why not a 9 volt battery?

I was just thinking about all the flashlights that I have been reading about recently, and many of them use exotic batteries, such as pilas, then a bit more common cr2, then cr123a.

I know there are 9 volt led attachments, that just fit on top of a 9 volt battery, but I was wondering why I haven't seen a 'regular' EDC flashlight run off a 9 volt battery? it seems fairly small, and provides the voltage, maybe the capacity? it is an odd size, but i think a flashlight could still be round, or it could be a bit more rectangular.

i guess more of a question and rambling, perhaps some grumbling too - I really like the look of a lof of the cr2, cr123a flashlights, but just don't like the idea of having to go to another size (though, I do have a QIII). I know 9 volt is another size, but i consider it to be easily available, and cheaper where available in a B&M store, not just online.

thoughts?

-Melvin

9V batteries are energy-dense, but they're not really designed for high output currents, IIRC - you could run a 5mm LED off one just fine, but your usual 9V incandescents or high-current Luxeons wouldn't run too well off these cells. The capacity's not the problem with the 9V cells - it's the current draw which is the problem, from what I recall.

gnef said:

I was just thinking about all the flashlights that I have been reading about recently, and many of them use exotic batteries, such as pilas, then a bit more common cr2, then cr123a.

I know there are 9 volt led attachments, that just fit on top of a 9 volt battery, but I was wondering why I haven't seen a 'regular' EDC flashlight run off a 9 volt battery? it seems fairly small, and provides the voltage, maybe the capacity? it is an odd size, but i think a flashlight could still be round, or it could be a bit more rectangular.

i guess more of a question and rambling, perhaps some grumbling too - I really like the look of a lof of the cr2, cr123a flashlights, but just don't like the idea of having to go to another size (though, I do have a QIII). I know 9 volt is another size, but i consider it to be easily available, and cheaper where available in a B&M store, not just online.

thoughts?

-Melvin

Click to expand...

How about the Pal light? I know its not very bright, but the "always-on" function, which advertised to last for about 2 years is very useful. I have 2, one in my backpak and the other in the flashlight cabinet with the little red-cone so I can find it (and then choose the suitable flashlight) easily.

Again, its not birght, but at least it provides enough light and signaling function when you need it.

Interesting--what about a flashlight based on somehting like the 2cr5 battery (6 volt) that many 35mm cameras (cannon for example) use? It's a little larger than 9volt, but is lithium...

9 volt battery, 2xCR123 batteries -- available

http://www.palights.com is the manufacturer of the 9-volt PALight models -- they're now a subsidiary of a UK company, both web addresses work.

(PALights is offering CPS users a price break, see the dealer/manufacturer forum, through October)

You asked about the lithium batteries -- a company using a very similar web page name, "palight.com" -- resells the PALights and also has recently started selling a 2xCR123 flashlight (not a PALight flashlight) that is a little bigger, with red and white LEDs.

Re: 9 volt battery, 2xCR123 batteries -- available

you'd get short runtimes on these if you tried to power a really bright light.

How about just a decently bright light that ran on 3 volts? because then you would be using only a third (about, not taking into consideration efficiency of circuits) of the amperage that it could supply? or would that draw still be too much for it?

i'm thinking more along the lines of an EDC flashlight. looking at the sizes of batteries, it seems a 9 volt could make for a decent EDC light in a small package. it wouldn't be the 'regular' round form factor, but i think it could look alright.

i remember reading a thread about the draw of alkalines, and how they can't support a high current draw for too long. what kind of leds could you drive at the full potential of the 9 volt battery? i mean wattage-wise, like the nichia jupiter? a luxeon 1 or 3 watt potentially?

-Melvin

I personally wouldn't buy a light that used a 9volt battery, as I hate those pushpin connectors used for the power leads.

9v connectors are useful for devices that don't need batteries changed often and have a separate on-off switch. The only times I"ve had any problem with a connector it was because I'd tried to install the battery backwards and crushed one of the four 'ears' out of line. Bend it back with a fingernail, no problem.

The only downside of 9v battery connectors I know of is having to wear earplugs when changing smoke detector batteries because of the 'test-on' squeal when the battery snaps into place -- but now that I'm using the long-lived lithium 9-volts in everything, I don't have that problem very often.

The other nice thing about lithiums (I'm using 9v lithiums in the PALights) is the devices work just as well below freezing -- where ordinary carbon and alkaline cell powered devices drop to very low voltage and have to be warmed up repeatedly by (shudder) tucking them inside the parka against warm skin.

And 9 volts were the first standard-sized battery (AA, AAA, C, D, 9V) that I was aware of a lithium option for (advertized for extended smoke detector running), although something like $10 each as I recall.

Interesting discussion because with regulation a 9v would only need to source 1/3 the current of a 3v lithium or 1/6 the current of a 1.5v AA.