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ANT BMS won't read cell 1

JoeyDaRench

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Apr 2, 2021
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I am using an Ant BMS 10s-24s 180A/450A with LCD system. I have it wired to 16 cells. I have 2 identical units. Each cell is 272AH. Both are software set to 16 cells.

One of the two systems is having trouble with cell 1 reading 0 volts. That in-turn has it saying the overall voltage of the pack is 49.2V. All the cells are brand new and read 3.27V. When I test the voltage on the PCB just below the connector (14 pin) it shows the correct voltage yet the BMS doesn’t see it. Each and every pin checked in the same mannor has the correct voltage. My thought was a bad BMS. I swapped them with my other system and the trouble stayed with the battery pack, in other words, both BMS’s did the same thing on that battery pack. Both when put on the other battery pack work properly.

Believing the trouble must be in my connector or the single cell, I replaced the cell 1 connector/wire in the housing which did not help. I swapped the number 1 and 2 cells just to see if the trouble moved, it did not.

Again, the voltage reading on the circuit board where the connector housing is soldered through reads correctly at 3.27V yet the BMS says it’s zero. I am able to get that reading with everything plugged in and running telling me that the BMS is indeed GETTING the 3.27V.

@erickh I saw your post with the same trouble from about a year ago. Were you able to solve the problem?

I appreciate any suggestions and help. Thank you.
 
Found the trouble. The ground sense wire (pin 1) had a problem near the connection to the battery. I eliminated the display and temp. sensors so the only thing left had to be the ground. As I moved the wire back and forth near the battery, I got a reading for cell 1. I cut about 2 inches out of the wire, crimped and soldered a new eyelet on and it's working properly.

This really threw me for a loop as all the other cells read correctly, just cell 1 had a dead (0 Volts) reading. Nonetheless, that was the fix.
 
If you have 2 of the same BMS.... you could also swap them to determine if the problem stays with the BMS or with the cells and connector.
 
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