Severe voltage drop with 18650 cells

[ebike11]

Hi guys
I have a bottle battery with Samsung 18650 cells. I bought it new and is a 13 cell.
Eventhough its new, the voltage drop for a dead stop to full throttle on take off is about 10 volts.
Theres no way for me to tell the true actual details of the cells, just that it was advertised that was
and I opened the casing to check the info on the cells. They are pink cells with Samsung 18650, but Ive seen many stories of rebranded cells from China.
I assume 10 volts is pretty severe, correct? Especially for being newly purchased recently.

Thanks!

 

[teslanv]

How many amps are you pulling from it? (What is your controller rated for?)

What is the Amp-Hour capacity of the battery?

What is the model of the Cell? -Or what is the cell's Continuous Discharge rating? (how many "C")

If you are over 2 "C" discharge, you probably need a bigger battery or different type of cell/chemistry.

 

[mushymelon]

If its the pink ICR18650-26F then It only has peaks of 2c and a continuous rating of 0.5c to 1c data sheet seems pretty vague. If you running a 13s battery in a bottle setup then I would expect a large amount of sag with these cells. Good thing Samsung cells are good quality.

 

[Hillhater]

Like the guys said, more info is needed to comment.
13 cell , or 13 "S" ie what voltage is the battery rated for...24, 36,48, ??
How many actual individual cells in the pack
what controller/motor current rating are you using it with.
To get 10 volts of sag on any normal pack you must either have ..
1) ..One or more bad contacts somewhere in the system ( or pack)
2) .. one or more bad cells in the pack
3).. a badly out of balance pack
4).. just a very undersize pack for your motor.

 

[ebike11]

ah sorry here is more info.

Its a 48V battery with, yes pink Samsung cells (full charge gives me 55V
10Ah rating
It uses BMS
Controller is set around 28-32A on a ku93
Motor was a 8Fun Bafang code 9

When I let off the throttle, the voltage of course creeps back up higher
Thanks

 

[teslanv]

Could be counterfeit cells, but even if they are genuine & new, you are discharging at close to 3C, which is quite hard on them. - You need a bigger battery or if you can limit the current on the controller or through your CA, that may suffice.

 

[ebike11]

Could be counterfeit cells, but even if they are genuine & new, you are discharging at close to 3C, which is quite hard on them. - You need a bigger battery or if you can limit the current on the controller or through your CA, that may suffice.

I see, actually I don't take off full throttle always, just my friend did it as a way to test the battery when he was riding on the bike

 

[dogman dan]

If the above specs on the pink battery is correct, I'm surprised you aren't getting more sag.

You are just hammering that thing, it's just too small for that type of cell to run a 30 amps controller. 15 amps, and preferably don't pull much more than 10 amps. Like, pedal to 10 mph then hit throttle.

You are going to have to lipo up, or get bigger pack with higher c rate cells.