Samsung 25R 10s4p serious battery life degradation

ESK8 Electronics
1

Hello, I’ve completed build at the beginning of april this year.

Parameters:

  • Samsung 25r 10s4p battery

  • Daly 10s BMS with 60A continuous

  • Flipsky smart anti-spark switch

  • 2x Flipsky 4.12 FSESC - Settings: 30A max draw limit per each = 60A max in total (BMS was bottleneck, cuz the cell continuous discharge rate is 20 according the specs)

  • 2x 6355 brushless motor

It was working like a charm till August I think (approx 20 km distance was no problem or approx 15 km in hilly area). Then I started to realise the distance I could take on one charge became to degrade until today when I am not even able to go to work and back on one charge (approx 7 km) which is not acceptable. That is why I am starting this topic. I want to find out if it is possible the battery can degrade as fast as my did (so far I have driven approx 300 km with this setup). I’ve disassembled the whole battery to check whether something is wrong, measured every cell’s voltage (it was the same within one group and maybe like 0.1V difference between the groups), so it seems, connections were not faulty. The BMS works too (at least under/over voltage cutoff), but the battery sag is huge (based on the observations while riding, don’t have any statistics that I can show you thought). What do you think? Is this normal? Should I replace battery? I dont have equipment so I can check the capacity of the cells. Is it normal, that battery needs replacement after 300 km of riding? Thank you for every response.

2

Where did you get the cells/ battery from? Sounds like you might have gotten fake cells rewrapped as 25r’s

1 Like
3

I’ ve bouht it on nkon, where almost everyone here. Moreover it was working fine for some time so I dont think so they were fake.

4

Can we see some pictures?

How is the battery mounted on the deck? is it exposed to some flex?

5

They are glued using foamy tape in battery handlers attached to the flexible console made of plastic which is attached to the board using bolts. It is like a sandwich. It’s this console, then electronics and then deck. Whole construction is then covered by glass fiber enclosure. I know that is maybe not the best solution, but I don’t have spot welder and needed custom battery pack so the construction is slim and flexible. Like I have written before, I have checked all connections and every cell. Everything seems to be ok. But maybe you have right with the flex. Maybe it can cause some connections to break for some time.

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