stevenborg
New Member
- Joined
- Sep 17, 2020
- Messages
- 9
I received a set of 52 Lishen 272Ah batteries, and am running a test of a 12V system as a representative sample to get a solid feeling about the quality of the batteries I received. I'm clearly doing something wrong, as my Ah measurements are coming in very, very low -- less than 1/3 of rated capacity. Can someone help identify what I'm doing wrong?
Here are the details:
- 4 Lishen 272Ah batteries in series for 12.8V nominal
- Charged to 14.18V (over 90%) with cell values as 3.551V, 3.551V, 3.553V, 3.551V (feels very balanced) at around 10 degrees C.
- Connected through a shunt-based capacity measurement device reset to zero
- Connected to a 12V heater (add-on for a car) rated at 150W
- External impedance at 3.2 ohms
Results:
- Immediately on adding load voltage drops to 13.5V (measured both a battery terminals and shunt)
- At 30 minutes voltage had dropped to 13.1V (measured both a battery terminals and shunt), individual battery voltages (under load) at 3.309V, 3.308V, 3.30V and 3.309V.
- Load measured at 3.9A and 51W (which is well below the 150W rating of the 12V DC heater)
- At 8 hours, voltage had dropped to 13.0V
- At 10 hours, voltage dropped to 12.9V (measurements indicated 618Wh, and 47.2 Ah
- At 10 hours, I removed the load to measure battery values without the voltage sag
Immediate readings: 13.08V total with individual readings 3.287, 3.284, 3.286, and 3.288V
After 30 minute rest: 13.12V total with individual readings 3.297, 3.295, 3.296, and 3.293V
- Reconnected load at 10:30 hours
Immediate readings: 13.0 at terminals and shunt
The test is still running, but we've crossed two important boundaries. According to the charts on this site, I have gone from over 90% capacity to under 10% capacity.
Start: 14.18V (over 90% SOC assuming 13.8V = 90%) : Assume 90% to be conservative, measuring at 0Ah starting
Pause: 13.12V (under 10% SOC assuming 13.2V = 10%) : Assume 10% to be conservative, measuring 47.3 Ah at pause, round up to 50Ah for simplicity
That implies I've used 80% of my capacity at 50Ah. That would imply a full capacity of around 60Ah, versus the listed 272Ah.
What am I doing wrong? I'm off by about a factor of 3! Even if I was shipped "bad" cells, I can't imagine they would ever be that bad. I'm likely doing something completely wrong and messed up, but I don't know what.
Should I post a photo? What would help?
Here are the details:
- 4 Lishen 272Ah batteries in series for 12.8V nominal
- Charged to 14.18V (over 90%) with cell values as 3.551V, 3.551V, 3.553V, 3.551V (feels very balanced) at around 10 degrees C.
- Connected through a shunt-based capacity measurement device reset to zero
- Connected to a 12V heater (add-on for a car) rated at 150W
- External impedance at 3.2 ohms
Results:
- Immediately on adding load voltage drops to 13.5V (measured both a battery terminals and shunt)
- At 30 minutes voltage had dropped to 13.1V (measured both a battery terminals and shunt), individual battery voltages (under load) at 3.309V, 3.308V, 3.30V and 3.309V.
- Load measured at 3.9A and 51W (which is well below the 150W rating of the 12V DC heater)
- At 8 hours, voltage had dropped to 13.0V
- At 10 hours, voltage dropped to 12.9V (measurements indicated 618Wh, and 47.2 Ah
- At 10 hours, I removed the load to measure battery values without the voltage sag
Immediate readings: 13.08V total with individual readings 3.287, 3.284, 3.286, and 3.288V
After 30 minute rest: 13.12V total with individual readings 3.297, 3.295, 3.296, and 3.293V
- Reconnected load at 10:30 hours
Immediate readings: 13.0 at terminals and shunt
The test is still running, but we've crossed two important boundaries. According to the charts on this site, I have gone from over 90% capacity to under 10% capacity.
Start: 14.18V (over 90% SOC assuming 13.8V = 90%) : Assume 90% to be conservative, measuring at 0Ah starting
Pause: 13.12V (under 10% SOC assuming 13.2V = 10%) : Assume 10% to be conservative, measuring 47.3 Ah at pause, round up to 50Ah for simplicity
That implies I've used 80% of my capacity at 50Ah. That would imply a full capacity of around 60Ah, versus the listed 272Ah.
What am I doing wrong? I'm off by about a factor of 3! Even if I was shipped "bad" cells, I can't imagine they would ever be that bad. I'm likely doing something completely wrong and messed up, but I don't know what.
Should I post a photo? What would help?