What Are the Key Technical Specifications of a Robot Battery Pack?

Integrating a battery into a robotic system involves complex choices about charging, chemistry, and safety. Making the wrong choice can shorten battery life, give you incorrect runtime calculations, or even create dangerous compatibility issues.

Key specifications include understanding charging protocols, like not keeping lithium batteries at 100%. You must also know how to calculate runtime and differentiate between chemistries like LTO, LiPo (Lithium Polymer), and standard Li-ion to ensure safety.

I once worked with an engineering team whose robot prototype failed during a key client demonstration. The cause? They had used an incompatible charger for their battery pack, which damaged the cells. This highlights why mastering these technical details is essential for success.

Is it bad to keep lithium batteries fully charged?

Many of us have a habit of keeping our devices plugged in. However, for a high-value industrial battery pack, this is a bad practice that can cost you money.

Yes, it is bad for the long-term health of most lithium-ion batteries to keep them at a 100% state of charge for long periods. A fully charged battery is under high stress, which accelerates its aging process and permanently reduces its capacity.

The Chemistry of Battery Stress

When a standard lithium-ion cell is at its maximum voltage (around 4.2V), it is in an unstable state. This high-energy state speeds up unwanted chemical reactions inside the cell. The liquid electrolyte can slowly decompose and form a resistive layer on the electrodes. This process, called "parasitic reactions¹," increases the battery’s internal resistance and lowers the amount of energy it can store.

Best Practices for Charging and Storage

As battery engineers, we recommend two key strategies to our clients to maximize the service life of their battery packs:

• For Daily Use: Program the charging system² for your robotic fleet to stop charging at 80% or 90%. This avoids the highest-stress voltage levels and can easily double the battery’s useful lifespan.
• For Long-Term Storage: If a robot will be inactive for a month or more, you should not store its battery fully charged or fully empty. The ideal storage level is around 50% state of charge. This is the most stable state for the battery’s chemistry.

How long will a 100Ah lithium battery run an appliance that requires 1000W?

This is a fundamental power calculation³ that every system designer must be able to perform accurately. The answer depends entirely on the system’s voltage.

A 100Ah lithium battery running a 1000W load will last for about 1.2 hours at 12V, 2.4 hours at 24V, or 4.8 hours at 48V. Higher voltage systems are more efficient and will provide longer runtimes for the same power draw.

The Calculation Formula

To figure this out, you need two simple steps based on the law of electricity: Power (Watts) = Voltage (Volts) × Current (Amps).

1. First, find the current your appliance draws in Amps.

   • Formula: Current (A) = Power (W) / Voltage (V)
   • For a 48V system: 1000W / 48V = 20.8A. The appliance will draw 20.8 Amps.

2. Next, calculate the runtime in hours.

   • Formula: Runtime (h) = Battery Capacity (Ah) / Current (A)
   • For our example: 100Ah / 20.8A = 4.8 hours.

Here is a table showing how voltage drastically affects runtime for the same 1000W load.

Note: This calculation is theoretical. In the real world, you also have to account for power loss from the inverter (if used), which is typically around 10-15%.

What is an LTO battery?

While most lithium-ion batteries⁴ are designed for high energy content, some specialized chemistries are built for other extreme capabilities. LTO is one of them.

An LTO battery is a type of lithium battery that uses Lithium Titanate Oxide (LTO) in its anode instead of the typical graphite. This special anode material allows the battery to operate for an incredible number of cycles and at very low temperatures.

The Pros and Cons of LTO

LTO is a niche chemistry for very specific applications where its advantages outweigh its significant downsides.

Key Advantages:

• Extreme Cycle Life: An LTO battery⁵ can last for 15,000 to 20,000+ cycles. This is nearly 10 times longer than a standard Li-ion battery.
• Very Fast Charging: It can be safely charged to over 80% capacity in less than 10 minutes.
• Wide Temperature Range: It performs well in extreme cold (down to -30°C) where other batteries would fail.

Key Disadvantages:

• Low Energy Density: LTO batteries are larger and heavier than other lithium chemistries for the same amount of energy.
• Low Voltage: The nominal cell voltage is only 2.4V, meaning you need more cells in series to build a high-voltage pack.
• High Cost: The raw materials and manufacturing process make LTO batteries very expensive.

What does LiPo stand for?

You see the term "LiPo" everywhere in the world of drones and hobby electronics. Let’s clarify exactly what it means.

LiPo is short for Lithium Polymer. The name refers to the use of a solid or gel-like polymer electrolyte inside the battery, which differs from the liquid electrolyte used in most other lithium-ion cells.

The Disadvantages of LiPo⁶ Batteries

While LiPo batteries are great for lightweight applications, they have serious drawbacks that make them unsuitable for most industrial robotic applications.

• Physical Fragility: LiPo batteries are packaged in a soft pouch. This pouch can be easily punctured or damaged during operation, which can cause a fire. Cylindrical Li-ion cells are protected by a strong steel case.
• Short Cycle Life: A typical LiPo battery has a lifespan of only 300 to 600 cycles. This is not enough for a commercial robot that needs to work every day for many years.
• Sensitivity to Mishandling: They are much less tolerant of being over-charged or over-discharged than robust industrial batteries that are protected by an advanced Battery Management System⁷ (BMS).

Can you charge a Li-ion battery with a LiPo charger?

This is a critical safety question. Mixing and matching chargers and batteries without expert knowledge is extremely dangerous.

It is highly risky and not recommended. While the basic charging method (CC/CV) is similar, key voltage limits and safety features can be different. Using a charger not specifically designed for your battery pack can lead to permanent damage or a fire.

Why It’s a Bad Idea

There are two main technical reasons to avoid this.

1. Voltage Mismatch: The most common LiPo and Li-ion cells both have a maximum charge voltage of 4.2V. However, a different Li-ion chemistry like LiFePO₄ has a max voltage of only 3.65V. If you used a standard LiPo charger on a LiFePO₄ battery, you would severely overcharge it, which is a catastrophic failure event.
2. Lack of Communication: In a professional system, the battery pack’s BMS communicates with the charger to ensure everything is operating safely. A simple hobby-grade LiPo charger does not have this communication capability. It blindly supplies power without knowing the battery’s temperature or cell health.

As a rule for all our engineering clients, we give this simple advice: Always use the specific charger that was supplied with or approved by the battery pack’s manufacturer. There are no exceptions.

Conclusion

Mastering a battery’s technical specifications—from charging rules to chemistry differences—is essential for engineering a safe and high-performance robotic system. Always prioritize safety, reliability, and compatibility when designing your robot’s power source.