In article <
mcmurtrie-42101...@news.sonic.net>, Kevin
McMurtrie <
mcmu...@pixelmemory.us> wrote:
> > > Trickle: Very low current for 10 to 20 hours. Reliable until the
> > > battery fails from repeated overcharging.
> >
> > timer based chargers are not reliable because they have no way to sense
> > end of charge. they just charge a preset amount of time, which will be
> > different depending on how discharged the battery is when put into the
> > charger.
>
> WTF. They always charge. Sometimes they overcharge.
they almost always overcharge because it assumes a fully discharged
battery. if the battery is only partly discharge, it will overcharge.
it's a timer. it's not checking the charge state.
> > > dV : Charge at a 3 to 1 hour rate and look for a slight voltage
> > > plateau. This plateau can can not be seen clearly if any conditions
> > > change (loose contacts, power fluctuations, temperature changes, etc.),
> > > so it's easy to over or under charge. A timed top-off trickle charge
> > > may be added if the battery did not become hot from overcharge.
> >
> > nonsense and it's actually a voltage drop, not a plateau (ndv). it's
> > very easy to detect and what most smart chargers do.
>
> That's NiCd. Difference chemistry and decade of prevalence. Try
> looking something up. NiMH just has a flattening of the voltage curve.
nope. nimh has ndv, it's just smaller.
nimh chargers, which can also charge nicad, use ndv and/or delta-t.
> > > dT : Charge at 1 hour rate and look for a temperature increase of 1C per
> > > minute or reaching 60C. The 1C per minute increase is difficult to
> > > detect if any conditions change (wind, heat, air conditioning, etc.), so
> > > it too is easy to over or under charge.
> >
> > more nonsense. a temperature sensor in the battery bay is all that's
> > needed and works well.
> >
> > wind?? are you charging batteries outside?
>
> Are you in a sealed room with no ventilation. That explains some things.
there is no need for a sealed room and even if there's a breeze, it
doesn't make any difference. the temperature sensor is in contact with
the battery.
> > > Pressure : Charge at 1 hour rate until gassing starts. Requires a
> > > pressure sensor in the battery.
> >
> > which aa batteries do not have.
>
> Except for all those consumer cells with the pressure sensor contact
> ring on the side, and many industrial cells.
not on aa cells.
> > > Magic : Charge slower than a 3 hour rate and claim that a magical CPU
> > > can sense the aura of a full battery. Usually needs magical conditions
> > > to work.
> >
> > nonsense.
> >
> > smart chargers do not use magic. they continually monitor the state of
> > charge of the battery and adjust accordingly. the better ones use
> > multiple charge stages, using a combination of constant current and
> > constant voltage and then switching to trickle charge at eoc.
>
> The state? What state? Check the charts for any name brand cells.
state of charge.
> The charge voltage remains constant.
nope. nimh is charged with constant current. otherwise, it could never
sense ndv.
<
http://dev.emcelettronica.com/files/u4/Typical_NiMH_NiCd_Charge_Profile.
png>
smart chargers can also detect failing cells and alert the user to
replace them.
> The impedance remains constant.
not an issue.
> Very little heat is produced - just that of the hydrogen gas catalyst.
wrong on that too. anyone who has put batteries into a charger knows
that they get warm, sometimes very warm.
> That leaves magic.
nope.
there is nothing magical about battery charging.