spht
New Member
- Joined
- Apr 21, 2021
- Messages
- 1
The actual question: is there a replacement BMS that could be swapped in to add low temp protection? I realize that entails cutting the case open and re-wiring the battery. Ideally I'd also love to get heating pads that warm the battery (but the BMS doesn't charge until it's at temp), plus bluetooth and/or even better ve.direct/ve.can compatibility.
My thinking with having a BMS act as the temperature gateway is that even if the battery is too cold for charging, the MPPT could be active and trying to send charging power which would allow all of the electronics to run off the solar, including a heating pad - once the battery is toasty then the rest of the power feeds into charging.
Detail time:
I have an Ampere Time 12v 300Ah LiFePO4 (before the rebrand to LiTime) that does not have low temperature protection, heating pads, any of that. For the last 3 winters, it's been living in a travel trailer next to my house, completely disconnected in "time out." This coming winter will be a different story, it's going to stay in a remote location and it'll get below zero for several months. There is a reasonably sized solar array that is connected to a Victron MPPT, along with a Victron battery monitor that has a temperature sensor and is configured to feed that data back to the MPPT. In theory this means that the MPPT will not send a charging voltage to the 12v system if the temperature is below threshold.
OK, that's cool, but what happens in February or March when the parasitic drain on the battery from all the stuff in the trailer (currently it's 15-20w for stuff like a VenusOS RPi and other gear) has it down to 0% SOC and there's no power for the battery monitor/temp sensor to tell the MPPT that it should start charging?
Does the Victron SmartSolar MPPT push out a limited amount of power when it sees voltage on the panels that's enough to wake up the other components, get them talking, and THEN ramp up the voltage and current? I did read the SmartSolar manual and it doesn't document the actual start-up process or what the low temperature protection actually DOES, just how to configure it.
My thinking with having a BMS act as the temperature gateway is that even if the battery is too cold for charging, the MPPT could be active and trying to send charging power which would allow all of the electronics to run off the solar, including a heating pad - once the battery is toasty then the rest of the power feeds into charging.
Detail time:
I have an Ampere Time 12v 300Ah LiFePO4 (before the rebrand to LiTime) that does not have low temperature protection, heating pads, any of that. For the last 3 winters, it's been living in a travel trailer next to my house, completely disconnected in "time out." This coming winter will be a different story, it's going to stay in a remote location and it'll get below zero for several months. There is a reasonably sized solar array that is connected to a Victron MPPT, along with a Victron battery monitor that has a temperature sensor and is configured to feed that data back to the MPPT. In theory this means that the MPPT will not send a charging voltage to the 12v system if the temperature is below threshold.
OK, that's cool, but what happens in February or March when the parasitic drain on the battery from all the stuff in the trailer (currently it's 15-20w for stuff like a VenusOS RPi and other gear) has it down to 0% SOC and there's no power for the battery monitor/temp sensor to tell the MPPT that it should start charging?
Does the Victron SmartSolar MPPT push out a limited amount of power when it sees voltage on the panels that's enough to wake up the other components, get them talking, and THEN ramp up the voltage and current? I did read the SmartSolar manual and it doesn't document the actual start-up process or what the low temperature protection actually DOES, just how to configure it.
