Re: 2005 U270 charging problem
Reply #3 –
Indeed, bad isolator.
But a little confusing: Reading on center lug (direct connection to alternator B+ terminal should be about .7 VDC higher than the two readings on the outer lugs (one to each battery bank). That .7 VDC loss is turned on to HEAT. That is why the diode-based isolator has the fins-- to dissipate the heat. You posted same readings for center and chassis battery lugs??
Short term fix would be to move the cable from the house post and add it to the lug for the chassis battery. Note: batteries will not only charge together, but will also discharge together.