10 MINUTES-RECHARGEABLE, VALVE-REGULATED, LEAD-ACID-BATTERY AFTER DEEP DISCHARGE AND STAND

Ten minutes-rechargeable, valve-regulated batteries for headphone ster eos were released on to the market in 1990. These were very thin batte ries, i.e., the PF2V0.28 (2 V, 0.28 Ah) unit was 6 mm thick and the PF 2V0.55 (2 V, 0.55 Ah) unit was 8.5 mm thick. The systems were well acc epted for normal operation, but the batteries could not be recharged r apidly after overdischarge and long stand. Therefore, batteries have b een developed that can be recharged quickly, even after being subjecte d to the most severe operating conditions experienced with portable el ectronic appliances. In order to simulate the operational problem, the batteries were evaluated in an overdischarge condition that consisted of one-week discharge through a resistor and long-term standing at op en-circuit at high temperature. The batteries have now been improved t o accept charge current in a few minutes, even under the most severe o f overdischarge conditions. The improved batteries also display good p erformance with respect to storage, overcharge and cycle life.