shawnm
1 µW
Hi:
I converted a three wheeled Heinkel microcar to EV power using a QS Motor 8kw hub motor and a 72v 24S LiFePo4 pack. It has exceeded all of my expectations except for one: it won’t run in cold weather. I am having problems with my BMS system in cold weather. My EV runs fine when the temperature is above 50F (10C). Below that temperature the BMS does not recognize the cells on board #2, and will not power the Kelly controller. If I charge the EV (also with a DeliGreen onboard DC charger) it will “wake up” the controller, but when you try to apply a load the BMS cuts off again.
I have attached some screen shots that demonstrate the problem. I suspect the problem is with the temperature cutoff settings.
This screen shot shows when I turn on the car in the morning. It was about 4c/ 40F outside. You can see that cells 15-24 have no reading. This corresponds to board 2 on the BMS. Based on the documentation I originally left “board 2 temp num” on the factory setting of zero. I did try to change it to 1 (see screenshot). It did allow me to see the voltage readings on cells 15-24, but the car still would not operate. I have since changed it back to zero.
These are the settings on my temperature control. My understanding of the “dischg low temp protect” is that the BMS will not send current if the temperature is 1C or less (about 34F). I do not know what “diff Temp protect” is, or if I need to change it. I used the settings that were in the documentation provided by DeliGreen. I suspect "diff temp protect" is the culprit.
If the car sits in the sun and the temp exceeds 50 all is well.
Can you tell me what needs to be done to fix this issue?
Thanks,
Shawn
I converted a three wheeled Heinkel microcar to EV power using a QS Motor 8kw hub motor and a 72v 24S LiFePo4 pack. It has exceeded all of my expectations except for one: it won’t run in cold weather. I am having problems with my BMS system in cold weather. My EV runs fine when the temperature is above 50F (10C). Below that temperature the BMS does not recognize the cells on board #2, and will not power the Kelly controller. If I charge the EV (also with a DeliGreen onboard DC charger) it will “wake up” the controller, but when you try to apply a load the BMS cuts off again.
I have attached some screen shots that demonstrate the problem. I suspect the problem is with the temperature cutoff settings.
This screen shot shows when I turn on the car in the morning. It was about 4c/ 40F outside. You can see that cells 15-24 have no reading. This corresponds to board 2 on the BMS. Based on the documentation I originally left “board 2 temp num” on the factory setting of zero. I did try to change it to 1 (see screenshot). It did allow me to see the voltage readings on cells 15-24, but the car still would not operate. I have since changed it back to zero.
These are the settings on my temperature control. My understanding of the “dischg low temp protect” is that the BMS will not send current if the temperature is 1C or less (about 34F). I do not know what “diff Temp protect” is, or if I need to change it. I used the settings that were in the documentation provided by DeliGreen. I suspect "diff temp protect" is the culprit.
If the car sits in the sun and the temp exceeds 50 all is well.
Can you tell me what needs to be done to fix this issue?
Thanks,
Shawn