How long will a 200Ah battery last with a 2000W inverter?

Short answer

Running a full 2,000 W, a 200Ah LiFePO4 bank lasts about 55 min (0.9 hours) through a 90% inverter, pulling about 173.6 A from the battery.

How to work it out

200 Ah × 12.8 V × 80% usable = 2,048 Wh
2,000 W ÷ 90% inverter = 2,222.2 W average
2,048 Wh ÷ 2,222.2 W = 0.9 hours (55 min)

Doubling both the battery and the load leaves the runtime where it was for a 100 Ah battery and a 1000 W inverter — under an hour at full tilt. What changes is the current, which is now well past what a single 100 Ah battery is built to deliver.

Adjust for your project

More options: DoD · Inverter eff. · Duty …

Usable depth of discharge (optional)

Blank uses 80% for LiFePO4 and 50% for lead-acid. Check your battery’s data sheet.

Inverter efficiency

Victron puts modern inverters above 90%.

Share of the time the load is on

For anything on a thermostat. A 12 V compressor fridge runs roughly 25–50% of the time (Victron’s example); a household fridge about a third (Virginia Cooperative Extension).

Inverter idle (no-load) draw, W (optional)

What the inverter uses just being on, all the time it is on. It matters most for small loads left running 24/7 — a CPAP, Starlink, a fridge.

Coldest battery temperature

°F

Batteries hold less when cold: Victron gives about 80% for LiFePO4 at 32 °F (0 °C) and 50% at −4 °F (−20 °C); lead-acid about 86% at 32 °F. LiFePO4 must not be charged below 41 °F (5 °C) unless it is self-heating.

Runtime0.9 hours

In hours and minutes: 55 min
Usable energy: 2,048 Wh
Average draw from the battery: 2,222.2 W
Battery current while running: 173.6 A

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12 V 100 Ah LiFePO4 battery55 min is short. A second battery in parallel doubles the runtime and halves the current each one carries.

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Runtime at other loads

Runtime at other loads
Load	Runtime	Battery current while running
25	73.7 hours	2.2 A
50	36.9 hours	4.3 A
100	18.4 hours	8.7 A
200	9.2 hours	17.4 A
500	3.7 hours	43.4 A
1000	1.8 hours	86.8 A
2000	0.9 hours	173.6 A

What to know about a 2000 W inverter on 200 Ah

174 A is a lot for 12 V. Two 100 Ah batteries in parallel share it, about 87 A each — inside the 100 A Victron recommends as continuous for its 12.8 V 100 Ah battery, but without much margin for a motor’s start surge.
24 V halves the current. The same 2,000 W from a 25.6 V 100 Ah bank (same energy) is about 87 A, and the cabling gets far more manageable.
Real use is intermittent. A microwave for 5 minutes, a kettle for 4, a hair dryer for 10 — each is a few percent of the bank. Runtime only matters for long loads such as space heaters and air conditioners.
Plan the recharge. Putting back the 2,048 usable watt-hours takes roughly 650 W of panels on a 4-sun-hour day; see how long to charge a 200Ah battery with a 200W panel.

Sizing the bank for that inverter properly is on what size battery bank for a 2000W inverter, and the inverter’s draw is on how many amps a 2000 watt inverter draws.

Different size? Use the full Battery Runtime Calculator.

What you’ll need

12 V 100 Ah LiFePO4 batteryPremium price
About 1.28 kWh rated in a box roughly the size of a group 24–31 lead-acid battery at around half the weight. Check the BMS discharge limit and whether it can charge below freezing.
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Pure sine wave inverter, 2000–3000 WPremium price
For microwaves, coffee makers and power tools. At 12 V these draw hundreds of amps, so the battery and cabling matter as much as the inverter.
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Battery monitor with shuntMid-range price
Counts amp-hours in and out, so you see true state of charge instead of guessing from voltage — which barely moves on a LiFePO4 battery until it is nearly empty.
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Frequently asked questions

How long will a 200Ah battery last with a 2000W inverter at half load?

About 1 h 51 min at 1,000 W.

How long will a 200Ah battery last with a 3000W inverter at full load?

About 37 min, pulling about 260.4 A — more than the 100 A each that Victron recommends as continuous for two 100 Ah batteries.

Other common sizes

How long a 100Ah battery runs a fridge — 41 hours — a 12 V compressor fridge (50 W, on half the time) on 100Ah LiFePO4
How long a 100Ah battery lasts with a 1000W inverter — 55 min at full load (12.8 V LiFePO4)
How long a 100Ah battery runs a CPAP — 15.4 hours at 60 W (LiFePO4, via inverter)
How long a 100Ah battery lasts with a 200W load — 4.6 hours (LiFePO4, via inverter)

Sources

Victron Energy — Lithium Battery Smart manual, technical data (opens in a new tab) — LiFePO4 12.8 V: cycle life 2,500 at 80% DoD, 3,000 at 70%, 5,000 at 50% (to 80% of capacity); 92% round-trip efficiency; 12.8 V 100 Ah: recommended continuous discharge ≤100 A (1C), maximum 200 A; capacity about 20% lower at 0 °C; charge only between +5 °C and +50 °C.
Trojan Battery — Technical support FAQs (opens in a new tab) — “We generally recommend a discharge of 20 to 50% of the battery’s rated capacity even though the battery is capable of being cycled to 80%”; 20-hour and 100-hour ratings; freezing points by state of charge.
Trojan Battery — 27TMX data sheet (opens in a new tab) — Group 27 flooded: 85 Ah (5-hr), 97 Ah (10-hr), 105 Ah (20-hr), 117 Ah (100-hr); state of charge vs open-circuit voltage table; charger settings.
Victron Energy — Energy Unlimited (book) (opens in a new tab) — Lead-acid charge efficiency 80–95% (85% suggested as a starting value); battery energy efficiency about 75% for full cycles, about 89% in partial state of charge; inverter efficiencies above 90%.
Champion Power Equipment — Generator Wattage Chart (opens in a new tab) — Typical running and starting watts for household, RV and job-site appliances (a manufacturer’s planning chart — your nameplate wins).