Do you know why the remote control car suddenly stops working, or the power bank tends to run out faster? Sometimes it happens as the battery does not correspond to the needs of this device. This problem can be fixed only by learning how to calculate the right size battery for any device.
If that sounds too technical, don’t worry. Everything will be fun and simple in this post. Let’s get started!
Why Battery Size Matters
Batteries are your device’s fuel tanks. If the tank holds too little, then your device is very quickly stopped. The tank size may enlarge to the point where it becomes bulky, too heavy to lift or too expensive to build.
Selecting the proper battery makes your device operate correctly, endure longer, and remain safe. An example of this could be your phone, flashlight, or even an electric bike that requires a battery of equivalent power.
Key Terms You Should Know
You should understand the basic terms before starting to calculate.
1. Voltage (V)
The strength of that electric push is voltage. The devices generally need such a voltage to work. For example, a phone will need 3.7V.
2. Current (Amps or A)
If power flow is happening it is measured by current. The more current, the more power will be used.
3. Watt (W)
The total power used is shown in watts. To get watts, multiply volts by amps.
Formula:
- Watts = Volts × Amps
- 4. Milliampere-hour (mAh) or Ampere-hour (Ah)
This term indicates how long a battery can keep your device running. A more mAh means less of a battery that lasts longer.
Step-by-Step: How to Calculate the Right Size Battery
So let’s go through a simple way of finding the right battery size.
The first step will be to determine the power consumption of the device.
Before anything else, refer to your device label, user manual or online specs. You need two main things:
- Voltage (V)
- Current (A or mA)
Example:
- You have a small LED lamp that needs 5 volts but 2 amps.
Step 2: Decide How Long You Want the Battery to Last
Now, ask yourself:
“To take, how many hours should this battery run before needing recharging?”
If you wish to have the LED lamp run for 5 hours.
Step 3: Use the Formula to Find Battery Capacity
Now use this simple formula:
Battery Capacity (Ah) = Current (A) × Time (h)
In our example:
Battery Capacity = 2 A × 5 h = 10 Ah
Thus, you would require a 10 Ampere hour battery.
If your battery is common for smaller ones and has capacity in mAh, just convert as follows:
1 Ah = 1000 mAh
So,
10 Ah = 10,000 mAh
Now you know you need a 10,000 mAh battery for your lamp to run 5 hours.
Step 4: Make Sure the Voltage Matches
Never forget this step!
Your device must be the same voltage as your battery. For our example the battery should supply 5 volts, just as the lamp.
The device may not turn on or be damaged if the voltage doesn’t match.
What Happens If You Use the Wrong Battery Size?
Following are the problems which can arise when you are using the wrong battery size:
- Too small: After a while, the battery discharges fast or overheats.
- Too big: Also, the battery is bulky and more costly than what is needed.
- Wrong voltage: It may not work, break, or even be damaged.
The battery is an important part and should always be calculated and double checked before choosing the battery.
Real-Life Example: Charging a Smartphone
Let’s say your smartphone uses:
- 3.7V
- 3000 mAh
- 2 hours from a 5V, 2A charger
If that would let you imagine, you would like to make a power bank that would charge this phone two times.
The following is how to figure out the battery size of the power bank.
Step 1: Total power needed for 2 charges
Phone battery = 3000 mAh
So, 2 charges = 3000 × 2 = 6000 mAh
You can add a little extra to account for power loss (about 20%).
6000 × 1.2 = 7200 mAh
Step 2: Choose a battery with at least 7200 mAh at 5V
The capacity of your power bank now needs to be a 7200mAh battery so your phone can be fully charged twice.
Tools That Can Help You
You aren’t expected to have to do all the math in your head. Use online tools and calculators. Go ahead and type “battery size calculator” into Google, and you will find multiple options.
Some tools only need:
- Voltage
- Current
- Usage time
They will tell you the size of the battery and it is instant as they are battery experts.
Tips to Pick the Best Battery
- Always match the voltage.
- Choose a spare battery with a little bit more than needed (just in case).
- Also, the battery needs to be sure that it physically fits your device.
- If you are buying batteries online check the review.
- Buy only from trusted brands or stores.
Common Battery Sizes for Teens’ Devices
| Device | Voltage | Current | Common Battery Size |
|---|---|---|---|
| Remote control toy | 3V–7.4V | 0.5–2A | 1000–2000 mAh |
| Bluetooth speaker | 3.7V | 1A | 2000–4000 mAh |
| LED strip lights | 12V | 1–3A | 5000–10000 mAh (or more) |
| Power bank for phones | 5V | 2A | 10000–20000 mAh |
Final Thoughts
It’s not as difficult as you think to learn how to calculate the right size battery. Once you understand volts, amps, how many you want your device to run for, the rest becomes easy.
Now you can build your own gadgets, fix broken ones or even design a cool science project. And keep it safe when dealing with electrical items.
Next time you purchase a battery, or DIY contraption, remember this guide and opt for battery sizing like a pro!
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