Ohms law will tell you that 2 ohms will discharge a 2500ma/hr cell to
dead in 1 hour*, I would recommend a larger resistor (maybe 5 ohms) for
a slower discharge rate. Of course, you do not want to discharge to
dead, so put a digital voltmeter in the circuit and discharge to one (1)
volt (NiMH/NiCad, do not try this with a Li-Ion cell). Going below one
volt can permanently damage the battery.
-----------------
| | |
voltmeter resistor battery
| | |
-----------------
By the way, Paul, a dead short is zero ohms, if there is a resistance it
is just a short.
*Yes, I am aware that is not quite accurate because we are dealing with
a dynamic system (voltage changes with charge state), but it is close
enough to work with.
--
graywolf
http://www.graywolfphoto.com
http://webpages.charter.net/graywolf
"Idiot Proof" <==> "Expert Proof"
-----------------------------------
Paul Stenquist wrote:
> When my son and I were racing electric radio control cars, I made a
> discharge unit that was basically a dead short with resistors in
> between the contacts. Worked fine. I had it set up to discharge at a
> very high rate to mimic the way the car's motor discharged. (It was
> about 1 ohm resistance.) I would think that a dead short with
> something like 20 ohms resistance wired in between would provide a
> nice discharge for the NIMH batteries.
> Paul
> On Jul 25, 2006, at 7:07 PM, Scott Loveless wrote:
>
>> On 7/25/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>>> Obviously these batteries aren't holding a full charge. I know
>>> that cycling
>>> batteries (drain, charge, drain, charge, etc) is supposed to help
>>> NiMH
>>> batteries regain their former capacity, but I haven't any ideas
>>> how to drain
>>> the batteries in a relatively short period of time.
>>>
>>> I suppose I could stick them in a flash and repeatedly hit the
>>> test button over
>>> and over until there's nothing left, but I've got a feeling this
>>> wouldn't be
>>> good for the flash tube.
>>>
>>> Does anyone have any ideas for discharging AA batteries?
>>>
>>> Or, should I just bite the bullet and buy all new sets?
>>>
>> I had the same problem recently. Cheap flashlights are notorious for
>> quickly draining batteries. I loaded up a couple of AA flashlights,
>> turned them on and walked away. The whole experiment was a big
>> failure and I saw very little, if any, improvement. Just get some new
>> batteries.
>>
>>
>> --
>> Scott Loveless
>> http://www.twosixteen.com
>> Shoot more film!
>>
>> --
>> PDML Pentax-Discuss Mail List
>> [email protected]
>> http://pdml.net/mailman/listinfo/pdml_pdml.net
>
>
--
PDML Pentax-Discuss Mail List
[email protected]
http://pdml.net/mailman/listinfo/pdml_pdml.net
