Battery Management System Tripped

[Adamsavage79]

I'm wondering, what would cause the BMS to trip on a Battery pack ? I was riding along normaly, but my front tire was bulging out so I was getting some pretty wicked viberations. I was just thinking about how bad it was getting, and then the BMS cut the power to the bike. It was not a dead battery, as I had more than enough juice to get home.

I kept going home, and then took a voltage reading. I got 11 something volts. I plugged the charger in for a couple seconds, and then turn it off and unpluged it. I then got a reading of 51.1 volts. The only thing I can think of, is that the Viberations caused the BMS to kill the power to protect the battery pack ? That or something in the kit (still my old kit and not Golden motor) itself, because of the viberations caused some sort of feedback that could of triggered the BMS to trip.

I should add that the Charger seemed to do a cell balancing as well, where it turns on and off several times. Then charges normaly for a few more minutes, before completing the charge cycle.

[Bikemad]

The BMS uses solid state components, therefore its operation should not be affected by vibration or shock loads.

However, it is possible that battery connector contacts could be affected by vibration and/or shock because they are physical connections usually held against each other by spring tension.

I suspect it is more likely to be a low battery voltage (or low individual cell voltage) that will have caused the BMS to cut of the power, as 51.1V seems to be pretty low compared to Ping's stated charging voltage of 60-61 Volts.

A 16S LiFePO4 battery measuring 51.1V has an average cell voltage of 3.19V, which is below the 3.2V nominal cell voltage even before a load has been applied.
 
As the typical minimum discharge voltage is 2.8V per cell, it is possible that a weak or unbalanced cell may have dropped below 2.8V under load, causing the BMS to shut off the power.

Alan
 

[Adamsavage79]

I don't know how many cells the pack has, and 60-61 Volts is pretty high for a 48v battery. I'm not sure I've ever seen it that high. The 51.1v reading was not a fully charged battery. That was after a good 10km or so of use at high speed. I may of simply had a unblanced cell, and that's why the charger had to balance the pack afterwards. I rode it today with out any problems.