Victron Multiplus 2 (with supplied temperature sensor connected)
CerboGX
SmartSolar MPPT
I have the system setup with a 24v battery bank (2x 12v 100Ah batteries). The batteries are LiFePo4. Currently, the temperature is -2 degrees Celsius outside, however I’ve noticed my solar array is charging the battery bank. I’ve been trying for the last few hours to prevent battery charging, however I still want the solar power to power the loads. I’ve tried the low temperature cut-off in the MPPT controller, however that stops all power being generated. I’ve also tried enabling “Stop Charging Below” in VeConfigure, however that also stops the MPPT from generating power too.
Outside is also the temperature inside the battery compartment?
The solar cannot choose where the power it generates goes. The battery ideally would need to refuse charge when necessary.
You may need to create a node red flow that freezes (pun intended) / caps the battery voltage.
Otherwise maybe some battery heat pads would help.
Surely this could be a feature to direct power away from the batteries. It already does this when they are fully charged, thus excess power goes to the loads and to the grid. The only difference is, when its below a certain temperature, to halt battery charging and direct the solar power to the loads/grid just like when they’re fully charged.
If this cannot be done, since I use Home Assistant (Multiplus talks via MQTT), could I simply change the setting from “On” to “Inverter only”? Would this do what I want?
@lxonline just regarding your suggestion of a heating pad, which kind of pads would be suitable? I guess I could use a relay to divert solar power to the pads via some Home Assistant automation until the battery temperature is higher than freezing.
Fully charged, the battery is sending charger limits, adjusting current and/or voltage. The system can use that to service loads and not charge.
When you want to override the behaviour of an uncharged battery, one that is sending parameters to encourage charging, the mppt has no control over where its energy goes.
You can either shutdown the MPPT, or you need to manually adjust (where possible) the parameters to restrict charging. Electrons don’t listen to instructions, they have to be steered.
Just out of curiosity, since I’m using ESS, would setting the Max Charge Current to 0 work? I’ve just tried it then and it’s shown the ESS #6 code. I’m not bothered about transient current still getting to the batteries due to varying AC loads. As long as it doesn’t maintain a charge at high current I guess is safer.
Ah, thanks for that. Should I enable DVCC in my case? Do I need that for the ESS Max Charge Current to take effect? Or should I use the DVCC charge current instead? I did enable it in my attempt to figure out how Low Temp Cutoff works. The only difference I saw was the temperature from my inverter syncs with the MPPT so the temp cutt off on the MPPT charger works. But, I can’t enable the temp cut off due to my original issue where no solar power is used.