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Home > Archive > Electrical Engineering > September 2007 > Checking NiMH cells?
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Checking NiMH cells?
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| Salmon Egg 2007-09-15, 9:25 pm |
| Some NiMH cells in blood pressure testers seemed to fail, I measured
voltage. That seemed to be OK. After recharging, I still got error messages.
Although there are warnings not to short the cells, I did test them using a
ammeter. Some cell ser delivering about 3A. What I take to be the bad ones,
delivered less than 1A.
I would appreciate any knowledge imparted to me.
Bill
--
Fermez le Bush--less than 18 months to go.
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| John Gilmer 2007-09-16, 3:25 am |
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"Salmon Egg" <salmonegg@sbcglobal.net> wrote in message
news:C311D6A8.9CB7A%salmonegg@sbcglobal.net...
> Some NiMH cells in blood pressure testers seemed to fail, I measured
> voltage. That seemed to be OK. After recharging, I still got error
> messages.
I have a relatively cheap blood pressure tester that takes 2 AAA cells. I
buy these cells "by the case" for less than $.25 each.
When I was "into" those little portable radios I purchased quite a few NiMH
cells. They cost several $dollars each and it seemed that only after a few
charging cycles would fail the test the charger put on them.
If I had to guess why your blood pressure tester isn't happy, it might be
the voltage is just a little too low. I think the rechargables are 1.2
volts. The "cabon/zink" cells, of course, put out 1.5 volts and the alka
cells put out something in the middle.
>
> Although there are warnings not to short the cells, I did test them using
> a
> ammeter. Some cell ser delivering about 3A. What I take to be the bad
> ones,
> delivered less than 1A.
>
> I would appreciate any knowledge imparted to me.
>
> Bill
> --
> Fermez le Bush--less than 18 months to go.
>
>
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| Salmon Egg 2007-09-16, 1:25 pm |
| On 9/15/07 7:43 PM, in article maudndfextTCBXHbnZ2dnUVZ_uCinZ2d@nni.com,
"John Gilmer" <nni/gilmer@nni.com> wrote:
> I have a relatively cheap blood pressure tester that takes 2 AAA cells. I
> buy these cells "by the case" for less than $.25 each.
I should have said that the device uses 4 AA cells.
Bill
--
The PC conservative does not believe in evolution but likes to see natural
selection proceed. The PC liberal believes in evolution but will do almost
anything to prevent natural selection from working.
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