Seplos V3 150A BMS for LiFePO4 cells. Heater control not working? Bug? Feature? Impatience?

The Seplos V3 BMS for Lithium Iron Phosphate cells with optional heater control does not turn on heater when the cells are too cold. Or does it? Hint: Patience is a virtue.
Seplos BMS website: www.seplos.com/battery-manage...

[@EmmieMaria265]

what a beautiful rug, where did you get it 🙃

[@Noeadm1]

@alexmakeandrepairblog Hello! i have question can u provide high resolution images of BMS v3 with heating options ? i have BMS v3 without and need prepare it working so need to know what to add on board i need foto where is connected heating pad and litte around it ;) PLEASE :) seplos wont help me :(

[@alexmakeandrepairblog]

Hi Noeadm1, the BMS is built into the box you see in the video and the box is built into my RV already. I am not sure how much work it is going to be to open it up in order to take a picture. I will try, but I can't promise you anything. You could also ask Andy over at the Off-Grid Garage but since he is living in 'sunny hot Australia' I doubt he ordered the BMS with the heating option.

[@Noeadm1]

​@@alexmakeandrepairblog Maybe you have some unpublished video/photos showing what mosfet is installed. I know that in the old version it was CRSS042N10N... I also wrote a message in one of Andy - @OffGridGarageAustralia recent videos about BMS seplos and I'm waiting for a reply... Thank you for your help and best regards :)

[@Noeadm1]

@@alexmakeandrepairblog PLEASE this make me crazy I dont find no-one more who have v3 with heat module... can u try ??? :D maybe I will send u some micro endoscope camera If u can't put phone inside and take photos ?

[@alexmakeandrepairblog]

@@Noeadm1 I will. But I won't be able to do it on short notice. The battery is built into my RV and the RV is not near my home.

[@alexmakeandrepairblog]

I made a couple of pictures. nc.tarthorst.net/index.php/s/3ssHWDn8qKeMyEf

[@craigster750]

Hey there! I am dealing with something similar right now. One question, I see there is an "Ambient" low temp warning/cutoff/recovery in addition to the normal values. Where did you set those?

[@alexmakeandrepairblog]

Hi! I am not sure I exactly understand your question. Where did you see those and what do you mean by 'normal values'? In the Seplos BMS studio, the ambient temperature related alarms, cutoffs and recoveries are parameters 64 thru 71 on the "Parameter Management" tab. But I suppose you already found those?

[@craigster750]

@@alexmakeandrepairblog That's what I was referring to. Not sure I want to use those at all, and am wondering if you just set those to be very low, or the same as the "Charging low temp" values.

[@alexmakeandrepairblog]

@@craigster750As I understand it (but the documentation is very limited to say the least) these settings influence the temperature protection of the board itself. Not the power MOSFET part, but the rest of it. For that reason I left them at the default settings. I may be changing under ambient temperature protection (parameter 71) because I don't see how freezing temperatures would be a problem for the BMS itself. But I will cross that bridge when I get there. I'll first check if it is really a problem in practice. The power temperature settings (72..75) refer to the temperature of the power MOSFETs. I wouldn't mess with those as setting these values too high may cause the BMS to get damaged under extreme conditions.

[@craigster750]

@@alexmakeandrepairblog I just don't want to be in a situation where the cells are reading 5deg C and the "ambient" is reading 0deg C. I don't want to prevent charging in this case, but I would like to use it as a backup. Perhaps I will see what the difference is between the sensors when not charging or discharging, and offset them by that much.

[@alexmakeandrepairblog]

@@craigster750 I guess you are not using heating then? If you are it's useless, since the ambient sensor is on the BMS board and likely not heated even if the cells are. But there is another issue with this approach: The absence of different limits for charge and discharge makes me believe this protection will stop the BMS from working alltogheter, also discharging. I did not test this, but that's what I would expect. In my build I am relying on the two supplied battery temperature sensors. I stuck them between the cells (one between 2 and 3 and the other between 6 and 7) . The BMS will prevent charging based on the lowest of the two.