Older Xantrex Inverter/Charger Trouble

[steve77]

We have an older Xantrex unit, model 81-3011-12. The unit was manufactured in late December, 2003. Recently, it has been shutting down and the red FAULT LED has illuminated. From the manual, this doesn't mean an electrical fault, it just means there is some internal problem and the unit is shutting down until it is fixed.

Shutting the unit down and restarting, it will run properly for about 24 hours before the FAULT light comes back on. During this time, it appears to be charging the batteries properly. We are in the boatyard, so we are not using the inverter section, only the charger.

Anyone have any ideas where to start troubleshooting?

We are in Portugal, and we have an isolation transformer to drop shore power to 120 VAC. Of course, the input frequency is still 50 Hz. Will 50 Hz power damage our inverter?

Any ideas appreciated. Cheers!

Steve