2,000 W load, 8 hours, 80% DoD, 90% eff
- Wh ≈ (2000×8)/(0.8×0.9) ≈ 22,222 Wh
- kWh ≈ 22.22
energy calculator
Battery Storage Sizing Calculator
Estimate battery storage capacity (Wh/kWh) based on load, runtime, depth of discharge, and efficiency.
Results
- Required capacity (Wh)
- 22222.22
- Required capacity (kWh)
- 22.22
How to use this calculator
- Enter average load in watts and hours of runtime you need.
- Enter usable depth of discharge and system efficiency.
- Review required Wh/kWh to choose batteries/chemistry sizing.
Inputs explained
- Depth of discharge
- Usable % of capacity (e.g., 80% for many lithium chemistries).
- Efficiency
- Round-trip/system efficiency; reduces usable capacity.
How it works
Required Wh = (Load × Hours) ÷ (DoD × Efficiency). kWh = Wh ÷ 1000.
Formula
Wh = (Load × Hours) ÷ (DoD × Efficiency) kWh = Wh ÷ 1000
When to use it
- Sizing home battery storage for outages.
- Planning portable or rack battery setups for backup loads.
- Estimating storage needs for off-grid or solar + storage projects.
Tips & cautions
- Add margin for inverter startup, temperature effects, and aging.
- If using lead-acid or lower DoD chemistries, lower the DoD input accordingly.
- Pair with load profiling to refine the average watts estimate.
- Simplified; uses average load and fixed efficiency.
- Does not include battery aging or temperature derate.
- DoD and efficiency inputs are user-provided; results depend on accuracy.
Worked examples
1,200 W load, 5 hours, 70% DoD, 85% eff
- Wh ≈ (1200×5)/(0.7×0.85) ≈ 10,084 Wh
- kWh ≈ 10.08
Deep dive
Estimate battery storage size by entering load, runtime hours, depth of discharge, and efficiency to get Wh/kWh required.
Use it to size home/portable battery systems for backup or off-grid use.
FAQs
- Does this include inverter sizing?
- No. It focuses on storage capacity. Inverter sizing depends on peak watts/surge.
- What about aging/temperature?
- Not modeled. Add margin to capacity for degradation and cold conditions.
- Is DoD auto-selected?
- No. Set based on chemistry (e.g., ~80–90% for many lithium, lower for lead-acid).
- Is this a purchase recommendation?
- No. It’s a sizing estimate. Verify with manufacturer specs and an installer.
- Can I include solar recharge?
- Not here. This focuses on storage needed for the specified runtime.
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