Battery Connection

PackProbe communicates with battery packs that adhere to the Smart Battery Standard, which includes almost all battery packs for laptops made in the last decade or so.

Before connecting to the battery pack, you should educate yourself on the risks of lithium ion batteries, including but not limited to:

  • The potential for damaging the electronics of the pack, your Arduino, or even if your computer if you wire things incorrectly.
  • The potential for burns or even fire in the event of a low-reistance connection between the positive and negative terminals of the battery pack.

To use PackProbe, first connect the Arduino ground to the pack’s negative terminal, and then connect the appropriate pins to the data (SDA) and clock (SCL) pins. You may also need to make a second connection between the ground and the Battery Enable/System Present pin.

That may sound easy, unfortunately, the standard doesn’t describe the connector pinout for battery packs. Connectors vary among manufacturers and even models from the same manufacturer.

To help you get started, we provide pinouts for packs we’ve encountered below. Please note, these pinouts should be verified with a multimeter before making connections to the pack in order to prevent escape of magic smoke, and other undesirable outcomes.

Determining the pinout for an unknown pack is relatively easy by checking voltages and resistances between pins with a multimeter to narrow things down, and then a little trial and error using PackProbe.

Some guidelines:

  • Most packs use the outermost slots for the positive and negative connections to the system.
  • Some packs label the negative and positive sides of the connector.
  • Many packs, particularly those for larger/more powerful laptops, double-up the positive and negative connections on the outer slots, with adjacent slots for more contact area.
  • Some packs present the full pack voltage on the appropriate pins at all times, as long as the voltage is over ~3v/cell. Others need to be turned on by connecting the battery enable pin to ground.
  • The slots exposing the SMBus data (SDA) and clock (SCL) signals are usually  next to one another.
  • The SMBus connections usually have ~0.5-1MOhm resistance to the ground/negative pin.
  • The Battery Enable (BE) pin, if present, will have infinite resistance to ground.
  • Every pack has one slot that provides a separate safety signal. This signal is carried on the “T-pin.” Under normal conditions, this pin will actually be tied to a thermistor to provide a reading of pack temperature, but under temporary or permanent fault conditions, the circuitry may alter the resistance.
  • Once you’ve definitively identified the negative/ground pin and connected it to the ground on your arduino, you can safely probe for the clock and data pins.

Known Pack Pinouts

WARNING:  The information below is provided as a starting point for establishing a data connection to your battery pack.

You must verify these pinouts with a multimeter, using the guidance above before connecting .


    • Negative power / charging contact (ground)
  • ++
    • Positive power / charging contact
  • SDA
    • I2C/SMBus serial DAta line
  • SCL
    • I2C/SMBus serial CLock line
  • T
    • Temperature / safety signal
  • BE
    • Battery Enable (System Present)
  • gap
    • A break in the spacing of pins/slots with no contacts present
  • ??
    • Unknown function


UM09B7D, UM09F36

From left to right, looking at connector from the narrow side of the pack, with the open edge of the slots facing up:

–, –, SDA, SCL, T, BE, ++, ++


PL32-1005 (AS035MD33E), AL32-1005 (AS085NJ35E)

From left to right, looking at connector from the narrow side of the pack, with the open edge of the slots facing up:

–, –, ??, SDA , SCL , ??, T, ++, ++


9T48V (YXVK234J)

From left to right, looking at connector from the narrow side of the pack, with the open edge of the slots facing up:

–, –, ??, BE, –, SDA, SCL, ++, ++

9T119 (8T533 8BN)

–, ??, ??, BE, ??, SDA, SCL, ++


–, ?, ?, ?, –, SDA, SCL ,? , ++


Compatible types: PD685, RD301, TD117 or UD088

–. ??, BE?, ?? ,SDA, SCL, ++, ++


8MSBG SQU-517 (MAL42ab)

–, –, SDA, SDC, T, ++, ++



NOTE: This packs connector is in the opposite orientation from mo

From left to right, looking at connector from the narrow side of the pack, with the open edge of the slots facing up:

++, ++, SDA, SCL, ??, T, –, —


PackProbe can’t currently obtain any data from the HP TD06 battery packs we’ve tested.

–, –, T, BE, SCL, SDA, ++, ++


–, ??, SDA, SCL, gap, ++

Lenovo / IBM


From left to right, looking at connector from the narrow side of the pack, with the bottom surface of the pack facing down:

–, T, SDA, SCL, gap, ++


From left to right, looking at connector from the narrow side of the pack, with the bottom surface of the pack facing down:

++, ++, gap, SCL, SDA, T, –, —


PackProbe can’t currently obtain any data from the Samsung battery packs we’ve tested, but we can get an acknowledgement from the appropriate SMBus address using the pinout below.


–, gap, –, T, SDA, SCL, ++, ++


29 thoughts on “Battery Connection”

    1. Yes, without it battery voltage is not provided to +/- pins and no charge is accepted. It is safeguard against shorted terminals.
      For some models BE can be more than simple switch and requires proper communication to enable.

  1. Lenovo model L11P6R01 have the same pinout as mentioned IBM-42T4619, ie.:

    ++, ++, gap, SCL, SDA, T, –, —

    Manufacturer Name: SANYO
    Device Name: L11P6R01
    Chemistry LION
    Design Capacity: 6271
    Design Voltage: 10800

  2. Dell T54FJ – pin out is the same as 9T48V (YXVK234J)
    –, –, ??, BE, –, SDA, SCL, ++, ++

    However the device respond as Samsung:
    Manufacturer Name: Samsung SDI
    Device Name: DELL JYPJ12AN
    Chemistry LION
    Design Capacity: 5600
    Design Voltage: 11100

    and it doesn’t shows cell voltages:

    Cell 1 Voltage: -1
    Cell 2 Voltage: -1
    Cell 3 Voltage: -1
    Cell 4 Voltage: -1
    State of Health: -1

    1. Thanks for sharing these details. I’m not working on PackProbe any more. Unfortunately I never figured out how to get individual cell values from Thinkpad or Dell packs.

  3. Works with older Macbook Pro battery. (model A1281)
    -, ?, SDA, SCL, ++

    It read a Lenovo 45N1037, but have odd values for Cell Voltages. (1: 16756, 2: 97, 3: 5911, 4: 19472)
    ++, ++, gap, SCL, SDA, T, -, –

    Couldn’t get a response from a Lenovo 42T4861 battery though, but I think it’s completely drained. I’ll have to charge it a bit first…

    Excellent project. Thanks

  4. Can anyone help with HP Elitebook 820? My laptop got wet. I thought it was okay, but it turns out it was running from the battery, which the laptop won’t charge anymore. I want to manually charge the battery a bit, so I can finish a work project.

    1. update: only dell packs not charging.
      asus and acer pack charging nicely.In seriall comunication with my arduino nano displays corect current.

    1. Usually on packs is resistance between pins different.
      Just measure with ohm metter a try.
      – conection to BE= 100Mohm
      SCL to – =60Mohm
      SDA to – =10Mohm
      – = negative terminall on the battery
      measured valuses arround the numers above

  5. HP ZZ08 (HSTNN-OB89) 63Wh pack
    – SDA SCL ? ? +
    top view to slots
    comunication is ok,but BE pin not found.Battery dont respond.
    This one have only 53 cycles, 63% absolute charge and allready dead (maybe fuse blow up?)
    Very “qualitty” battery 😀

  6. Hi,

    Do you maybe have the pin-out for an internal Asus Transformer TF700, battery model number is C21-TF301. The battery has 8 pins (Black, Black, Green, Yellow, White, Blue, Red, Red).


  7. HP CI03XL

    |—————- — |
    Pin1 … Pin8

    ++, ++, SDA, SCL, ?? , —, —, —
    The ?? pin appears to be not connected.

    Inside 3 cells LGUH6NF6060

  8. Does anyone know the pinout for a Toshiba satellite PA3536U-1BS battery please? I measured resistance to ground and found pin 3,4 about 500kOhms and 5 about 10kOhms. Thank you.

    1. I need help, I’m building a portable radio, that also works off 110 volts, my issue is changing, I have a 7.2v, x4 wire, red, blk, white, white, battery (p/n040-1310901 ni-mh), i need to charge off a 12v power supply, im using a 8v voltage regular, to charge battery, and run Amp while plugged in, with a switch to turn of volts to battery so im not over charging, but i dont knkw what im doing as far as charging, can i just leave charging,??, or, can I use a smaller, 6v voltage regulator to charge 7.2v battery pack, all day with out any issues?, there’s very limited space, and i dont want to ruin battery pack or start fires, so i just let charge for a few hours, then turn switch off, to sever battery, and leave plugged in, but can I just leave charging longer, incase I forget, over night??, or use smaller supply voltage to charge battery?, so it never really gets full charged?, Amp will work down to 3volts, thanks

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