SMBus - smart battery managment

[Misterbenn]

Hi guys

i'm trying to build a smart battery monitor / charger

So far i've got my smart battery, but i'm still trying to work out the layout of the SMBus conector. Its a HiModel 11.1v 1300mAh battery pack, with power out and then a 4 pin connector.

From what i've found on SMBus it should have a clock, data and analouge 'safety' signal. the safety signal should just be a resistance value i belive.
Out of the four wires (black, yellow, blue, red) i've been able to work out that black and red have a PD equal to that of the battery - which suggests power terminals. However if they are just power terminals then i've only got 2 pins left, not the three required by SMBus specs.
Also looking at the yellow and blue in regards to black they have seemingly random but constant voltages - i expected them to be logic low as the smart device should be off.

Has anyone out there had experience working with Smart Battries?

 

[justDIY]

smbus is an open collector bus, so the slave's clock and data lines will just be floating without a pull-up resistor ... also the slave will not be initiating any conversation, without a master.

do you know what the batteries smbus address is?

a simple test would be to pull the unknown lines high with a 4.7kohm resistor. if they stay high, then they're likely data lines, if they fight being pulled up, then they're likely not smbus lines, and it's back to the drawing board.

are you recycling this battery from something? your best bet is going to be putting the battery back where it came from and mapping the connections between battery and host, use a logic analyzer or o-scope to watch the connections and see if you can determine what is what.

 

[Misterbenn]

I belive the address for a smart battery is 0001010 - and a final bit indicating write or read. i belive this is a generic address for smart batteries -i found this in smart battery data specification.

Its a new battery, but the manufacturer HiModel doenst provide any discription of the connector - only that it is compatible with most standard chargers.