LR44 batteries are used to energize numerous devices which are handy and compact. These devices could be related with ordinary daily lives, medical or recreational purposes. LR44 batteries are non-rechargeable small button size batteries so changing them repeatedly might be bothering. This urges manufacturers to test battery’s capacity and keep improving it. Moreover, performances of devices of critical use, like glucose meter and thermometers, relies heavily on performance of battery so its performance also becomes an important parameter to be tested and improved.
This article covers almost all aspects related to performance and capacity testing of LR44 batteries.
What are LR44 Batteries and what are They Used for?
LR44 batteries are small sized batteries which have nominal voltage output of 1.5V. These are also called button cell or coin cell batteries. These are non-rechargeable batteries which are used in small devices or gadgets which could be analog or digital. When it comes to their chemistry, they are alkaline batteries. Equivalents or alternatives of LR44 battery cells include AG13, 357A, and A76. Alternatives might have other chemistries also. Their wide use emerges from them being compact and reliable
It is also important to pay attention to applications of LR44 batteries to emphasize their importance. As mentioned earlier. These mini cells are used in handy gadgets which could be digital or analog. Some examples of these gadgets include:
Gadgets of Critical Use:
LR44 alkaline cell batteries are used widely in medical devices where accuracy is of critical importance. For example, thermometers, glucose meters, and hearing aids use these cells. In essence, these devices need small, reliable, and large capacity energy source; LR44 batteries serve this purpose very well.
Gadgets of Daily Use:
Many gadgets of daily use are also powered using LR44 batteries. For example remotes for TV, calculators, watches, security devices, and camera accessories contain these cells because all mentioned devices are portable so space for cell is also little which can fit LR44 cells feasibly.
Recreational Use
Many toys and games for kids are also powered usinLR44 coin battery cells. For example. Toy laser lights have LR44 batteries to power them. It must be noted that despite increased use of button batteries, they are not recommended for use in toys. It is because of their chemistry which can severely damage organs if kids swallow it, somehow.
Specifications of LR44 Battery Cells:
To analyze performance of any battery or battery system, its specifications must be known so a comparison could be made between tested and standardized figures. Here are some of specifications for LR44 battery. Mechanical specifications are also stated along with electrical ones to give a better idea to the reader.
- It weighs around 2.0 grams and has coin like shape. That’s why it is also called coin or button cell battery.
- Its diameter is 11.6mm and height is 5.4mm.
- Its nominal voltage is 1.5V and cut-off voltage falls between 0.9 and 1.0V. Both voltage parameters depend upon chemistry, usage conditions, and storage conditions of battery cell.
- LR44 battery cell can operate between 0 and 60°C. It would operate at its best if made to operate at 20°C. It must also be noted that at permissible temperature extremes, supply voltage will not remain at 1.5V.
- Apart from operating temperature range, it is important to store LR44 button batteries between 5 and 30°C.
- Capacity is another important performance parameter for any type of battery. LR44 is used in portable gadgets usually and is non-rechargeable so its capacity consideration is even more important. Typical capacity of this battery is 110 to 130mAh.
What is meant by Battery’s Performance?
Testing and analyzing battery’s performance is an important task. But before testing performance parameters of an LR44 battery, you must know what is meant by battery’s performance or what performance parameters for a battery are.
To evaluate performance of any electronic product, a range of electrical parameters are identified (based slightly on the type of product), tested, and analyzed. Product response for these parameters, collectively, gives an idea of performance. Similarly, for LR44 batteries or any other battery, multiple electrical parameters are listed here which are tested and evaluated to analyze battery’s performance.
- Voltage which is open circuit voltage (OCV)
- State of Healthwhich is collection of minimum capacity or reserve capacity, cold start capability, and capability for charge acceptance.
- Internal Resistance
- Shelf life
- Energy density
What is meant by Battery’s Capacity?
For any type of battery, its capability to store charge stands as its core feature. And how much charge a battery can store, indicates its capacity. Higher the capacity (with minimum size indicating higher energy density), better the battery is. In other words, capacity of a battery is referred to the total amount of charge, it can store. Capacity is expressed in Ah units. From unit, you can get another definition of capacity. How much current a battery can provide for how much time, is capacity; because it is multiple of current (A) and time (hour). An LR44 button cell battery, typically, has 110 to 130mAh capacity. Its average capacity falls around 120mAh. Though no battery can deliver current until its stored charge drops to zero. Means, there is a cutoff or minimum capacity at which battery stops performing its function. For LR44 battery, 8mAh is that minimum capacity. This is also called reserve capacity which is not utilized.
In essence, capacity is one of the battery’s performance parameter – an important one.
Testing Performance and Capacity of LR44 battery:
Once all important performance parameters are identified and understood, it is time to know basic tests which are conducted to analyze LR44’s cell performance along with its capacity.
Voltage Testing:
As mentioned earlier, an LR44 battery cell has nominal voltage of 1.5V. This is Open Circuit Voltage (OCV) and is to be tested while keeping cell terminals open or without attaching any load to its terminals. So a digital multimeter or a specialized testing equipment can be used to perform this test.
Apart from nominal voltage, cut-off voltage is another important parameter. This is linked with cut-off capacity and attached load. For this test, load is attached with LR44 cell and it is let to discharge to its fullest or minimum capacity. As battery keeps discharging, supply voltage keeps dropping slowly until it stops giving current. For LR44 battery, cut-off takes place at 0.9 to 1.0V.
Voltage tests give an idea about internal resistance and efficiency also.
Shelf Life Testing:
Shelf life pertains to the period for which a battery can be stored still retaining significant (ususally 80%) amount of charge within it. It must be ensured that no current flows during this time and no corrosion happens at positive electrode of battery. Capacity drop happens due to self-discharge and internal resistance.
It, highly, depends upon storage conditions of battery. For LR44 button batteries, shelf life is between 2 and 5 years. To conduct shelf life testing, battery is passed through accelerated aging process.
Capacity Testing:
As discussed earlier, capacity is all about amount of charge stored in a battery cell. This charge can be drawn slowly or rapidly from the cell affecting duration for which load can be powered and cut-off or minimum capacity. Residual or reserve or cut-off capacity of an LR44 battery cell is 8mAh. During capacity testing, a load is attached with battery and later is let to discharge. Voltage is monitored and plotted continuously. As voltage reaches, cut-off voltage, battery shuts-off and this is minimum capacity.
Amount of current drawn and time of operation is noted and their multiplication gives capacity. It is compared with claimed capacity of LR44 battery cell. Higher storage capacity and lower minimum capacity are desirable features for any kind of battery including LR44.
Measuring State of Health
State of health of a battery is not indicated by any single parameter. Instead, it indicates overall condition of battery. For example, if a batch of battery cells is stored for some time; it might be needed that manufacturer accesses its remaining life and usefulness before dispatching it in the market as it will affect company’s reputation and client’s trust level.
To access state of health (SOH) for such purpose for an LR44 battery cell, its available capacity or state of charge, internal resistance, and supply voltage are measured.
Thermal Testing:
Thermal testing of a battery is very much related to its reliability and safety. For thermal testing of an LR44 battery, it is stored within its storage temperature range (tests to be conducted multiple times for multiple temperature points) and tests are run to see how state of charge, internal resistance, efficiency, and open circuit voltage are impacted. It is also ensured that battery doesn’t explode and pose safety concerns during its storage.
After storage thermal tests are run and parameters are analyzed, thermal testing is done during operation mode also. Temperature is changed and for different temperature values; OCV, internal resistance, capacity, and depth of discharge are measures and analyzed. Moreover, it is ensured that LR44 battery keeps operating safely even if temperature goes as high as 60°C and as low as 0°C.
FAQs
Q1. How is cycle life testing done for LR44 button battery?
Cycle life testing is performed to know how many charge and discharge cycles, a battery can endure before its storage capacity falls below its minimum capacity. Definition of life cycle testing suggests that this test involves charging and discharging of a battery. You already know that LR44 is a non-rechargeable battery which is disposed of after one-time use. So life cycle testing is not for LR44 battery and no test procedures are required to realize this.
Q2. What is the chemistry of LR44 Battery Cell?
LR44 are alkaline batteries making them high charge density primary cells. Positive electrode is made of manganese dioxide and negative electrode is made of metallic zinc powder. Sodium hydroxide or Potassium hydroxide are used as electrolyte. Two compartments are separated using a separator which could be some polymer film.
Q3. Are LR44 batteries safe?
LR44 batteries are considered safe for environment because of their alkaline chemistry. As these batteries don’t contain any toxic material like lead, cadmium, or mercury so they don’t carry severe pollution aspects. Anyhow, these batteries might corrode or leak over time just like any other battery. Moreover, their ingestion can damage internal organs so these must be kept away from kids. Touching open batteries with skin or eye can also be problematic as chemical burns and irritation can happen. Conclusively, it is advised to use these batteries while following all safety instructions.
Q4. Are there any alternatives to LR44 batteries?
As far as title or name is concerned, LR44 batteries are also known as button cell batteries or coin batteries due to their small size and coin-like shape. Alternatives, in terms of product, are also available in the market. Some have little change of nominal voltage or chemistry type. Other are same. These alternatives include AG13, A76, 357, and 76A.
Conclusion:
Readily availability of LR44 coin cell battery, paired with its small size, high efficiency, and low price makes its suitable for many applications including electronic products, toys, and games. To ensure that a LR44 battery performs reliably, safely, and efficiently; it is essential to measure and monitor some of its performance parameters and capacity. Tests are run to access and analyze each parameter individually. Capacity is one of those parameters. Anyhow, it is given more importance because of its linkage with many other parameters like depth of discharge, efficiency, cut-off voltage, reserve charge, and state of health. You can use simple multimeters and simulation tools to run these tests or buy automated testing equipment designed specifically for testing LR44 coin cells.