I know the 3DS has issues with battery life with the 3D (and wifi obviously) activated- but i've also noticed that it seems to drain with the 3DS closed crazy fast- and i'm not even playing a 3DS game. (pokemon black). It's been a pretty unpredictable experience- sometimes it'll last for a while, sometimes it won't. Do I need to put games to sleep a certain way? I noticed the power off procedure is a lot more involved now so maybe thats it.

The 3DS was designed to spend a lot of time in the charge cradle. It's much less of a mobile device than handhelds typically are, and with that in mind you kind of have to treat it as such. I hear there's some kind of aftermarket battery that will double? the battery capacity - maybe check into that.

Try turning your wireless off. If it's in sleep mode it'll still be sucking in stuff from online. That seems to be the biggest drainer when it's not in use.

Buying the first iteration of a Nintendo handheld huh?

@coakroach said:

Buying the first iteration of a Nintendo handheld huh?

Hey, somebody's gotta.

Bought one for my son for continuation, and yeah, it's a killer on the battery. Pelican sells a replacement battery that supposedly doubles the battery life, but it also add a little more bulk to the 3DS itself. Thinking about ordering one of those for my son tho regardless. We're going on a trip next week and it would be nice to have the extra battery life.

I haven't had many issues but my definition of a portable console is being able to play it on bed and on the toilet. When I'm out and about games are the last thing on my mind, so it effects people differently I guess. You can always switch to power saving mode, and activate sleep mode as opposed to just shutting it but then you do quit the game and might as well turn it off.

@coakroach: People have to. As long as some people do then it won't turn in to a failure.

Define crazy fast?

I left mine in sleep mode this entire weekend. When I resumed it on Monday the battery was pretty low but not red light or anything. Not sure how long it lasted after that, but 2-3 days in sleep mode has been normal for me.

I'm wondering what people mean by their 3DS drainning battery really fast. Mine seems to last for a while. I played mine for an hour or 2 and leave  it on standby for the rest of the day. It seems to barely wast battery. I put Power Save mode on and Brightness to 3.  

Play with the wifi off, brightness level 1, power save mode on, and turn the 3D off.

I had the same experience yesterday. Left it for about 12 hours closed and it was dead by the time I opened it back up

Make sure you go to the home menu and then hold the power button for a second and aren't in a DS game when you go to sleep. I've left mine on for hours in sleep and battery stays full. When I'm home I put it into sleep and on the cradle. I've yet to get it below 3/4 bars. I play it quite a lot, and am actually way surprised at how well the battery's holding up. 
 
Since it has the charging cradle, just put it into sleep and onto the cradle when you're not playing, that's what it was designed for. It won't hurt the system or battery (manual says to do this.) 
 
But remember - exit out of DS game (I think you can just hit home and keep a 3DS game open, haven't tested for long time though), then at the home screen hold the power button for a second until it goes to the sleep screen, then close it. 
 
@coakroach said:

Buying the first iteration of a Nintendo handheld huh?

Mine lasted about three hours in sleep mode this weekend off a fresh charge. I opened it up and it died within three minutes.

Play with the wifi off, brightness level 1, power save mode on, and turn the 3D off.

Ah - for some reason 'brightness level' never occurred to me. Could you adjust that in the older DS models?