How long will a 200Ah battery last with a 2000W inverter?
A 200Ah battery with a 2000W inverter typically lasts 1–4 hours, depending on battery voltage (12V, 24V, or 48V), inverter efficiency (85–95%), and discharge depth limits. For a 12V system: Runtime ≈ (200Ah × 12V × 0.95 efficiency × 50% discharge depth) / 2000W = 0.57 hours (34 minutes). For a 48V system, this extends to ≈2.28 hours. Actual runtime decreases under high loads due to Peukert’s effect, which reduces effective capacity at higher currents.
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What factors determine battery runtime?
Runtime depends on battery voltage, inverter efficiency, and load percentage. A 12V 200Ah battery stores 2.4kWh, but only 1.2kWh is usable at 50% discharge depth. With a 95% efficient 2000W inverter, continuous draw becomes 2105W (2000W ÷ 0.95), yielding 34 minutes at full load.
Beyond voltage considerations, Peukert’s law significantly impacts lithium and lead-acid batteries. At 2000W draw on a 12V system, discharge current reaches ≈175A (2000W ÷ 12V ÷ 0.95), far exceeding the 0.2C rate (40A for 200Ah). This high current reduces effective capacity by 30–40%. Pro Tip: Use lithium batteries (LiFePO4) for better high-current performance—they retain 95% capacity at 1C vs. lead-acid’s 50%. For example, a 48V 200Ah LiFePO4 pack powering a 2000W load lasts 2.5 hours (48V × 200Ah × 0.95 ÷ 2000W) versus 1.2 hours for AGM.
How does voltage affect runtime?
Higher system voltage reduces current draw, extending runtime. A 48V 200Ah battery delivers the same energy (9.6kWh) as four 12V 200Ah batteries but with 75% less current (41.7A vs. 166.7A at 2000W), minimizing Peukert losses.
| Voltage | Current (2000W) | Runtime (LiFePO4) |
|---|---|---|
| 12V | 175A | 0.9h |
| 24V | 87.5A | 2.1h |
| 48V | 43.8A | 4.3h |
Practically speaking, 48V systems are optimal for sustained high loads. For instance, off-grid solar setups using 48V 200Ah batteries with 2000W inverters can power refrigerators (150W) and lights (100W) for 18+ hours when load drops to 250W. Pro Tip: Parallel multiple batteries for high-wattage applications—two 48V 200Ah units double runtime to 8.6 hours at 2000W.
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FAQs
Yes, but they must be identical age/capacity. Series connection creates 24V 200Ah (4.8kWh), doubling runtime versus single 12V at 2000W.
Why does my 200Ah battery last less than calculated?
High loads trigger voltage sag and Peukert losses. At 175A draw, lead-acid’s effective capacity drops to ≈120Ah, reducing runtime by 40%.