AVR-Chat

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
>