Operation of AccuMate is completely automatic. It uses a 1.2A constant current charge as the main stage, while monitoring the battery voltage. When this reaches a pre-set cut off point, it then switches to an intermediate constant voltage 'float charge'. Only when AccuMate has detected that the battery is properly charged will it switch to the final stage for correct long-term battery maintenance and indicate a green LED. If at any time AccuMate detects that the battery has discharged, it will automatically revert to the constant current stage. Do not be fooled by other similar compact chargers of the same price range, which do not have the complex circuitry to safely charge batteries over long term periods. AccuMate 6-12V - 4 step charger & maintainer for 6V and 12V batteries. Features: - Versatile, 4-step, automatic charger and maintainer for all modern and classic 6 & 12V lead-acid batteries up to 75Ah. - Perfect for all types of rechargeable lead-acid batteries: filler cap types; absorbed acid "MF" for motorcycles; valve regulated (VRLA); & GEL-electrolyte types. - Very easy to use - Select 6V or 12V charging output according to battery type and then connect to battery and mains power. The rest is fully automatic. - Comprehensive & intelligent LED indications * AC power on; battery voltage selection; wrong polarity connection; charging; and maintain (charge completed). - The green maintain (charge completed) LED means exactly that, charging has been completed. - No risk of overcharging – designed for long-term connection. AccuMate`s special monitoring circuits vary & regulate the current & voltage exactly according to the battery manufacturer’s specifications. - SAFE & foolproof - No worries about wrong connections, accidentally shorting the battery clamps or blowing fuses. Automatic protection even suppresses sparks. - Compact, yet powerful - Will safely charge 12V batteries discharged to as low as 3V (1.5V for 6V batteries) when other chargers are unable to. Charging time equal to a 3 Amp conventional charger despite the compact size. - No risk of overheating - Automatic temperature control regulates charge current to a safe level in hot or enclosed conditions. AccuMate’s advanced 4-step charging program: (6V values in brackets) STEP1: Boost – Constant current charging of 1.2A up to 14.3V (7.15V) - Yellow CHARGE LED on STEP2: Absorption - Voltage held at 14.3V (7.1V) until current drops below 200mA - Yellow CHARGE LED on STEP3: Maintenance - Float voltage held at 13.5V (6.7V) for ideal long-term battery care - Green MAINTAIN LED on STEP4: Interactive standby - Active only once a battery has reached step 3: Monitors if current exceeds 200mA or voltage drops below 13.2V and cycles between step 2 and 3 to prevent the battery from losing any charge due to permanently connected devices such as an alarm or parasitic drain caused by aged or faulty vehicle wiring. With interactive standby your battery will always be ready to start your vehicle.