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How do NiMH battery chargers work?
After a certain time, or when the cell voltage reaches a certain point, a cool down period is placed into the charge cycle. The charge cycle then proceeds at a lower current. The NiMH charger then applies further current reductions as the charge progresses. This scheme continues until the battery is fully charged.
Can NiMH batteries be left on charger?
A NiMH charger can also charge NiCd; a NiCd charger would overcharge NiMH. Do not leave a nickel-based battery in the charger for more than a few days.
What’s the best charge rate for a NiMH battery?
Slow charging NiMH batteries: NiMH battery slow charging is not to be recommended. Using charge rates of between 0.1 and 0.25C do not provide the indicators needed to detect the end of charge.
How is a NiMH nickel metal hydride battery charged?
Unfortunately charging NiMH nickel metal hydride batteries is not as easy to achieve compared to other types of cell or battery. The NiMH cells, like NiCds require charging using a constant current. The rate of charge is normally specified on the case of the cell and this rate should not be exceeded.
How does thermal detection work on NiMH batteries?
Thermal detection: Detection of the end of charge of an NiMH cell by detecting the cell temperature also poses difficulties. While the cell will often feel warm when it is being overcharged, sometimes the temperature rise can be difficult to assess accurately as the centre of the cell will be much hotter than the exterior.
How is the charging efficiency of nickel based batteries?
It is interesting to note that the charging efficiency of nickel-based batteries of all forms is close to 100% up to about 70% of the full charge. This means that initially there is little temperature rise, but later as the charge level rises, the efficiency drops and heat is generated, raining the temperature of the cell.