Hi Kamilb, I´ll try to help you. In theory, every kind of battery have his own kind of charger. If I remember well, the original charger of Sinclair is rated for leaded acid batteries about 33 amps of capacity and offer about 2.5 amps/hour. Some chargers cut when they reach 14.5 volts and some near 15 volts. But with some careful procedures, you can use that charger with a lot of kinds of batteries, sealed or not, AGM or acid leaded. The basic idea you must remember is the power of the charger must be around 10% of battery capacity. More power can blow up the acid into the battery and became it unuseful. An example; as I use several kinds of electric vehicles, my electric tandem, my C5, and use differents voltages, tandem use 36 volts and the C5 use 12 volts, I have several AGM batteries rated at 12 volts and 12 amps and make combinations to get the desired result. I drive my C5 using two packs of three elements, getting 12 volts and 72 amps, with 25 pounds of weight the whole and charge them using a standard charger of leaded batteries, rated at 12 volts and 6 amps/hour. Before two years of use, the batteries are still in perfect condition
. The only limitation to use standard chargers are the LIPO batteries. I´ve seen a lot of this packs blow away in the moment of charging, even using a special charger with termal control. But if you use acid or AGM don´t be worry, only don´t use a very big charger and that´s all, for me at least.
I hope this comment can be useful for you.
Regards, Rafael