Bestech D131 24S Lipo BMS Set Up for 18S

[number1cruncher]

Recently, there was a group buy for Bestech BMSs coordinated by member Dnmun. The process went really smooth and I thought I would post my set up and initial results. Although the BMS has the capacity for 24 cells, I set it up for 18.

Below is a picture of the D131 24S Lipo BMS I selected:


First, I soldered the main wires using 10awg for B-, P- and 12awg for C-.


Next, I connected the sense wires to 7 pin JST connectors, so I could swap out packs easily. I included both female connectors for the pack balance connections and male connectors for CellLogs.



All direct connections to the BMS are finished, so now I assembled a positive harness including a fuse using 10awg for the P+ and 12awg for the C+.


I then tested the setup outside of the case to ensure easy troubleshooting. No problems.


I picked up a $7 toolbox at Walmart to use as a case. The discharge cable is routed out the side, down through an overhang. The celllog connectors and charge cable is routed out the top, which has a lid to keep the water out.



I have been using the pack for about two weeks now. It balances all 18 cells to within 17mV, from 4.183 to 4.200.

The LVC and HVC functions have not been tested yet. When I have a chance to do this I will post my results.

Thank you Dnmun for taking the time to set up the group buy. This BMS should make my ebikes a lot safer and hopefully extend the pack life.

 

[dnmun]

the trick to making the cycle life longer is to keep the lipo uncharged until you need it and then charge up to full charge so it gets a chance to balance any of the cells which have a little more self discharge than the others.

i have a set of cellogs wired into the sense wires so i can monitor cell voltages. that helps me keep track of where the cells all end up and i kinda just depend on seeing the same numbers every time.

but i had abuncha bad cells in the second lipo pack that i put in parallel with the first and i could see the channels that were not pulling up to the same voltage anymore because the drain down internally was too high for the regular balancing so i separate the two packs i had operating in parallel under the BMS and that led me to the bad channels.

then i had to separate all the channels in rows in that 21S3P of 8Ah nanotechs to find the dullards. ended up scrapping 7 pouches, and lost another 3 pouches when i was attempting to cut a new 5S nanotech pack apart to use it for replacements.

now i am about to put that shrunken pack back together as 21S2P with the pouches i have left and i will have an extra 13S i can use to add to my 13S li ion 48V15Ah pack to make it into a combined 48V23Ah pack with the lipo and li ion wired up in parallel under two D127v2 13S lipo BMSs wired together in parallel.