Home Brew Chargers anyone?

Years ago I started working on what was supposed to be an alternative to
the 
Alpha 4.  The basic concept seemed simple enough but I wasn't sure how to 
get components to handle reverse polarity and short circuits without
smoke. 
About the time other multi-chemistry chargers came on the market, I quit 
working on it.  The interest has been there and over the years I've
learned 
what I needed to know then.  Also, now there is more available in free 
simulation tools, etc.

I've been studying different switch mode power supply topologies.  SEPIC 
would allow you to charge batteries over a wide voltage range but I
haven't 
found very high powered SEPIC controllers.  I have found Linear
Technologies 
has Boost controllers that can give 50V at 5A (250 Watts) from a 12V 
(Actually 10V to 28V) source.  Then you can use a buck converter to lower 
the voltage to what you are charging.  Add some analog outputs and op-amps

to allow a microcontroller to set the current and analog inputs to read
the 
voltage and current and that should be a pretty powerful charger.

I'm interested in getting something going on this and let the schematics
and 
firmware be open source.  That way the software can be improved, features 
added, or new charging algorithms added as new battery technology comes
out. 
If anyone's interested I can give links to the simulation software and 
circuits.

I'm not sure on the microprocessor or microcontroller to go with.  I want 
something that anyone interested can program for low cost.  Anyway, I've
got 
to get the details ironed out and tested in the analog circuitry first.

RogerN