AA batteries, grip and DSLRS

[markta]

Hi,

Question is...I swear by Sanyo Eneloops and have recently bought a battery grip for my 40D. It came with a battery magazine for 6 x AA batteries.

Now I'm wondering whether to use the low discharge Eneloops instead of the dedicated battery blocks, thinking I may get more shots per charge.

Is anyone using/has used AAs in preference to the cameras' dedicated units? If so, did the AAs last longer.

For reference, in the case of 40Ds, the BP-511 battery packs are 1390 mAh each, and the Sanyo Eneloops are 2000 mAh each. Common sense is telling me the Eneloops will last longer, but is there more to it than just mAh? Also, I guess, the BP-511 blocks are about three times the physical size of each Sanyo...

Cheers, Mark

EDIT: just to include another thought - the BG-E2N grip takes two of the BP-511 packs, and 6 AAs put together are roughly the same physical size as the 2 blocks, so when I multiply 6 AAs at 2000 mAh, equals 12000 mAh, and the two BP-511s equal 2780 mAh.

So, is the total mAh the factor here?

Cheers again

 

[Witch]

I think the dedicated batteries - even if not the "official" canon ones - would last longer. When I got my battery grip I remember being told that the AA option was really just a back-up.

I use batteries in mine that I seem to remember paying £10 for the pair of - I regularly turn out over 2k shots between charges.

 

[kfridge]

Lithium batteries have a constant output throughout their charge meaning that when the camera gives up the batteries are more or less completely empty, i.e. the mAh rating you quote will be constant until the batteries are exhausted. With AA's the mAh rating drops off during use meaning that when the camera gives up there will be quite a lot of charge left in the batteries but not enough to carry on powering the camera

 

[mrgubby]

The battery packs are rated at 7.4V / 1.39A . The six batteries are probably wired in series to give a maximum voltage of 9V / 2A which be regulated to give the voltage that the camera requires.

Assuming that the camera wants 7.4V then 2 x (7.4 x 1.39) beats 7.4 x 2.

I hope that makes sense

 

[andrewc]

I only resorted to the AA battery pack on my old 350D once, and used ordinary duracells. Didn't last long. Should have used higher capacity ones, but after that I regarded them as a lifesaver option only and just bought some cheap original style ones and they worked a treat.

 

[markta]

Thanks guys, really helpful.

Will stick with the BP-511s then. If only they used the same technology as the Eneloops we'd be laughing.

Cheers again, Mark

 

[mrgubby]

Thanks guys, really helpful.

Will stick with the BP-511s then. If only they used the same technology as the Eneloops we'd be laughing.

Cheers again, Mark

We'd be crying, Lithium Ion batteries have the highest commercially available charge density. The Eneloops might be 2000mAH but they are only 1.4V (ish). You need nearly 4 x Eneloops to match the power of 1 x BP511.

4 x 1.4 x 2.00 = 11.2 (Eneloop)
1 x 7.4 x 1.39 = 10.3 (BP511)