Dual card battery use on 5D Mk3

I've just started to use an SD card in the slot as a backup to the CF card. Set it to record to mulltiple with both recording full RAW.

I've only just had a brief try of about 100 shots but battery use looks higher then usual. It could just be that I'm panicing ... This was with a pair of of fully charged batteries - they're not new and I have noticed in the past that the first 10% can vanish pretty rapidly once you start shooting. I've got a proper shoot tomorrow so that will be a better guide.

I was wondering through - has anyone else noticed that having a second card in drains the battery much faster and if so how much faster...?

Cheers

geofflove wrote in post #18453562
I've just started to use an SD card in the slot as a backup to the CF card. Set it to record to mulltiple with both recording full RAW.

I've only just had a brief try of about 100 shots but battery use looks higher then usual. It could just be that I'm panicing ... This was with a pair of of fully charged batteries - they're not new and I have noticed in the past that the first 10% can vanish pretty rapidly once you start shooting. I've got a proper shoot tomorrow so that will be a better guide.

I was wondering through - has anyone else noticed that having a second card in drains the battery much faster and if so how much faster...?

Cheers

While writing to 2 cards rather than one may increase the battery usage slightly, I wouldn't base my observations on 100 images or even the full charge of this battery. I would wait to pass judgement on the impact over several charge cycles. On my 7D Mark II I shoot raw and have a fast CF and SD card for redundant backup. My battery usage varies widely depending upon how much I chimp, my flash use, high speed use and probably other factors like HDR and bracketting.