what is the problem when the auto shut-off battery charger will not shut off, the charger is the best Academy sells, thought maybe it was the charger, so took it back and got another, first time worked, second time left it hooked up for at least three hours (didn't use the trolling mtr. that much (maybe 2hrs) the battery is a deep-cycle. thanks

It may take more time to reach a full charge depending on the battery condition and charger output. Have the battery load tested and if it checks out good then you may need to charge for 12 hours or more before it shuts off. A volt meter is a good tool to have and the best way to measure the charge level.

The time to recharge would be dependent on how much draw the trolling motor has. It could be pulling a lot of juice when you use it. If for example it is drawing 15 amps and you have a 10 amp charger, you should not expect it to recharge in less that 3-4 hours under optimum conditions. I have a 3 bank 15 amp unit and it generally takes 7 or more hours to recharge my batteries.

thanks...

I hit mine with 50 amps for about 5 seconds to "shock" it...and get everything flowing ( heated up). Then I charge them about 30 min to an hour at 10 amps. After that...I switch it to 2 amps because these cheap chargers dont always shut off. A long slow charge seems to be better than a quick one.

how the auto-shut-off feature works:

A battery has an "internal resistance", which goes down as the battery is discharged, and increases as it's recharged.

As resistance increases, current (measured in "amps") must decrease, or else voltage must rise. This is true in every electrical circuit, not just battery charging.

So, the state of the battery controls the charging current up to the setting you select on the charger -- other words, if you select 12 amps, it'll start with a maximum of 12 amps, and hold at that level until the battery voltage climbs to 14.5 volts.

At that point, the charger holds the voltage constant, and as battery resistance continues to rise, current decreases.

When the charger senses that the current has stopped decreasing, it signals "done" and shuts off, because the battery isn't taking any more charge.

If the battery has an internal short circuit in one or more cells, it may never reach a fully charged state.

A 2-amp setting may never trigger the "fully charged" signal, and under normal circumstances, with a battery in good condition, that's ok -- won't cause any damage. But under certain conditions, a "trickle charge" can overcharge a battery, or even boil it dry.

The best way to maintain a battery is with an automatic charger that switches to "float" or "maintain" mode -- it's a constant 200-300 milliamp charge that keeps the battery topped off.