[G2 and Desire Z Accessories] crazy talk:
we'll start with a pretty picture.

the stock HTC G2 1300MAH Battery is

4.46mmx64.68mmx43.87mm

(all measurements were done by me)

the red CHICHITEC battery, unmodified is

5.09mmx64.7mmx44.08mm

so, were doing good with the exception of being .63mm too large (.025 Inches)

and we have a big difference in the tab design between the two batteries.

fortunately, fixing the tab issue is very easy. just get some nail clippers and cut the tabs off on both sides so they look like this.

(bottom battery obviously...)

so at this point the battery will physically fit and turn on. you should verify the battery will work at this point before you spend too much time modifying it since we're dealing with cheap chinese cells here.

but, do NOT attempt to close the battery door. it's not even close and you'll mess something up.

so the easy first thing to do is take the red sticker off of the battery. this gets our dimensions down to

4.8mmx64.7mmx43.76mm

(here is the PN for reference if anyone needs it, the 1550 at the end leads me to believe this is actually a 1550MAH battery. but who knows)

now the difference in thickness is only a mere .34mm (.013 inches)

the good news is at this point if your using a case your done. the battery cover will fit, albeit poorly.

looks pretty terrible right? yeah i thought so too. for reference here is the phone with no battery in it (looks the same with the stock battery as well)

Chasing perfection

so, you're a manly man and cant be bothered with girly cases and like to live dangerously right? in that case the battery fitment depicted above probably doesn't have you too excited. you can feel it very easily with your fingers and it will drive you insane. so it's time to break out the sandpaper.

i started with 220grit paper and worked my way up to 600 grit to get a nice smooth finish.

this brought our dimensions down to

4.75mmx64.7mmx43.76mm. now were only .29mm (.011 inches) away from perfection and the battery fits much better.

when your sanding be sure to avoid concentrating on one spot for too long and try to use your whole hand to apply pressure to the paper and not just one finger to avoid any high/low spots in the cell.

depending on your battery you may need to sand the plastic on both sides to make sure it's flush with the metal part of the cell, one of mine needed it on the top/bottom. one didnt. so just use your eyes. also note that when i sanded the battery i only sanded the top (the side you see with the cell in the phone) you have the option of doing both sides. but i do not feel it is necessary (with the exception of cleaning up the plastic)

i actually went back over the battery after this picture alittle more aggressively and got the thickness down to

4.68mmx64.7mmx43.76mm only .22mm thicker. or about the thickness of 2 piece of paper.

at that point you really cannot tell the difference between stock and the CHICHITEC cell. so i didnt bother to take any photos.

things to keep in mind.

you need to put a piece of scotch tape between the battery and the MicroSD card cage to prevent shorting.

if you are rooted be sure to go into recovery>advanced and wipe battery stats. my cells wouldnt show 100% charged until i did so. and expect the battery gauge to be inaccurate for the first charge. mine stayed at 100% for around 2 hours of use and suddenly dropped 15%. dont spaz out when you see this happen, it will correct itself after the first charge-discharge cycle (run it till the phone shuts off)