Increasing battery power by zapping (BU48)

Remote control (RC) racing enthusiasts have experimented with all imaginable methods to maximize battery performance. One technique that seems to work reasonably well is zapping nickel-cadmium cells with a very high pulse current. Zapping is said to increase the cell voltage by 20 to 40mV when measured under a 30A load. This would increase the cell voltage from 1.25V to about 1.28V. (Note that industry tends to rate nickel-cadmium at 1.25V whereas the consumer market has adapted 1.20V. It is simply a preference of rating). According to experts, the voltage gain is stable; only a small drop is observed with usage and age.

During the race, the motor draws 30A from a 7.50V battery (6 cells connected in series). This calculates to over 225W or about a quarter HP of power. The race lasts for roughly four minutes. By raising the cell voltage by say 30mV from 7.50Vto 7.68V per pack, an extra 5W can be drawn. Although small, this extra power is critical to the winning team.
According to experts, zapping works only reliably with nickel-cadmium cells. nickel-metal-hydride has been tried but the results are inconclusive. The zapping process is done with a 47,000mF capacitor charged to 90V. Best results are achieved if the battery is cycled twice after treatment, then zapped again. Once in service, zapping will no longer improve the cell's performance. Neither does zapping regenerate a cell that has become weak.

Companies specializing in zapping batteries use top quality Japanese-made nickel-cadmium cells. The cells are normally sub-C and are handpicked at the factory. Specially labeled, the cells arrive in a discharged state with an open cell voltages of 1.11 to 1.12V. If below 1.06V, the cell is suspect and zapping does not work well. A low voltage may hint at elevated self-discharge or chemical deficiencies. The 1.1V is produced through the electro-chemical potential of the nickel-cadmium cell. This voltage is present even with no charge. Applying a load would cause the open terminal voltage to collapse.

There are no apparent side effects to zapping, however, the battery manufacturers remain non-committal. No scientific explanation is available and only little is known on the longevity of the cells after treatment.
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Created: March 2003, Last edited: March 2005