I've got a Multiplus 24/100/16 connected to a BlueNova 26V 108Ah 2.8kWh LiFePO4 battery. This works fine. Now I'm adding a SmartSolar 100/50 which will charge the battery when there's sunlight, while the Multiplus will charge it from the mains at night and on cloudy days. I have also added a separate Phoenix inverter fed from the same battery.
Since the MPPT and the SmartSolar both charge the same battery (in parallel) they should have the same charging profile. The instructions for the Multiplus state that one should connect it to just the battery, set it up properly and only then connect it to the mains. So I did the same with the SmartSolar: I connected it to the battery with the expectation that that would allow me to set it up before connecting the PV array.
However, the SmartSolar appears to short out the battery: as soon as I connect it the battery clamping voltage drops to 2-3V. There's no arcing and the battery fuses don't blow, so my guess is that the BMS throttles everything down to prevent overloads. Disconnecting the SmartSolar restores normal battery voltage and the Multiplus works normally again, as does the Phoenix inverter.
Is shorting out the battery normal behavior for the Multiplus if there is no PV array connected? Is there a way for me to set the SmartSolar to work with the proper charging profile first before connecting the PV array? Connecting the PV array would mean that the SmartSolar will begin to charge the battery before I've had the opportunity to set the proper charging profile. But maybe I'm wrong and going about this the wrong way.
Any advice would be helpful. Tnx!
// FvW
