Nickel Iron (NiFe) Batteries
This rechargeable battery was introduced in 1901 by Thomas Edison. It is a very robust battery which is tolerant of abuse and can have very long life even if so treated. It is often used in backup situations where it can be continuously charged and can last for 20 years. Also called Nickel Alkaline of NiFe batteries.
The open circuit voltage of these cells is 1.4 V, and the discharge voltage is about 1.2 V.
Withstands overcharge and over-discharge
Accepts high depth of discharge - deep cycling.
Can remain discharged for long periods without damage, whereas a Lead Acid battery needs to be stored in a charged state.
The ability of this system to survive frequent cycling is due to the low solubility of the reactants in the electrolyte - Potassium hydroxide (KOH).
Lifetime of 30 years possible
Low cell voltage.
Very heavy and bulky.
The low reactivity of the active components limits the high rate performance of the cells. They cells take a charge slowly, and give it up slowly.
Low coulombic efficiency, typically less than 65%
Steep voltage drop off with state of charge
Low energy density.
High self discharge rate.
More pronounced Hydrogen gassing than Nickel-Cadmium
Fork lift trucks
Less expensive than Nickel- Cadmium cells