Ideal Li-Ion battery cutoff voltage

[Sigmoid]

This question came up in relation to my single-board computer (Banana Pro) I intend to use as a portable network analysis tool. Its power management chip supports Li-Ion cell management by default, however it doesn't have well-behaved ACPI, and since I'll be running Linux, I'd like to do a safe, graceful system shutdown well before the power management IC pulls the plug.

I can monitor the battery voltage and current via i2c... So the question is, what should I use as a "software cutoff voltage"? 3 Volts seems to be the industry standard, but I've read in places that 3.3V is probably more appropriate for increasing battery lifetime. There are examples of 2.7V being used, on the other end of the scale... Is there a point in taking current draw into account for battery cutoff (like letting it get away with lower voltages if there's a high current...)

[KL27x]

^ Yes, to all of that. (Only part I'm sketchy on, I think 3.3V is super conservative!)

Yes, of course I would consider relationship between current draw and internal resistance slash output capacity. Your circuit can't measure the battery's internal voltage drop, directly. And of course this matters. For relatively higher current draw in relations to output capability/ISR of the battery, there is a larger discrepancy between max load voltage and the float voltage. For a relatively large current draw for battery, you would generally want to move your bar closer to 2.7. And for lower draw, move that bar higher.

[mrrrwhat]

Depends on which type of Li-ion battery you use, the cut off voltage will be different.
For high drain type, the lowest cut off voltage are 2.5v.
For high capacity type, the lowest cut off voltage are 2.75v.

[Seekonk]

3.3V doesn't seem overly conservative if looking for long life.

[Audioguru]

The electronics in my radio control model airplanes gives a low voltage warning by pulsing the motor when the Li-Po battery measures 3.15V per cell and completely cuts off the motor (but the receiver and controls still work) when the voltage measures 3.05V per cell. The manufacturer says: "Warning. Repeated operating to low voltage cutoff will damage the battery". The batteries are Very High Drain type.

[mrrrwhat]

Voltage measures with or without load,the cutoff voltage also will be different