In this work, we seek to answer the following question: “How long will a battery last if it is discharged at its maximum possible power?” Various primary battery chemistries (Zn-MnO₂, Ag-AgO, Zn-air) and secondary battery chemistries (Ni-MH, Li-ion) are investigated. The maximum power point tracking (MPPT) algorithm, which has been used in photovoltaic devices so far, is applied to draw the maximum power possible from these batteries.

In the MPPT algorithm used here, a fixed magnitude of current is applied and the new value of power is calculated. If the new value of power is greater than the previous one, the current is varied in the same direction until the maximum power is reached. This algorithm is simple to implement and consumes low computing power. However, the magnitude of a current step should be optimized. If the current step is very small, the time taken to reach the maximum power will be too long. And if the current step is very large, there will be a large oscillation near the power maxima.

We present the effect of current steps in reaching the maximum power on batteries. The optimal current step is different from one battery to another. For fair comparison, the current steps are normalized to the discharge rate to achieve 1 C capacity. For rechargeable batteries, the effect of charging rates on the maximum power obtainable is also investigated.

The information obtained from this study can be a useful guide to designing a battery management system that gets the maximum performance out of any battery.

References

1. Selvan, P. Nair and Umayal, “A review of phot voltaic MPPT algorithms,” International Journal of Electrical and Computer Engineering, 6, 2016, 567-582.
2. A. B. Vieira and A. M. Mota, “Maximum power point tracker applied in batteries charging with PV panels,” 2008 IEEE International Symposium on Industrial Electronics, Cambridge, 2008, 202-207.
3. Kim, S. Mohan, J. B. Siegal and A. G. Stefanopoulou, “Maximum power estimation of lithium-ion batteries accounting for thermal and electrical constraints,” Proceedings of the ASME 2013 Dynamic Systems and Control Conference, California, 2013.