BMS problems

[Zombo]

Hello to all,

a few weeks back i have purchased an Empuls R from 2015. This bike has been in a research facility for the last couple years and has only 1300km.

I have the proble that one cell in pack 4 is at 4.14V and the rest is down to 4.04V.

Charging stops if the highest cell is at 4.16V, then the lowest cell is still at 4.04V

I connected to the BMS but in the Softare there is nothing to set up. I can only upload a new firmware which i dont have.

does anybody know how to fix the problem or has any idea?

thx Zombo

[Leander]

it will stop charching but it will continue ballancing when at 100% if left plugged in.

[Zombo]

Hi Leander,

unfortunately it will not. it is on the charger for 5 days and it is not going above 92%.

[Richard230]

Hi Leander,

unfortunately it will not. it is on the charger for 5 days and it is not going above 92%.

The exact same thing happened to my daughter's 2014 Zero.  A couple of years ago it would stop charging at 98%, then it would stop charging at lower and lower voltages, until it wouldn't charge past 88% earlier this year.  I was sure that it must have had a cell or two that was going bad and was spiking when being charged, causing the BMS to cut off the juice.

However, I decided to replace the charger with an updated model that I purchased from Zero.  That completely solved the problem and now the bike is charging to 100%, the battery cells are balanced and it is running like new again.  Who knew that chargers could suffer a slow death instead of just dying all at once. 

[Leander]

then maybe it is the charger. but I have not encountered that as a problem on a brammo.

fortunaly the empulse charger is easy to open up and check for lose or damaged components.

[MiBa]

It might be worth a try to do this:

Drive down to a low SoC.

Ignition on.
Press both dash buttons.
Start drive mode.

Check the Bat. Values for Low and High.

The VCU and Sevcon standby current consumption
plus the headlight etc. will drain the Bat. (after some hours) to a very low state.
Thats called "bottom balancing".   

According the BMS "qualification parameters" the cells can go down to 3.0V.

Try to reach that point - or at least down to 3.3V

Last step: Charge and monitor the cells (via the dash).

Regards
Michael

[Zombo]

I tryed this before. battery was down to 0% but the voltagedifference between high and low was 200mV. I don't want to bring the low cells to undervoltage. There is still the one high cell.

I'm wondering where are the balancingresistors inside the modules? I can only see 3 suitable resistors on your pictures. Or do they use the four heatingplates to balance the cells?

kind regards