Uploaded August 2022 | Updated September 2026, 3 weeks ago

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I got 8 new JK BMSes, 6x JK-B2A24S15P and 2x JK-B2A8S20P. The two B2A8S20P are the same model number as the one Andy got in the video below. In his case, it supported 4s (12v) configuration. The version I got, same model number, do not. When I asked about this, I was told that any version made after August 2022 will again support 4s.

So this is the second time I got a brand new to me, same model number JK BMS that had missing features / capabilities. Twice now, I found that my JK BMSes are "too old". The model numbers don't change, and there is no version number I can find. I have no idea how people buying JK BMSes can know what variant with what capabilities they will get.

I hate these BMSes, and I had to order two more.

Off-Grid Garage, B2A8S20P - youtube.com/watch?v=LDalnC01MZE
Off-Grid Garage, Boost Converted to run Smaller Batteries - youtube.com/watch?v=xdNEMl72z9s
Off-Grid Garage, Bring a High SoC Battery Online With Low SoC Batteries in Parallel - youtube.com/watch?v=Z1ajHrRdDfo

0:00 - Opening a new box
0:38 - 24 or 12 volts
1:15 - Crunched Boxes
2:20 - 4s Support?
3:19 - 16s BMSes and Top Balance Plans
4:22 - Connectors Keep Changing
6:11 - This Should Support 4S...
6:53 - RS-485 goes into GPS because Reasons
8:20 - Parallel Not Supported?
9:24 - Trying 4S
14:26 - First 4S Try
15:25 - An Annoyed Mermaid
16:08 - Verifying BMS Works, First Time
17:17 - Act 2! Why This Might Not Work in 4S
19:39 - Parallel Battery Concern
22:01 - Doing More Science! 4S Try 2
26:18 - 4S Try 3... A Question of Grounding
28:40 - Verifying the BMS is Still Alive