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9 volt alkaline battery

F

fashazee

Jan 1, 1970
0
Hello,

Technically speaking, at what voltage is a loaded 9 V alkaline battery
considered dead?

Thank you in advance,

Mike
 
B

BobG

Jan 1, 1970
0
fashazee said:
Hello,
Technically speaking, at what voltage is a loaded 9 V alkaline battery
considered dead?
Thank you in advance,
Mike
===================
6.6V? (1.1V/cell x 6 cells)
 
C

Chris

Jan 1, 1970
0
fashazee said:
Hello,

Technically speaking, at what voltage is a loaded 9 V alkaline battery
considered dead?

Thank you in advance,

Mike

Hi, Mike. When consumer batteries are rated for A-h (amp-hours), they
are typically given a constant load, and are considered dead when the
output voltage reaches 60% of specified voltage (in the case of a 9V
transistor battery, that would be 5.4V)

Of course, any battery is _really_ dead by the time it reaches 60% of
rated voltage. I'd consider a 9V battery with a 25mA load very dead by
the time it got to 7V or so. Once the output voltage slides below 80%
of nominal, it's got one foot in the grave.

Good luck
Chris
 
P

Phil Allison

Jan 1, 1970
0
"fashazee"
Technically speaking, at what voltage is a loaded 9 V alkaline battery
considered dead?


** When whatever it is powering ceases to function properly.




........ Phil
 
D

Don Klipstein

Jan 1, 1970
0
Chris wrote: said:
Hi, Mike. When consumer batteries are rated for A-h (amp-hours), they
are typically given a constant load, and are considered dead when the
output voltage reaches 60% of specified voltage (in the case of a 9V
transistor battery, that would be 5.4V)

Of course, any battery is _really_ dead by the time it reaches 60% of
rated voltage. I'd consider a 9V battery with a 25mA load very dead by
the time it got to 7V or so. Once the output voltage slides below 80%
of nominal, it's got one foot in the grave.

I just got a look at: http://data.energizer.com/PDFs/522.pdf

Looks to me there is a bit of a "knee" in the discharge curve with the
"center of the knee" at 7 to 7.2 volts (1.1667-1.2 volts per cell), but
the "knee" only stands out a little. With intermittent duty and a
constant resistance load, the time to 5V is about 50% longer than the time
to 7V.
The constant current discharge curves show mAH about or slightly more
than 7/6 as great when discharged to 4.8 volts as at discharge to 6 volts.

Meanwhile, as for what voltage to design something to work at with this
battery? Since the datasheet has constant resistance and constant current
hours-to-specified voltage curves (as a function of resistance or current)
only for 6 and 4.8 volts, I would design something using this battery to
keep working at least until the voltage decreases to 6 volts.
Although I think it's OK for a product using this battery to work but
not quite meet its specifications below 7.2 volts, I believe that a
product designed to use this battery should work reasonably at least down
to 6 volts.

Meanwhile, in general design of products using alkaline batteries: I
believe they need to work well with NiCd and NiMH that are typically 1.2
volts per cell, and considered discharged at 1.1 volts per cell *or less*.
So I believe a product needs to work well at 1.1 volts per cell.

- Don Klipstein ([email protected])
 
P

Phil Allison

Jan 1, 1970
0
"Don Klipstein" :


( snip agreed stuff)
Meanwhile, in general design of products using alkaline batteries: I
believe they need to work well with NiCd and NiMH that are typically 1.2
volts per cell, and considered discharged at 1.1 volts per cell *or less*.
So I believe a product needs to work well at 1.1 volts per cell.


** There is no need to assume that a Ni-Cd or NiMH battery ( made to
replace the 9 volt single use size) will have only 6 cells - 7 cell
examples of both have been available for a long time and more recently 8
cell ones too. These have nominal 8.4 and 9.6 volt ratings as opposed to
7.2 for the old 6 cell ones.

Also, where an item uses a 9 volt single use battery and no mention is made
in the handbook of suitability of use with rechargeables, owners are not
wise to assume it is safe to do so.

A NiCd cell ( and many NiMH too now) can deliver a dangerously large current
if shorted or reverse connected and the item concerned must be designed to
cope with this without damage if the use of rechargeables is allowed.




........ Phil
 
D

David L. Jones

Jan 1, 1970
0
fashazee said:
Hello,

Technically speaking, at what voltage is a loaded 9 V alkaline battery
considered dead?

Thank you in advance,

Mike

Energizer specify the capcity of their 9V alkaline to a discharge
voltage of 4.8V
This makes sense as alkaline batteries are typically physically
constructed of 6 "AAAA" batteries in series, and single AAA/AA/C/D
cells are specs to be "dead" at 0.8V. So 0.8V x 6 = 4.8V
So in theory, to use all the available capacity of a 9V battery, a
device should be designed to operate down to 4.8V. Not many devices are
though, they will die at a much higher voltage and hence won't use all
the capacity of the battery.

Dave :)
 
R

Rich Grise

Jan 1, 1970
0
Hello,

Technically speaking, at what voltage is a loaded 9 V alkaline battery
considered dead?

Thank you in advance,

Mike

When it won't operate the thing it's powering any more.

Cheers!
Rich
 
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