question

My guess is that the firmware might have been upgraded and accordingly your configuration settings may need to be reviewed and reconfigured to better accommodate your setup and usage.

VE.Configure software with a MK3 to USB cable is required to check the current configurations and make any required changes.

There are MANY potential causes of why the MultiPlus is rejecting the incoming power supply &/or overloading (in addition to a true constant overload), so its a bit hard to recommend what to change without monitoring the system while the issue occurs and knowing what the current settings are.

Some suggestions of what settings to possibly review (in no particular order);

- 'Dynamic current limiter' option (generally better ON with a gen-set)

- 'Power Assist' option (generally better ON with a gen-set)

- Assist current boost factor

- UPS function option (generally better OFF with a gen-set)

- 'Accept wide input frequency' option (may be required if gen-set has an inconsistent AC output frequency)

- 'Weak AC input' option (may be required if gen-set has a poor AC waveform, but less efficient)

- AC1/AC2 input current limit

- System frequency

- Inverter output voltage

- AC low & high voltage disconnect/connect voltages

- DC input low shut-down voltage

- 'Shut-down on SOC' option

- SOC low shutdown %

- Any 'assistants' you may be running

These settings should really be reviewed and altered if necessary by an experienced INSTALLER or DEALER - ideally after properly monitoring any related parameters live to better understand the primary cause of the disconnection/error (rather than by trial and error).

Running with the MultiPlus fully ON (inverter & charger mode) should also help - as if the incoming power supply is insufficient or limited then the inverter will assist (even if it's only temporarily to cover a high start up load). This will also not draw any additional current from your battery during normal operating conditions, as the MultiPlus will typically always be in 'charger' mode anyway.

For further reading refer to;

- MultiPlus Generator FAQ

https://www.victronenergy.com/live/multiplus_faq

- New VE.Configure online manual

https://docs.victronenergy.com/veconfigure.html#introduction-and-requirements

If its found to not be setup/configuration related, then I would refer back to the dealer/service agent that completed the recent repair.

Fault finding for me starts with what has changed even before the board was replaced. How old are the batteries? Also 7 years?

Have reviewed settings via Mk 3. Will try Dynamic Current Limiter. Power Assist doesnt make any difference, Sat there watching the lights on the inverter and you can see, with for instance the iron, the mains just dropping out for 30 seconds or so then coming back on. Normally when the mains is connected the blue mains indicator flashes fof 30 seconds before the mains is established in this case there is no flashing, it just comes back.

I had thought about frequency variation but I can see no option to set it, anyway, watching the display the input frequency only varies by 0.1 hz when + or - 5hz is the default.

The thing is that for the first hour or so everythkng works ok. After that, switching on a high resistive load causes the shutdown.

If you leave the load connected when the majns comes back on line it powers everything as if nothing had happened. Could it be a temperature related problem.