Will a car battery replace a CP-E2 for a 580EX?

[fatphotographer]

An unusual question I know, but I was wondering if anyone has experience of "upping the power input" into a speedlite.

I have an external power pack for my speedlite which ups the refresh rate and reduces the amount of battery changes. Instead of the 4x AA 1.5V batteries in the speedlite body (6v?) it adds another 6x AA batteries into the equation. There are other power Canon and Quantum packs (and probably others) that add even more power, so it has got me thinking.

I am looking to set up a speedlite of camera, trigger it wirelessly, and leave it to shoot about 5000 pics over the space of a day. Charging and changing a gang load of AA batteries is not an option. So I am looking to use the cable from the CP-E2 to provide a power input from a much bigger / more powerful / longer lasting battery – possibly a 12v car or leisure battery or a 6v motorbike battery. Which one I use, depends upon how the flash works inside, and that it why I am posing the question.

Is there anyone out there with electrical / camera repair knowledge, that can point me in the right direction?

Does it add the power in parallel or series? Is the key to a faster refresh rate and long life, the Volts, the Milliamps or some other magical electrical mumbo jumbo?

What do I need to do to prevent an ingenious little fix turning into a ball of flaming plastic and an unusual insurance claim?

Any suggestions from direct experience will be greatly received, but please don’t just guess!

Thanks

Gary

[msowsun]

Don't use 12v. Read all about it here: http://photography-on-the.net/forum/showthread.php?t=524596&highlight=cp-e4

and here: http://photo.net/canon-eos-digital-camera-forum/00H19m

[fatphotographer]

Thanks for the links, I didn't think it was going to be straight forward!

Cheers

Gary

[tim]

Just use AA cells in the CP-E2, they already cycle fast enough. Well the CP-E3 and CP-E4 do, no idea about the CP-E2.

[fatphotographer]

The recycle time is probably sufficient, but I can't see the batteries lasting 5000 shots. I am probably looking more for the longevity than anything else. Even if I had several sets of AA high capacity batteries, I would be draining them faster than I could charge them, the high capacity ones take 12 hours to recharge fully. I had sort of planned one large lead acid battery lasting all day.

[tim]

What kind of photography do you do? 5000 shots is a hell of a day, and if flash is your main light for all those shots you're going to need a Quantum or something to power things, or a proper portable studio light kit. Speedlites aren't designed to be the main light all day, especially outside trying to overpower the sun.

Perhaps a rethink of your flash strategy would be a better option. Most of the time I use flash as fill outside, but I take perhaps 200 shots with flash as the main light outside, and quite a few in the evening. Higher ISO is your friend, except in bright sunlight.

[fatphotographer]

Motorsport Events. I have a large Land Rover show coming up where there will be 500 vehicles with up to ten pictures each. Studio lights are out of the question, 240v, and rain don't mix. I have used "on camera" Metz and Speedlites before, but never liked the overpowering bright foreground. You are right, the power of the sun and the distance to the subject would really push the limits of the speedlite. I was looking to hide a speedlite very close to the vehicle on about 1/4 or 1/8 power to give a little burst of fill in light as the vehicle goes over the obstacle. The "fit and forget" idea of a lead acid battery modification was probably the easiest, cheapest, least hassle, safest, option.

Thanks for the input,

Cheers

Gary

[tadrscin]

Take a look at the Black Boxes by Al Jacobson. You're supposed to be able to get at least 1000 full power flashes on a single charge. At 1/4 power you'd have to change the battery once if you can live with that. At 1/8 power you should be golden. I use them, but I've never come close to 1000 shots. The most I've done is about 500. http://www.aljacobs.com/THE%20BLACK%20BOX.htm I'd give him a call and see what he says.

[tim]

The Al Jacobs black box is just a sealed lead acid battery in a box. He adds value by making it a nice box, and supplying connectors. Seems like a great guy, and a good product, but you can do it yourself.

[tadrscin]

Yes he actually used to give out the plans and still might, but not all of us can or are interested in DIY.

[fatphotographer]

Excellent link, thank you!