What is Arduino Battery Capacity Tester

An Arduino battery capacity tester is a simple circuit built around an Arduino microcontroller that allows measuring and analyzing the actual capacity and health of various battery types. By understanding battery capacity testers and how to build one with an Arduino, you can reuse and optimize batteries for your projects.

Overview of Arduinos

First, a quick introduction to Arduinos for those unfamiliar. Arduino is an open-source electronics prototyping platform using easy to program microcontroller boards and code libraries.

Key attributes include:

• Flexible hardware with expandable sensors/actuators
• Approachable programming IDE
• Extensive documentation and projects
• Affordable and hacker friendly

The Arduino ecosystem helps makers create all kinds of unique projects from robotics to IoT, instrumentation to art installations and more.

Now let's explore building a battery tester with Arduino...

How Battery Capacity Works

Before measuring capacity, it helps to understand what battery capacity represents.

Battery capacity refers to how much electric charge a battery can provide, measured in Amp-hours (Ah) or milli-amp-hours (mAh). Higher Ah ratings indicate more charge storage.

However, several factors influence usable capacity:

• Battery chemistry performance varies
• Environmental conditions impact output
• Age and recharge cycles degrade capacity over time

An Arduino capacity tester helps quantify actual vs rated performance.

Building an Arduino Battery Capacity Tester

The basic concept involves fully charging a battery, then using a fixed load to drain it through the Arduino while measuring net duration. Key steps include:

Supplies Needed

• Arduino board (Uno, Nano etc)
• Shunt resistor
• Voltmeter
• Breadboard
• Jumper wires
• USB cable
• Battery holder
• Code loaded on Arduino IDE

Basic electronics supplies enables building the tester.

Circuit Design

Here is a typical circuit diagram:

The shunt resistor provides a fixed load, while voltage is monitored during discharge.

Connect components carefully point-to-point on a breadboard or PCB.

Calculating Resistor Values

Select the shunt resistor value based on expected load current:

• Use lower current for smaller batteries
• Allow safe peak and average current draws
• Generate sufficient load to fully drain battery

For a common 9V alkaline battery, 10 ohms provides ~900mA load.

Arduino Sketch Overview

The Arduino program:

1. Prints starting voltage
2. Turns on load
3. Prints voltage every 5 seconds
4. Repeats until voltage drops below set threshold
5. Prints discharge duration

Duration in seconds / load in amps gives capacity in mAh.

Putting It All Together

Follow these main steps:

1. Gather supplies
2. Build circuit with Arduino, shunt resistor and voltmeter
3. Load capacity tester program code to Arduino
4. Fully charge battery to test and insert into holder
5. Open serial monitor in Arduino IDE to view output
6. Allow test run until battery drained
7. Record duration and calculate capacity

Now let’s explore some more advanced tester options...

Advanced Arduino Battery Tester Options

While a basic resistor load tester works, here are some ways to expand capabilities:

Battery Chemistries

Test various battery types:

• Alkaline
• Lithium primary
• NiMH rechargeable
• Li-ion rechargeable

Each chemistry has distinct discharge profiles.

Electronic Load

Use a dedicated load controller for more precision vs a fixed resistor. Features:

• Sets constant load current level accurately
• Periodic load pulsing capability
• Measures mAh capacity directly
• Tests wide voltage range

Significantly enhanced functionality over resistors.

Logging Results

Log results to a microSD card with time stamps instead of relying on serial monitor.

• View logged data later in Excel
• Monitor tests remotely
• Identify performance changes over time

Data loggingcreates portable test records.

Wireless Connectivity

Add Bluetooth or WiFi to Arduino with serial comms to enable:

• Battery status dashboards on PC/mobile
• Cloud-based monitoring
• Alert notifications at voltage thresholds

Wireless extends tester functionality considerably.

LCD Display

Incorporate a character LCD to show:

• Test battery voltage
• Running discharge time
• Capacity used / remaining
• Load current level

An LCD provides at-a-glance tester status.

Enclosure Option

For frequent use, create a permanent enclosure:

• Contains tester circuit safely
• Battery holder mounted externally
• Display and controls accessible

Robust packaging maintains components securely.

By integrating combinations of the above features, very sophisticated Arduino battery capacity testers can be built to characterize performance.

Real-World Applications

Practical uses for DIY Arduino battery testers include:

Rechargeable Battery Banks

Test actual capacity of your:

• Reusable alkaline and NiMH AA/AAA
• Li-Ion battery packs
• Power tool batteries

Optimizing home battery reuse saves money.

Model Vehicles

Hobby areas like drones, RC cars, robots often use proprietary lithium packs. An Arduino tester:

• Validates labeled capacity
• Identifies weakest packs
• Predicts run times

Get maximum mileage from special batteries.

Solar Storage Systems

For home solar energy storage:

• Test deep cycle lead-acid capacity
• Monitor degradation over years/cycles
• Identify when replacement needed

Maintain renewable system performance.

Battery Production

Even battery manufacturers can employ Arduino testers:

• Simple go/no-go QA testing
• Statistical lifetime sampling
• Rugged enough for factory floor

Provides basic metrics quickly at low cost.

Frequently Asked Questions

To wrap up, here are some common questions about Arduino battery capacity testers:

What skills are needed to build a tester?

Some basic soldering and Arduino coding is helpful. Those new to electronics may want to start with commercial tester kits to familiarize first before custom circuits.

Where do you obtain replacement batteries tested?

Online retailers provide individual cells and battery packs for many applications. Local battery specialty stores also offer various chemistries.

How accurate will capacity measurements be?

Depends on testing methodology used - resistance load techniques get +/- 10% while more advanced electronic loads achieve +/- 3% or better accuracy.

Can Li-ion and LiPo batteries be safety tested?

Special considerations required for lithium batteries - use conservatively designed load levels with monitoring to avoid damage from over-discharge or short circuits.

What kind of battery is best for capacity testing?

The Arduino platform allows testing most portable battery types from household alkaline and lithium cells to lead-acid and lithium battery packs up to 24V or so.

Conclusion

Building an Arduino battery capacity tester is an easily achievable and educational electronics project using basic components. Testers can characterize battery reuse for cost savings, validate labeled performance, predict run times of packs, and identify replacements needing purchase.

Advanced testers with electronic loads, data logging, wireless communications and displays take testing to an professional level. Evaluate your batteries today with an Arduino capacity tester!