i have 3 X 12V battery i use them to drive a dirt bike .i want to charge them with a 36v-30A power supply the maximum charge current is 6 amps that is given by the manufacturer . will this damage my battery packs ? more over how many amps would the battery draw? i am not using current limiting circuits
A power supply rating does not indicate how much it will "charge" a battery. It's the max current that can be drawn from the device until it shuts down/blows a fuse/etc.
With that being said, it has the capability to exceed the max charging current of your batteries. Which is nooo bueno.
It may be better to use some purpose built led acid chargers and charge the individual batteries. These purpose built chargers have the necessary safe guards in place to make sure not to blow up your battery and switch to a trickle charge mode after the bulk of the charging is done. These types of batteries require that extra bit because they self discharge much faster than other chemistries.