THE ART OF 10% TO 90%
☀ Sunny hello to everyone ☀
Would be nice and useful if we could collect some methods how to keep ones cells within 10 - 90% SoC.
Since application, circumstances and understanding differs, methods differ.
I start things up, I am going to share my method and journey to maximise the cycle life (till 80% DOD) of my cells.
Application and setup: 18V 60W panel, 20A mppt Lumiax Win500 SC, 12.8v 53Ah lifepo4. Powering a small hut in the forest, daily estimated average consumption around 250Wh.
My cells and tools:
4 x 53Ah EVE LF50K 3.2V Lifepo4 cells, 0 cycles yet (according to datasheet more than 3500 cycles till 80% DOD)
1 x JBD 4s smart BMS 60Ah w/ Bluetooth
1 x original imax B6 mini professional battery charger 60W
1 x Vokpro VP1009 true RMS multimeter
How I determined the voltage of 90%SoC while charging, discharging and at rest.
Step one - top balancing cells:
1. Charged whole pack with 3.5A (0.066C) till 13.6v then stopped
2. Next charged each cell separately with 3.6V CV and 1.5A till amps dropped to zero.
3. After about 30min rest charged again each cell with 3.6V CV and 1.5A till amps dropped to zero (less than 35 mah could still be squeezed in)
4. Assembled back to a 4s pack
Step two - noting down voltage readings at 90%SoC while discharging, charging and at rest:
1. Discharged with 48W load:
At 90%SoC, cells were at 3.310V average
At 85%SoC, still 3.310V average
2. 45min resting at 85%SoC = 3.333V average
3. Charged with 48W:
At 85%SoC = 3.345V average
At 90%SoC = 3.368V average
4. 2 hours resting at 90%SoC = 3.340V average
Step three - noting down voltage readings at 10%SoC while discharging:
1. Yet to be done but according to the official chart it is around 3.1V while discharging with 0.2c.
Step four - programming charge controller and BMS:
1. BMS:
1.1 overvoltage = 3.5V
1.2 release = 3.33v
1.3 undervoltage = 3.1V
1.4 release = 3.2V
2. Charge controller:
2.1 overvoltage = 13.5V
2.2 release = 13.32V (to prevent micro cycling)
2.3 undervoltage = 12.6V
2.4 release = 12.9V (to prevent micro cycling)
Step five - observing and adjusting:
1. Yet to be done
What's your application and setup, how do you stay within the manufacturer recommended 10 - 90% window? What are your observations, tips and tricks?
☀ Sunny hello to everyone ☀
Would be nice and useful if we could collect some methods how to keep ones cells within 10 - 90% SoC.
Since application, circumstances and understanding differs, methods differ.
I start things up, I am going to share my method and journey to maximise the cycle life (till 80% DOD) of my cells.
Application and setup: 18V 60W panel, 20A mppt Lumiax Win500 SC, 12.8v 53Ah lifepo4. Powering a small hut in the forest, daily estimated average consumption around 250Wh.
My cells and tools:
4 x 53Ah EVE LF50K 3.2V Lifepo4 cells, 0 cycles yet (according to datasheet more than 3500 cycles till 80% DOD)
1 x JBD 4s smart BMS 60Ah w/ Bluetooth
1 x original imax B6 mini professional battery charger 60W
1 x Vokpro VP1009 true RMS multimeter
How I determined the voltage of 90%SoC while charging, discharging and at rest.
Step one - top balancing cells:
1. Charged whole pack with 3.5A (0.066C) till 13.6v then stopped
2. Next charged each cell separately with 3.6V CV and 1.5A till amps dropped to zero.
3. After about 30min rest charged again each cell with 3.6V CV and 1.5A till amps dropped to zero (less than 35 mah could still be squeezed in)
4. Assembled back to a 4s pack
Step two - noting down voltage readings at 90%SoC while discharging, charging and at rest:
1. Discharged with 48W load:
At 90%SoC, cells were at 3.310V average
At 85%SoC, still 3.310V average
2. 45min resting at 85%SoC = 3.333V average
3. Charged with 48W:
At 85%SoC = 3.345V average
At 90%SoC = 3.368V average
4. 2 hours resting at 90%SoC = 3.340V average
Step three - noting down voltage readings at 10%SoC while discharging:
1. Yet to be done but according to the official chart it is around 3.1V while discharging with 0.2c.
Step four - programming charge controller and BMS:
1. BMS:
1.1 overvoltage = 3.5V
1.2 release = 3.33v
1.3 undervoltage = 3.1V
1.4 release = 3.2V
2. Charge controller:
2.1 overvoltage = 13.5V
2.2 release = 13.32V (to prevent micro cycling)
2.3 undervoltage = 12.6V
2.4 release = 12.9V (to prevent micro cycling)
Step five - observing and adjusting:
1. Yet to be done
What's your application and setup, how do you stay within the manufacturer recommended 10 - 90% window? What are your observations, tips and tricks?
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