I recently had time to break up my 20s4p 74V20Ah 25-50C nanotech battery I got from hobbyking.
Here is my use characteristics:
1) Battery age from purchase: 1.5 years
2) Average Amp Usage: 30A-50A (1.5C-2.5C)
3) Peak Amp Usage: 65A (3.25C)
4) Average Ah usage before charging: 10Ah
5) Charging characteristics: 3.6V-4.1V
Out of 8 10s packs, one was severely puffed. The voltage is also weak and weird. i.e. changing when I am using my icharger. In short, I removed it. I did not even try the discharge test on it. Too dangerous.
I only was able to test 2 of the remaining 7 pack.
In this capacity discharge test, I used my icharger 1010b+. Since it only 30W (0.5A) discharge limit, it took 10 hours for each battery assuming they are fully charged. Luckily I had 2 icharger to speed things up. I also set start and end voltage as 4.2V and 3.0V respectively to get a good idea of capacity in the battery.
Here results after the discharged:
Pack 1:
1: 3.28V
2: 3.27V
3: 3.30V
4: 3.38V
5: 3.25V
6: 3.23V
7: 3.38V
8: 3.44V
9: 3.26V
10: 3.34V
Total AH: 4643mAh. So: 4643/5000 = 92.86% assuming it was 5000mAh to begin with.
Pack 2:
1: 3.24V
2: 3.27V
3: 3.35V
4: 3.37V
5: 3.30V
6: 3.21V
7: 3.47V
8: 3.40V
9: 3.44V
10: 3.39V
Total AH: 4585mAh. So 4585/5000 = 91.7%
So so far base on these 2 batteries, the capacity looks fine. But it important to note at least it's not at 80% even after > 250 charge cycle. I guess you do get more charge cycle if you charge from 3.6V to 4.1V. The other thing to note is some cell are stronger than others. Keep in mind these are battery are paralleled together so this is why you see the end cell (7-10) are still strong compared to (1-6). I guess these will be the last to die. They help keep each other strong.
I will update this thread once I test all the other sticks.
Here is my use characteristics:
1) Battery age from purchase: 1.5 years
2) Average Amp Usage: 30A-50A (1.5C-2.5C)
3) Peak Amp Usage: 65A (3.25C)
4) Average Ah usage before charging: 10Ah
5) Charging characteristics: 3.6V-4.1V
Out of 8 10s packs, one was severely puffed. The voltage is also weak and weird. i.e. changing when I am using my icharger. In short, I removed it. I did not even try the discharge test on it. Too dangerous.
I only was able to test 2 of the remaining 7 pack.
In this capacity discharge test, I used my icharger 1010b+. Since it only 30W (0.5A) discharge limit, it took 10 hours for each battery assuming they are fully charged. Luckily I had 2 icharger to speed things up. I also set start and end voltage as 4.2V and 3.0V respectively to get a good idea of capacity in the battery.
Here results after the discharged:
Pack 1:
1: 3.28V
2: 3.27V
3: 3.30V
4: 3.38V
5: 3.25V
6: 3.23V
7: 3.38V
8: 3.44V
9: 3.26V
10: 3.34V
Total AH: 4643mAh. So: 4643/5000 = 92.86% assuming it was 5000mAh to begin with.
Pack 2:
1: 3.24V
2: 3.27V
3: 3.35V
4: 3.37V
5: 3.30V
6: 3.21V
7: 3.47V
8: 3.40V
9: 3.44V
10: 3.39V
Total AH: 4585mAh. So 4585/5000 = 91.7%
So so far base on these 2 batteries, the capacity looks fine. But it important to note at least it's not at 80% even after > 250 charge cycle. I guess you do get more charge cycle if you charge from 3.6V to 4.1V. The other thing to note is some cell are stronger than others. Keep in mind these are battery are paralleled together so this is why you see the end cell (7-10) are still strong compared to (1-6). I guess these will be the last to die. They help keep each other strong.
I will update this thread once I test all the other sticks.
