DON'T PANiC
New Member
- Joined
- Dec 26, 2021
- Messages
- 4
Cells: 16x EVE LF280k (new, just received from Jenny Wu @ Docan Tech)
BMS: Overkill 12v 4s
Configuration: 12v 4p4s each 4s with its own BMS
Top Balanced cells in parallel to 3.6-3.65vpc
Final installation: Sailboat. BMS will be set to 3.0vpc for low cutoff, 3.55vpc for top cutoff and chargers will be set to 14v (3.5vpc). Ideally I'll cycle the charge from 10-15% to 85-90% avoiding the knees.
I just completed top balancing the cells and running them through their first cycle.
Three of the batteries balanced fine without any issues noticeable to this noob.
One had some noticeable issues when discharging. I cycled this battery twice, including a second top balance and the same thing occurred.
Looking to see if i have a problem cell that I should return and get replaced.
When discharging one cell got way out of balance: Voltage diff 0.320
Cell 1: 2.781vpc
Cell 2: 3.101vpc
Cell 3: 2.856vpc
Cell 4: 2.831vpc
This was from the second cycle. I didn't record the first cycle, but it was worse since I let it trigger the 2.5vpc cut off. I recall it getting to V Diff 0.500+ Cell 2 was still over 3.0vpc while cell 1 (if I remember right) triggered the cutoff at 2.5vpc
As I recharged the cells back after the second balance & discharge to 90%ish I tracked the cell Voltage:
Time____________Cell1_____Cell2_____Cell3_____Cell4____V Diff_____ AH
21:40:00_________2.781____3.101_____2.856____2.831____0.320______0.00
22:39:07_________3.247____3.266_____3.249____3.250____0.019_____24.22
23:57:10_________3.295____3.323_____3.300____3.301____0.028_____55.22
00:51:40_________3.325____3.340_____3.328____3.330____0.015_____76.91
01:14:42_________3.330____3.341_____3.334____3.335____0.011_____86.02
01:15:35_________3.312____3.318_____3.314____3.316____0.006_____86.10___(Taken when battery was at rest, no charging)
Stopped the Charging at this point and went to sleep. I resumed charging the next morning. The AH in the battery was kind of shocking because nothing was attached to the battery to charge, everything was off. The shunt I had attached confirmed that nothing was charging, it showed 30% for both above/below. Bad BMS? After this point I didn't trust the AH capacity numbers.)
09:26:35_________3.296____3.301_____3.298____3.300____0.005____142.41___(Taken when battery was at rest, no charging)
09:29:48_________3.332____3.344_____3.336____3.338____0.012____143.50
10.43.05_________3.338____3.349_____3.342____3.342____0.011____172.42
11.43.41_________3.339____3.351_____3.343____3.343____0.012____196.30
12:44:09_________3.345____3.360_____3.347____3.350____0.015____220.15
13:44:30_________3.365____3.374_____3.367____3.369____0.009____243.90
14:45:05_________3.374____3.380_____3.375____3.375____0.006____267.64
15:45:37_________3.377____3.384_____3.379____3.380____0.007____289.31
16:45:53_________3.381____3.388_____3.382____3.384____0.007____289.31___(AH is not a typo, it didn't move since the previous recording. This capacity is close to what the shunt reported when I did the discharges on this battery)
17:01:29_________3.345____3.347_____3.346____3.347____0.002____288.83___(Taken at rest, stopped charging, Shunt reported 90%.)
1) Do I have a bad cell that should be returned/replaced?
2) If this cell is kept, will if degrade the other cells? The other batteries?
3) Do I have a bad BMS?
BMS: Overkill 12v 4s
Configuration: 12v 4p4s each 4s with its own BMS
Top Balanced cells in parallel to 3.6-3.65vpc
Final installation: Sailboat. BMS will be set to 3.0vpc for low cutoff, 3.55vpc for top cutoff and chargers will be set to 14v (3.5vpc). Ideally I'll cycle the charge from 10-15% to 85-90% avoiding the knees.
I just completed top balancing the cells and running them through their first cycle.
Three of the batteries balanced fine without any issues noticeable to this noob.
One had some noticeable issues when discharging. I cycled this battery twice, including a second top balance and the same thing occurred.
Looking to see if i have a problem cell that I should return and get replaced.
When discharging one cell got way out of balance: Voltage diff 0.320
Cell 1: 2.781vpc
Cell 2: 3.101vpc
Cell 3: 2.856vpc
Cell 4: 2.831vpc
This was from the second cycle. I didn't record the first cycle, but it was worse since I let it trigger the 2.5vpc cut off. I recall it getting to V Diff 0.500+ Cell 2 was still over 3.0vpc while cell 1 (if I remember right) triggered the cutoff at 2.5vpc
As I recharged the cells back after the second balance & discharge to 90%ish I tracked the cell Voltage:
Time____________Cell1_____Cell2_____Cell3_____Cell4____V Diff_____ AH
21:40:00_________2.781____3.101_____2.856____2.831____0.320______0.00
22:39:07_________3.247____3.266_____3.249____3.250____0.019_____24.22
23:57:10_________3.295____3.323_____3.300____3.301____0.028_____55.22
00:51:40_________3.325____3.340_____3.328____3.330____0.015_____76.91
01:14:42_________3.330____3.341_____3.334____3.335____0.011_____86.02
01:15:35_________3.312____3.318_____3.314____3.316____0.006_____86.10___(Taken when battery was at rest, no charging)
Stopped the Charging at this point and went to sleep. I resumed charging the next morning. The AH in the battery was kind of shocking because nothing was attached to the battery to charge, everything was off. The shunt I had attached confirmed that nothing was charging, it showed 30% for both above/below. Bad BMS? After this point I didn't trust the AH capacity numbers.)
09:26:35_________3.296____3.301_____3.298____3.300____0.005____142.41___(Taken when battery was at rest, no charging)
09:29:48_________3.332____3.344_____3.336____3.338____0.012____143.50
10.43.05_________3.338____3.349_____3.342____3.342____0.011____172.42
11.43.41_________3.339____3.351_____3.343____3.343____0.012____196.30
12:44:09_________3.345____3.360_____3.347____3.350____0.015____220.15
13:44:30_________3.365____3.374_____3.367____3.369____0.009____243.90
14:45:05_________3.374____3.380_____3.375____3.375____0.006____267.64
15:45:37_________3.377____3.384_____3.379____3.380____0.007____289.31
16:45:53_________3.381____3.388_____3.382____3.384____0.007____289.31___(AH is not a typo, it didn't move since the previous recording. This capacity is close to what the shunt reported when I did the discharges on this battery)
17:01:29_________3.345____3.347_____3.346____3.347____0.002____288.83___(Taken at rest, stopped charging, Shunt reported 90%.)
1) Do I have a bad cell that should be returned/replaced?
2) If this cell is kept, will if degrade the other cells? The other batteries?
3) Do I have a bad BMS?