What size battery do I need to run a 3000W inverter?

A 3000W inverter typically requires a 12V 600Ah, 24V 300Ah, or 48V 150Ah lithium battery for 1-hour runtime at full load, assuming 90% inverter efficiency and 80% depth of discharge (DoD). Actual capacity needs multiply by runtime hours—e.g., 48V 600Ah for 4 hours. Lead-acid alternatives require 2X capacity due to 50% DoD limits. Always oversize by 20% for surge loads and voltage drop compensation.

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How is battery capacity calculated for inverters?

Battery capacity combines voltage (V), ampere-hours (Ah), and discharge time. For 3000W: (Watts ÷ Volts) × Runtime Hours ÷ (Inverter Efficiency × DoD). Example: 3000W/48V × 4h ÷ (0.9 × 0.8) = 347Ah.

Let’s break this down: A 48V system reduces current draw compared to 12V, minimizing heat losses. If you used 12V instead, you’d need 3000W/12V = 250A—thick cables and perfect connections become critical. Pro Tip: Lithium batteries handle deeper discharges than lead-acid, so a 100Ah LiFePO4 effectively delivers 80Ah vs. 50Ah from AGM. For example, powering a 3000W air conditioner for 2 hours would require a 48V 174Ah lithium battery (3000×2) ÷ (48×0.9×0.8).

What voltage system works best?

Higher voltage systems (24V/48V) outperform 12V for ≥2000W loads. 48V systems cut current by 75% vs 12V, reducing cable costs and resistance losses.

Practically speaking, 48V 3000W inverters only pull ~65A (3000W/48V/0.95 efficiency), allowing 4AWG wiring instead of 0000 AWG for 12V. But what if your equipment requires 12V? Use a DC-DC converter for accessories while keeping main loads at 48V. Real-world example: Solar installations often pair 48V battery banks with 3000W inverters—Enphase and Victron systems follow this standard. Pro Tip: Match battery BMS current limits to inverter surge capacity—some 3000W inverters spike to 6000W momentarily.

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