Hello Sushi,
On Sat, 8 Dec 2001, Sushi wrote:
> >
> >This is a bad idea!! You should NEVER discharge a
> >battery pack (with NiCDs,NiMH) below about .6V/cell,
> >.8V/cell is perfectly acceptable.
>
> Hey Speedy,
>
> Disagree with your "This is a bad idea!" comment. I have done this on
> numerous devices besides the Newton and have never had a problem with it.
> Not once!
Then you've been lucky. Taking a battery pack of rechargable cells down
past .6V/cell is dangerous "." I have scores of data including literature
from Sanyo, Duracell, Energizer and other companies that show how cell
reversal damages batteries, etc.
Advice from these companies not withstanding, myself and numerous other
engineers who *design* equipment with or for re-chargable batteries can
attest to ill-effects of cell reversal(as in, we've seen it first hand).
This advice comes from the engineering world, so it's not hocus pocus.
In all of these URLs, search for "cell reversal" (you may have to do it
several times)
http://www.varta.com/eng/navigation/index.html?content=knowhow/gloss-c.html
http://www.flightlines.com/introduction/batteries.htm
http://www.rayovac.com/busoem/oem/specs/ren8b.shtml
http://data.energizer.com/batteryinfo/buttons/glossary.htm
http://www.battery-index.com/memory-nickel-metal-hydride-batteries.shtml
BTW: There is a LOT of misinformation about batteries, I didn't check
these sites for their correctness on other topics (such as memory,
charging, etc), so don't take my posting the URLs here as an endorsement
of anything other than the definitions of cell reversal.
You can however assume, besides the marketting, sites like Rayovac,
Energizer, Varta, etc will have correct info.
>
> In this case, after the Newton shuts down after giving you the low
> battery warning, let it set for a second or two, then switch it on again.
> Let it shut itself off. Try it once more, if it will do it. Then after
> the Newt shuts itself down the second time, then plug in the adapter and
> recharge the battery until it is completely charged.
>
I am not sure what voltage cut-off the Newton is using, I *suspect* 3.3V
as anything below that and the Newton would be unable to reliably power
the memory, etc.
3.3V for the pack is above .8V/cell, but this is still a crap-shoot as
each time the Newton tries to turn on, it attempts to draw current from
the batteries.
It is thus possible in an attempt the Newton will depress the pack past
2.3V, because, as I mentioned earlier, re-chargables have a steep
discharge curve and moving them from .8V/cell to .6V/cell is pretty easy.
>
> Remember, the Newton circuitry is determining whether or not it can turn
> on by the amount of juice that is available. If there isn't enough, it
> simply won't turn on. All the devices that I have that come with
> rechargeable batteries basically work the same way.
This is very untrue.
The only thing the Newton hardware/software checks to see if the total
voltage is above/below some point, and if so, it will or will not turn on.
However, the Newton has know idea how much "juice" is left. The voltage
check is a saftey, again taking the cells down below a certain point would
damage the pack. The voltage on the cells/pack only gives you an *idea*
how empty the batteries are, it is not an absolute measure!
Many devices (like Walkmans, CD players, etc) have low-battery warnings
and beyond some voltage, fail to operate simply because they *need*
sufficient voltage/current to run and the batteries will no longer do.
However, because the unit turned off at a certain point, doesn't mean it
used smarts to do it, the it's very likely the batteries just could drive
the units anymore (thus the unit could have taken the batteries down
beyond a certain point).
If you still want to discharges you batts all the way go ahead, just be
aware of what might happen.
Thanks,
Speedy2.
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