On Mon, Dec 6, 2010 at 7:01 PM, Olin Lathrop <olin_piclist@embedinc.com>wro=
te:

> That graph shows voltages rather higher than what I've seen in other NiMH
> spec sheets and have measured myself.  If that graph is to be believed,
> then
> Eneloops are a bit different from other NiMH, and they will indeed work
> down
> to 1.2V/cell, or 4.8V/pack nicely, and you'll get most of the capacity fr=
om
> them.  Keep in mind that graph shows no min/max range, so is probably
> typical and at room temperature.  There will be some temperature dependen=
ce
> that would be visible at the level of detail that graph shows.
>
> Look at that graph closely, and you'll see something else you have to
> consider.  Even at 1A it shows about 1.4V initial level per cell, with it
> dropping to 1.3V after 200mAh, which is 12 minutes at 1A.  That's again a
> bit higher than other NiMH batteries I've looked at.  USB power can be up
> to
> 5.5V if I remember right, so your phone must certainly be designed to at
> least that.  4 cells at 1.4V make 5.6V, which in theory is overvoltaging
> your phone.
>
> However, I think it's very very unlikely that anything below 6V is going =
to
> hurt the phone, especially since it has to be able to take 5.5V.  If ther=
e
> is a linear regulator in there as Martin's phone appears to have and
> Russell
> thinks your phone has, then it will just get a little warmer during the
> first few minutes of charge.  If your phone has a switcher in there, then
> it
> won't even get warmer.
>
> Either way, I don't think is in fact a real problem.  But you were
> unwilling
> to risk your "$900 phone" to measure its current draw with a bench supply
> in
> the totally valid range of 4.0-5.5V.  I'm just pointing out that seeing
> what
> will happen at 5.7V is a lot riskier.


Would there be a way to put a regulator of some sort on there that would
drop the voltage to 5.5 volts if the input voltage is higher, but still pas=
s
current through even when voltage is below 5.5 volts (for example).
--=20
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