Any data to support this on charging LiFePO4 and charging other Lithium ion cells is appreciated.
Also noteworthy is the change in cycles x capacity of Lithium cells
vs Depth of Discharge (DoD)
vs initial charge voltage, Vi .. every 0.1V drop in charge voltage doubles life expectancy according to http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
I used their data and computed the total capacity consumed and computed the optimum initial Charge voltage and DoD with unexpected results.
Comments?
This suggests that if you reduce the charge voltage by 0.1 V and limit the DoD to 10%, you can extend the battery life by 15x at the expense of 10x more charge cycles required.
This is based on the website's data as follows;
| Depth of discharge | Discharge cycles | Table 2: Cycle life as a function of |
| depth of discharge | ||
| 100% DoD | 300 – 500 | A partial discharge reduces stress and prolongs battery life. Elevated temperature and high currents also affect cycle life. |
| 50% DoD | 1,200 – 1,500 | |
| 25% DoD | 2,000 – 2,500 | |
| 10% DoD | 3,750 – 4,700 |
| Charge level(V/cell) | Discharge cycles | Capacity at full charge | Table 4: Discharge cycles and capacity |
| as a function of charge | |||
| [4.30] | [150 – 250] | [110%] | Every 0.1V drop below 4.20V/cell doubles the cycle; the retained capacity drops accordingly. Raising the voltage above 4.20V/cell stresses the battery and compromises safety. |
| 4.2 | 300 – 500 | 100% | |
| 4.1 | 600 – 1,000 | 90% | |
| 4 | 1,200 – 2,000 | 70% | |
| 3.92 | 2,400 – 4,000 | 50% |
Higher ambient temperature will reduce the efficacy of these results.