Power Supply Basics: Choosing the Right Battery for Your Project

Looking to power your electronics efficiently? Explore a wide range of batteries and power supplies at Tomson Electronics, perfect for DIY projects, industrial needs, and academic use. Find reliable, high-performance power supply components all in one place. Whether you’re building a simple LED gadget, a wireless sensor node, or a mobile robot, choosing the right battery is one of the most crucial (and overlooked) parts of the project. Power it wrong, and your fancy electronics can under perform, misbehave or worse, get damaged.

In this guide, we’ll walk you through everything you need to know about batteries: the types, voltages, capacities, and how to match one perfectly to your electronics project.

Why Battery Choice Matters

A project is only as reliable as its power source. The battery you choose will directly affect:

• Runtime – how long your device can stay on
  

• Performance – sensors or motors may under perform if under powered
  

• Portability – a huge battery adds bulk and weight
  

• Safety – mismatched batteries can overheat or leak
  

So don’t just grab any battery, choose smart.

Step 1: Understand Your Power Needs

Before picking a battery, ask yourself:

1. What voltage does your circuit need?
   

• Most microcontrollers like Arduino run on 5V or 3.3V
  

• Motors and actuators might require 6V–12V
  

2. How much current (amps) will it draw?
   

• LEDs use milliamps (mA), motors use amps (A)
  

• Add up the current draw of every component in your circuit
  

3. How long do you want it to run?
   

• Multiply current draw (in amps) by runtime (in hours) to get capacity needs in amp-hours (Ah) or milliamp-hours (mAh)
  

Example:
A 5V project drawing 300mA for 5 hours needs at least:
300mA × 5h = 1500mAh of capacity

Step 2: Know Your Battery Types

Here’s a rundown of the most common battery types used in electronics:

1. Alkaline (AA, AAA)

• Voltage per cell: 1.5V (drops to ~1.0V as it drains)
  

• Cheap and widely available
  

• Good for: Low-drain, short-term projects
  

• Not rechargeable
  

Example: A 3x AA battery holder gives you 4.5V—perfect for Arduino Uno.

2. NiMH Rechargeable

• Voltage: 9V
  

• Rechargeable ~500–1000 times
  

• More eco-friendly
  

• Lower voltage than alkaline but steadier output
  

Use case: Replace disposable batteries.

3. LiPo

• Voltage: 3.7V per cell (4.2V fully charged)
  

• Lightweight, high capacity, rechargeable
  

• Great for: Drones, RC vehicles, IoT devices
  

• Needs protection circuit to prevent overcharge/discharge
  

• Can be dangerous if mishandled
  
  

Tip: Use a 2S or 3S LiPo pack (7.4V or 11.1V) with voltage regulators for stable output.

4. 18650 Cells (Li-ion)

• Popular for high-drain devices like flashlights, robots
  

• Rechargeable and powerful (up to 3500mAh per cell)
  

• Often used in 2S or 3S battery packs with BMS boards
  

Pro tip: Always use a battery management system (BMS) to balance charging and protect against overcurrent.

5. Coin Cells (CR2032, etc.)

• Tiny, 3V non-rechargeable cells
  

• Ideal for memory backup or ultra-low-power gadgets
  

• Low capacity (~200mAh), not good for frequent use

6. Lead-Acid (Sealed)

• Voltage: Typically 6V or 12V
  

• Heavy and bulky, but rugged
  

• High current output
  

• Used in: Large robots, power tools, backup systems
  

Step 3: Matching Voltage and Current

Voltage:

• Too low = underpowered device, erratic behavior
  

• Too high = fried circuit
  

Solution: Use a voltage regulator or buck converter if your battery exceeds the project’s voltage requirement.

Example: If your Arduino needs 5V and your battery is 7.4V, use a LM7805 or DC-DC buck converter to drop it down safely.

Current:

• Batteries don’t “push” current; your device draws what it needs.
  

• But your battery must be capable of supplying that current.
  

Example: If your motor needs 2A, don’t power it with a coin cell. It can’t provide the needed current and may shut down or overheat.

Step 4: Capacity (mAh) and Runtime

Battery capacity is measured in milliamp-hours (mAh) or amp-hours (Ah).

• 1000mAh = 1A for 1 hour
  

• Higher mAh = longer runtime
  

Runtime = Capacity / Current draw

2000mAh battery with 400mA circuit:
2000 / 400 = 5 hours

Always plan for 20–30% overhead, because real-world efficiency is rarely perfect.

Step 5: Rechargeability

Ask yourself:

• Will you reuse the project often?
  

• Is the battery hard to access or replace?
  

If yes → go rechargeable (Li-ion, LiPo, NiMH).
If not → alkaline might be fine for temporary or demo projects.

Tip: Rechargeable batteries save money in the long run but require compatible chargers and safety practices.

Accessories You’ll Need

• Battery holders (AA/AAA, 18650, etc.)
  

• JST connectors for LiPo batteries
  

• Protection circuits (especially for Li-ion)
  

• Voltage regulators (AMS1117, LM7805, buck/boost converters)
  

• Battery indicators or fuel gauges
  

• Charging modules (like TP4056 for 18650 cells)
  

Safety Tips

1. Never short-circuit a battery
   

2. Don’t overcharge or over-discharge Li-ion or LiPo
   

3. Don’t mix battery types (e.g., new + old cells, or AA + AAA)
   

4. Store batteries in cool, dry places
   

5. Always follow the specs!
   

If your project is for kids, wearables, or unsupervised use, stick with protected batteries and low voltages.