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Old 02-26-2013, 08:39 PM
larrymoencurly larrymoencurly is offline
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Quote from immad View Post :
No this is not designed to charge dead battery. These are maintainer, they are mean't to keep your batteries charged.
Actually a lot of regular automatic chargers are also not meant to charge completely dead batteries because they require at least 8 volts across the terminals or else they won't send any current into the battery. This is related to a feature that prevents sparks when connecting the cables to the terminals.

Quote from MIjnWraak View Post :
As per a review, "it can only charge batteries up to 550 CCA". I have the same charger (bought a few months ago) and used it to charge my dead battery, which has 650 Cold Crank Amps. Once it gets to 100%, if you remove it and apply it again it will state it's at 95%.

So if your battery has more than 550 CCA, I'd find a different charger unless you needed to charge a dead battery overnight.
This I don't understand because I don't think there's any way for a charger to accurately measure the amp rating, and when it comes to charging, the more important ratings are the for the energy capacity, usually stated in amp*hours (typically about 60 amp*hours) or reserve capacity (number of minutes battery can put out 25 amps and stay above a certain minimum voltage). A battery can be built a high amp rating at the expense of energy capacity, such as by increasing the surface area of the plates and using thinner plates. However for a last-ditch method of preventing battery damage, some chargers use a timer in case they can't sense full charge by voltage, which can happen if a battery cell is shorted.

Here's how much capacity no-maintenance batteries (all plates are lead-calcium) and low-maintenance batteries (at last half the plates are lead-antimony) lose in storage (also shown is how much water each type loses):

So if no-maintenance batteries retain 95% of their capacity after 180 days while low-maintenance batteries retain only 75%, why use them? Because they can withstand deep discharge better, 6 times versus 1-2 times for no-maintenance lead-calcium batteries. I can't find such information about completely sealed car batteries, like the Optimas and Diehard Platinums, which have no calcium or or antimony in their plates.

Last edited by larrymoencurly; 02-26-2013 at 10:20 PM..