Something else I forgot to mention is that apparently the "new" rebuilt alternator installed previously puts out max 190 amps. The old original isolator in the coach was only 160 amp. We now have a new one ... 200 amps.
Also the alternator was wired into the system incorrectly and is now getting the proper trigger from the ignition to fire up the charging circuit which makes the tach work again.
It shows about 12.5V on the voltmeter at idle and about 14V at about 1200 rpm and up. The best it has ever done before was about 13.5V with nothing much drawing power.
Don

Sounds like all is good Don.
This all brings up a very good point! Battery isolators DO NOT cause a 0.7 VDC drop if they are connected correctly into the charging system closed loop. I am writing up a battery charging comparison paper because there are some wrong concepts and changes are being made when it is not necessary.

Again hope to see you in March

I agree - isolators tend to be whipping boys, when the issues are elsewhere.

Depends on the wiring for sure. If you have a remote voltage sensing wire the isolator can be used no problem.

Unfortunately, the GM alternators on the Chebbies have internal voltage sensing. I haven't figured out how to beat the diode drop on those.

Ed, I look forward to everything you post!