JK BMS 8-17s 100amp won’t initialize

[Rfish]

I recently installed a JK 8-17s 100a BMS for my Eve 4-cell 100AH battery. I wired it up and all seems correct. I’ve tried initializing using the 9v battery jumper and nothing. The BMS will not start up. I also received a power switch with the BMS and installed it in the port, doesn’t do anything.
Is there an issue using a 8-17s BMS with only 4 cells? I don’t get why that would be an issue, just not monitoring as many cells. I talked to the retailer technical support and they really didn’t know.
Any help or suggestions are greatly appreciated.

 

[squowse]

Its for 8 to 17 cells. I imagine if it could work with 4 cells then it would be called a 4s-17s bms. These bms power themselves from the balance leads so there is that.

 

[Rfish]

I respectfully disagree, there is a dedicated line from the BMS to the main positive of the battery that powers the BMS. Usually it's the last balance wire in the series. The 9v battery jumped between B- and P- should initialize the BMS even if the balance leads are not connected.

 

[ScrotusGobbleBottom]

Pretty sure th

even if the balance leads are not connected.

That I have not heard before. Are you sure? Where did you hear this?

 

[Rfish]

reading on the KJ website, they suggest using the 9v battery jump to initialize the board. Initializing the board takes a low voltage, thus the 9v battery. Dont get me wrong, I jumped with the board completely connected to the battery. I was just saying that in theory you only need the 9v pulse to initialize the BMS.

 

[ScrotusGobbleBottom]

reading on the KJ website, they suggest using the 9v battery jump to initialize the board. Initializing the board takes a low voltage, thus the 9v battery. Dont get me wrong, I jumped with the board completely connected to the battery. I was just saying that in theory you only need the 9v pulse to initialize the BMS.

My confusion was the part about no balance leads connected.

 

[Rfish]

Sorry for the confusion, balance leads and board power leads are connected.
One other confusing thing is that this board has bluetooth but there is no bluetooth connection light on the board as most other JK with BT have. Maybe I have a bad board...Thoughts?

 

[ScrotusGobbleBottom]

Sorry for the confusion, balance leads and board power leads are connected.
One other confusing thing is that this board has bluetooth but there is no bluetooth connection light on the board as most other JK with BT have. Maybe I have a bad board...Thoughts?

I dont think mine has a blue bluetooth light either. I think its the red light that is usually constant blinks just a couple times when blue tooth is connecting.

 

[gotbeans]

Pretty sure th

That I have not heard before. Are you sure? Where did you hear this?

Yea he isn't wrong, not sure how well it works though.
This info has been around for years, it's even here where he uses a buck booster in series:

Its for 8 to 17 cells. I imagine if it could work with 4 cells then it would be called a 4s-17s bms. These bms power themselves from the balance leads so there is that.

I agree with this though


You used to be able to run the BMS with no balance leads connected at all, they might have updated and changed that but obviously any "limits" on the cell over or under voltage don't get detected there

 

[Rfish]

Mine has no light at all...no indicator light on the bottom of the board.

 

[MattiFin]

Goddamnit these chinese junk BMS not working totally outside of specifications. Shocking experience.

 

[gotbeans]

I think the cell count range is basically just the voltage range required for that specific BMS to boot up, since they work with buck boosters etc

obviously any software update can require the cells to be cooked up though. But mine still runs if I disconnect all the balance leads

 

[Rfish]

Thanks for the video, Gotbeans. I now see the issue. I need to supply a 48v charge if I choose to use this BMS. So how will this effect the 12v charge draw from the appliance?

 

[gotbeans]

Well I assume since it's "8" minimum it's 8*3 so 24 volts (probably 20) to turn it on
Otherwise it couldn't turn on if you only had 8 cells and were on the low end

and the max voltage must be ~60 volts since 17 cells * 3.6 is about 60

no idea how it'll effect anything LOL I wouldn't run it like that.
obviously if the buck boost isn't in series with the main power it won't be involved though

 

[Rfish]

Agreed, I'm gonna send this one back.
Thanks a tone for the help.

 

[timselectric]

Is there an issue using a 8-17s BMS with only 4 cells?

Yes