16V SLA battery charger

[david90]

Does anybody have a circuit for it?

Is there anything wrong with charging the battery with a wall AC adapter and discontinue charging when the current draw slow down?

 

[VVV]

Check out this website www.powerstream.com/NiMH.htm

Se the heading "How to charge batteries".

 

[david90]

would there be a problem if I use two different AC wall adpater and connect their output in series to obtain a desired voltage to charge the battery? I have a 12V adapter and an adjustable AC adapter. One is 800mAh and the other is rated at 1.5A. My charge current will be under 800mAh.

My battery requires 19V but there aren't a lot of cheap AC adapter that can provide it.

 

[VVV]

Personally, I would build a real regulator, even if it means spending some money. You can build a boost circuit to step up the voltage from 12V to 19V.
Check out National, Linear Tech or Maxim websites for boost converters.

Or, if you have an old computer power supply, you can use the switching regulator from it to build a boost.

 

[david90]

what does the switching regulator in an old computer power supply look like? I have a old supply that i don't use.

 

[VVV]

It's a chip. Many of them are TL494, or some equivalent.
Just see what chips yours has inside and we'll look them up then decide how you can use them.
I have to warn you that you will need an inductor, though. You will have to either build it or buy a ready-made one.
Other than that, you will need a MOSFET, an ultrafast or Schottky diode and resistors/ capacitors.