Reverse current charging

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Under reverse current charging , also known as reflex charging referred, refers to a charging method in which a battery with periodic current pulses as the pulse charging process is loaded, but which are also separated by short Entladestromimpulse. The reflex charging process is one of the so-called rapid charging processes and was patented in 1954 by Ernst Beer under patent number 2,752,550 in Holland and under 937,477 in Germany .

Procedure

Current curve during reverse current charging

When rapidly charging an accumulator with a constantly high charging current, the problem arises that the electrochemical processes in the cell mainly form gaseous oxygen , which is not recombined quickly enough and, in the case of gas-tight accumulators, can lead to an impermissible increase in pressure in the cell. The gas formation leads to an increase in the internal resistance of the cell, as the reaction area of ​​the electrodes decreases. This also increases the thermal load.

During reverse current charging, the charging current I R is interrupted by periodic pauses and by short discharge current pulses with the strength - I E , as shown schematically in the adjacent figure. As a rule, the amount of the discharge current pulses is greater than that of the charging current pulses. Due to their short length, they do not lead to a significant discharge, but enable the accelerated recombination of gases in the cell. In total, a larger amount of charge can thus be charged into the accumulator in a shorter time with less thermal load.

The reflex charging process is suitable for nickel-cadmium and nickel-metal hydride batteries, even if they do not have a sintered nickel electrode. Batteries with sintered electrodes are referred to in the trade as being capable of being charged quickly , since the sintering results in a larger electrode surface and the formation of gas does not have such a pronounced effect on these types of batteries. With nickel-cadmium batteries, the discharge pulse also reduces the undesired formation of metallic cadmium crystals in the cell.

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