Grips - do batteries discharge sequentially?

Both my 20D and 5Dc are gripped. I recharge after every shoot, or at least every two days, and I've noticed that when topping up that the left-hand battery always seems to take more charge than the RH battery.

So . . . it there a circuit in the grips that takes current from the batteries sequentially, or this this an empirical observation that is quite simply wrong; ie the camera draws from both batteries simultaneously?

Found this on DPREview:

The Canon battery grip draws down first on the battery with the highest charge and then when level with the other draws on both batteries from that point onward. This was explained by Chuck Westfall on robgalbrath.com about a 1 1/2 years ago. If it were me I would stick to using identical batteries in the grip.

http://forums.dpreview​.com …sage=3122769&ch​angemode=1

A google search also showed a few retailers saying the same thing.

Thanks for the info. I do keep my sets separate - Canon branded in the 5D; generic 511s in the 20D. I have no complaints about the batteries - the Canons are on 4 years, the generics are three years old. Still hold their charges well.

The question was idle curiosity - it is certainly true that the LH battery starts up on the two-flash charge setting and takes 30 minutes to fully charge, while the RH takes about 30 seconds to cycle up to steady-state fully charged. This is invariable.

I personally dont believe the "takes from one until they are both the same" theory.

I have noticed that after 2 to 3 weeks of shooting with a gripped 30D the right hand battery will be 100% dead and the left hand battery may be 75 or 80% full.

JoeyBowman wrote in post #11271785
I personally dont believe the "takes from one until they are both the same" theory.

I have noticed that after 2 to 3 weeks of shooting with a gripped 30D the right hand battery will be 100% dead and the left hand battery may be 75 or 80% full.

That would point the other way from what I found. I checked canon's site earlier with no luck.

The two in my 30D don't do anything consistantly. I've seen both at similar discharge levels on some occasions while at other times they are wildly different.

I always imagined that the two batteries were wired in parrallel, but if that was the case then both should discharge equally.

Hmmm... this behavior can't be good for the batteries.

Thanks , I have an XTI and when battery condition says 2/3 , I change both . I have noticed that one will be charging longer , but figured just the charger / battery combo .

Put two fully charged batteries in a flashlight leave it on for 3-4 hours and check the voltage on them.

Without a regulator which are integrated in some battery packs there is no way for batteries to maintain equal levels of power.