Myles Best avatar image
Myles Best asked

MPPT 150/100 died

good-solar-charger.pngHowdy trying to investigate this failure with my MPPT 150/100. Installed new solar panels and updated the battery wiring since the factory gauge (RV) was small and came from the factory cut / with exposed copper on the red wire... On battery alone with PV cut off, no lights and no longer available on bluetooth. Did notice a few hours before that it was 'rebooting' frequently / the bluetooth was not stable. It is connected to a Venus/Cerbo GX (w dual MultiPlus 3000VA 12v and 1,000 amp smartshunt). during that time, I noticed the battery configuration was wrong and corrected it (settings showed 24v battery, but was 12v). But found that the corrections did not stay. I wasn't sure if it was because Venus/CAN was setting things up and the configuration was no-op or not. But looking at the graphs, it looks like around the time of the failures it legitimately thought 24v and was not saving the settings, but you can see previously it did not have that issue. Back to the wires, 2ga (US) from panels and to battery (wasn't sure what to put on battery side so decided larger would just lead to less efficient charging on lower end, but not leave me in a pickle on the higher end.)

Questions I'm trying to solve:

  • Is any of this expected?
  • Is this something that I should warranty? - less than a year in service and $800 USD
  • How do I know replacing the MPPT 150/100 won't cause the same issue again?
  • Is it possible the wire sizing caused this?

Graphs :) - the missing time period is when the charger seemed to die. When that happened the multipluses also went down- so unaware of what happened during that time. Might be time to install a UPS for the "home lab" in the RV.

Battle born batteries 12v. So 14.2 is right.


Here 18.9v is, quite wrong. I think this is going back to that 24v setting I mentioned.

bad-solar-charger.pngnothing out of the ordinary with the pv

pv-vs-soc.pngif you're curious about multiplus since that would be the other feeder of dc voltage


Not seeing anything unusual on the battery either,


Oh, one thing that was weird too, the battery terminals:


Solar PanelsolarMQTTsmart solar charging behaviour
bad-solar-charger.png (146.2 KiB)
pv-vs-soc.png (155.7 KiB)
battery-info.png (204.5 KiB)
all-ports.jpg (215.4 KiB)
batt-ports.jpg (175.5 KiB)
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
Alexandra avatar image
Alexandra answered ·

@Myles Best

It is possible the battery is shutting down. And there is not battery reference for the mppt (hence the incorrect redetect of battery voltage.)

If you are happy the battery is ok. Then maybe the battery connection from the mopt is not ok (blown fuse, clamped on insulation or clamped on heat shrink on lugs?)

If there was no reverse polarity. There is definite evidence of an exciting event on the terminal there from a live (or loose) connect on the mppt. Or most likely they just got hot from undersized wiring.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Myles Best avatar image
Myles Best answered ·

forgive me for my sin; ah- yeah it might have been changing the [live] battery wires during the day. My battery disconnect fried from the amperage of the multipluses and I haven't gotten around to installing the new disconnect since the spark of 3 x 100A batteries on 2/0 gauge wire is... not fun. Alright going to install two more DC quick disconnects (battery and another on panels in the bay) close to the mppt then too so it's not just on the roof from the panels.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Related Resources

Additional resources still need to be added for this topic

Victron MQTT readme