Batteries
Depth of Discharge Calculator
Depth of Discharge Calculator is meant for one defined batteries case. Run a separate case when the equipment, period, or connection changes.
Build the Depth of discharge case
Use one Depth of Discharge case at a time; save a new run when a condition changes.
The Depth of Discharge equation
A clean Depth of Discharge result confirms the arithmetic for depth of discharge; it does not prove the equipment rating or source data is the right one.
Before entering rated capacity
On Depth of Discharge, confirm decimal placement and unit scale before using depth of discharge; small prefixes can move an electrical result by orders of magnitude.
- Capacity removed. Example value: 60 Ah. Enter capacity removed in Ah.
- Rated capacity. Example value: 100 Ah. Enter rated capacity in Ah.
When capacity removed is uncertain, run a low and high case instead of hiding that uncertainty in one entry.
Use Battery C-Rate after saving the Depth of Discharge case so the linked result does not overwrite these assumptions.
Detail checks for depth of discharge
Depth of Discharge should be read with chemistry and state-of-charge notes. The same amp-hour value can represent a different usable-energy case at another discharge rate.
When depth of discharge becomes an input to another worksheet, copy the value only after the units and source condition have been verified.
Pre-use check for Depth of Discharge
- Keep the result note attached when copying the answer.
- Compare the result with the relevant rating or limit before acting on it.
Notes to save with Depth of Discharge
Attach chemistry, state of charge, temperature, and the test condition used for the Depth of Discharge entry.
| Input set | Capacity removed, and Rated capacity |
|---|---|
| Result | Depth of discharge |
| Condition note | Capacity ratings depend on test rate and temperature. |
Common Depth of Discharge questions
Which value should be rounded first?
Keep capacity removed at source precision during Depth of Discharge; round depth of discharge only where presentation or purchasing requires it.
What should be recorded with the answer?
Save the Depth of Discharge inputs, unit basis, operating case, and result note so depth of discharge can be reproduced later.
Why did the answer move so much after one input changed?
Many electrical relationships are proportional, inverse, squared, or tied to a denominator. A small change in rated capacity can have a visible effect when the other entries stay fixed.
Should nameplate and measured values be mixed?
Only mix nameplate and measured values in Depth of Discharge when that mix represents the actual case. Otherwise keep them in separate runs.