Xbox 360 battery pack teardown

Reader, [Fox9p3400], opened up an Xbox 360 controller battery pack so we could all see what goes into one. It contains two Sanyo 2100mAh NiMH AA rechargeables (Model HR-3U 1.2V). In addition to that, there is an Atmel microcontroller (not pictured) and the copper temperature probe you can see above. He has more pictures on Photobucket.


  1. BronzeG3 says:

    SDA and SCL look like an I2C bus. Anyone probe those lines to see what is being sent?

  2. error404 says:

    That’s not a microcontroller, it’s a 4kbit I2C serial EEPROM. Probably to tell the controller’s microcontroller (confused yet?) what type of battery pack it is, or possibly used by the charger to set charge parameters.

  3. Fox9p3400 says:

    I would if i could/knew. I don’t have the knowledge or the equipment. I just cracked it open over a bet with a freind. (I’m $20 richer)

  4. John says:

    Wow no way…guess what I did that like 1 year ago…we ripped open a battery pack wow!!!! Woop dee do!

  5. Rob says:


  6. pip says:


  7. nubie says:

    So it isn’t even a Li-Ion?

    Hello lighter controllers? Maybe a smaller battery bay?

  8. BronzeG3 says:

    Now I know that it is an EEPROM, I think I’m going to try to get a memory dump. I’m assuming this works by the controller taking the P+ and P-, regulating it, and then providing the Vcc back to the battery pack so the EEPROM has the required voltage, while using the P- as a GND. Anyone have any thoughts?

    I would hate to pry this sucker open and then not have it fit in my controller anymore. I’m too cheap to spend $12 on another one.

  9. fox9p3400 says:

    The case was welded together, ur gonna have to invest in clamps and epoxy

  10. poopysock5 says:

    Its an EEPROM. They tend to get corrupted and cause the batteries to not charge (happened to two of mine). Those packs are rediculous. You can just put two AA rechargable batteries in the original pack that comes with the controller for waaay less than these things cost. When mine broke I just pulled out the batteries, slapped them in a charger, and used them in my stock battery pack.

  11. godzivan says:

    the data stored in the i2c 256 byte contain the S/N of the battery and simple counter system for recharge and battery life.

    the icon battery in the dashboard is in function of the counter and not of the real battery life.

    so in not a reliable system….


  12. Harrison says:

    If I remember right, when these were first released someone did this on the Xbox-Scene forums. There is one byte in the eeprom that changes one it has been charged for the first time.

    It really wasn’t anything interesting IMHO.

  13. Bill says:

    I ripped mine open a while ago when it died (30 min of power = lame/dead) and the chip seems to be there to monitor battery temps to prevent overheating the battery pack on a charge. The thermoreistor attached to the batteries was the only thing worth scavenging out of it that I could figure.

  14. Rajesh says:

    any idea what chip are they using for battery charging?

  15. Hannah says:

    Does someone know when Velvet Assasin for Xbox360 will be released?

  16. EvilBob says:

    I need to take a P. Maybe even a P+.

  17. jimmy says:

    hey i was wondering by were does the charge from the outlet go into the battery pack which ones of the
    p-,sck, sda, p/+,vcc

  18. Jerry Lees says:

    I took mine apart tonight trying to get it to charge properly, since it wasn’t charging properly. (Doing the typical charge for 10 seconds then stopping charging with the plug and play pack)

    Everything I’m about to say may not be correct, because the board itself may have issues. However, It appears that the two AA batteries are in series together just like the AA pack for the 360. It looks like the Thermistor is in series between the two batteries. (This would make sense, as the batteries heat up from charging the resistance changes to slow the charge.)

    P+ from the pic above seems to go straight to the + side of this series of batteries and P- appears to go to the – side of the batteries. I tested this with a multimeter that does a continuity check, and the pins do seem to connect directly there.

    I don’t know that connecting 3.3V here would not fry anything on the circuit though, it stands to reason it would be OK.

    • Jon S. says:

      I actually hot melted a 18560 lipo to the bottom of a stock battery shell and put a charge controller inside where the AAs would normally be. Cut a hole for charging via USB and now I don’t have to deal with those lame rechargeable packs. I was concerned the 3.7v-4.0v on the battery would fry everything, so I used my old beat up controller. It works great and no magic smoke! It has been running for ~9 hours continuously and no signs of stopping any time soon!

  19. peet says:

    how can i view the pics on photo bucket?

  20. peet says:

    check put

    there are the pics too

  21. Nick says:

    The chip is an AT24C04. An Ateml 2-wire Serial EEPROM 4KB

  22. kurt says:

    so in other words if i swapped the batteries for two 3.7 surefire batteries (equivalent size to AA’s) i would get about triple runtime ? or would i need more circuitry ?

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