ANT BMS shortcircuit

[qguy]

Got a weird ANT BMS problem everytime I fix my ebike

NMC batteries, 21 cells in series, at full charge 88v

1. Turn off circuit breaker
2. Disconnect phasewires or the positive or negative cables.
3. Turn on circuitbreak, loud beep
4. Turn on ebike, panel lights up for half a second and shuts down.
5. Reset circuit breaker, same results as step 3 and 4, did this several times
6. Turn off breaker
7. Turn on ANT BMS application on android phone, I would see the DISMOS of OPEN, Reset breaker DISMOS is Shortcircuit, reset breaker and then DISMOS is OPEN, start ebike and Dismos stays OPEN
8. Reset breaker, dismos now is OPEN, from this point everytime I reset the breaker, dismos is Open

Basically I would need to open the ANT BMS android app before I can use the ebike after repair, any ideas on how to fix this?

 

[eee291]

Are you precharging the controller before closing the circuit breaker?

 

[qguy]

Newbie alert, what is precharging?

 

[floydr]

precharge charges the capacitors in the controller so you don't trip the high current protection.
Later floyd
edit brings the capacitors voltage to 90% of battery voltage there by reducing the inrush current which trips the bms over current protection

 

[eee291]

There is one ANT BMS that can precharge.
Could you send a link or snap a pic of your BMS?

 

[floydr]

There is one ANT BMS that can precharge.

Do you know the model of the Ant BMS that can precharge?
Later floyd

 

[eee291]

Do you know the model of the Ant BMS that can precharge?
Later floyd

https://www.aliexpress.com/item/32826820690.html

The double layer version.