How many LiFePO4 Batteries do I need to be Off-Grid?

At LiFePO4 OZ, based in Yatala, Queensland, we help Australians size and build off-grid battery systems every day. The number of LiFePO4 batteries you need depends on four variables: your daily energy consumption, your system voltage, how many days of backup you want, and whether you have solar or wind recharging. This guide walks through each step with a real worked example.

Step 1 - Calculate Your Daily Energy Consumption

Your daily energy consumption is the total watt-hours (Wh) your appliances use across 24 hours. List every appliance, its rated wattage (found on the spec sticker or manual), and how many hours per day you run it. Multiply wattage × hours for each appliance, then total them up.

Appliance	Rated Watts	Hours/Day	Daily Wh
Refrigerator	150W	8 hrs	1,200 Wh
LED Lights × 5	50W	5 hrs	250 Wh
TV	120W	4 hrs	480 Wh
Laptop	65W	6 hrs	390 Wh
Phone chargers × 2	20W	3 hrs	60 Wh
Ceiling fan	75W	8 hrs	600 Wh
Air conditioner (small)	900W	2 hrs	1,800 Wh
Inverter losses (~10%)	-	-	478 Wh
Total			5,258 Wh (~5.4 kWh/day)

Divide your total by 1,000 to convert Wh to kWh. The example above gives 5.4 kWh per day.

Step 2 - Measure Your Appliances Accurately

Spec sheet wattages are maximum ratings - not real-world averages. A fridge rated at 150W might only average 80W over 24 hours because its compressor cycles on and off. Measure actual consumption with a plug-in energy monitor (wattmeter).

For caravans, campervans, motorhomes & RVs

Pick up a wattmeter from Bunnings or Jaycar for around $20. Plug it into a mains power point (GPO), plug your appliances into the wattmeter, and run them normally for 24 hours. Read the total kWh directly from the display. The wattmeter also shows peak amps - useful for sizing your inverter and cable gauge.

For off-grid homes

Go to your electricity meter box and write down the current kWh reading. After exactly 24 hours, take a second reading and subtract the first from the second. Do this on a typical day for the most representative result.

Step 3 - Calculate the Number of LiFePO4 Batteries You Need

Battery capacity is sold in amp-hours (Ah), so you need to convert your daily watt-hour figure into Ah at your chosen system voltage.

Choose your system voltage

• 12V - Caravans and small campervans. Standard equipment, easiest to wire.
• 24V - Mid-size RVs, cabins, small homes. Good balance of efficiency and simplicity.
• 48V - Off-grid homes and large systems. Most efficient - thinner cables, less heat loss, fewer batteries needed. Recommended for homes.

The battery sizing formula

Worked example - 24V system, 5,400 Wh/day

Calculation	Working	Result
Daily consumption	From appliance list	5,400 Wh
System voltage	24V inverter chosen	24V
Ah needed (Step A)	5,400 ÷ 24	225 Ah
Apply 80% DoD (Step B)	225 ÷ 0.8	281 Ah minimum
Recommended kit	24V 230Ah + solar offset	24V 230Ah LiFePO4 Kit

Quick reference - common system sizes

Daily Usage	System Voltage	Min. Capacity (80% DoD)	Recommended Kit
1–2 kWh/day	12V	104–208 Ah	12V 100Ah × 2
3–4 kWh/day	24V	156–208 Ah	24V 230Ah Kit
5–6 kWh/day	24V	260–312 Ah	24V 230Ah Kit + solar
7–10 kWh/day	48V	182–260 Ah	48V Battery System

Step 4 - Wire Your Batteries Correctly

To reach the amp-hour capacity and voltage you need, you will connect multiple batteries or cells together. There are three configurations:

Series - increases voltage, capacity stays the same

Connect the positive terminal of one battery to the negative terminal of the next. Each battery's voltage adds together, but the total amp-hours stays the same as a single battery.

Example: 8 × 3.2V 206Ah cells in series = 25.6V 206Ah (5.27 kWh)

Parallel - increases capacity, voltage stays the same

Connect all positive terminals together and all negative terminals together. Voltage stays the same, but total amp-hours multiply by the number of batteries.

Example: 8 × 3.2V 206Ah cells in parallel = 3.2V 1,648Ah

Series-Parallel (2S8P) - increases both voltage and capacity

For larger battery banks, combine both methods. In a 2S8P configuration, connect 8 cells in series to raise voltage, then connect two of those strings in parallel to double total capacity.

Example: 16 × 3.2V 130Ah cells in 2S8P = 25.6V 260Ah (6.65 kWh)

Step 5 - Factor In Your Solar or Wind Recharging

Any power generated during the day reduces how much you need to store overnight - which directly reduces how many batteries you need. This is the step most guides skip.

Solar panels (most common in Australia)

Australia receives some of the highest solar irradiance in the world - most regions get 4 to 6 peak sun hours per day.

Example with 8 hrs solar @ 30A/24V:

Without solar	With 8 hrs solar @ 30A/24V
Must store 24 hrs of power	Must store 16 hrs of power only
5,400 Wh storage needed	3,600 Wh storage needed
281 Ah minimum capacity	~188 Ah minimum capacity
~3 batteries needed	~2 batteries needed

This is why our 24V EVE 230Ah LiFePO4 Battery Kit is the perfect fit for this setup - 230Ah @ 24V (5.89 kWh) with Smart BMS included, covering the 188Ah minimum with comfortable headroom.

Wind turbines

Wind generates power around the clock - not just during daylight hours. Wind and solar together provide the most reliable off-grid combination, and is most effective in coastal, rural, and elevated areas with consistent airflow.

Generator backup

A generator is best used as a last resort. A small 2kW generator running 3–4 hours during extended cloudy periods can prevent you from significantly oversizing your battery bank. If generator backup is part of your plan, you can safely reduce your calculated battery capacity by 20–30%.

Frequently Asked Questions

How many LiFePO4 batteries do I need to be off-grid?

Most Australian homes need between 2 and 8 LiFePO4 batteries. A typical home using 5.4 kWh per day on a 24V system needs approximately 225Ah of battery capacity before applying the 80% depth of discharge rule. With solar recharging factored in, a 24V 230Ah battery kit covers most households comfortably.

How long do LiFePO4 batteries last off-grid?

LiFePO4 batteries are rated for 3,000 to 5,000 charge cycles at 80% depth of discharge. Cycled once per day, that is 8 to 15 years of service life - far longer than lead-acid batteries which typically last 2 to 5 years.

Can I mix LiFePO4 batteries with lead-acid batteries?

No - never mix battery chemistries in the same bank. LiFePO4 and lead-acid batteries have different charge voltages and discharge curves. Mixing them causes uneven charging, accelerated degradation of both battery types, and creates a serious safety hazard.

Do I need a BMS for LiFePO4 batteries?

Yes, a Battery Management System (BMS) is essential. It protects your cells from overcharge, over-discharge, overcurrent, short circuits, and temperature extremes. Running LiFePO4 batteries without a BMS can cause permanent damage or fire. All LiFePO4 OZ battery kits include a Smart BMS as standard.

What size inverter do I need for my off-grid battery bank?

Your inverter should handle your peak load - the total wattage if all major appliances ran simultaneously. A safe rule: inverter rating = peak load × 1.25. For the 5,400 Wh/day example in this guide, a 3,000W to 5,000W inverter is sufficient. Browse our inverter range here.

What is the easiest way to convert Ah to kWh?

Multiply amp-hours × voltage ÷ 1,000. For example: 230Ah × 24V ÷ 1,000 = 5.52 kWh. Use our free Ah to kWh Converter to do this instantly.

How should I store LiFePO4 batteries when not in use?

Charge to 50–60% and store in a cool, dry location away from direct sunlight. Avoid storing at 100% or below 20% for extended periods. Check stored batteries every 3 months and top up to 50–60% if the charge has dropped.

Summary

• Step 1: List your appliances and calculate total daily Wh. Add a 20–25% buffer.
• Step 2: Measure accurately - wattmeter for caravans, electricity meter reading for homes.
• Step 3: Divide daily Wh by system voltage (Step A), then divide by 0.8 for 80% DoD (Step B).
• Step 4: Wire in series for higher voltage, parallel for higher capacity, or series-parallel for large banks.
• Step 5: Subtract daily solar or wind generation from total storage needed to find your true battery bank size.

For the 5,400 Wh/day example used throughout this guide, our 24V EVE 230Ah LiFePO4 Battery Kit (5.89 kWh) with Smart BMS is the ideal solution - ready to connect out of the box and backed by our Australian support team.

Have questions about sizing your system? Contact the LiFePO4 OZ team - we're happy to help you get the right setup first time.