jkinney2 wrote:
> <[email protected]> wrote in message
> news:[email protected]...
>
>>
>> What confuses you about screw base 3.5 v bulbs?
>>
>>
>
> I had no idea there would be so many choices. I thought I had a good idea
> in taking my petzel mega light and using it on my bicycle the darn thing is
> very bright and works great for my use. This year I got tired of buying
> batteries so I went and purchased some AA NiMh so far so good. Charged them
> up and started to use them, my commute is in the dark both ways. I noticed
> that even new the light was not as bright as it was with regular batteries.
> Not being to bright myself I found that the rechargeable ones only produce
> 1.2 volts, I just figured that if I could find a bulb that ran on 3.6-3.0
> volts it would solve my problem. While looking for bulbs I also came across
> a web site for led bulbs not sure I want to spend 25.00 US for a bulb but it
> does interest me.
OK.
Picking bulbs is a little more complicated than you think. Three 1.5
volt batteries and three 1.2 volt batteries might actually do well with
the same bulb.
Why? Because the battery's voltage rating is measured when it's
delivering zero current. But batteries have not only voltage, but
internal resistance. When the current flows, the voltage is actually less.
How much less? Depends on the amount of current, and on the internal
resistance of the battery. I know that 1.2 volt Ni-Cads have
significantly less resistance than 1.5 volt alkalines. So they may
produce pretty much the same effective voltage when the bulb is lit.
I admit, I haven't played with NiMh batteries yet, so I don't really
know their characteristics. I use generators for almost all my bike
lighting, so my issues are different.
- Frank Krygowski
