Fast charging vs slow charging

Charging Ni-MH batteries with the lowest possible current is not always the most beneficial for their service life.

With modern automatic chargers, the assessment of when the battery is fully charged is largely dependent on the value of the charging current.
The best charging result is achieved with a current value of not less than 1/5 of the battery capacity (e.g. 400 mA for an Eneloop AA battery min. 1900 mAh).
Remember that faster charging with higher charging currents is not harmful to batteries as long as it does not lead to a sudden increase in cell temperature above 50°C, which should not have a negative impact on the even with a charging current equal to 1/2 of the battery capacity.