Is it my Ultra 2? freezing outside

I went out today to get some photos of the kids with my 20D and had problems... The shutter worked fine like it took a photo but some of the photos didnt go to the Ultra 2 CF card.. Could it have been too cold for the card to operate properly? it was snowing and freezing outside. I was using my 580EX with high speed sync as well and got an err99.. I dont get those often.. The card would allow some shots to write to it but it started getting worse the longer I was outside.. What do you think? Thanks for your feedback guys..

How cold was it? Could also have been the cold affecting your batteries, dropping the level too low for successful writing especially in rapid-fire activity.

Sandisk guarantees operation down to -13 degrees farenheit, but the 20D's operating range is only listed down to 32 degrees. I know I've shot below freeezing before without a problem, but probably no lower than 25 degrees in my case.

"For the utmost in reliability, SanDisk has used its expertise and more than a decade of experience in providing flash memory cards to the industrial market, to develop the SanDisk Ultra II card, that features the industry's widest guaranteed operating temperature range to ensure flawless performance in extreme temperatures--from well below freezing (minus 13(degrees)F/minus 25(degrees)C) to near boiling (185(degrees)F/85(degr​ees)C)"

I would be more suspect of the batteries than the CF card in low temps...it is amazing how fast batteries drop off in the cold...shooting rapid fire sequences can kill them in a hurry...

Woolburr wrote in post #2556780
I would be more suspect of the batteries than the CF card in low temps...it is amazing how fast batteries drop off in the cold...shooting rapid fire sequences can kill them in a hurry...

But, if the batteries were giving out would it still fire the shutter? The mirror fliped each time like it was taking a picture just didnt go to the card.. What do you boys think? Do you think it could still be the batteries causing that behavoir?

Actually, tripping the shutter takes very little power. The real drain's in processing and writing the image. Look at how long a film camera, with all the same requirements up to the moment of exposure, goes on a 2CR5 compared to the life of a BP511 in a 20D. If the 20D could run on the throwaways efficiently, Canon would have used them. See also alkalines vs. Li onr NiMH throwaways in digicams.

Thanks Jon for your explanation. I'm pretty well versed in equipment so I should have known but, I just wasnt sure it was the batteries but, it makes very good sense. In fact I'm using the Grip with two batteries that havent been charged in quite some time...

If the batteries haven't been charged in some time...coupled with the cold...you could get exactly the results you experienced...I had a similar experience several years back at a NASCAR event at Rockingham...never got above freezing that day....after a couple of hours of shooting...I just happened to notice that I wasn't seeing any histograms....the shutter was activating...but....no​thing was going to the card...swapped for a warm set of batteries from my pocket and it immediately began writing to the card again and displaying a histogram.