# NTLK mAHs

From: Gruendel, Frank 3837 PPE-WT (Frank.Gruendel@de.heidelberg.com)
Date: Thu Apr 27 2000 - 04:07:03 CDT

Robert said...

>Just to have this clear, as far as I understand the 1600...1700mAh
batteries
>give the same voltage, just last longer (hence the higher numbers with the
h
>of hour at the end ?)

Right. The mAh value provides information on how long a certain current can
be
drawn while the battery maintains the specified voltage (of 1.2 volts).
If I remember correctly this value is based on a discharge current of one
tenth
of the capacity. In other words, a 1500 mAh battery would maintain 1.2 volts
for
10 hours if you discharge it with 150 mA. It would *not* maintain that
voltage
for 5 hours if discharged with 300 mA, but for less. It would *not* maintain
that
voltage for 20 hours if discharged with 75 mA, but for more.

>Where do you get these batteries

I live in Germany. But I won't expect them any more expensive in the US.

Ed chimed in...

>If you mix batteries with different discharge rates
>(meaning that one battery in the pack dies sooner than
>the others) than that battery acts as a load to the
>rest of the pack leading to premature discharge rates
>for the entire pack.

Right. This is something you should *never* do. Why?
The lowest voltage the Newton is able to work with is about
3.6 volts or so. This is a voltage that can be provided by
3 of your 4 batts alone, so the Newton would see no reason to
shut off and the fourth battery would be deep discharged.
Something you should avoid at all costs. It is a safe way to
kill NiCad batteries, and I'd expect NiMH's aren't too happy
avoid deep discharging my precious power supplies).
Considering that a new pack for the eMate will set you back about
\$10 or less, it doesn't make sense to use anything but the best,
i. e. the same brand, bought at the same time and at the same place,
of the highest capacity NiMH you can find.

Frank
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