The FMS 2+ chlorophyll fluorimeter is powered by a 2.0 Ahr lead-acid battery, capable of >8 hours of continuous measurement in the field. Batteries can be easily exchanged in the field as they become discharged.

2 batteries are supplied with the FMS 2+ which, when both fully charged, easily provide at least 2 full days measurement in the field. The FMS 2+ carrying bag has space in the bottom to carry the spare battery.