However it should be removed to prevent over charging once the battery is completely charged.Ī maintenance charger is the new terminology to denote a smart 2 amp charger that can stay connected to the battery and will automatically cycle off if once the battery is topped off. They are designed to feed a low charge over a period of time to prevent discharge. With a maintainer, it would take over 15 hours to get that same charge!Īn auto mechanic uses a multimeter voltmeter to check the voltage level in a car battery.Ī trickle charger provides a continues “trickle” of a charge to keep maintain your battery “topped” off without the risk of overcharging.
#SMART TIMER CHARGER BATTERY CHARGER FULL#
And a 50% discharge for a large vehicle’s battery can take a full day to several hours to recharge using a standard over-the-counter model.Ī little larger 20-amp charger can do that in half of the time, or in 1.5 hours. At 50% empty it will takeĢ7.5 amp hours X (1.15% reserve) = 31amps/10 amp hour charge rate = 3 hours to a full charge on a 10 amp charger.Īs you can see, what seems like a small discharge (12.2v) is actually a 50% discharge. Divide that amount by the amp hour charge rate.Ī 400 amp truck battery will have 55 amp -hours. Add 20% to this percentage measurement to accommodate the internal resistance of the battery.Ĥ. Find a close estimate of the Amp hours and reserve capacity by dividing the cold cranking amps by 7.25ģ. Multiple the percentage against the total amperag-hours of the battery (not the amperage, the amp-hours). A specialized automotive battery tester can tell you exactly how discharged the battery is. At 12.2 volts a car battery is about 50% empty. See Related: Reach the hard places in your engine bayġ. After sitting for a long period of time, the battery has been discharged too much to every properly hold a charge. This also explains why used cars so frequently have dead batteries on the lot and need a battery replacement shortly after you buy them. It also protects the batteries’ lifespan.ĭeep cycle and marine batteries are often used as a reserve power source and need a slower charging source to get them filled up. This is why RV owners, ATV owners, fishermen and even farmers like to use them to keep their batteries in good condition and ready for use. These low amp chargers maintain your battery and prolong its lifespan. Additionally, batteries have a slow, self-discharge that must be combated (although, electronics are generally the bigger problem.)Ī 2 amp trickle is ideal to keep a steady, slow charge in the battery to keep it from becoming so discharged that your vehicle will not start.Ī battery that has been overly discharged can be completely damaged or have a shortened service life.