BG-E2N Battery Grip Questions

I just picked up a BG-E2N for my 40D and I have a few questions about it.

First, has anyone used the AA batteries in this? Good, bad??

Second, when you put two reg. canon batteries in, does it drain both equally?

Thanks,
JJ

- i guess i should update my sig

1. Yes, not good.
2. I think it does it serially .

Using AA batteries is to be considered as emergency power.

It will discharge one battery at a time, according to my experience.

Be a bit careful when mounting/dismounting. The plastic wheel drives smaller cog wheels inside the grip. The cogs on the plastic wheel strips easily.

Never tried AA batteries. Haven't had the need, but I do carry around the tray with me in case all of my other batteries are dead.

And I believe it drains both equally. You can put one in either spot and it will run off of one battery, so It should just be wired in parallel.

My experience will all the Canon Grips is that the batteries are in parallel and drain equally - not serially.

The AA battery holder would be for emergency use only IMO.

Well, I had used my grip for quite some time, starting with two charged Canon batteries.
Then I decided that it was probably time to charge, since I knew I would use the camera a lot the next day.
One battery took a long time to charge, in the charger for the 40D. The next battery quickly went to three flashes in a row, saying 75% charged, then completed the charge short thereafter.

To me, this suggests that the camera had used the left battery first, then started depleting the right one.

That has been my experience, left first and then right.
Is there a graphic that shows which battery to put in if you use only one in the grip?

I use AA's in the grip often. It is useful in an emergency, because AA's can be found everywhere. Compare that to trying to buy a replacement Canon special in rural Mongolia. Or even Auxerre in France, where I had my camera battery (in my Eos-3) go flat on me late one night, no means of charging and no means of replacement on the way to an F1 GP at Magny Cours.

Thats one reason I always use the grip. It gives me a choice. The other reason is the size of my hands - the camera without the grip is just too small.

I forgot to add:

The AA batteries are arranged in a series/parallel circuit, with 2 groups in series, 3 in parallel in each group. Thres no way Canon could selectively drain any of them.

SOT wrote in post #6071262
That has been my experience, left first and then right.
Is there a graphic that shows which battery to put in if you use only one in the grip?

Nope, either position will power the camera. I tried finding a schematic for the grip, but Canon obviously doesn't provide that info online. I do remember reading a paper some time ago that stated the battery with the highest charge would provide the power to the camera. Once that charged dipped, the other battery would take over and the batteries would alternately switch until they were both depleted.

That a battery in either slot could power the camera leads me to believe the paper was accurate. A series circuit doesn't make any sense because that would double the voltage applied, whereas a parallel circuit would achieve the effect described by the paper. Unfortunately, I don't have any specific documentation to support my assertion (just my electronics background), and there could be a switching circuit built into the grip that would allow serial depletion, but that seems a rather complicated solution when a simple parallel circuit would suffice.

Having taken my grip apart because I got sand in it by being stupid, I can say for sure that the circuit for the Canon batteries is in parallel so they should discharge equally but as no two batteries are identical, actual experiences may differ.

I did a bit of testing with AA batteries because I was going on a trip where there would be no chance of recharging and found the following:

Good (expensive) lithium AA batteries (Energizer Lithium) last about the same amount of time as a single Canon BP-511A battery and about half the time of a Hahnel HL 511. Good Alkaline AA batteries (Duracell Ultra) last for about half the time of a Canon BP-511A. Cheap Alkaline AA batteries (Electronics store own brand) wouldn't even power it on.

I concluded that it's cheaper to buy lots of Hahnel HL 511s (other third party BP-511 equivalents are also generally better value than Canon's own too).

At least a simple parallel connection has to provide some means for stopping one battery from charging the other. Otherwise, putting a newly charged battery in there together with a depleted one would cause undesired effects. Such simple circuits often suffer from forward bias voltage drops. A switching circuit could be made more efficient.

my experience both bge3 and bge2 are almost identical, both battery drains equally.

Brain fart time - I found a use for the AA holder from my BG-E2 and BG-E2N. If you have a Dyno Roadster with lights, 12 1.2v NiMH batteries will give you 14.4v (two holders wired in series). Not sure how much the batteries like 1.5A being sucked out of them.

Gotcha...

the thing I was looking at was on the back of the grip door (inside)
It shows one battery in the right, two for the middle, and one bat and one external connect bat on the left.