Was my BMS selection correct?

peleap

100 mW
Joined
Nov 27, 2016
Messages
49
I'm creating a battery pack. For a 1000-watt electric bike
I use battery cell NCR18650GA in 4 parallel 13 series.total 52 Pcs. and i use BMS Spec discharge 45 Amp (continue discharge) in pack

Six months after use. I feel my electric bike does not accelerate. But the battery does not cutoff.


The question is .Is there a problem with my BMS? Or should I use a lower specification (ฺBMS have CDR < 30Amp )?


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thank you
 
if the battery doesnt shutdown then it's not the cause of the system being too slow.

Either
you simply don't have enough power to go teh speed you're after (faster you go the more pwer it takes; wind resistance/etc)
, or
you don' thave a high enough voltage to get the motor speed,
or
if it's a non-hubmotor, you don't hae the right gear ratio between motor and wheel to get the motor speed you want.
or
your controller is limiting the speed


as for using a *lower* current BMS, that would make your problem *worse*, not better, because the BMS will shutdown at a lower current demand, so if the problem is insufficient power to go the speed you want, you'll have even less available before the BMS shuts off and you are left with zero power.
 
I recommend getting a meter called the Cycle Analyst. With that you can see how much amps or watts or you are pulling at any instant as well as voltage sag. Helps to understand what is going on.
 
Jon NCal said:
I recommend getting a meter called the Cycle Analyst. With that you can see how much amps or watts or you are pulling at any instant as well as voltage sag. Helps to understand what is going on.

i use watt mater. Can measure 600 watt battery Cutoff. The battery is not deteriorated.but i think voltage sag.
 
amberwolf said:
if the battery doesnt shutdown then it's not the cause of the system being too slow.

Either
you simply don't have enough power to go teh speed you're after (faster you go the more pwer it takes; wind resistance/etc)
, or
you don' thave a high enough voltage to get the motor speed,
or
if it's a non-hubmotor, you don't hae the right gear ratio between motor and wheel to get the motor speed you want.
or
your controller is limiting the speed


as for using a *lower* current BMS, that would make your problem *worse*, not better, because the BMS will shutdown at a lower current demand, so if the problem is insufficient power to go the speed you want, you'll have even less available before the BMS shuts off and you are left with zero power.

thank you i think battery pack have not enough power ( voltage drop ) . NCR18650GA (4P) may not be enough for a 1000 watt motor.
 
peleap said:
Jon NCal said:
I recommend getting a meter called the Cycle Analyst. With that you can see how much amps or watts or you are pulling at any instant as well as voltage sag. Helps to understand what is going on.

i use watt mater. Can measure 600 watt battery Cutoff. The battery is not deteriorated.but i think voltage sag.

Can you explain what you mean by "Can measure 600 watt battery Cutoff." That battery should be able to supply 1200w or more.
 
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