recommend a different replacement isolator. The Victron ArgoFET 200-2AC has the requisite "ignition" terminal AND, in contrast to diode isolators, has virtually zero voltage drop between the alternator post and the battery posts.
Amazon.com: Victron Energy Argofet Battery Isolators 200-2AC (2 Batteries...
Amazon.com: Cole Hersee 48162 Battery Isolator : Automotive
https://www.truckspring.com/products/Alternator-Wilson-180-Amp-New-28SI-Type__90-01-4721N.aspx
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