Battery datasheets quote amp-hours; system designs often end in watt-hours. This guide walks through the battery capacity converter (Wh to Ah): energy in Wh, nominal voltage, and the Ah capacity to match on price lists and install quotes.
Benefits
- Rated Ah = Wh ÷ bus voltage.
- Normalize kWh rack specs to 12 V, 24 V, or 48 V Ah shopping lists.
- Compare vendor Wh claims to Ah listings before parallel/series layout.
How it works
- Enter pack or bank energy in watt-hours (or kWh × 1,000).
- Add nominal system voltage your inverter and loads use.
- Read equivalent amp-hour capacity for bank sizing and SKU selection.
FAQ
How does a battery capacity Wh to Ah converter work?
Ah = Wh ÷ V. A 4,800 Wh (4.8 kWh) target at 12 V → 400 Ah bank. The same 4,800 Wh at 24 V → 200 Ah. Capacity in amp-hours always depends on voltage—state both when quoting installs.
Can I convert a 5 kWh home battery spec to Ah?
Yes: 5 kWh = 5,000 Wh. At 48 V nominal → 5,000 ÷ 48 ≈ 104 Ah equivalent. At 12 V that would be ~417 Ah—same energy, very different wiring and BMS. Match voltage to your architecture, not the marketing photo.
Does chemistry affect Wh to Ah conversion?
The formula Ah = Wh ÷ V is chemistry-neutral. LiFePO4, AGM, and NMC differ in usable DoD and cycle life—not in this math. Apply chemistry after rated Ah: LiFePO4 may use 80–90% of rated Wh; lead-acid often 50%.
Technical specifications
- Bank Ah = total_Wh ÷ bus_V.
- kWh → Wh: multiply by 1,000.
- Usable Ah target ≈ (usable_Wh ÷ DoD) ÷ V.
- Related: battery-bank-size, ah-to-wh, battery-cost.
Wh specs are how energy is sold; Ah is how banks are stocked
Wall-mounted 10 kWh systems, portable power stations, and solar quotes lead with kilowatt-hours. Your distributor stocks 100 Ah 12 V boxes. Dividing pack Wh by your bus voltage bridges procurement—without assuming a 400 Ah listing equals 10 kWh unless the voltage matches.
Voltage choice changes the Ah shortlist
A fixed 6,000 Wh autonomy target is 500 Ah at 12 V, 250 Ah at 24 V, or 125 Ah at 48 V. Higher voltage reduces copper loss and Ah count but requires compatible inverters and BMS. Run the converter at each voltage you are considering before committing to a bus architecture.
From converted Ah to bank layout
Once Ah is known, split across parallel strings for current capacity and series for voltage—Ah and V trade off but Wh stays fixed. Verify each candidate SKU with Ah × V back to Wh. Pair converted Ah with Battery Bank Size when C-rate, fuse limits, or maximum parallel count constrain the physical layout.