Unlike chargers with a iu characteristic this unit uses a constant current this speeds up the charge procedure considerably as batteries are charged using the maximum current through to the end of the charge cycle a further advantage is the ability to charge batteries to 100 of their capacity controlled gassing is desirable as it significantly affects the build up of sulphate layers and thus extends battery life up to a voltage of 147 v or 73 v with 6 v rechargeable batteries 6 v on