Calculator

Forklift battery runtime calculator

Battery energy from volts and amp-hours: kWh = V × Ah / 1000. Enter your numbers below; the formula and its source are shown under the result.

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The formulas

Battery energy from volts and amp-hours

kWh = V × Ah / 1000

Nominal figure. OEM literature can differ: Crown's TR 4500 sheet lists a 24 V 750 Ah battery as 21.5 kWh, while V × Ah gives 18 kWh. Use the battery label or OEM kWh when available.

Worked example: Redway: 24 V 50 Ah = 1.2 kWh.

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Battery runtime estimate

runtime_h = (Ah × DoD × V) / (load_kW × 1000) (equivalently runtime_h = usable_Ah / average_current_A)

Average draw varies with duty, so present as an estimate. Supralift: wet batteries should not go below 80% discharge, maintenance-free below 60%; cold reduces available capacity. Lithium DoD comes from the battery maker.

Worked example: ZDX: 300 Ah x 0.8 = 240 Ah; 240 x 24 / (1.2 x 1000) = 4.8 h. Supralift: 300 Ah at 15 A = 20 h.

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Depth-of-discharge limits for lead-acid traction batteries

DoD_max = 0.80 (wet / flooded lead-acid); 0.60 (maintenance-free lead-acid)

Supralift glossary guide figures; cold electrolyte reduces available capacity further.

Worked example: n/a

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Estimate only. The capacity on the machine's data plate is the legal limit; never exceed it.

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Sources

  1. How To Convert Amp Hours (Ah) Into Kilowatt Hours (kWh)? (Redway Power, battery manufacturer blog) (retrieved November 4, 2026)
  2. How to calculate the runtime of a forklift battery (ZDX, battery supplier blog) (retrieved November 4, 2026)
  3. Electrolyte Temperature and Available Capacity (Supralift materials handling glossary) (retrieved November 4, 2026)