LiPo and NiMH batteries, widely utilized in similar domains, often ignite discussions about their dissimilarities. Our article delves into the LiPo vs NiMH battery debate, offering comprehensive insights into various aspects.
To make a right decision which one to get, you need to be armed with information about the technological disparities, differences in weight, cost, and numerous other factors.
NiMH & LiPo Battery Comparison
| Criteria | NiMH Batteries | LiPo Batteries |
|---|---|---|
| Energy Density | Lower energy density | Higher energy density |
| Voltage | Nominal voltage of 1.2V per cell | Nominal voltage of 3.7V per cell |
| Discharge Rate | Lower discharge rates | Higher discharge rates |
| Charge Cycles | 500-1000 cycles | 200-300 cycles |
| Self-Discharge | Higher self-discharge rate | Lower self-discharge rate |
| Memory Effect | Susceptible to memory effect | No memory effect |
| Safety | Less sensitive to mishandling | More sensitive, requires caution |
| Cost | Generally more affordable | Often higher priced |
Energy Density
Energy density refers to the amount of energy that can be stored in a given volume or weight of a battery.
It represents how much power a battery can hold relative to its size or mass. Batteries with higher energy density can provide more power or run for a longer duration before needing to be recharged. This is particularly advantageous in applications where space and weight constraints are critical.
Higher energy density allows for smaller and lighter battery designs without sacrificing performance. It is an important factor to consider when selecting a battery, as it directly impacts the capacity and runtime of a device.
Voltage
Battery voltage refers to the electrical potential difference between the positive and negative terminals of a battery. It represents the force or pressure at which electrons flow from the negative terminal to the positive terminal, creating an electric current.
Battery voltage is measured in volts (V) and determines the power output or capacity of a battery. Devices typically require a specific voltage to operate correctly, and matching the required voltage is crucial for compatibility.
Higher voltage batteries provide more power and can drive devices that require higher energy demands, while lower voltage batteries are suitable for devices with lower power requirements.
Discharge Rate
Battery discharge rate refers to the speed at which a battery can release stored energy. It measures how quickly the battery can deliver power to a connected device or system.
The discharge rate is typically expressed in terms of the maximum current that a battery can provide continuously without a significant drop in voltage. Higher discharge rates allow batteries to supply power rapidly, making them suitable for applications that require quick bursts of energy or sustained high-power output.
Different battery chemistries have varying discharge rate capabilities, and selecting a battery with an appropriate discharge rate ensures that it can meet the power demands of the specific device or system it powers.
In fact, one of the ways to fuel more demanding engines is to have batteries with higher discharge rates, this is one of the ways to make your RC car go faster.
Charge Cycles
Charge cycles refer to the number of complete charge and discharge cycles that a battery can undergo before its capacity significantly diminishes.
Each charge cycle represents the process of fully charging the battery and then completely discharging it. For example, if a battery is charged from 0% to 100% and then discharged back to 0%, it completes one charge cycle.
Self-Discharge
Battery self-discharge refers to the natural loss of charge that occurs over time when a battery is not in use or disconnected from a power source. It is the internal chemical reactions within the battery that slowly drain its stored energy.
Self-discharge rate varies among different battery types and is typically expressed as a percentage of charge lost per unit of time.
Batteries with high self-discharge rates lose their charge relatively quickly, while those with low self-discharge rates can retain their charge for longer periods. Low self-discharge batteries are advantageous for devices that are infrequently used or require long shelf life, as they maintain their charge for extended periods without needing frequent recharging.
Memory Effect
Battery memory effect, also known as voltage depression, is a phenomenon that can occur in certain types of rechargeable batteries, such as nickel-cadmium (NiCd).
It refers to the gradual loss of battery capacity when the battery is not fully discharged before recharging. If a battery is consistently recharged without being completely discharged, it “remembers” the shortened capacity and exhibits a reduced ability to deliver its full capacity over time. This can lead to a perceived decrease in the battery’s overall performance and runtime.
Memory effect is less prevalent in modern battery chemistries like lithium-ion (Li-ion) and nickel-metal hydride (NiMH), making them less susceptible to this issue.
Safety
Battery safety refers to the precautions and measures taken to prevent accidents or hazards associated with the use, charging, and storage of batteries. Safety considerations include preventing overcharging, over-discharging, short circuits, overheating, and physical damage to the battery.
Proper handling, following manufacturer guidelines, using compatible chargers, and storing batteries in appropriate conditions are essential for safe battery use. Certain battery chemistries, like lithium-ion (Li-ion), require additional safety measures due to their sensitivity to high temperatures and potential risk of thermal runaway.
Adhering to safety practices mitigates the risk of battery malfunction, leakage, fire, or explosion, ensuring the well-being of users and property.
Cost
Cost of batteries is an important factor as you will go through a number of batteries in your RC bobby.
Generally, advanced and specialized battery chemistries, such as lithium-ion (Li-ion) and lithium-polymer (LiPo), tend to be more expensive than traditional battery types like nickel-metal hydride (NiMH).
NiMH Battery Overview & History
Nickel Metal Hydride (NiMH) batteries were developed as an improvement over Nickel Cadmium (NiCd) batteries, addressing the environmental concerns associated with the latter.
The history of NiMH batteries dates back to the late 1980s when a team of researchers at Stanford University, led by Dr. Stanford Ovshinsky, developed the first practical NiMH battery. Their goal was to create a more environmentally friendly and higher-capacity battery than NiCd. The key innovation was the use of a metal hydride alloy for the battery’s negative electrode (anode) instead of toxic cadmium. This breakthrough made NiMH batteries a safer and more environmentally friendly option.
NiMH batteries offer several advantages over NiCd batteries. They have a higher energy density, allowing them to store more energy per unit of weight or volume. This translates to longer runtimes and higher capacities. NiMH batteries also have a lower self-discharge rate compared to NiCd, meaning they can hold their charge for longer periods when not in use.
Over the years, NiMH batteries have found widespread use in various applications such as portable electronics, hybrid electric vehicles (HEVs), and power tools. Their ability to deliver higher capacities and environmentally friendly nature has made them a popular choice among consumers.
However, NiMH batteries do have some limitations. They suffer from a phenomenon called memory effect, where the battery loses capacity if not fully discharged before recharging. This effect has been reduced in modern NiMH batteries but is still something to consider. Additionally, they have a lower energy density compared to Lithium-ion (Li-ion) batteries, which limits their use in applications that require higher power or longer runtime.
Despite these limitations, NiMH batteries continue to be widely used due to their reliability, affordability, and comparatively lower environmental impact compared to certain other battery chemistries. Ongoing research and development aim to further improve their performance and address their limitations, ensuring their relevance in the evolving landscape of rechargeable batteries. In fact, the smaller RC cars are, the most likely they are to use NiMH batteries rather than LiPo, so most mini RC cars are powered by NiMH.
LiPo Battery Overview & History
Lithium Polymer (LiPo) batteries have become increasingly popular in various industries, including consumer electronics, drones, RC cars, and electric vehicles. Here’s an overview of LiPo batteries and their history:
LiPo batteries originated as an advancement in lithium-ion battery technology, which itself emerged in the 1970s. The development of LiPo batteries can be attributed to the efforts of several researchers and companies seeking to improve battery performance and address the limitations of other chemistries.
The first commercially viable LiPo batteries were introduced in the early 1990s by a research team at Bell Labs, led by Dr. Michel Armand. These batteries utilized a polymer electrolyte instead of the liquid electrolyte found in traditional lithium-ion batteries. The polymer electrolyte allowed for the construction of flexible, lightweight, and more compact battery cells, paving the way for the widespread adoption of LiPo technology.
LiPo batteries offer numerous advantages over other battery types. Their high energy density means they can store more power in a smaller size and weight, making them ideal for portable electronics and applications where space is a constraint. LiPo batteries also have a low self-discharge rate, meaning they can retain their charge for extended periods without significant power loss.
One of the significant advantages of LiPo batteries is their ability to deliver high discharge rates. This characteristic makes them suitable for applications that require a burst of power, such as RC vehicles and drones. LiPo batteries can provide the necessary current for rapid acceleration and sustained high-performance output. In fact, due to its ideal RC applicability, LiPos have started one of the most controversial topics in the RC world, which is Nitro vs. Electric.
However, LiPo batteries also come with certain considerations. They require special care and attention during charging, usage, and storage to ensure safety. Overcharging, over-discharging, or mishandling LiPo batteries can lead to thermal runaway, a potentially hazardous situation where the battery can swell, leak, or even catch fire. Proper charging equipment, storage bags, and adherence to manufacturer guidelines are essential for the safe use of LiPo batteries.
In recent years, ongoing research and advancements have focused on improving the safety, performance, and longevity of LiPo batteries. These efforts include the development of enhanced electrode materials, improved electrolytes, and advanced battery management systems to monitor and control charging and discharging processes.
Overall, LiPo batteries have revolutionized the rechargeable battery market with their high energy density, lightweight construction, and ability to deliver high currents. Their versatility and performance have made them a popular choice for a wide range of applications, driving innovation and further developments in the field of rechargeable battery technology.
