Batteries in 40D Battery Grip

Just a quick question, i got home from a day shooting with my 40D and it was showing low-flat battery so i took them out, 1 was dead (From left side - Away from the shutter button) and the other (From the right side - Near the shutter button) was fully charged already, it seems it meters the battery from the left and runs that down but does it even use the other? Contacts look ok and they both lock in normally.

when you say low/flat? is the battery indicator flashing?

just a note... as far as i'm aware, the battery in my BG-E4 is used from right to left.... i.e. drains the right one first, then drains the left (I think it's that order).

This was interesting to read, as my 40D has a Canon grip and stock Canon batteries. I have just shot well over 400 exposures (weekend of July 5-6), and not recharged them, so i figured after reading these messages to measure their voltage before topping them up, as I planned to do today anyway ...

So both read exactly the same with my multimeter ... 8.64 volts. So unless they recharged themselves (or equalized themselves) since the shooting weekend, my 40D with grip uses both batteries simultaneously, not one and then the other ....

Maxdave

Interesting. I also have the Canon Grip, but, I never thought that the camera knew or could suck the juice from one battery or the other at will. Makes no sense to do that, nor can I see how it can do that. Are you using a voltmeter to test? I will have to find my brothers meter and test mine. I'll let you know what I find.

My guess is, you have one bad battery of the two, which will run them both down fast.

canonloader wrote in post #5927635
Interesting. I also have the Canon Grip, but, I never thought that the camera knew or could suck the juice from one battery or the other at will. Makes no sense to do that, nor can I see how it can do that. Are you using a voltmeter to test? I will have to find my brothers meter and test mine. I'll let you know what I find.

My guess is, you have one bad battery of the two, which will run them both down fast.

Happens with any combo of my 5 batteries. Im using my charger which has a 4 stage meter.

Have you tried uing one battery in the grip? Maybe try it on one side, then the other? I have forgotten now what the instructions say to do in the case of one battery.

In either case, I always use two, and have never once run them down to the point the camera wouldn't work. I have left them in there for well over 3000 clicks.

<edit>

OK, I just tried mine with one battery. It works fine on either side, nor does it show anything but full charge on the camera meter. Can't tell though till my brother gets home and I can use his meter. Camera meters are never right.

My brother got home and we just checked both my batteries that have been in the grip, last charged maybe 4 days ago and have about 500 shots on them. They both read exactly 8.05 volts. I do a lot of chimping, I use a 70-200 non-IS in AF mode and the camera switch is on all day, most every day, cause it sits here beside me to shoot out into the yard. Just saying, so you know what I do.

I think you have either one dead or bad battery that doesn't hold a charge, or, there is something wrong with the grip. Is it a real Canon BG-E2N?

canonloader wrote in post #5931034
My brother got home and we just checked both my batteries that have been in the grip, last charged maybe 4 days ago and have about 500 shots on them. They both read exactly 8.05 volts. I do a lot of chimping, I use a 70-200 non-IS in AF mode and the camera switch is on all day, most every day, cause it sits here beside me to shoot out into the yard. Just saying, so you know what I do.

I think you have either one dead or bad battery that doesn't hold a charge, or, there is something wrong with the grip. Is it a real Canon BG-E2N?

It is the only BGE2N - IE Official Canon, i would list its other name if it wasnt.

I'd be extremely surprised if Canon complicated things by using batteries sequentially.

On the rare occasions I've measured discharged AA battery voltages, they have always shown the same voltage. The 511A's do tend to read slightly different, but not massively.

I use the standard BG-E2, and the optional AA "cassette" seems to link the 6 batteries in a simple series/parallel circuit* to achieve the voltage needed. I'm unwilling to dismantle my 30D, so cannot confirm how the two BP-511A's are wired. But it would seem logical to keep things simple unless there's a good reason not too.

Differences in internal battery resistance might be a reason for using them seperately, and might explain differing discharged voltage levels. But it does seem an expensive solution.

Richard

* Wired as a group of 3 in parallel, in series with another group of 3 in parallel. Giving 4.5V nominal.