How to Choose the Right AGV Battery for Your Fleet

Choosing the right AGV battery is one of the most important technical decisions you make for an automated guided vehicle project. The battery defines:

• how long each AGV can run between charges,
• how many charging stations and spare packs you need,
• how reliable and predictable your operation is, and
• what you really pay over the next 5–10 years.

This guide walks through a simple, engineering-style method to size an AGV battery – even if you are not an electrical engineer. We focus on system voltage, capacity (Ah / kWh) and charging windows, using common 24 V and 48 V examples. The same logic applies if your AGV runs at 36 V, 60 V, 72 V or higher.

How Do I Choose an AGV Battery?

If you only need the big picture, selecting an AGV battery comes down to five steps:

1. Confirm your AGV system voltage
   24 V, 36 V, 48 V, 60 V, 72 V or another value – this is defined by the vehicle, not the battery supplier.
2. Estimate how much energy the AGV uses per day
   Use the average power and operating hours per shift to get a rough kWh figure.
3. Convert energy into battery capacity (Ah and kWh)
   Divide by the system voltage and consider usable depth of discharge (DoD) plus a safety margin.
4. Check charging windows and charger power
   Make sure your charging time and charger kW are enough to put back at least as much energy as you take out.
5. Verify chemistry, mechanical fit, safety and communication
   The pack must physically fit, meet safety standards and communicate correctly with the AGV controller.

For many small and medium warehouse AGVs, the system voltage is 24 V or 48 V. Larger or forklift-style AGVs often use 60 V, 72 V or more.

If you already know your voltage and want to see standard pack options, you can compare your calculations with your supplier’s 24 V / 48 V LiFePO4 AGV battery range, then refine the numbers based on real duty cycles.

Step 1 – Confirm Your AGV System Voltage

The system voltage is the foundation of all sizing work. Everything else – capacity, current, charger power – depends on it.

Typical AGV system voltages

The system voltage is dictated by the AGV’s drive and control system, not by the battery manufacturer. Typical voltages include:

• 24 V – small AGVs, carts, small mobile robots
• 36 V – some medium-sized AGVs and tuggers
• 48 V – very common in warehouse and factory AGVs
• 60 V / 72 V and above – heavy-duty, forklift-style or high-payload AGVs

Higher voltage allows the same power with lower current, which reduces cable losses and heating, but it may have different safety and standard requirements.

How to find the correct voltage if you’re not an engineer

If you are not sure about the system voltage:

• Check the rating label on the existing battery (for example “24 V 200 Ah”).
• Look at the AGV nameplate or technical manual.
• Ask the AGV manufacturer or integrator directly.

Do not guess or “upgrade” the voltage on your own. Using the wrong voltage can damage motors, inverters and controllers, and can create safety risks.

Common system voltages and typical use cases

You can think of the main voltage levels like this:

System Voltage	Typical AGV size / use case	Comments
24 V	Small AGVs, carts, light-duty mobile robots	Higher current for the same power, thicker cables
36 V	Medium carts and general-purpose AGVs	Less common, often in legacy platforms
48 V	Mainstream warehouse and factory AGVs	Good compromise of efficiency and safety
60–72 V+	Heavy-duty and forklift-style AGVs, long-distance tugs	Usually custom or high-end designs

In the rest of this guide we will use 24 V and 48 V as examples because they match many real projects. If your system is 36 V, 60 V or 72 V, you simply replace the voltage in the formulas.

Step 2 – Estimate Energy Consumption for Your AGV

Once voltage is clear, the next question is:

“How much energy does my AGV actually use in a day?”

You don’t need exact lab data. A good engineering estimate is enough to size the battery.

Basic concepts: power, current and energy

You only need three simple ideas:

• Power (kW) describes how fast the AGV consumes energy.
• Current (A) shows how much electrical flow is used at a given voltage.
• Energy (kWh) is power multiplied by time.

Two useful equations:

• Power (kW) ≈ Voltage (V) × Current (A) / 1000
• Energy (kWh) = Power (kW) × Time (hours)

Method A – Estimate from average power and runtime

If you know your AGV’s typical power draw, you can estimate daily energy:

Energy per day (kWh) ≈ Average power (kW) × Operating hours per day

For example, if a 48 V AGV draws on average 1.5 kW and runs 8 hours per day:

• Daily energy ≈ 1.5 kW × 8 h = 12 kWh

Method B – Use the existing battery as a reference

Many retrofit projects already have a lead-acid pack in use. In that case, you can work backwards:

• Suppose your current 24 V 200 Ah lead-acid battery can support about 4 hours of work before it must be changed or fully charged.
• Nominal energy = 24 V × 200 Ah / 1000 = 4.8 kWh.
• In practice, lead-acid is often used only to about 50–60% DoD, so usable energy is maybe 2.4–2.8 kWh.
• If the AGV runs 4 hours on ~2.6 kWh usable, its average power is ~0.65 kW.

This gives you a starting point for planning a LiFePO4 replacement.

Example: small 24 V AGV and medium 48 V AGV

• Example A – small 24 V AGV
  • The AGV draws an average of 35 A at 24 V and runs 6 hours per day.
  • Power ≈ 24 V × 35 A / 1000 ≈ 0.84 kW.
  • Daily energy ≈ 0.84 kW × 6 h ≈ 5.0 kWh.
• Example B – medium 48 V AGV
  • The AGV averages 2.0 kW over an 8-hour day.
  • Daily energy ≈ 2.0 kW × 8 h = 16 kWh.

We will use these two examples in the next steps.

Step 3 – Convert Energy Needs into Battery Capacity (Ah and kWh)

Now we translate daily energy needs into battery size.

From kWh to Ah at your system voltage

The relationship is:

Capacity (Ah) = Energy (kWh) × 1000 / Voltage (V)

Using our previous examples:

• Example A – 24 V, 5.0 kWh
  • Required Ah (theoretical) ≈ 5.0 × 1000 / 24 ≈ 208 Ah.
• Example B – 48 V, 16 kWh
  • Required Ah (theoretical) ≈ 16 × 1000 / 48 ≈ 333 Ah.

This is the theoretical capacity if you could use 100% of the battery without ageing or efficiency losses. Real batteries cannot be used like this.

Consider usable depth of discharge (DoD)

Different chemistries have different usable DoD:

• Traditional lead-acid / AGM: typically 50–60% of nominal capacity
• LiFePO4: often 80–90% usable DoD

To get the nominal capacity you should buy:

Nominal Ah ≈ Required Ah / (usable DoD)

Using a conservative 80% usable DoD for LiFePO4:

• Example A – 24 V AGV, 5.0 kWh per day
  • Required Ah at 100% DoD ≈ 208 Ah
  • Nominal Ah for LiFePO4 ≈ 208 / 0.8 ≈ 260 Ah
• Example B – 48 V AGV, 16 kWh per day
  • Required Ah at 100% DoD ≈ 333 Ah
  • Nominal Ah for LiFePO4 ≈ 333 / 0.8 ≈ 416 Ah

Add a safety margin

Real life is messy. AGVs face:

• cold temperatures,
• occasional heavier loads,
• future degradation after thousands of cycles.

Most fleet operators add roughly 10–20% margin on top of the calculated capacity.

If we apply a 15% margin:

• Example A – target ≈ 260 Ah × 1.15 ≈ 300 Ah
• Example B – target ≈ 416 Ah × 1.15 ≈ 480 Ah

These are not exact numbers, but they give you a realistic order of magnitude when talking to suppliers.

Example sizing table for different duty cycles

You can use a simple table like this as a cheat sheet for LiFePO4 packs:

Use Case	System Voltage	Daily Energy (kWh)	Suggested LiFePO4 DoD	Calculated Capacity (Ah)	Recommended Pack (Ah)*
Light-duty, single-shift AGV	24 V	3–4 kWh	80%	150–210 Ah	200–250 Ah
Medium-duty, two-shift AGV	24 V	5–6 kWh	80%	210–260 Ah	260–300 Ah
Medium-duty, two-shift AGV	48 V	8–10 kWh	80%	210–260 Ah	260–300 Ah
Heavy-duty, multi-shift AGV	48 V	12–16 kWh	80%	310–420 Ah	400–500 Ah

*Rounded to typical pack sizes. Exact values depend on your supplier’s design.

Step 4 – Match Battery Capacity with Your Charging Strategy

Battery capacity alone does not guarantee uptime. You must also ensure your chargers can put back the required energy within the available charging windows.

Charging patterns: overnight, opportunity and fast charging

In AGV projects, you typically see three patterns:

• Overnight charging – AGVs run during the day and charge in one long block at night.
• Opportunity charging – AGVs take many short charges during loading, waiting or breaks.
• Fast charging – high-power chargers quickly refill the battery in short windows.

LiFePO4 batteries are very well suited to opportunity and fast charging, while lead-acid and AGM are more sensitive to frequent partial charges.

Checking if your charger power is enough

To see whether your charger is strong enough, use:

Energy put back (kWh) ≈ Charger power (kW) × Charging hours per day × Efficiency

If the energy you can put back is less than the energy the AGV uses, the battery will slowly run down over the day or week.

Example:

• Daily energy use: 10 kWh
• Charger: 3 kW
• Available charging time: 3 hours per day
• Efficiency: ~90%

Energy put back ≈ 3 kW × 3 h × 0.9 ≈ 8.1 kWh – not enough.
Either capacity or charging power must be increased.

Example: what charger size is needed for a 24 V AGV?

Suppose your 24 V AGV uses 6 kWh per day, and you want to cover most of this with opportunity charging during 2 hours of total charging time.

You need:

Charger power ≈ Energy per day / (Charging hours × Efficiency)

Charger power ≈ 6 kWh / (2 h × 0.9) ≈ 3.3 kW

So a 3.3–4.0 kW charger (or multiple smaller chargers in parallel) would be reasonable.

Charger power cheat sheet

A simple rule-of-thumb table:

Daily Energy Use (kWh)	Total Charging Hours per Day	Approx. Charger Power Needed (kW)*
4	4	~1.1
6	3	~2.2
8	3	~3.0
10	3	~3.7
12	4	~3.3
16	4	~4.4

*Assuming ~90% efficiency and the goal of recovering almost all daily energy use.

This table is not a design standard, but it helps you see whether a proposed charger size is realistic.

Step 5 – Check Discharge and Charge C-Rates

Even if the voltage, capacity and charger power look fine, you must confirm the battery can safely handle the current in your application.

What is C-rate?

C-rate describes how fast a battery is charged or discharged relative to its capacity.

• 1C means you charge or discharge the full capacity in 1 hour.
• 0.5C means 2 hours.
• 2C means 30 minutes.

For example, a 48 V 400 Ah pack at 1C discharge supplies 400 A. At 0.5C it supplies 200 A.

Peak vs continuous current

AGVs often have:

• short peak currents during acceleration, lifting or ramp climbing;
• lower continuous current during cruising.

When reviewing a battery pack specification, check both:

• continuous discharge current rating (for long driving), and
• peak discharge current rating and allowed duration (for starts and lifts).

The same applies to charging: fast chargers may push 0.5–1.0C or more during opportunity charging. Your battery must be designed for this.

Step 6 – Consider Chemistry and Lifetime

This article focuses on sizing. Chemistry is covered in more detail in a separate guide, but we still need a quick overview because it affects usable DoD and cycle life.

Lead-acid / AGM vs LiFePO4 for AGV sizing

In short:

• Lead-acid / AGM
  • Lower purchase price per kWh
  • Usable DoD typically 50–60%
  • Sensitive to frequent partial charging
  • Shorter cycle life at deep cycles
• LiFePO4
  • Higher purchase price per kWh, but
  • Usable DoD ~80–90%
  • Excellent for opportunity charging
  • 3,000–6,000+ cycles possible at high DoD
  • Maintenance-free

Because of higher usable DoD and longer life, LiFePO4 often allows you to specify smaller nominal Ah than equivalent lead-acid for the same usable energy, and still enjoy much better uptime.

When LiFePO4 makes the most sense

LiFePO4 especially suits:

• multi-shift AGVs running many hours per day,
• fleets that rely on opportunity or fast charging,
• operations where maintenance labor is limited, and
• projects optimized for total cost of ownership, not just purchase price.

For a deeper comparison of chemistries, you can reference your chemistry-focused article about the best AGV battery type.

Step 7 – Mechanical, Safety and Communication Checks

Before finalising an AGV battery specification, take time to review mechanical, safety and communication requirements.

Mechanical fit

• Dimensions and weight – does the new pack fit into the existing compartment?
• Mounting and access – can the pack be fixed securely and removed for service?
• Cooling and airflow – is there enough space for heat to escape?

Safety and standards

Check that the pack design includes:

• appropriate fuses and contactors,
• insulation and earth-fault monitoring where required,
• correct IP rating and shock/vibration robustness,
• relevant safety and performance certifications for your region or industry.

BMS communication

Modern AGV LiFePO4 packs normally integrate a Battery Management System (BMS) that communicates with the vehicle controller via CAN, RS485 or I/O signals.

Clarify with your supplier:

• which protocol your AGV uses,
• what signals are required (SOC, SOH, alarms, charge limits), and
• whether the pack can be configured to match your system.

Worked Examples: Sizing AGV Batteries Step by Step

To see how the pieces combine, let’s walk through two simplified examples.

Example A – Small 24 V AGV with single-shift operation

• System voltage: 24 V
• Operating hours per day: 6 h
• Estimated average current: 35 A
• Daily energy ≈ 24 V × 35 A / 1000 × 6 h ≈ 5.0 kWh

Sizing a LiFePO4 pack:

1. Required Ah at 100% DoD ≈ 5.0 × 1000 / 24 ≈ 208 Ah
2. At 80% usable DoD, nominal Ah ≈ 208 / 0.8 ≈ 260 Ah
3. Add 15% margin → target ≈ 300 Ah

A 24 V 300 Ah LiFePO4 pack would be a reasonable starting point.
If the AGV only charges overnight with a 1.5 kW charger:

• Energy put back ≈ 1.5 kW × 6 h × 0.9 ≈ 8.1 kWh – comfortably above 5.0 kWh daily use.

Example B – Medium 48 V AGV with two shifts and opportunity charging

• System voltage: 48 V
• Operating hours per day: 12 h (two shifts)
• Estimated average power: 2.0 kW
• Daily energy ≈ 2.0 kW × 12 h = 24 kWh

Sizing a LiFePO4 pack:

1. Required Ah at 100% DoD ≈ 24 × 1000 / 48 ≈ 500 Ah
2. At 80% usable DoD, nominal Ah ≈ 500 / 0.8 ≈ 625 Ah
3. Add 15% margin → target ≈ ~720 Ah

But with opportunity charging, you may not need to cover full 24 kWh from the pack alone. For example:

• Pack: 48 V 500 Ah (≈ 24 kWh nominal, ~19 kWh usable at 80% DoD)
• Charger: 6 kW
• Total daily charging time: 2.5 h

Energy put back ≈ 6 kW × 2.5 h × 0.9 ≈ 13.5 kWh

Daily usable capacity + charging ≈ 19 kWh + 13.5 kWh ≈ 32.5 kWh

In this case, a 48 V 500–600 Ah LiFePO4 pack plus 6 kW of opportunity charging power might be enough, depending on your safety margin and peak loads. A specialist can verify currents and thermal limits.

Common Questions When Sizing an AGV Battery

How do I choose the right AGV battery voltage?
You normally do not choose the system voltage yourself – it is set by the AGV manufacturer. Start by reading the rating label on the existing battery or checking the vehicle documentation. Common voltages are 24 V, 36 V, 48 V and higher. Your replacement or upgraded battery must match this voltage, even if you change chemistry.

How big should my AGV battery be in Ah or kWh?
First estimate the daily energy use in kWh from average power and operating hours. Then convert kWh to Ah using Ah ≈ kWh × 1000 / V. Finally apply usable depth of discharge (for example 80% for LiFePO4) and a 10–20% safety margin. The result gives you a reasonable starting capacity to discuss with suppliers.

What is the difference between a 24 V and a 48 V AGV battery?
For the same power, a 48 V system draws roughly half the current of a 24 V system. This reduces cable losses, heating and voltage drop. Many small AGVs and carts use 24 V, while 48 V is common in mid-sized warehouse AGVs. From a sizing point of view, you use the same steps; you simply plug the appropriate voltage into the formulas.

How do charging windows affect AGV battery sizing?
If you can charge only overnight, the battery must hold almost a full day’s energy. If you can opportunity-charge during the shift, part of the daily energy comes from the charger, and the battery can be somewhat smaller. Always check that charger power × total charging hours is at least equal to your daily energy use, with some margin.

Can I use my existing lead-acid charger with a LiFePO4 AGV battery?
Sometimes it is possible, but not always. The voltage range, charge profile and protections of the charger must be compatible with the LiFePO4 pack and its BMS. In many projects, operators switch to a charger designed for LiFePO4 to get faster, safer and more efficient charging. Always confirm compatibility with your battery supplier.

What information should I prepare before asking for an AGV battery quote?
You will get better proposals if you can provide: system voltage, approximate daily operating hours, current or power estimates, existing battery size and runtime, available charging time and power, ambient temperature range and any communication requirements (CAN or RS485). With this data, an AGV battery specialist can quickly recommend a suitable LiFePO4 pack and charging layout.

How SAFTEC Can Help you?

Sizing an AGV battery can feel complex the first time, but you do not have to solve every equation yourself. Saftec Energy can take your duty cycle, charging windows and mechanical constraints and translate them into:

• the right voltage and capacity range,
• appropriate C-rates and thermal limits,
• a matching charger strategy for overnight or opportunity charging, and
• a pack design that fits your vehicle and communication interfaces.

For many fleets, the answer is a 24 V or 48 V LiFePO4 AGV battery with the right Ah rating, designed around your real operating pattern. The goal is simple: keep your AGVs working shift after shift, with predictable runtime and a total cost of ownership that makes sense for your business.