building a portable lead-acid charger?

i have two lead acid batteries rated
6v 4.5 AH (is AH ampere? or ampere/hour)
boast/equalize 7.2-7.5v
float 6.75-6.9v
max charge current 1.35A

both my batteries are identical
the question now is.. i want to build a charger for it and something to lower is current
so some feature i want is 
1) rechargeable by a simple plug in adapter (i have a 12v 4A ac-dc adapter)
2) output of usb voltage and current (optional adjustable current and voltage)
3)led indicates
4)optional: a switch to power usb devices directly from the adapter/bypass battery to extend battery life
5)around 5 usb out puts?

i want to build this project cos i have the won batteries which are in good conditions but not being used in anyway..
i hope someone can help me with the technical specs..especially on the circuit diagram 
 have access to an electrical components shop but it does not sell chips so i need to salvage them




Kiteman6 years ago
If they're 6V, could you not simply connect them in series to a 12V car-battery charger?
michaelgohjs (author)  Kiteman6 years ago
ok.. emm are there car battery chargers that are for home wall plugs? ac
and how am i going to reduce the power to usb rating? i think 5v and 500mA
Yes. Any car-spares store should stock them.

michaelgohjs (author)  Kiteman6 years ago
ok thanks a lot . will pop into one of the store to have a look when i am free..(3 months time?)