If ‘ve a Victron installation with MULTIPLUS and cerbo GX in ESS-mode, solarinverter at AC1out, Pylontec Batteries and a MPPT with some additional solarmodules. At AC1out a lot of refrigarators are connected.
The cerbo is supplied from the 48V battery.
If in case of a grid failure the MULTIPLUS will feed my refrigarators. Thats running very well.
But if there is a longer grid failure the battery will go to 0%. I think the cerbo than will switch off.
For this scenario I installed the MPPT with some additional solarmodules. The MPPT has to recharge the battery till the cerbo begins to restart and as a result the Multiplus restarts. Now there is 50Hz on AC1 and my inverter can really recharge the battery.
Here is my question, because i see no possibility to test the scenario above:
Does the MPPT, which is programmed to be controlled by the cerbo, automaticaly falls back in the standard charging program if there is no cerbo available and my system really restarts?
If you have killed the battery by over discharging it, you will need to follow their restart procedure. It may not just recharge. Set meaningful cutoff limits to avoid issues. Exceeding specs will void your warranty.
once I debugged a system with 4x Pylontech US2000, MP2 3k, MPPT150/35 and Cerbo.
The system was starting up in the morning and than switched off with Low Battery Warning.
We found out, the fuse to the battery stack was blown.
Just after sunrise, the MPPT power the DC bus bar (w/o batter, due to blown fusre). MP2 started up including inverter to provide power house net. The power was more than the sun could deliver and the DC net failed.
Why do I tell the story?
The MPPT will start up as soon as it get powered from the sun and provide 48V to the DC bus bar. This might be sufficient for the Cerbo. Set the low volatage cut off of MP2 to mayb 15% SOC or accordian voltage. The MPPT can first power up Cerbo for logging while start recharging battery. If battery reaches a certain SOC/voltage let the MP2 restart (low voltage recovery).
That way it should work - but I haven’t tested yet.
But I use Lync Distributor with additonal hardware and software to use the build in fuse monitoting and alerting.
If the standby MPPT is in “BMS Control mode” as soon as the cerbo powers down, then it will go to error 63 - No BMS contact, and shut down.
Only way to get one to black start a cerbo is to have it in ‘dumb’ mode, with a max output voltage of 52V so it does not overcharge the bus in any condition.
I think that this is in the settings>>battery section.
If the external control mode shows - possibly only in error mode, there is also a ‘reset’ button, which causes the MPPT to forget that it is BMS controlled. ‘Dumb’ mode is my way of saying that the MPPT has NO external control or data connection, it just operates on it’s own internal settings.
If you need black start: Decide how small an MPPT unit you need, then DON’T connect the data to anything.Having a shunt for this is redundant, as the total energy developed should be quite small. If the Abs voltage of this MPPT is set to <52V, then it should spend most of it’s time in the off state.
Just set proper cutoff thresholds for the battery so it can power the cerbo until sunrise.
There is no need to run a battery to bms shutdown . Something that is bad for your warranty.