Problem: When connected to shore, excess incoming voltage causes charger
I have a steel
built in 1990, that I bought in 2011. From May to September, when connected to shore power
, we never noticed any problems. Last month I connected my boat to shore power
, and my Mastervolt 24/40-3 charger
(installed new six months ago) registers “FAILURE 266U” and the voltmeter on the boat’s main electrical
panel is at the very top of its scale (>250v).
We measured voltage of 238v at boat end of shore cable...and taking off the cover of the charger, measure incoming voltage to the charger at 251v.
When connected to shore power, I can hear a humming sound buried somewhere in the cabinetry...and according to the boat’s wiring
diagram there is an isolation transformer.
When running the boat’s Onan 6.5kw generator
, the charger works fine.
Any suggestions? Is it possible that the isolation transformer is stepping up the voltage?