Min Discharge Voltage of Battery

Go to the battery manufacturer's website, it's the best place for reliable information about your specific battery.
Failing that check the website of a manufacturer of a similar battery.
Del

It depends on the type of battery and how many cells are in it. The limit is based on preventing an individual cell in the series string from fully depleting and reversing its polarity. When that happens, discharge of the other cells results in uncontrolled charging of the reversed cell. Overheating, deformation, fire and explosion can all occur as a result of cell reversal.

• A standard lead-acid battery has a minimum cell voltage of 1.75 VDC. Cut-off for a 6-cell automotive-type battery should be 10.5V.
• Lithium ion cells have a minimum of 2.5-2.7 volts/cell.
• Nickel Cadmium cells should remain above 1.05 volts/cell.
• Nickel Metal Hydride cells should be cut off at about 0.85 volts/cell.

This was something I didn't know either, and it explains a lot! I just had to replace the main battery pack on my wife's Prius (we got 10 years, 190,000 miles out of it contrary to the popular 100k mile myth). According to the computer code it had one bad cell (I don't know how they know that, maybe each cell is monitored?). My wife asked me why we couldn't just replace the bad one (she's cheap that way). I tried to explain it to her, but this makes it more clear.

Thanks.