How to Build a Fast Charger for Car Lead Acid Battery?

[kengloong]

I'm now using a car lead acid battery in my UPS System, now almost a week already my battery still not fully charged yet.

So, I planned to build a fast charger in my UPS, any someone can give me some idea how to build it?

Regards,
Keng Loong, Liew

 

[echo47]

A typical safe charge rate is 0.1 times the battery's capacity, so it takes about half a day to charge it. If it's a 60 ampere-hour 12V battery, then your charging supply should output about 13.8V and limited to 6 amps.

You can apply several times that much current for quicker charge, but refer to the battery data sheet for reliability info.

 

[kengloong]

What is the formula to calculate this charging time? Any circuit that you can provide to myself that I can build up the fast charger for my UPS.

Can anybody advice that to build up another fast charger to attach to the UPS so that I no need to modify the UPS original circuit?

Please advice, Thanks!