Motor cutting out under load

Zheroz00

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Feb 28, 2023
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Hello. I have a Bafang 1000w mid-drive with a 52v pack that suddenly is cutting power under almost any load. Regardless of whether its throttle or PAS it cuts out almost immediately when power is applied and the red indicator light on the display lights up. (DPC-18) This does shut the system off, just cuts power and comes back immediately. I had rode the bike the night before for about 30km and there were no issues. Went out the next night and as soon as I got to the furthest point of my ride the motor started cutting out. This is mainly a road bike so there are not many hard bumps, but they have happened. Nothing of note before it broke down though. I've tried the following so far but wanted to check before I went further.

  • 52v pack. Pins are the same as in the attached pic. They already looked brand new as I've only removed the pack a few times. I cleaned them with alcohol to be sure. The pack connects very snug.
  • I've disconnected and re-connected every connection.
  • Cleaned the wheel speed sensor and magnet. The red light blinks on each rotation.
  • The brake cutoff sensor seems to work fine. If I lift the rear wheel (no load) and throttle up the wheel spins and the motor cuts when I touch the brake. I've disconnected the brake sensor to test and the motor still cuts out under load.
  • I've charged the pack to full and tested with a multimeter and got approx. 58v.
After going through the forums its making me think it could be the BMS, but I have no idea. Does this issue sound like a BMS issue? Are there other steps I should be taking to diagnose this?

Cheers
 

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I'm not familiar with the DPC-18 Display.
Full charge on 52v battery will be 58.8v Could be a bad cell or two.....or BMS...wuts the low voltage cut off set to?
:unsure:
 
I'm not familiar with the DPC-18 Display.
Full charge on 52v battery will be 58.8v Could be a bad cell or two.....or BMS...wuts the low voltage cut off set to?
:unsure:
Thanks for the reply. I just checked and the voltage fully charged is 58.7v. I've attached photos of my settings. I've had those like that for about five months. How do the settings look? I also just perform the 'internal BMS reset' where you unplug the BMS, connect the charger and then connect the BMS again. Bike worked on throttle and PAS for about 10 seconds and then started doing what it was previously.
 

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Your settings and my settings are alot different.
My BBSHD, I only use PAS1 in Road and PAS1 in Offroad.

My Low Battery Protect is set to 40
Current is set to 20
my Assist 1 is Limited Current 8 Limited speed 10

Pedal type is BB-Sensor-32
My Start current is 8
My Keep Current is 38
My Start Up Degree is 5


Are you comfortable with changing a BMS?
 
Your settings and my settings are alot different.
My BBSHD, I only use PAS1 in Road and PAS1 in Offroad.

My Low Battery Protect is set to 40
Current is set to 20
my Assist 1 is Limited Current 8 Limited speed 10

Pedal type is BB-Sensor-32
My Start current is 8
My Keep Current is 38
My Start Up Degree is 5


Are you comfortable with changing a BMS?
I don't recall where I got the settings from, but it from from a popular forum. I was pretty happy with how it was running. I would def. have a go at replacing the BMS. Do you happen to have a link for what I would be needing?
 
Oh i don't know anything about BMS hopefully someone here that does will chime in and give you some good info :)
 
sounds like a bad cell im no expert but ive seen videos about this .does youre battery charge really quickly and die at high percentage if so its probably bad cell .theres a guy on youtube called ebikeschool hes got video called repaired dead battery
 
How old is this battery, how many charge cycles, how much do you weigh, when did you change those settings, and how long ago did the problem start happening.
 
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