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Re: Nicad charging.

Subject: Re: Nicad charging.
From: Walter Knapp <>
Date: Sat, 09 Nov 2002 16:50:42 -0500
Jeremiah Moore wrote:

> Is anybody aware of higher-voltage NiMH cells in AA?

As a AA is a single cell, it's voltage is set by the chemistry of the 
NIMH. So not much hope. You would get longer run time out of the newest 
generation of NIMH as they maintain voltage at a higher level through 
most of the discharge than the older ones did. And on top of that they 
are higher capacity.

I would wonder if it's shutting off at that high a voltage it's not 
really using up the alkalines either. Have you checked to see if it's 
just your individual one?

I really wish that this would all be fixed by a regulation that required 
all battery operated devices for which NIMH are available to be designed 
for them. It's amazing how many companies think we want to spend on 
disposables. Maybe a big tax on any that failed to meet that criterion, 
a battery waster's tax. Only place I use alkalines is where they may set 
for very long periods between uses and need to work. Like emergency 
flashlights.

My Sound Devices MP2, for instance had a spring in it that did not 
contact on NIMH rechargables, but would on alkalines and most Nicads. I 
turned out a small brass interface to get it to work. To their credit, 
they have fixed this in newer production runs. And when I talked to them 
they would replace my battery holder with the new design for free. My 
MP2 is off getting that done right now.

> Walt: I noticed your mention of a NiMH replacement 9-volt which 
> delivers equivalent voltage to alkaline - this gives me hope!

That is simply putting more cells in. The 9 volt batteries are 
multi-cell and for some reason the rechargeables are made with the same 
number of cells as alkaline. The chemistry of the alkaline cell gives a 
higher per cell voltage, and a higher total for all cells. In the 
Plainview batteries by adding two cells they went from a 7.2 volt, to 
9.6, which makes up the difference. Since it's in the same size package, 
each cell must be physically smaller. They manage it and also have a 
higher capacity than most other rechargable "9v". (170 mAh) I do wish 
other manufacturers would do the same.

Walt





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