Dud Canon BP-511?

[The Impact]

I have three genuine BP-511 batteries for my Canon 10D which I use with a battery grip. Through trial and error with the batteries I have found that one is a dud.

Or at least I am lead to believe its a dud. When shooting with it I have found that in the battery grip the camera quickly loses half the battery power and then the other half lasts significantly longer. I have assumed this means its a dud, right? Is this a normal characteristic of a dud battery?

... anyway the problem is that at Bathurst I lost the order of my batteries. I have narrowed it down to two thanks to a mark on one of the batteries but I'm not sure if there's an easy way to figure out which one is a dud without having to use it on a few day shoots and switch the batteries around through trial and error.

Thanks for your help, Josh

[Wilt]

Why don't you remove the battery grip, and put the one suspected dud directly into the camera and see how many flash shots you get out of it before it is discharged? Just aim the camera out into your front yard at night with your camera on ISO100 and a small aperture on the lens, so the flash has to output full power for every shot, shortening the amount of time spent on the test!

[The Impact]

Ok, thanks for that suggestion. I'll give it a shot. It shouldn't have a disastrous affect on my shutter life should it?

[Wilt]

Do you think a few hundred shots (vs. the 50k that your shutter is expected to last) is significant? That's only 0.6% of the statistical life!

It is appropriate to pace the number of consecutive full output flashes for external flash units powered by rapid recycle battery pack, but the longish recycle time between shots with your in-camera battery will probably take care of that issue satisfactorily.

[The Impact]

0.6%... Good point, thanks for you help mate!

[Billginthekeys]

yes like wilt said, best way to figure this out would be to take the battery grip out of the equation.

[The Impact]

I'm pretty sure I can just put one battery in the grip anyway. Just wanted to check if there were any easier ways than taking lots of shots.

[DavidW]

You can indeed just put one battery in the grip. I usually work that way - that way, I know how many flat and charged batteries I have, also it makes things a little lighter.



David

[Woolburr]

Just as a point of curiosity...why don't people label their batteries? A permanent Sharpie would do the trick...A,B,C...or 1,2,3 etc....then there is no mistake as to which battery is which. Makes it easy to tell which battery is in use...and also provides a method of identifying them from each other in the event of a problem.

[The Impact]

LOL, That's too smart for most of us ;)

Anyway, where's the fun in that. Its sorta fun sitting in a dark room making lightening to test your batteries.

[roundy]

I had about the same problem with my 20D and BG-E2. I'd lose all power after about 300-400 exposures. After three trips to the Canon Service Center they finally fixed it by readjusting battery cutoff point in the camera software and putting a shim in the grip.

I'm now getting well over 1700 exposures. Not great but better than before. I also think that heavy use of IS may affect battery life more than I realize. After all the lens has to get it's power from somewhere.