AVR-Chat

Look here:  http://www.angelfire.com/electronic/hayles/charge1.html

I built a couple just like this...works very well.  Good information on this site, anyways.

--- In AVR-Chat@yahoogroups.com, "syberraith" <syberraith@...> wrote:
>
> I looked that up already.  It's a 10C rise accompanied by a 10mV drop, at least according to PowerStream datasheets.
> 
> The simple voltage cutoff is actually for recharging disposable alkalines, cutoff at 10% of rated voltage.  :)
> 
> Fred
> 
> --- In AVR-Chat@yahoogroups.com, Dennis Clark <dlc@> wrote:
> >
> > Hi,
> > 
> >    Your method of checking voltage to determine cutoff would work 
> > somewhat for LiIon cells but not so well for NiMh.  NiMh have a pretty 
> > flat discharge curve and their charge curve is best served by monitoring 
> > temperature rise, the "peak" voltage of an NiMh is subtle and not always 
> > easy to catch without some pretty good charge circuitry.  I'd have to 
> > look up the optimal temperature rise to detect a full charge, I forget 
> > the details.  Check out battery sites to get more charge details.
> > 
> > DLC
> > 
> > On 3/14/10 6:45 AM, syberraith wrote:
> > > I'm unsure if I want to go straight to my final design in one step.  I might want to build a simple/limited version first.  For my most simple version I have the current being regulated by a linear regulator, and all the controller needs to do it turn it off when the system reaches a set voltage.
> > >
> > > More elaborate versions could include such things as pre-testing charge state, and automatic discharge of any remaining charge before charging.  However, my goal at the moment is just to get a simple one done and working.
> > >
> > >
> > >
> > > --- In AVR-Chat@yahoogroups.com, Philippe Habib<phabib@>  wrote:
> > >    
> > >> I think that pretty much anything with an ADC would be enough.  You
> > >> could also get something with built in PWM so you could vary the
> > >> charge voltage as the charge nears completion.  The ATMega 16HVA, HVB,
> > >> and 32HVA, HVB are designed to be chargers.  You could also go with a
> > >> general purpose device.
> > >>
> > >> Finally, although you can get by with a 6 or 8 pin chip for what you
> > >> want, you might want to go with more pins so you can dedicate pins to
> > >> the programming header.
> > >>
> > >>
> > >> On Mar 13, 2010, at 11:01 AM, syberraith wrote:
> > >>
> > >>      
> > >>> I want to build a battery charger with a bit of intelligence, just a
> > >>> bit.
> > >>>
> > >>> I would like the charger to check the battery voltage every so
> > >>> often, one a minute at most, and if it has reached a set value, I
> > >>> would like the charger to shut it self off.
> > >>>
> > >>> I would also like charging to commence with a push of button to
> > >>> prevent a power interruption from starting a new charging cycle.
> > >>>
> > >>> To accomplish this I was wondering what device would be
> > >>> appropriate.  All it has to do is control a relay, and have a single
> > >>> ADC.
> > >>>
> > >>> Any suggestions?
> > >>>
> > >>>
> > >>>
> > >>>
> > >>>
> > >>> ------------------------------------
> > >>>
> > >>> Yahoo! Groups Links
> > >>>
> > >>>
> > >>>
> > >>>        
> > >>      
> > >
> > >
> > >
> > > ------------------------------------
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >    
> > 
> > -- 
> > Dennis Clark
> > TTT Enterprises
> >
>