I recently bought two battery capacity testers in-order to test a box of 50 used Molicel IRC18650H cells. I purchased them from Alarm/Battery_Hookup. They are one of the biggest retailers of used batteries in the U.S.A. and have great reviews. The batteries were claimed to be all between 1400mah - 1600mah. Which I believed to be true.
The testers I am using, use a resistive load to determine battery Ah. They also fluctuate the amp draw as the battery voltage decreases. I have one 5W 7.5ohm resistor connected to each tester which applies a load of no more then .5 amps.
I am fully charging each 18650 to 4.2v and I set the tester cut off voltage to 3.0v under load
I have tested 10 cells so far and the tester is showing that all of the cells have been between 0.850Ah - 0.930Ah (850mah - 930mah) on a .5a load
But when the test is over the cells are immediately bouncing back up to 3.6v - 3.7v - Is this causing the low mah readings? I know that under load the voltage is lower then resting voltage. but is 3.7 to high? thats there nominal voltage... Should I set the cut-off voltage lower then 3.0v?
I kind of want to believe the sellers claim that all 50 cells are about 1500mah. The seller is extremely highly rated. Im thinking that my testing method may not be right. but I have also used my B6 RC charger to do a discharge test on a few of the cells and it basically has the same results.
Ive also tried using a 1amp load and the capacity reading is only around .620mah
Im using about half of these cells to make a 4s5p or maybe 4s6p battery pack to power a max of 10a load. So i dont really need the actual mah ratings in-order to group the cells as close together as I can but would still like to know there mah capacity...
I have the feeling that i need to set the cut-off voltage lower so the cells dont immediately bounce back to 3.7v when load is disconnected. But I know that 3.0v is the lowest voltage for lithium ion. ????
Here are the testers I am using:
https://www.amazon.com/HiLetgo-Lead...d+Battery&qid=1550563561&s=hi&sr=1-1-fkmrnull
P.S. If I have a 4s5p Battery pack and a 10a load on it, what is the amp draw per cell?
*** I have messaged the seller, and asked for there testing parameters. And my concerns. Waiting on a reply ***
The testers I am using, use a resistive load to determine battery Ah. They also fluctuate the amp draw as the battery voltage decreases. I have one 5W 7.5ohm resistor connected to each tester which applies a load of no more then .5 amps.
I am fully charging each 18650 to 4.2v and I set the tester cut off voltage to 3.0v under load
I have tested 10 cells so far and the tester is showing that all of the cells have been between 0.850Ah - 0.930Ah (850mah - 930mah) on a .5a load
But when the test is over the cells are immediately bouncing back up to 3.6v - 3.7v - Is this causing the low mah readings? I know that under load the voltage is lower then resting voltage. but is 3.7 to high? thats there nominal voltage... Should I set the cut-off voltage lower then 3.0v?
I kind of want to believe the sellers claim that all 50 cells are about 1500mah. The seller is extremely highly rated. Im thinking that my testing method may not be right. but I have also used my B6 RC charger to do a discharge test on a few of the cells and it basically has the same results.
Ive also tried using a 1amp load and the capacity reading is only around .620mah
Im using about half of these cells to make a 4s5p or maybe 4s6p battery pack to power a max of 10a load. So i dont really need the actual mah ratings in-order to group the cells as close together as I can but would still like to know there mah capacity...
I have the feeling that i need to set the cut-off voltage lower so the cells dont immediately bounce back to 3.7v when load is disconnected. But I know that 3.0v is the lowest voltage for lithium ion. ????
Here are the testers I am using:
https://www.amazon.com/HiLetgo-Lead...d+Battery&qid=1550563561&s=hi&sr=1-1-fkmrnull
P.S. If I have a 4s5p Battery pack and a 10a load on it, what is the amp draw per cell?
*** I have messaged the seller, and asked for there testing parameters. And my concerns. Waiting on a reply ***
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