Turtle Beach attributes low battery life to a number of things, but who wants an explanation when they can have a fix?
We're going to rewire this headset to run off of two pairs of AA batteries (no more buying AAA batteries!), since wikipedia says a AA holds about three times the capacity of a AAA, we can expect about a 6x increase in battery life!
Step 1: What You'll Need
Multimeter - Make sure you have good solder joints, and more importantly; that you don't fry your expensive headphones!
Small length of two core wire - For the power. It will be outside, so make sure it looks nice and blends in. I used the wire from an old AC adapter.
Mini screwdriver set - for taking apart the headphones
Soldering iron - gotta make these connections last because they're on the outside, and might take some knocks. No twisted-together wires and electrical tape!
Two 2xAA series connected battery housings - You need two housings that hold two AA batteries in a series connect. They need to be in series to reach the required 3 volts. You need two because you're going to connect them in parallel (thus doubling battery life without raising voltage). If you want to use just one housing, or AAA housings, feel free, but try taping them to the headset so you can get a feel for the weight first, because it is a little different. I do not recommend using four D batteries. Those things are heavy, and these need to be comfortable!
Four AA batteries - Obviously :)
Two short plastic housing screws - (not pictured) They look like mini wood screws. They'll screw into untapped plastic and hold tight. You'll need them for attaching your battery housings to your headphones. Don't get ones that are too long, or they'll come into contact with the adjustable height sliders for the earpieces. If you don't know where to find these, just open up anything made of plastic. You'll find a bunch.
Step 2: Remove the Earpads
As the material stretches, you'll see a lip on the inside. Get this lip over the ring that it's wrapped around, then carefully work your way around, until the lip is off of the base.
This material will stretch well, and return back to its shape nicely. Don't worry too much about it becoming loose.
Once the ear pad is removed, use your mini screwdrivers to unscrew the three screws holding the headphone cover in place, then carefully open the
Step 3: Get Inside
The whole piece will come off with two wires still attached to it (the two connections for the speaker), set the piece aside, but don't strain the two wires attaching it. No need to make more work for yourself.
Inside you'll see where the two power wires attach to the battery housing. There should be two nice, big blobs of solder for us to attach to.
Step 4: Make the Battery Housing Connections
First, connect the two battery packs together in parallel. To do this, you must connect negative to negative and positive to positive!
Before you solder, use your multimeter to confirm you are connecting them correctly.
IF YOU CONNECT POSITIVE TO NEGATIVE, YOU WILL DOUBLE THE VOLTAGE INTO YOUR HEADSET AND FRY THEM!
CHECK THE OUTPUT WITH YOUR MULTIMETER EVERY STEP OF THE WAY!
If you connect the negative to the negative and the positive to the positive, your multimeter should show about 3 volts (3.2v for fresh AA batteries), this is what we want.
If you are NOT getting about 3 volts, check your solder joints. You can do this by applying your multimeter probes to the metal battery leads inside the battery housing, then applying the probes to your solder joints on the outside. It should be 3v at the battery leads. If it's not 3v at your solder joints, it's probably a bad solder connection. If it's not 3v at the end of the wire, then it's probably a bad solder connection to the wire.
If you're getting 3v at the end of the power cable, then remove a battery from one of the packs, and check again. It should still be 3 volts. Then replace that battery, and remove one from the other pack, then test again. It should still be 3 volts. If you don't get 3 volts after removing a battery from one battery pack, then there is a problem with the connection on the other battery pack.
Once the two are connected, attach a cable to the battery pack on the left headset side (the side where the batteries go in). Leave a little extra space because we will need the slack if you extend the ear muffs when you use them.
Step 5: Attach the Power
I chose to drill a hole in the battery cover so I could run the power cable through it, this is optional. You can leave the battery cover off if you choose.
Once the cable has been run into the housing, extend the ear muff (if you extend it when you or anyone else uses it), and figure out how much slack you need on the cable. If you drill a hole in your battery cover, you can loop the cable down, then back up so it takes up more space inside the built-in battery housing for a little extra slack.
When it's time to make your connections STOP AND TEST WITH THE MULTIMETER AGAIN! It needs to be about 3v! Please do NOT fry your headphones! Also, use your multimeter to double check which lead is negative and which is positive. You need to hook them up to the matching leads; negative to negative, positive to positive! (the negative side is the one with the springy battery connector on it!) Run a connectivity test from the negative leads on both battery housings to the wire to confirm. You need to get this right!
Once you're ready to solder, I recommend splitting or twisting your wire to make it easier to situate inside the housing. This is the most important soldering job of this project. Don't heat it so much that the original power wires fall out, but heat it enough to get a strong connection to your external power wires.
Once you're done, put your multimeter probes on the power connection solder joints you just attached to, and confirm, once again, about 3 volts.
Before you attach the battery housings to the headphones, try powering them on, and confirm everything is working well.
Step 6: Mount the Battery Housings to the Headphones
Unscrew them to get easier access to the outer pieces, then screw the battery housings into the plastic piece, then reattach to the headphones.
UPDATE: The plastic screws let the battery housing rotate slightly, I found that plunging a hot soldering iron into the plastic of the battery pack where it was flush against the headphone housing (to the left or right of the screw) until I saw white plastic, and letting it cool bonded the plastic between the two pretty well. If there's a gap between the two plastic pieces, the excess will bleed out to the side, and it won't bond. This bond is not super strong, so I did it on both sides and kept the screw in as the primary support.
Step 7: Enjoy!
Add some electrical tape to cover up the exposed solder connections. (see last pic)