The following maintenance practices will enable your nickel-iron batteries to continue to perform optimally: Replace the electrolyte every 10 years - The electrolyte degrades over time due to carbonate buildup, so replacing it every 10 years can help recover this loss. Add distilled water to your batteries every 1-3 months- Water in nickel-iron batteries is also lost during electrolysis as oxygen and hydrogen. Charge and discharge the battery regularly- Nickel iron batteries are designed for intense cycling, so you should always be charging and discharging them.