Battery Charger Drops Voltage Under Load

[Heikki]

We have a Mastervolt IVO smart 12-40/3 battery charger. It has served nicely for almost 10 years - but not anymore. Something went wrong with it last winter. It has not worked right on this season anymore.

If it has absolutely nothing connected to it, the output voltage is 13.8V. When the batteries are connected to it, the maximum output voltage is 13.1V. If there is any device connected to the batteries and under load, the output voltage drops to 12.6V or under. Sure enough, with this kind of voltages the batteries will not get charged.

Furthermore, if the temperature sensor is connected, the charger fails completely - all the lights on the charger go out. I have not measured if there would still be output voltage.

I am sure someone has had the same problem. Is this a fixable issue or do I just have to let it go and spend €700/$1000 for a new one?

[GordMay]

The User Manual (Ch 7, Troubleshooting) might help:
➥ http://images.mastervolt.nl/files/Ma...er070821EN.pdf