- Joined
- Jul 27, 2019
- Messages
- 12,576
- Location
- Midlothian, VA
- RV Year
- 2017
- RV Make
- Newmar
- RV Model
- Ventana 4037
- RV Length
- 40' 10"
- Chassis
- Freightliner XCR
- Engine
- Cummins 400 HP
- TOW/TOAD
- 2017 Chevy Colorado
- Fulltimer
- No
I completed my monthly battery cycle by letting them run down to 30% SOC by remotely setting the two inverters to "inverter" mode instead of "ON" which is inverter + charger for Victron. I usually let it run down lower but I didn't want to forget as the coach is in storage and the heat is on. This morning as it approached 30% I changed the two inverters back to "on."
This evening I checked the status of the charge and see that it did not charge at all, the Victron lynx bms was in an error state. I tried cycling the BMS from standby to on and no luck. I reached out to SES and heard back not long after and he said I'd need to go to the coach (30 minutes away) and use bluetooth to turn the bms off and then on. But I had a hunch it may be a thermal situation as it's been very cold and it's 29F out. However, I have heating pads and they are temp controlled by a sensor and the temp showed 39.7F which is the temp at the ceiling of the enclosure by the ruuvi sensor. I typically cycle the temp so it comes on automatically at 35 and turns off at 40 so it keeps the batteries above freezing. I raised the window to come on now at 40 and turn off at 45 and then after waiting 30 minutes the bms enabled charging again. Fortunately I can control the relay settings for the heating pad remotely to resolve this via the Victron Cerbo GX and VRM.
The heating pads I have installed wrap the outside of the batteries so my guess was the inner section of the battery bank, opposite the heating pads, were lower and the cells were probably reading 32F or lower. I could see the temps via the Victron app if at the coach but remotely I can't see the actual cell temps.
So good lesson learned, keeping the heat higher on the heating pads to ensure the entire enclosure is at a high enough temp. But the moral here is if your batteries get to 32F or lower, they will not charge. If using LiFePO4 (lithium) batteries you really need to look at a heating solution or your batteries can discharge until the bms (internal or external) blocks them from charging until back above 32F.
This evening I checked the status of the charge and see that it did not charge at all, the Victron lynx bms was in an error state. I tried cycling the BMS from standby to on and no luck. I reached out to SES and heard back not long after and he said I'd need to go to the coach (30 minutes away) and use bluetooth to turn the bms off and then on. But I had a hunch it may be a thermal situation as it's been very cold and it's 29F out. However, I have heating pads and they are temp controlled by a sensor and the temp showed 39.7F which is the temp at the ceiling of the enclosure by the ruuvi sensor. I typically cycle the temp so it comes on automatically at 35 and turns off at 40 so it keeps the batteries above freezing. I raised the window to come on now at 40 and turn off at 45 and then after waiting 30 minutes the bms enabled charging again. Fortunately I can control the relay settings for the heating pad remotely to resolve this via the Victron Cerbo GX and VRM.
The heating pads I have installed wrap the outside of the batteries so my guess was the inner section of the battery bank, opposite the heating pads, were lower and the cells were probably reading 32F or lower. I could see the temps via the Victron app if at the coach but remotely I can't see the actual cell temps.
So good lesson learned, keeping the heat higher on the heating pads to ensure the entire enclosure is at a high enough temp. But the moral here is if your batteries get to 32F or lower, they will not charge. If using LiFePO4 (lithium) batteries you really need to look at a heating solution or your batteries can discharge until the bms (internal or external) blocks them from charging until back above 32F.
