How to calculate percentage of depth of discharge of a battery? ?

How to calculate percentage of depth of discharge of a battery? Please explain in detail. I have a 12v 110ah lead acid battery which shows 13.8v in it's full charge.but i had not discharged it fully . So i dont know the voltage at full discharged state . Low my question is how to find out at what voltage it has 90%,80%,70%,60%40% charge. Please explain in detailHow to calculate percentage of depth of discharge of a battery? ?
Full discharge means the battery is badly damaged. Ordinary lead acid batteries cannot be fully discharged without damage.



reference has lots of data on this topic. It is NOT simple. The curve on the third page (numbered 68) is the best. But it doesn't agree with your curves, the 13.8 number is too high, unless the battery is being charged at the time you made the measurement. But it's low for that condition.



But the voltage depends on the charge or discharge rate. At a very low rate of discharge, about 1 amp, the numbers from that curve are:



12.7 volts from 100% to 60%, where it decreases to 12.6. After that it becomes steeper.

100% 12.7

90% 12.7

80% 12.7

70% 12.7

60% 12.6

50% 12.5

40% 12.4

30% 12.3

20% 12.2

10% 11.9How to calculate percentage of depth of discharge of a battery? ?
Cannot do it with calculation in percentage.

No load at full discharge voltage varies from 11.8 V to 12.0 V

With load at full discharge reads 10.5 V.

Drain acid cell completely shall lost its full capacity even damage the cell.How to calculate percentage of depth of discharge of a battery? ?
Most battery mfr.'s publish the curve of voltage vs. Charge level. It is non-linear so you cannot use a math formula.