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My Cerbo GX reports that my Multiplus II State is “Unknown”. The unit appears dead. There are no LED’s lit. Rocking the switch does nothing. However, when I turn on my generator it begins the standard charge cycle, reports a state of “Bulk”, and the corresponding LED’s are lit. But when I stop charging it reverts back to “Unknown” and will not invert or do anything (no LED’s). Seems to only be responsive with an AC input. Any thoughts on what might be happening? Thanks.
Turn the unit off.
Disconnect the VE.Bus cable from the Cerbo.
Turn the unit on.
What happens?
This is a typical symptom of a system that has no physical connection to the battery. Check if you can measure a voltage on the DC terminals when the generator is off.
Likely if the fuse and connections are ok, the battery voltage is under the inverter restart value.
Doesn't explain why it is not charging though when connected to mains and on? So check programming
The voltage is now 13.1. I believe it is configured correctly. It was working but quit. I had been getting a number of L1 temperature warnings when I charged from the generator, even though I reduced the max charge current to 50 amps. I don’t get the error when charging from the mains even with much higher current. Anyway at this point I can’t communicate with the Multiplus .
I guess it is in float which is why the voltage is 13.1. For Lifeline AGM batteries, 12.7 volts is more than a 90% SOC.
It turns out that the problem was a faulty temperature sensor. Once i disconnected it everything was restored to normal. Strange but true.
Great. But also 12.7v is too low for AGM. Those batteries will be killed by undercharging.
