Stationary battery screening equations
The calculator first integrates DC ampere-hours, then applies explicit efficiency, usable-capacity, temperature, aging, and design factors.
Ahbase = Σ(Ii × ti)Ahrequired = Ahbase × Faging × Fmargin / (η × Fusable × Ftemperature)Nseries = max(ceil(Vnom/Vcell), ceil(Vmin/VEODV))Nparallel = ceil(Ahrequired/Ahcandidate)Icharger ≈ Icontinuous + Ahrequired/trechargewhere:
- Ahbase
- Integrated uncorrected duty-cycle capacity[Ah]
- Ii
- DC load current during period i[A]
- ti
- Duration of period i[h]
- η
- DC conversion and distribution efficiency
- Fusable
- Usable-capacity fraction
- Ftemperature
- Capacity factor at minimum battery temperature
- VEODV
- End-of-discharge voltage per cell[V]
This energy-integration screen does not replace manufacturer discharge tables or the limiting-period cell selection required for a complete stationary battery design.
How to use the Stationary Battery and DC System Sizing Calculator
Choose a constant-load estimate or a duty-cycle screen. Define the DC voltage window and cell voltage first, then enter the load periods and explicit capacity factors. The result keeps energy capacity, peak-current capability, series cell count, parallel strings, charger recovery current, and DC protection reference separate.
- Choose constant-load or duty-cycle screening.
- Enter nominal and minimum DC voltage plus cell end voltage.
- Enter continuous and additional load periods.
- Apply manufacturer or project temperature, aging, usable-capacity, and margin factors.
- Check corrected Ah, peak C-rate, strings, charger current, and DC protection reference against manufacturer data.
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. Loads are expressed at the DC bus Energy integration is a preliminary screen, not the IEEE 485 Hoxie/Kt cell-selection method Parallel strings share current equally A passing or recommended result means the entered mathematical conditions are satisfied; it does not certify the complete installation or a particular product combination.
- Loads are expressed at the DC bus
- Energy integration is a preliminary screen, not the IEEE 485 Hoxie/Kt cell-selection method
- Parallel strings share current equally
Selection limits and next checks
Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions. Complete stationary lead-acid selection requires the exact manufacturer discharge data at the specified duration, end voltage, temperature, and duty cycle. Do not apply this lead-acid-oriented screening result directly to Ni-Cd or lithium systems; those technologies require their own manufacturer data, protection, BMS, and applicable method. 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
- Loads are expressed at the DC bus
- Energy integration is a preliminary screen, not the IEEE 485 Hoxie/Kt cell-selection method
- Parallel strings share current equally
Important Warnings
- Preliminary engineering estimate only. Verify the final design against the current applicable standard, local rules, manufacturer data, and project conditions.
- Complete stationary lead-acid selection requires the exact manufacturer discharge data at the specified duration, end voltage, temperature, and duty cycle.
- Do not apply this lead-acid-oriented screening result directly to Ni-Cd or lithium systems; those technologies require their own manufacturer data, protection, BMS, and applicable method.