In this article we will learn how to choose a battery according to the specifications and requirements of your application. Some applications need more energy and others need to be cheap and less energy-intensive. There are several factors and parameters that must be considered when choosing the best battery for your application.
Figure 1. Different battery factors to consider
No battery is perfect for all applications. Factors to consider when choosing a battery for your specific applications are provided below.
- Rechargeable or non-rechargeable
- Voltage
- Capacity, power and energy
- Self-discharge
- Temperature
- Cost
- Size and shape
- Lifespan
- Battery Chemistry
- Availability
- Transport
Rechargeable or non-rechargeable
When choosing a battery, the most important point is that it is rechargeable (secondary batteries) or non-rechargeable (primary batteries). This choice will depend on the application. For example, suppose the device is made for occasional use as a flashlight. In this case, or in the case of a toy, calculator, smoke alarm, etc., you can use a non-rechargeable (primary) battery that requires very little power and will work for a long time.
Devices that are used continuously and require continuous discharge, such as laptops, smartphones, smartwatches, must work with rechargeable batteries.
Voltage
Battery voltage is another important factor. A lead-acid battery has a nominal voltage of 2 V, ranging from 2.40 V to 1.8 V. Ni-MH and Ni-Cd batteries have a nominal voltage of 1.2 V, ranging from 1.55 V to 1.1 V. The Li-ion battery has a nominal voltage of 3.7 V and varies from 3.7 V to 3 V. The voltage can be used according to the capacity of your circuit.
Most circuits run on 3V. So we can use two lower voltage batteries in series to get 3V or higher, or use a lithium-ion battery.
Some circuits operate at 5V and 12V or higher. Here again you can use a boost converter to meet the requirements or you can use batteries in series to get a specific voltage.
There are also buck converters available that reduce the voltage. The discharge curve of all batteries is given below. You can see that all batteries have a rough approximate discharge curve.
Capacity, power and energy
Battery discharge time or battery run time depends on battery capacity. Capacity is defined on the battery in Ah or mAh; this is the discharge current capacity to deliver for one hour.
Li-ion cell can provide more power than other Ni-Cd or Ni-MH batteries. The power is multiplied by the current supplied by the battery with battery voltage. If the battery voltage is 3.6V and the current it can supply is 2A, you can use the power calculation given below.
P = V x I (where V is in voltage, I is in Ampere) P = 3.6 x 2
P = 7.2W
Energy is defined as how long energy can be provided by a battery – or we can say energy is multiplayer for time. The battery is capable of delivering 2A for one hour.
E = P x T
E = 7.2 x 1
E = 7.2 Wh (watt-hour)
Let's look at another example using a tank full of water. The power of the tank is the capacity to store 10 liters of water. Now let's open the tank tap and let the water come out. The tank will empty in one hour. This is your energy. It can empty 10 liters in one hour.
Figure 3. Example of power versus energy.
The wattage rating is completely dependent on the manufacturer. You can choose the battery according to your need, either by connecting in series, we can increase the voltage or connect in parallel to increase the current.
Self-discharge
The primary battery has many attractive features as it has a much lower discharge rate. That's why they are perfect for the device that is used occasionally. But the secondary battery has greater self-discharge and charging. If the app can adjust the charging device before use, a secondary battery can be used.
Temperature
Temperature reacts to charging and discharging. The temperature of the lithium-ion battery ranges from 20 to 45 degrees. The temperature can be reduced by reducing the charging current, but this increases the charging time. Discharge temperature depends on how much energy is drawn from the battery; may exceed the calculation of 60 degrees.
Ambient temperature also affects battery performance. The electrolyte may freeze under calculation of 0 degrees. The lithium-ion battery can operate down to -40°C, but performance may be reduced as shown in the graph below.
Figure 4. Temperature for different batteries.
Cost
Cost is important to take into consideration when mass producing the device. If the device needs to be cheap and affordable, there is no question of battery performance; then you can choose the main battery which is cheap and easy to get. The voltage can be increased by connecting it in series.
If there is high power consumption in the device, a secondary battery should be chosen even if it is expensive, as the user does not want to have to change or buy a new battery after one to two hours.
The same goes for performance. If a device needs better performance, you have to compromise on cost.
Size and shape
Batteries come in standard sizes: AA, AAA, AAAA, C, D, 9V, CR123A, 23A and CR2032, allowing you to choose according to power or size. But in devices that don't have much space to place standard size batteries, the lithium-ion battery is available in slim sizes and is also customizable as per your needs.
Figure 5. Standard battery size.
Lifespan
The life cycle number will tell you how many times the battery can be charged or discharged. Lithium-ion battery has a cycle of about 400 to 1200. Ni-Cd and Ni-MH have a cycle of about 2000. The cycle is specified in the manufacturer's data sheet and may vary depending on several factors, such as the amount of current applied to charge it, temperature, etc.
Battery chemistry
There are many types of batteries available on the market that have different chemistry. The most popular are lead-acid, Ni-Cd, Ni-MH and lithium-ion. Battery can be chosen according to requirements.
Availability
If the battery of the device is secondary, it will work for a long time. For the primary battery, the battery must be easily available on the market.
Transport
There are certain rules and regulations for transporting batteries. Alkaline, Ni-Cd and Ni-MH are considered “dry cells” and are not listed as hazardous or hazardous materials by the US. But lithium-ion batteries are listed as hazardous materials, so this is regulated in shipping. The lithium-ion battery must not charge more than 30% for transportation.
Choosing a battery
The following table shows the difference between some of the readily available batteries.
Which battery should I choose?
Considering all the above points, you can choose a battery for your specific application. Here are some additional points to consider.
Primary battery
- If the device can run on low power and there is no need for frequent battery changes
- If you want to make your device cheap
- If device use is occasional
- If it is not possible to load
- If the device is used in the survival area where charging is not possible
- If your device is super small, you can use a coin cell
Acid lead
- If you need more power to run as a projector or any sound system
- The device is fixed anywhere
- If high current with cheap cost is required
Ni-Cd
- If your device is small and can use a standard battery
- If there is no problem with toxic chemicals
- If you want to transport the device
- Low energy density compared to other batteries
- Long life
- High discharge current about 15°-20°C
NiMH
- The energy density is higher than that of Ni-Cd
- Life cycle is shorter than Ni-Cd
- A non-toxic chemical used
- If your device is small and can use a standard battery
- If you want to transport the device
- The discharge current is about 1°-10°C
lithium ion
- Energy density is very high than Ni-Cd or Ni-MH
- Discharge 5°-15°C
- If your device doesn't have much space
- Very expensive
- Can be transported with less than 30% load
References
- https://batteryuniversity.com/learn/archive/whats_the_best_battery#:~:text=Nickel%20Cadmium%20(NiCd)%20%E2%80%94%20mature,relatively%20low%20in%20energy%20density.&text= %20NiCd%20contains%20toxic%20metals,NiMH%20contains%20no%20toxic%20metals .
