Batteries in Series

Batteries connected end to end (positive terminal to negative terminal) are said to be connected in series.

System Voltage

The total voltage of the batteries connected in series will be a sum of the individual battery voltages in the series string.

System Capacity

The system capacity, measured in mAh, does not increase in a series string compared to an individual battery.

Potential Pitfalls

Incorrect Installation

Reversal protection is recommended to prevent the charging of an incorrectly installed battery in a string of three or more. For information on reversal protection see page 10 of this document.

Deep Discharge

Batteries in a series configuration are susceptible to deep discharge. This will occur when a battery is

discharged to less than 0.8V. There is an increased potential of internal gassing and subsequent leakage concerns when a battery is deep discharged. A device that uses a single battery that is closely monitored can be discharged down to 0.5V. If the batteries are deep discharged and cannot be disconnected from the load,a maximum drain of 50 μA is recommended to limit internal gassing over time.