Thinkpad 760 battery pinout question

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Hi, all.

My apologies for this is a crosspost from ibm.ibmpc.thinkpad because it
was very quiet over there.

I use my old 760 for some stepper motor experiments.
Only one cardbus slot can be enabled right now and it would
be nice to have both.
From researching the net I've concluded that:
1. I need to enable IRQ steering.
2. I need to update my BIOS to enable steering.
3. I need a charged battery  to update the BIOS.

I only ever use this laptop on AC so I really don't want to
spring for a new battery just to flash the BIOS. I understand
that this units battery has embedded logic so my question is this:
Is there some way to supply a reference voltage to the charger
signal pins to emulate a fully charged battery?
I have successfully booted by supplying power to the main
power pins.
Any help would be appreciated.

Re: Thinkpad 760 battery pinout question

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The laptop queries the charge controller/gas gauge IC in the battery
over I2C. You would need to emulate the correct responses. It's not
just a simple ref voltage.

Having said that, there are ways to skip the battery check.



Re: Thinkpad 760 battery pinout question

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Thanks for the advice.
You'd have to be an IBM insider to know the proper I2C data to send
None of the batteryless workarounds I've found are for the 760 although
I still risked trying them.
I guess I'll have to spring for a battery.


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