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How to use
- Enter Voltage V.
- Enter Capacity Ah.
- Enter Depth of discharge %.
- Enter Efficiency %.
- Calculate, then review power, price and period before comparing.
How it is calculated
Nominal kWh = V × Ah ÷1000; usable = nominal × DoD × efficiency
Example
A 48 V, 200 Ah battery stores 9.6 kWh nominally; at 80% depth of discharge and 90% efficiency, usable energy is about 6.912 kWh.
Important notes
Actual voltage varies with state of charge and chemistry, and Ah does not always translate to constant energy under high loads. This is a planning formula.
Worked examples and interpreting results
| Case | Calculation | Result |
|---|---|---|
| Nominal | 48 × 200 ÷ 1000 | 9.6 |
| Usable | 9.6 × 0.8 × 0.9 | 6.912 |
Frequently asked questions
Should I use 100% depth of discharge?
Only if the battery specification allows it; usable depth depends on chemistry and desired life.
Is the result an actual utility bill?
No. It is a calculation from your usage, price and inputs; real tariffs, taxes and fixed fees may add other items.
How can I improve accuracy?
Use measured or device-specific power and usage plus the actual electricity price for the same period.