Battery capacity conversion equations
Series units increase pack voltage, while parallel strings increase ampere-hour capacity.
Vpack = Vunit × NsCpack = Cunit × NpEnominal = Vpack × CpackEusable = Enominal × DOD × ηwhere:
- Vpack
- Nominal pack voltage[V]
- Cpack
- Nominal pack capacity[Ah]
- Ns
- Number of units connected in series
- Np
- Number of parallel strings
- Enominal
- Nominal battery energy[Wh]
- DOD
- Permitted depth of discharge
- η
- Discharge-system efficiency
Nameplate capacity varies with chemistry, temperature, age, and discharge rate, so this is an energy conversion rather than a battery qualification.
How to use the Battery Capacity Converter
Convert battery Ah, mAh, Wh, and kWh while accounting for voltage, series and parallel configuration, depth of discharge, and efficiency. Start by choosing the operating mode, then enter values from nameplates, measurements, or project documents in the units shown. The result updates immediately and keeps intermediate quantities visible for review.
- Confirm the system and calculation mode.
- Enter measured or manufacturer-rated values.
- Review the primary result and intermediate metrics.
- Continue with the related protection or equipment-selection checks.
Calculation method and validation
The equations and symbol definitions above show the complete calculation basis. Inputs are checked before calculation so zero, negative, incompatible, or physically impossible combinations are flagged instead of silently producing a misleading result.
How to interpret the result
Use the main result as a starting value and read every supporting metric. Nameplate voltage and capacity describe the same battery state and discharge-rate basis Series connection raises voltage but not Ah Parallel connection raises Ah but not voltage DOD and efficiency are planning factors A passing or recommended result means the entered mathematical conditions are satisfied; it does not certify the complete installation or a particular product combination.
- Nameplate voltage and capacity describe the same battery state and discharge-rate basis
- Series connection raises voltage but not Ah
- Parallel connection raises Ah but not voltage
- DOD and efficiency are planning factors
Selection limits and next checks
Actual capacity depends on chemistry, temperature, age, discharge rate, BMS limits, cell balance, and manufacturer test conditions. Do not use energy conversion alone to size battery protection, conductors, contactors, chargers, or fault-current withstand. Compare the output with the current applicable standard, local rules, exact VIOX product datasheet, environmental conditions, protection coordination, and the engineer's project requirements before procurement or installation.
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Assumptions
- Nameplate voltage and capacity describe the same battery state and discharge-rate basis
- Series connection raises voltage but not Ah
- Parallel connection raises Ah but not voltage
- DOD and efficiency are planning factors
Important Warnings
- Actual capacity depends on chemistry, temperature, age, discharge rate, BMS limits, cell balance, and manufacturer test conditions.
- Do not use energy conversion alone to size battery protection, conductors, contactors, chargers, or fault-current withstand.