In-Reply-To: <491782.57229.qm@web39307.mail.mud.yahoo.com>

Alan,

> So in general, given a NiHM cell, the mAh capacity is the amount of curre=
nt it can deliver over a given time into a set load, correct?
>=20
> I have some unmarked AAA cells, so I charged them with my commercial char=
ger and set up a fixed load (power resistor 75ohm 5W) and then proceeded to=
 log the current it was delivering over time.  The curve was not really wha=
t I expected, it showed a slo-
w discharge for about an hour and then a very sharp drop to where it then f=
lattened out.
>=20
> Am I measuring this incorrectly to find the mAh capacity of the cell?  Fr=
om what I can see, it tells me that I have a 275mAh to 310mAh cell (those a=
re the starting points to where it dropped off sharply)
>

The correct unit is mAH, the capital H stands for Hour.

e.g. a fully charged 1000mAH cell should be able (approximately anyway) to =
supply 1000mA for an hour.

More generally an x mAH cell is able to supply a current i mA for x/i hours=
.. (That's x divided by i)

For a NiMH cells the end should be taken as when the voltage drops to somew=
here in the region of 1V
which usually means almost all the energy has been used up and the voltage =
will plummet towards
zero pretty quickly after that.

Brian Gregory.
briang@cix.compulink.co.uk

--=20
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