12 volt 20A battery charger using computer PSU

 

I am trying to recall my electronics 101 education.

Can I series the 5V supply of three computers power supplies to give a 15V
20A fast charger?
Old AT psu's are a dime a dozen and much cheaper than  a 20A 12 volt
charger.
This would be powered by one of those el cheapo 500W generators to top up my
225Ah batteries of my solar setup.

 

I agree with the theory, and I'd give it a try...
but my gut sensation is that they'll go up in smoke.

My 2 cents,

Bud Weather
http://www.thesolarshop.net/

Norman Webb wrote:

 



     The answer may not be as simple as you first think.  Remember that these
power supplies are switchers and are not necessarily transformer isolated.  For
starters, do a simple test to find out if the power supplies are referenced to
AC ground.  If so, it won't work.  That done, you are still not home free but at
least you have a good start.

     Also, I remember that you have to do something to make them start.  I seem
to recall that they need +5 on a certain lead.

     If you could lay your hands on a surplus 24 Volt transformer and a Variac,
you would just need to add a heavy diode bridge and an ammeter and stick it all
in a case to build yourself a dumb fast-charger that would probably last you for
the rest of your life.  You might even be able to substitute a lamp dimmer or
fan control for the Variac.

Vaughn

 


Vaughn wrote in message ...

The old AT type just needed a load to start.

The "new" (last ten years??) ATX supplies have some type of signal between
the psu and motherboard

 


If you can limit the current it might work, but the supplies will do
foldback (shutdown on overcurrent) instead of a hard current limit at
(say) 20A.  Look for a surplus 15V power supply with adjustable
current limit or a real battery charger...