What size battery do I need for a 1,000W inverter?

For a 1,000W inverter running at full load, you need at minimum a 12V 100Ah battery for about 45 minutes of runtime (accounting for 50% DOD and inverter losses). For 4 hours of runtime, you would need approximately four 12V 100Ah batteries. The exact requirement depends on your actual load — most people do not run their inverter at full capacity continuously.

Can I use an AGM battery with any inverter?

Yes, AGM batteries work with any standard DC-to-AC inverter. However, you must ensure the inverter charger is set to AGM mode (not flooded or gel) for correct charging voltage. Most inverters have a battery type selector. Also verify that the battery bank voltage matches the inverter input voltage — 12V, 24V, or 48V.

How long will an inverter battery last?

An AGM inverter battery in standby use (grid power available, battery only for backup) typically lasts 5-8 years. In daily cycling use (like solar off-grid), lifespan depends on depth of discharge — expect 3-5 years at 50% DOD with quality AGM batteries (800+ cycles). Gel batteries last longer in cycling applications: 5-7 years at 50% DOD (1,200+ cycles).

Is it better to use one large battery or multiple smaller batteries?

Multiple smaller batteries in parallel offer advantages over one large battery: easier replacement (swap one instead of all), better redundancy (system continues working if one battery fails), easier installation and handling (a 200Ah battery weighs 60+ kg). However, keep parallel strings to a maximum of 4 to avoid uneven current distribution. For systems requiring more than 4 parallel strings, increase the system voltage to 24V or 48V instead.

What is the best battery for a home inverter in a hot climate?

Gel batteries are the best choice for hot climates (above 35°C regularly) because the gel electrolyte resists thermal degradation better than AGM. Naradex OPzV gel batteries maintain 80% of rated capacity at 40°C and deliver 1,500+ cycles at 80% DOD. For moderate climates (25-35°C), AGM batteries offer better value with adequate heat tolerance.

Inverter Battery Guide: How to Choose the Right Battery for Your Power Inverter

Why Inverter Battery Selection Matters

An inverter converts DC battery power to AC power for your appliances. But the inverter is only as good as the battery behind it. Choose the wrong battery and you get shorter runtime, premature failure, and wasted money. Choose the right battery and your inverter system delivers reliable backup power for years.

This guide covers everything you need to know about selecting inverter batteries — from calculating the right capacity to choosing between AGM, gel, and lithium technologies. As a battery manufacturer supplying inverter batteries to 100+ countries, Naradex engineers have helped thousands of customers size their inverter battery systems correctly.

Types of Inverter Batteries

AGM (Absorbed Glass Mat) Batteries

AGM batteries are the most popular choice for inverter systems. They are sealed, maintenance-free, spill-proof, and deliver excellent high-rate discharge performance. AGM batteries handle the surge current demands of inverter startup and motor loads better than gel batteries due to their lower internal resistance.

Best for: Home inverters, commercial UPS, telecom backup, solar hybrid systems Typical lifespan: 5-8 years in standby, 800+ cycles at 50% DOD Price point: Mid-range — higher than flooded, lower than lithium

Gel Batteries

Gel batteries use a silica-based gel electrolyte that provides superior deep cycle performance and heat resistance. They are ideal for regions with high ambient temperatures (35°C+) where AGM batteries would degrade faster. However, gel batteries have higher internal resistance, which limits their peak discharge current.

Best for: Deep cycling applications, hot climate installations, solar off-grid Typical lifespan: 8-12 years in standby, 1,200+ cycles at 50% DOD Price point: Higher than AGM — justified by longer lifespan in demanding conditions

Flooded Lead-Acid Batteries

Flooded batteries are the cheapest option but require regular maintenance — checking water levels monthly, cleaning terminals, and ensuring proper ventilation. They produce hydrogen gas during charging, which creates safety concerns in enclosed spaces.

Best for: Budget installations with dedicated battery rooms and maintenance staff Typical lifespan: 3-5 years, 200-400 cycles at 50% DOD

Lithium Iron Phosphate (LiFePO4) Batteries

LiFePO4 batteries offer the highest energy density, longest cycle life (3,000-5,000 cycles), and fastest charging. However, they cost 3-4x more than AGM upfront and require a Battery Management System (BMS). They are increasingly popular for solar-inverter systems where daily deep cycling is expected.

Best for: Daily cycling solar systems, space-constrained installations, premium applications Typical lifespan: 10-15 years, 3,000-5,000 cycles at 80% DOD

How to Calculate Inverter Battery Size

Proper sizing ensures your inverter system delivers the runtime you need without oversizing (wasting money) or undersizing (damaging batteries with excessive discharge).

Step 1: List Your Loads

ApplianceWattsHours/DayDaily Wh LED Lights (10)1006600 Refrigerator150243,600 WiFi Router1524360 TV1204480 Laptop Charger653195 Fan (2)1008800 **Total****550**—**6,035**

Step 2: Determine Inverter Size

Your inverter must handle the peak simultaneous load plus a 20-25% margin for surge current. From the example above: 550W × 1.25 = 688W minimum inverter size. A 1,000W or 1,500W inverter provides comfortable headroom.

Step 3: Calculate Battery Capacity

Use this formula:

Battery Ah = (Daily Wh × Backup Days) ÷ (System Voltage × DOD × Inverter Efficiency)

For the example above with 1 day backup, 12V system, 50% DOD, and 90% inverter efficiency:

Battery Ah = (6,035 × 1) ÷ (12 × 0.50 × 0.90) = **1,117 Ah**

This requires approximately nine Naradex ND12-120 (12V 120Ah) batteries in parallel, or a more practical 48V configuration with three parallel strings of four 12V 100Ah batteries.

Step 4: Quick Sizing Rule of Thumb

For approximate sizing: every 100Ah of 12V battery capacity provides about 1,000 watt-hours of usable energy at 80% DOD. For 50% DOD (recommended for lead-acid), every 100Ah provides about 600 Wh.

Inverter Battery Sizing for Common Scenarios

ScenarioTypical LoadBackup TimeRecommended BatteryNaradex Model Home (lights + WiFi)200W4 hours12V 100Ah × 2ND12-100 Home (full essentials)500W8 hours12V 100Ah × 8ND12-100 Small Office1,000W2 hours12V 100Ah × 4ND12-100 Telecom Tower2,000W8 hours12V 200Ah × 8ND12-200 Commercial Building5,000W4 hours2V 500Ah × 24 cellsNL2-500

Key Factors When Choosing an Inverter Battery

1. Discharge Rate Compatibility

Your battery must deliver the current your inverter demands. A 3,000W inverter on a 12V system draws 250A — not all batteries can handle this. Check the battery's C-rate specifications. Naradex AGM batteries are rated for up to 10C discharge, supporting even the most demanding inverter loads.

2. Temperature Range

Battery capacity drops in cold temperatures and lifespan shortens in heat. If your installation location exceeds 35°C regularly, consider gel batteries with better heat tolerance. For cold climates below 0°C, oversize your battery bank by 25-50% to compensate for reduced capacity.

3. Charging Compatibility

Ensure your inverter charger output matches the battery's charging requirements. AGM and gel batteries require different charge voltages — using AGM settings on gel batteries (or vice versa) causes premature failure. Most quality inverters have selectable battery type settings.

4. Cycle Life vs Upfront Cost

Calculate total cost of ownership, not just purchase price. A battery that costs 30% more but delivers 60% more cycles has a significantly lower cost per cycle. Naradex AGM batteries deliver 800+ cycles at 50% DOD — substantially better than the industry-standard 400-500 cycles.

5. Safety and Installation

Sealed AGM and gel batteries produce no hydrogen gas during normal operation and can be installed indoors. Flooded batteries require a ventilated battery room and eye-wash station. For residential inverter installations, sealed batteries are strongly recommended.

Common Inverter Battery Mistakes

Using car batteries: Automotive starter batteries are not designed for deep cycling. Using them with an inverter causes failure within months. Always use purpose-built deep cycle batteries.

Undersizing the battery bank: Running batteries below 50% SOC regularly (for lead-acid) dramatically shortens lifespan. Size your battery bank for 50% DOD maximum to protect your investment.

Mixing battery types or ages: Never combine AGM with gel, or old batteries with new ones. Mismatched batteries create circulating currents that degrade the weaker battery and reduce overall system performance.

Ignoring charge time: Your charging source (grid charger, solar panels, or generator) must be able to fully recharge your battery bank within the available charging window. Chronically undercharged batteries sulfate and fail prematurely.

Conclusion

Choosing the right inverter battery requires matching battery technology, capacity, and discharge rate to your specific loads and operating conditions. AGM batteries offer the best all-round performance for most inverter applications, while gel batteries excel in deep cycling and hot environments.

Naradex manufactures inverter batteries from 7Ah to 3,000Ah across AGM, gel, and OPzV technologies. Our engineering team provides free inverter battery sizing calculations — send us your load list and we will recommend the optimal configuration. MOQ from 100 pieces for standard models.