Should NiMH batteries be fully discharged before charging?
NiMH Battery Chemistry
NiMH battery are rechargeable batteries and use a nickel oxide hydroxide cathode and a hydrogen-absorbing anode. They are widely used in consumer electronics, hybrid vehicles, and power tools. Unlike some older battery technologies, NiMH battery doesn’t suffer from the memory effect, a phenomenon that will forgets its full capacity if not fully discharged before recharg.
The Myth of Full Discharge
One of the prevailing myths surrounding NiMH battery is the belief that they should be fully discharged before recharging to maintain their health and performance. This notion likely stems from practices associated with older nickel-cadmium (NiCd) batteries, which did exhibit memory effect issues.
However, NiMH battery are not prone to memory effect, and their performance is not significantly affected by partial discharges. In fact, subjecting NiMH battery to full discharges on a regular basis can be detrimental to their lifespan.
Battery Memory Effect
Memory effect occurs when a battery “remembers” the depth of its previous discharges and subsequently reduces its capacity to the remembered level. This phenomenon was more prevalent in older NiCd batteries. However, NiMH battery are designed to be more resilient to memory effect.
Optimal Charging Practices for NiMH battery
Contrary to the myth, NiMH battery benefit from different charging practices:
Avoid Full Discharges: NiMH battery perform well with regular, partial discharges. Fully discharging them unnecessarily can lead to increased stress on the battery and reduce its overall lifespan.
Top-Up Charging: NiMH battery tolerate top-up charging well. In fact, charging them before they are fully depleted can enhance their longevity. This is a convenient feature, especially in devices where the battery level is challenging to monitor accurately.
Temperature Considerations: NiMH battery can experience heat buildup during charging. It is advisable to charge them in a cool environment and avoid exposing them to high temperatures during the charging process.
Use a Quality Charger: Opt for a charger specifically designed for NiMH battery. These chargers often incorporate features like temperature monitoring and delta V charging to ensure the battery is charged optimally without overcharging.
Do NiMH Batteries Deteriorate?
