The battery refresher is connected to the battery and withdraws energy in a recurrent process which is immediately returned as a current pulse. Crystals of sulfate deposits distintegrate - charging voltage, cold testing current and capacity are increased again. Old batteries can be brought to life again, new ones are protected against ageing too fast. Suitable for lead-acid-batteries and gel-batteries up to a capacity of 300 ah. Switch-on voltage is 12.6 ± 0.2 V. Dimensions W 10 x H 2.5 x D 6.7 cm, weight 120 g.