Battery Selection: Some Factors to Consider

How do you select the correct battery in PCB design

Ⅰ Introduction

The energy storage units of several devices we come across every day are batteries; they are available in various shapes, sizes, parameters, and shapes. They can usually be found in vehicles, emergency power sources, mobile devices, tablets, iPads, and many other portable electronic devices. But not all devices will use the same type of battery; each device has its own specifications and power supply requirements, and to choose the right battery for your application, you will need a battery selection guide. So, the considerations to consider when choosing a battery for your next electronic product design will be investigated in this post. If you are completely new to batteries, then it is recommended that you read this article on battery types and their applications before continuing further to understand the fundamentals of batteries.

Catalog

Ⅰ Introduction

Ⅱ Some Factors to Consider

Ⅲ Rechargeable / Non-Rechargeable Batteries

Ⅳ Availability of Space

Ⅴ System Operating Voltage

Ⅵ Operating Temperature

Ⅶ Capacity-Power & Energy

Ⅷ Chemistry

Ⅸ Cost

Ⅹ Shelf Life

Ⅺ How to Choose a Battery

Ⅻ FAQ

Ⅱ Some Factors to Consider

You must be aware of the important parameters involved in its activity when selecting a battery for your application. The truth of the battery is that, because no battery is ideal, there is no common form of battery for all applications. You should be able to manage the exhaustion of other parameters when you choose to use one parameter of the battery. For example, if you want your battery to provide a lot of energy for your application, the internal resistance of the cell should be reduced, which can only be accomplished by increasing the surface area of the electrode. Inactive components such as current collectors and conductive aid are also improved by this because energy density is traded off to gain power. You must give up anything to get the other in a battery in order to get exactly what you want in your application. In the following picture, the important battery parameters are given.

Now, to understand its significance and effect on battery efficiency during service, let's briefly look at each battery parameter.

Ⅲ Rechargeable / Non-Rechargeable Batteries

In deciding between a main and secondary battery, there might not be much uncertainty, you only have to decide whether you want the battery to be used once or several times. The primary (non-rechargeable) battery can be used for occasional applications such as toys, flashlights, smoke detectors, etc. They are also used in products such as pacemakers, wristwatches and hearing aids where charging is not feasible. The secondary (rechargeable) batteries can be used in applications where a standard power source such as cell phones, computers, cars, etc. is needed. Compared to primary batteries, secondary batteries often have a higher self-discharge rate because of their ability to recharge, which is an ignorant fact.

Ⅳ Availability of Space

The batteries, including button cells, cylindrical cells, pouch cells and prismatic cells, are available in different shapes and sizes. In order to make your computer comfortably portable, the battery size really matters. AA, AAA and 9V batteries suitable for portable devices are the standard sizes available. In applications where there is less room but more power needed, lithium batteries (pouch type) are widely preferred. If the power demand is lower since they are very lightweight and the smallest of battery types, coin cells may also be considered.

Battery size

Ⅴ System Operating Voltage

One of the most significant characteristics of the battery, which is calculated based on the electrode & electrolyte used, is the battery voltage (Chemical Reaction). There is a common misconception that in any device, it is not the case that a fully discharged battery would have 0V. In fact, if the battery reads 0V, it's probably dead. A battery's output voltage should always be read from its nominal voltage level.

Water is used as an electrolyte by the zinc-carbon battery and nickel-metal hydride battery and provides a nominal voltage of 1.2V to 2V, while the lithium-based batteries use organic electrolytes that can provide a nominal voltage of 3.2 to 4V. Most of the equipment's electronic parts run in the 3V voltage range. A single cell battery would be enough to power the equipment if you use a lithium-based battery. Note that the battery voltage will not be constant and will differ between the minimum value and the maximum value, depending on the battery power available. This is the minimum and maximum value shown below for each battery.

Your nominal voltage would only be 3.2V to 4V if your circuit is running at 5V and you are charging it with a lithium battery. Boost converter circuits are used in these cases to convert the battery voltage required for the circuit to 5V. If your operating voltage is very high, like 24V or 12V, you can either use a 12V lead-acid battery or combine more than one lithium cell in series to increase the resulting output voltage if you need high power density.

Ⅵ Operating Temperature

For example, the battery operating with aqueous electrolytes can not be used in temperature conditions below 0 ° C as the aqueous electrolyte could be frozen below 0 ° C, in the same way, the lithium-based batteries could work up to -40 ° C, but the efficiency could be reduced. The battery performance can be drastically modified by the temperature.

The optimum charging rate for the lithium-ion batteries is between the temperature ranges of 20 ° C to 45 ° C. If you want to use a lower current/voltage outside this temperature range, this will result in a longer charge time. Lithium dendrite plating can be produced in the electrolyte if the temperature drops below 5 ° C or 10 ° C, which must be avoided by trickle charging.

Ⅶ Capacity-Power & Energy

The battery's strength determines the battery's runtime. Battery power/capacity is expressed in watt-hours (Wh). By multiplying the battery voltage (V) by the amount of current a battery can produce over a given amount of time, the watt-hour is determined. The battery voltage is almost set and the current that can be supplied by a battery is written on the battery, expressed in the Ampere-hour rating (Ah or mAh).

Consider a 5V battery with a capacity of 2 amp-hours (Ah), so it has a power of 10Wh. The 2Ah battery will produce 2 Amps for 1 hour or 0.2A for 10 hours or 0.02A (20mA) for 100 hours. At a given discharge rate, temperature, and cut-off voltage, battery manufacturers often specify the power, where the capacity always depends on all three variables.

A battery's capacity can tell us how much energy it can supply to an application. For instance, consider a 12V, 10Ah car battery, the battery's actual capacity is 120Wh (12V x 10Ah), but it will have a capacity of 36Wh in a 3.6V laptop battery that has the same 10Ah dissipation (3.6Vx 10Ah). You can see from the example that the amount of power a car battery can hold is three times higher than a laptop battery, even though they have the same Ah.

High-power batteries always have quick discharge capabilities at high drain speeds, such as power tools or applications for vehicle starter batteries, with poor energy capacity for most high-power batteries.

Ⅷ Chemistry

You would have learned by this time that all the characteristics of a battery are often dependent on the chemistry involved in the battery, so when selecting the type of battery, you should be more conscious. Batteries are known as Lead Acid Batteries, Alkaline Batteries, Ni-Cad Batteries (Nickel Cadmium), Ni- MH Batteries (Nickel Metal Hydride), Li-Ion (Lithium-Ion) and LiPoly (Lithium Polymer) Batteries based on the chemistry used in the process.

Ⅸ Cost

The battery will be one of the costly things in the Bill of Materials (BOM) for most portable electronic devices, so it will impact the total cost of your electronic applications most of the time. Therefore, you should know your product specifications and budget and then pick the right battery for your product.

Ⅹ Shelf Life

Not all batteries are used directly after development, but they remain on the shelf for a long time before they are used. A battery's shelf life informs you how long it is possible to keep a battery unused. In primary batteries, the shelf life is largely known as a reality only because the secondary batteries can be recharged once they are used. The battery could sit idle there for years, for example, in a fire alarm siren device, until it detects a fire and activates the alarm. The battery maintains its output even if it is left unused for a long time, so care should be taken.

Ⅺ How to Choose a Battery

Now that we've looked at the criteria that you should consider before selecting the battery for a portable electronic application, let's look at the common battery selection cases. Bear in mind that these are just tips and not difficult written guidelines.

• You can use lead-acid batteries for items that consume more electricity, including projectors, large sound systems, and motorized projects. You can go for 'Sea deep cycle' batteries if you're going to have heavy battery use.

• You can go for the lithium coin cells or small lithium polymer cells if your electronics need to be very small, about an inch on either side.

• If you are going to manufacture the part, use inexpensive alkaline batteries of common sizes in large quantities. So the client considers it easy to replace them.

• If you want the product to be user-serviceable, the battery can be adjusted by the customers themselves for batteries of 9V or AA capacity.

• Use 3 Alkaline (4.5V) or 4NiMH (4.8V) cells if the circuit needs an input of approximately 5V.

• Use a battery holder from your local shop to build a rechargeable battery pack and stick it with NiMH batteries and then begin recharging your battery.

• If you want to replace any of the rechargeable batteries with your alkaline battery, test your system to make sure it will work at a lower voltage without any problems.

• Always use a high-quality charger with sensors to ensure proper charging and trickle charging if you want your battery to have a longer life span since using a cheap charger would destroy your cells in the battery pack.

Ⅻ FAQ

1.How do I select a battery for an inverter?

The main points to take into consideration while selecting a battery for an inverter are the load to be supplied and the backup time required. The load would decide the capacity of the inverter and hence the voltage of the battery. The backup time decides the capacity of the battery to be used. Both combined decide the number and capacity of batteries required.

2. How do I select a battery for a electric device?

This depends on total power consumption of the device, Volt * current = power.

Now how many hours battery should work, Multiply with power rating, add 20 ℅ extra for loss and maintenance.

3. How do you select the correct battery in PCB design?

It is not the PCB design that matters, it is the circuit. There are many factors that go into battery selection for a device. The voltage required, the power drain vs desired run time, the space available are the main parameters. The cost and availability of the batteries are also factors. If your product uses an N cell or a AAAA, then users will not be so happy when they go to purchase one.