Actually the 4 amp limit isnt how much you can charge it at as much as how long you charge it at that amount.


You can charge it at 50amps as long as you dont do it but for so many minutes.


Overcharging a battery causes excessive gassing — the electrolyte gets hot and both hydrogen and oxygen gas are generated. On older vented batteries, the electrolyte could cook away, leaving the plates exposed and ruining them. On sealed batteries, the buildup of gases could cause the battery to burst.


Batteries can be a pain. Trickle charging aka using a low amp charger say in the 1 amp or less will actually harm the battery by allowing plate buildup. Above 1 up to 2 amps is ideal most of the time for long term storage.


On the solar setup I have for one of my houses the charger actually blast the batteries at the start of the charging cycle to "clean up" the build up that can form and then it backs off to a normal charge till the batteries are full. So the thing can range between 50 amps down to less than an amp if they are full.

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