"M" series * LED indicators for remaining charge * rated at 7.2V, 29.8Wh, 4140mAh * 1-9/16"W x 2-3/8"H x 2-3/16"D * weight: 7.9 oz. * warranty: 90 days
1 Long-lasting power -- at a price
The good news is that I got what I wanted from this battery. I can go on all-day outings to the zoo, an amusement park, or any place far from an AC outlet, and just keep my camcorder turned on without worrying about running out of juice. Or, I can use my camcorder on battery power for several days running without having to recharge the battery. Furthermore, that battery level indicator on the back is a neat extra added attraction that lets me see how much juice I have left without having to use any in the process.
However, this extra security comes at a price -- and I don't just mean in dollars and cents. Granted, none of the drawbacks I'm about to discuss are actual show-stoppers (and come to think of it, a dead battery literally would be a show-stopper, wouldn't it?), but they're worth thinking about if you want to buy yourself some additional battery time and you're trying to decide whether to buy it in the form of this high-capacity battery or several lower-capacity batteries.
The first problem is admittedly the least important because you can get around it simply by either planning ahead or buying one of those separate battery chargers that does the job faster than the camera itself. But if you do rely on the camera to recharge your battery, this baby takes a LONG time to go from fully drained to fully charged. No big deal if you remember to start it charging the night before the day you need it, but if you forget, you can't start it before breakfast and expect to have a full charge by the time you've finished your eggs
But there's one other reason why this is a lesser worry. Unlike some other rechargeable batteries*, the NP-QM91D** can be recharged before it's fully drained with no resulting loss in capacity. My understanding is that if you try to do this with some batteries, the amount of charge they can hold at that point becomes the maximum amount they can EVER hold again. For example, if said battery originally had a capacity of six hours and you recharged it after using up only four, the battery could then take only four hours worth of charge, and so would would only hold a four-hour charge from that point on. Because the NP-QM91D** can be recharged at any time, you never have to let it fully drain once you've charged it, and thus never have the LONG wait for it to fully charge after you've done it once..
The more significant drawbacks for me come from this battery's increased weight and size ...
The NP-QM91D's increased weight doesn't make the camcorder uncomfortably heavy by any means, but it does shift its center of gravity significantly, which took some getting used to.
But the larger SIZE of the NP-QM91D, and its resultant shape, is what's really been causing me trouble. The lower capacity batteries, such as the NP-FM50 I'd been using, slide nicely down into a recessed area on the back of the camera, and are held snugly in place until you release them because their back surface is flush with the back of the camcorder. This higher capacity battery fits into that same recessed area, but protrudes beyond the back of the camcorder. Yes, the viewfinder can be extended to accommodate this, and I usually use that LCD screen on the side of the camera anyway -- which I can now much more readily afford to do because I don't need to worry so much about the extra drain on the battery. But the protruding battery it makes much harder to connect the AC power adaptor.
More importantly, the battery isn't held in place nearly as securely, because it's a long, heavy rectangle that's being gripped only at one end. I've actually had it come loose and fall off the back of the camera several times. On one of these occasions, that meant I missed a shot I wanted to get because I was reattaching the battery. However, I admit this probably wouldn't have happened if the camera had been mounted on a tripod.
So maybe the real problem is that this battery was intended for professional videographers, and I definitely ain't one. If you definitely ain't one either, you might want to hesitate before buying this battery -- although, as I said at the start, it has been helpful, despite the problems.
* Such as the one in my cell phone or my cordless razor.
** Along with all Sony camcorder batteries, and most other camcorder batteries nowadays, as I understand it.
