Chuck Harris wrote:

Joerg wrote:

Lord Garth wrote:

"Chuck Harris" wrote in message
news

Do you care to share your schematics and code Chuck?


You might be able to talk me into posting an earlier version that
did pretty much everything I said, but used an 8 bit ADC in a PIC16C73.


Yes!

pant, pant, drool ...

But only if that for sure doesn't get you into hot water.


No problem there, I own the design, and the company.

I did that one as a prototype for the US ARMY. It was a little
brutal on
the LiION batteries, as 8 bits doesn't give you a whole lot of
resolution
on your CV/CI regulator.


PWM resolution is another concern. Not so much for a charger but for a
regular switcher. Otherwise it'll go into a "burpy" mode if, for
example, you want to run the PWM at 500kHz but the timer clock can't
be more than 10MHz or so.


The resolution is a problem for the feedback loop. I measure the supply
voltage using the PIC's 8 bit ADC with the help of a stupid simple range
selector.

The charger had to handle batteries from a couple of volts up to 28V.


That's a tall order, especially for LiIon.


The LiION batteries need the voltage held to a fairly close value, so
I adjusted the ADC's reference just for them. NiCAD's, and NiMH are more
interested in relative voltage levels, so they aren't at all critical.


Hopefully the on-chip ADC is quiet enough all the time.



-Chuck



Until the most recent amateur radio convention in Plano, I was charging
my HT batteries with my bench supply.

Seeing as how your design can do lead acid and Nimh, that would be nice.

I don't have any lithium batteries in the radios though I did note
the new
HT designs used them...Man, are they pricey and small.


I wish that radios, cordless phones, drills and whatnot would be run
off regular AA cells. But no, one has to plunk down big bucks the
instant the battery dies. I'd rather forego the increased capacity of
LiIon.


There is something to be said for using standardized power sources. LiIon
are available in the usual A, AA, AAA sizes as are NiCads.


To me mainstream means when you can buy them at CostCo, Walmart and at
the major tourist places for a reasonable price ;-)

--
Regards, Joerg

http://www.analogconsultants.com