LiFePO4 BMS Wiring Help

[flyons78]

This is my first time wiring up a BMS and the instructions are a little sketchy for a first-timer. My setup is for 16S LIFEPO4. See the attached picture of my pack.

My initial question is... How do I properly count the cells?

Is this correct?

8|9
7|10
6|11
5|12
4|13
3|14
2|15
1|16

Or this:

15|16
13|14
11|12
9|10
7|8
5|6
3|4
1|2

[flyons78]

For some reason the picture is rotating on upload.

According to the picture, I want the bottom-right cell to be #1.

I'm fairly certain the cell count for wiring up the BMS would go like this, but just figured I'd ask before assuming.

09 10 11 12 13 14 15 16
08 07 06 05 04 03 02 01

[Sergio]

Assuming the box "right side" is the one with three holes, your description is correct.

Pack negative will be #1 bottom right next to the hole.

Cell #8 (bottom left) positive will have a cable going to cell #9 (top left) negative cell.

Pack positive will be #16 (top right) next to the hole.

I guess that middle hole is for the BMS balancing wires which will work great.

[WalterM6]

This is how I have My batteries setup and wired.

[flyons78]

Originally Posted by Sergio

Assuming the box "right side" is the one with three holes, your description is correct.

Pack negative will be #1 bottom right next to the hole.

Cell #8 (bottom left) positive will have a cable going to cell #9 (top left) negative cell.

Pack positive will be #16 (top right) next to the hole.

I guess that middle hole is for the BMS balancing wires which will work great.

Yep, you just confirmed everything for me. Middle hole is also for the BMS balancing wires. Thanks!

[flyons78]

Originally Posted by WalterM6

This is how I have My batteries setup and wired.

Thanks, Walter! That helps a lot. I've been using your build as inspiration since we have the same batteries and bms. Hope your battery issue speedbump is almost resolved.

[WalterM6]

I'm top balancing my batteries now. Might be another day or two before I put it back together. Since you have the same BMS I'm attaching a wiring diagram for connecting a 16S battery. They are kind of rare, I found it on a solar forum. It's in Chinese but you can see where the wires go.

[Sergio]

The 16S BMSs are pretty common, that wiring diagram looks convoluted because it is a 20S BMS wired for 16 cells.

[flyons78]

Originally Posted by WalterM6

I'm top balancing my batteries now. Might be another day or two before I put it back together. Since you have the same BMS I'm attaching a wiring diagram for connecting a 16S battery. They are kind of rare, I found it on a solar forum. It's in Chinese but you can see where the wires go.

I was following the wiring diagram and instructions on this site (you provided in another thread). I'll be combining wires BC14-18 and connecting them to cell 14. This is what it says to do for a 16S configuration.

https://www.lithiumbatterypcb.com/pr...bluetooth-bms/


One other thing I'd like to confirm is that my connection between cell 8 and 9 is a 4 AWG wire. Will that be sufficient?

[WalterM6]

The size of that wire will be determined by the amp rating of your controller. A stock controller would be ok with #6. A 500A Alltrax would need a #2. One other thing and excuse me if you already noticed. The screws provided are barely long enough to get a grip with the larger connection on B+ and B- and the two you just mentioned. What I'm doing to prevent ripping the threads out is to make a stud connection. I'm going to get a longer M4 screw and cut the head off. Rethread with a nut and screw into the battery. Then I will just stack all the cables on and tighten down with a nut and won't have to worry about stripping the threads out.