Battery Runtime Calculator – 24V

Q: How long will a 24V 200Ah battery last?

At 50% DoD and 90% efficiency: 200 × 24 × 0.5 × 0.9 = 2,160 Wh usable. At 200W load: 2,160 ÷ 200 = 10.8 hours. At 400W: 5.4 hours.

Q: Why use 24V instead of 12V?

24V halves the current for the same power, allowing thinner cables and reducing losses. A 24V system is preferred for loads above 500–1000W. It also allows more efficient inverter operation for most consumer inverters.

Q: Can I connect 12V batteries to make 24V?

Yes — connect two identical 12V batteries in series (positive of one to negative of the other). This doubles voltage while keeping Ah the same. Always use batteries of the same age, capacity, and chemistry when connecting in series.

24V systems halve the current compared to 12V at the same power, reducing cable size and losses significantly. Common in solar setups above 500W, larger inverters, and commercial vehicles. Enter Ah capacity and load to find exact runtime — including DoD and efficiency losses.

Calculate 24V Battery Runtime

Battery Capacity (Ah)

Battery Voltage (V)

Load (Watts)

Depth of Discharge (%)

System Efficiency (%)

Runtime Results

—

Runtime (hours)

—

Hours & Minutes

—

Usable Energy (Wh)

Formula

Usable Wh = Ah × Voltage × (DoD ÷ 100) × (Efficiency ÷ 100)
Runtime (hrs) = Usable Wh ÷ Load Watts

24V Battery Runtime Quick Reference (50% DoD, 90% efficiency)

Battery	Usable Wh	100W Load	300W Load	600W Load
24V 100Ah	1,080 Wh	10.8 hrs	3.6 hrs	1.8 hrs
24V 150Ah	1,620 Wh	16.2 hrs	5.4 hrs	2.7 hrs
24V 200Ah	2,160 Wh	21.6 hrs	7.2 hrs	3.6 hrs

Frequently Asked Questions

How long will a 24V 200Ah battery last?

At 50% DoD and 90% efficiency: usable energy = 200 × 24 × 0.5 × 0.9 = 2,160 Wh. At 200W load: 10.8 hours. With lithium at 80% DoD and 95% efficiency: 200 × 24 × 0.8 × 0.95 = 3,648 Wh ÷ 200W = 18.2 hours.

Why use 24V instead of 12V?

For the same power, 24V draws half the current of 12V. Halving current allows quarter the cable losses (losses ∝ I²R), thinner and cheaper cables, and more efficient inverter operation. 24V is practical for systems of 500W–2kW. Above 2kW, consider 48V. Below 500W, 12V is convenient and widely supported.

Can I connect 12V batteries to make 24V?

Yes — two 12V batteries in series (positive terminal of one connected to negative of the other) gives 24V at the same Ah rating. Always match batteries: same chemistry (don't mix lead-acid with lithium), same capacity, same age (ideally same batch). Mismatched batteries in series leads to imbalanced charging and premature failure.