P3D Re: Ni-Cad batteries

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Gabriel Jacob wrote:
> 
> Bill Stickley
> >I would disagree that higher currents supplied by ni-cads is the
> >reason.
> 
> Sorry Bill, but this is not true. The major reason ni-cads are not
> recommended IS because of the higher current.
> 
> >It is much more likely that ni-cads of a given size are
> >rated as less voltage than comparable alkaline batteries. For
> >example size AAA, AA, C and D alkaline cells are rated at 1.5 volts.
> >The equivelent ni-cads are generally rated at 1.2 volts.
> 
> The differing voltages is immaterial in these discussions. Most P&S
> cameras, flashes, etc. are made to work under a range of voltages
> due to the voltage decrease with use of regular batteries. Thus they
> are very tolerant of voltage. In anycase the manufacturers are not
> saying don't use ni-cads because it won't work with your camera but
> because it might ruin your camera and never work. Sure they need a
> minimum voltage to operate but ni-cads are not a problem in this regard.
> 
Sorry Gabriel, but proper voltage is essential. The Nikon p&s
I tested would not operate at 2.2 volts. This was because the frame
advance motor stalled due to insufficient voltage. Without the proper
potential(voltage) in a circuit, you will have no current flow even
if you have a power supply with no internal resistance and capable of
unlimited current. 

>Most alkaline cells are considered completley discharged at 0.8 volts.
> >With this in mind you can see that fully charged ni-cads act like
> >they are halfway discharged alkalines.
> 
> Your making some erroneous conclusions here. You can't equate the
> voltage of the DIFFERENT types of batteries with it's current capacity.

To deliver the current to the load, it is essential that you have the
potential(voltage) to cause the current to flow. 

> Your comparing apples and oranges by comparing a fully charged ni-cad
> to a halfway discharged alkaline. If were comparing the the voltage of
> an alkaline at 1.2 vs. a 1.5 you can make some kind of generalization
> but not with a ni-cad. An easy example (from many) to understand this
> is a 1.5V D size alkaline battery vs. a 1.5V AAA size alkaline battery.
> Same voltage, same internal chemistry but very different current
> capabilities!
>
Again the current is not the problem, the proper amount of current would
flow through the motor if the potential(voltage) were proper. The motor
uses POWER which is calculated by voltage x amperage, if the load(motor)
remains constant when the voltage is reduced the current will be reduced
and also the power produced and consumed will be reduced.

> So in closing, manufacturers don't recommend ni-cads (in certain cases)
> because they might fry your equipment and not because it might not
> operate your equipment. If that was the case (not operate) they wouldn't
> bother with the warning.

Perhaps you have better contacts than I, we would certainly benefit
from having the real reasons from the manufacturers. My efforts to get
an answer directly from Nikon were fruitless, they would neither 
confirm or deny. The only practical alternative was to do the empiricle
testing I did.

Bill Stickley


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