>I think you're overestimating the required precision.
> LM-317 / 338 based chargers are all over the place, and working 
> fine.

Perhaps I am.
*BUT* battery suppliers and all who talk at any length about their 
maintenance make a big deal about the float voltage being correct to 
something around +/-0.1 Volt. I really don't want to have to trim this 
manually during setup (pot/labour/training/Murphy). And the eg LM317 
spec sheet guarantees that you can't get anywhere near the required 
specs without adjustment.

The semi processor-controlled system in my next email has the 
advantage that the processor's voltage reference calibration, which is 
automated, looks after the battery charger voltage calibration. Cost 
is comparable to simple LM317 schemes and has some advantages.

Lest anyone think I raise topics like this solely to tell you what I'm 
doing (ta da !) rather than actually ask questions - the input from 
people in the last 12 hours has significantly influenced my current 
intentions and helped clarify existing thinking.


        RM


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist