Easy Solar Calc

What size battery bank for a 2000W inverter?

Short answer

For a 2000W inverter at full load for one hour on 12 V, plan on about 217 Ah of LiFePO4 — 3 × 100 Ah 12.8 V in parallel — with the battery supplying about 174 A.

How to work it out

  1. 2,000 W ÷ 90% × 1 h = 2,222 Wh
  2. 2,222 Wh ÷ 80% usable ÷ 12.8 V = 217 Ah = 217 Ah
  3. 217 Ah ÷ 100 Ah per battery → 3 × 100 Ah 12.8 V in parallel

Two thousand watts is a popular inverter size for vans and travel trailers: enough for a 1,000 W microwave with headroom for its surge, a toaster or a small hair dryer.

Adjust for your project

Watts the inverter supplies
Sets how much of the rated capacity you plan to use: 80% for LiFePO4 (Victron rates cycle life at 80% depth of discharge), 50% for lead-acid (Trojan recommends 20–50% for long life).
For counting batteries. 100 Ah is the common size; lead-acid: use the 20-hour rating.
More options: Inverter eff. · DoD · Battery temp
%
%
Blank uses 80% for LiFePO4 and 50% for lead-acid. Check your battery’s data sheet.
°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.
Battery bank needed217 Ah12 V
Made up of
3 × 100 Ah 12.8 V in parallel
Batteries
3 batteries · LiFePO4
Energy the bank must deliver
2,222 Wh
Rated energy of that bank
3,840 Wh
Battery current at full inverter load
174 A
Before you wire itWire and fuse sizes come from NEC/ABYC ampacity tables and the equipment manual — have a qualified installer check them.

For this job · affiliate link
12 V 100 Ah LiFePO4 batteryBuy matching batteries — same make, model and age — so they share the load evenly in parallel.
View on Amazon (opens in a new tab)

Bank size for other days of autonomy

Bank size for other days of autonomy
Days of autonomyBattery bank neededBatteries
0.5217 Ah3 batteries
1217 Ah3 batteries
2217 Ah3 batteries
3217 Ah3 batteries
5217 Ah3 batteries

What to know about a 2000 W inverter’s battery

  • Energy says three, current says two. One hour at full load needs about 2,222 Wh, which is three 100 Ah LiFePO4 batteries at 80% usable. The 174 A current alone would need two, at Victron’s recommended 1C.
  • Real use is bursts. A microwave drawing 1,500 W for 5 minutes takes about 140 Wh from the battery through the inverter. If that is the biggest load, a smaller bank works — but it must still carry the current.
  • 24 V halves it. At 24 V the same inverter draws about 87 A.
  • Lead-acid: about 370 Ah on paper, about 535 Ah in practice. At 50% usable and 185 A, the Peukert correction for an AGM bank adds nearly half again — six 100 Ah batteries.

How long a given bank lasts at this load is on how long a 200Ah battery lasts with a 2000W inverter; the current is on how many amps a 2000 watt inverter draws. The bigger version is what size battery bank for a 3000W inverter.

Different size? Use the full Battery Bank Size 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.

    See options on Amazon (opens in a new tab)
  • 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.

    See options on Amazon (opens in a new tab)
  • Vented battery boxBudget price

    Covers the terminals so a dropped tool can’t short them and keeps a lead-acid battery’s spills contained. Flooded batteries need the vent.

    See options on Amazon (opens in a new tab)

As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.

Frequently asked questions

What size battery bank for a 2000W inverter at 24 V?

About 109 Ah at 25.6 V (4 batteries: 2 strings of 2 × 100 Ah in series), drawing 87 A.

What size battery bank to run a 2000W inverter for 30 minutes?

About 109 Ah of 12.8 V LiFePO4 — 2 × 100 Ah 12.8 V in parallel. Energy alone needs a little over 100 Ah, so two batteries, and the 174 A current needs two as well.

Other common sizes

Sources