car battery testing methods explained
Not all shops are willing to invest in such a broad array of tools for battery service and diagnostics, so it’s important to have a good understanding of all the options.
Variations commonly found amongst 12V batteries on the market are absorbed glass-mat (AGM) and flooded lead-acid batteries (serviceable and non-serviceable). While diagnostics are similar, service and maintenance vary based on accessibility and chemical/structural variances amongst each type. Common testing procedures include the use of the following tools: digital multimeter; conductance tester (low amperage tool); refractometer (if battery is serviceable); load tester (high amperage tool); and/or PicoScope 4425A Digital Storage Oscilloscope (battery test option in PicoDiagnostics software).
Not all shops are willing to invest in such a broad array of tools for battery service and diagnostics, so it’s important to have a good understanding of all the options.
Digital multimeter (DMM) testing
While DMM’s do not provide a light-speed reaction to voltage variations based on sample rate, they do provide a stable enough reading to project static voltage, continuous declines in voltage, and charging system voltage output. One major issue to consider is where to make connection with the battery during such readings. In knowing that battery voltage is limited to connectivity between post and terminal, I recommend comparing post-to-post readings of battery voltage to post-to-terminal readings. Note that this process may be impacted by battery design, such as side post batteries.
While slight variances do exist amongst manufacturers to indicate a battery’s 100 percent state-of-charge, I typically project 12.6V is the norm (lead-acid). While cranking, a measurement of at or below 9.6V indicates severe battery degradation or poor maintenance, and further assessment must be conducted, such as charge and re-test following battery manufacturer’s recommendations, cell inspection (if serviceable), etc.
Conductance testing
Conductance testers utilize battery source voltage to measure current and infer resistive values in a complex, yet simple manner. This technology is similar to the use of DMM’s when performing basic testing procedures (voltage, resistance, and current measurements) to mathematically project measurable outcomes. The major benefits of utilizing conductance testers to determine battery conditions are the tool’s cost and size. Conductance testers are traditionally handheld, consume very little space, and are typically less expensive than dedicated carts used to assess battery condition. Conductance tester manufacturers currently equip their tools with exportable data files or immediate printable results to document battery condition at the time of measurement, and often include summaries of battery design, post arrangement (side/top/stud), voltage output, inferred amperage output, and battery condition based on tool analysis. This type of testing allows technicians to easily document their findings and display evidentiary results upon completing the test.
As the industry continues to use advanced methods of testing, my personal preference for assessing a battery’s condition is the Pico Diagnostics Battery Test. This test centralizes the most comprehensive data, projects dynamically physical values of voltage and current, and creates a file that can be saved, printed, shared, and displayed for reference and illustration.
The industry trend demands environmental testing conducted in fully integrated environments. Various physical parameters, including vibration (acceleration, velocity and displacement), temperature, humidity, pressure, torque, and electrical signals such as those from CAN bus should be monitored and controlled by one system.
The Spider-101i is designed to perform tests subjecting the DUT to simultaneous temperature cycling and variable humidity. The Spider-101i controls both temperature and humidity in a chamber system, which includes external heating/cooling and humidification/dehumidification systems. PTP time synchronization technology and Ethernet connectivity allows all Spider hardware to be accessed and configured as one integrated system.
When vibration control is required along with temperature and humidity control, users are able to conveniently access the parameter and schedule setup between all combined physical quantities from one fully integrated user interface. If a THV (temperature, humidity, vibration) system (chamber shaker) is equipped with a Spider-101i controller, the controller software allows the addition of a Spider vibration controller and operates the two systems as one while providing an integrated user interface. Users can execute vibration tests such as Random, Sine, Shock, SoR, RoR, and other types together with various cycle settings of temperature and humidity.
- One user interface for setting up run schedules for temperature, humidity, vibration, etc.
- Fully networked allowing users to connect multiple hardware devices through Ethernet which allows one PC to control all devices at the same time
- Ability to extract battery information through a CAN bus and take various actions including emergency shutdown.
- Access and control with one software application
- Data acquisition is accurately time-synchronized
- One combined test report. If test reports are generated separately from several apps, the time clock and schedules will not be coordinated, unlike the integrated test report generated by Crystal Instruments’ EDM THV Software
Record CAN bus data, peak CAN data, time data, dynamic measurements (APS, FRF, frequency domain data, etc.), cycling data logging (voltage, current, battery, etc.)
Combine a Spider vibration controller with a Spider-80SG unit to acquire data from a strain gage or a wide range of sensors. With the help of precision excitation voltage, the Spider-80SG/SGi can support strain gage based sensors, MEMS sensors, IEPE and DC sensors (to name a few) thus expanding the scope of the Spider-80Xi hardware platform to support the synchronized acquisition of a wide range of measurement quantities including Force, Torque, Pressure, Acceleration, Velocity and Displacement. It can be used for strain measurement and many other types of sensors that requires external power.
The Spider hardware platforms (including the Spider-80X/Xi and the Spider-80SG/SGi) share the flexibility of scaling up in channel count and functionality. The Spider-80SG/SGi can combine with any Spider-80Xi device to create a high channel count system with up to 512 channels to perform data acquisition during vibration tests. A dedicated massive storage hard disk (a 250 GB solid-state drive) allows the time signals of all input channels to record at up to 256 kHz/channel. Accurate time synchronization results in excellent phase match in the frequency domain between all channels, either on the same Spider front-end or across different front-ends.
CAN bus alarm and abort rules can be configured during a vibration test with a customer’s DBC file and a custom-built Crystal Instruments USB CAN adapter. For example, a user running vibration tests on an EV battery can configure EDM to monitor the battery’s temperature and stop or pause the test in response to the temperature matching or exceeding a particular value.
EDM supports the custom-built Crystal Instruments USB CAN adapter as well as the PCAN-USB adapter developed by Peak Systems.
While performing vibration or THV (temperature/humidity/vibration) tests on a battery pack, the accelerometers, temperature, and humidity sensors can measure the external environment of the battery pack. The Battery Management System (BMS) monitors the internal battery pack status and communicates with external components using CAN bus. The integrated CAN bus support allows EDM to monitor the internal and external status of a battery pack and take actions according to pre-defined conditions.
Supports multiple CAN Bus channels and records data simultaneously to a solid-state drive. Expand data storage to 2 TB with the addition of a Spider-NAS.
How Does It Work?
As the name suggests, the testers work by testing the current that comes from a battery. Most basic battery testers use conductive ink that responds to minute temperature changes.
When contact is made with both positive and negative contacts on the battery, the current is released. This conductive medium measures the battery charge (amperage). Each tester comes with a gauge that reflects the level of the charge.
Take note, though, that these testers only measure current. On batteries like lithium, the reading results tend to be inaccurate. This is because the current does not wear down evenly. It takes a significant drop at certain charge levels.
over, the batteries will read fully charged even if they only have a half remaining. To test a lithium battery, you need to use a battery conditioner or a tester designed for rechargeable batteries.
As battery testers solely measure current, they provide more accurate readings.
Note: The red one is positive. the black one is negative (-). Never connect the red cable to the negative battery terminal or a vehicle with a dead battery. Otherwise, this will cause a full or dead short circuit.
Different Types of Battery Testers
There are different types of battery testers, each suited to varying battery types and sizes.
Electronic battery tester
The electronic and digital types are the most common ones used for testing the remaining capacity of a battery. Most digital models feature an LCD, showing the result in a clear and easy to read format.
Depending on the model, the result is displayed in the form of bars or a graph. This enables quick reading and analysis of the test results.
Domestic battery tester
Also known as the household battery tester, this type is usually used for testing cylindrical batteries. This includes double and triple A batteries and 9V PP3 batteries.
A domestic battery tester covers the majority of everyday household batteries. It is also suitable for testing a combination of battery types, such as C and D batteries.
These battery testers units are a great example — and are worthy of investment if you are looking for one!
All in One Battery Tester – AAA/AA/C/D/Lithium Button Cells – No longer available
The All-In-One Battery Tester can test the battery strength of more than 12 types of batteries. Suitable for standard AA/AAA/C/D/9V batteries, button cells, and lithium batteries, e.g. in digital cameras.
Features an easy-to-read LCD indicating the battery level capacity.
Mini Battery Checker AA, AAA, C, D, 9V Coin Cells
An inexpensive, compact and convenient battery testing solution. This unit accommodates AAA, AA, C, D and 9V battery sizes and makes testing your batteries a snap.
Universal battery tester
Universal battery testers are suitable for batteries in a range of different sizes. Similarly to domestic battery testers, they are primarily used for cylindrical batteries.
Universal Battery Tester
This lightweight, easy to carry Universal Battery Tester is a simple yet effective model. It works with standard and rechargeable household batteries, including Lithium-based batteries.
With this unit, you can test voltage, capacity, and internal resistance. Plus, it also works with alkaline and various other non-rechargeable batteries.
Car battery tester
Car battery testers are intended for use with lead-acid batteries. These testers connect to vehicle batteries to provide a clear sign of the following:
Battery testers for automotive applications are important. It is crucial as high currents are drawn during start-up. Ensure that your tester is compatible with lead-acid batteries before use for safe testing conditions.
Have a look at this 12VDC lead-acid battery tester for vehicles below!
12VDC Lead Acid Battery Tester including SLA, AGM, GEL – No longer available
This battery tester works on all automotive 12V lead-acid batteries. Suitable for testing various battery types, including:
- Ordinary lead-acid battery
- AGM flat plate battery
- AGM spiral battery
- GEL battery
It can quickly and accurately measure the alternator’s charging and starter’s cranking conditions. Plus, it can identify batteries with bad cells.
With reverse polarity protection design and meets major battery testing standards such as:
Additionally, this battery tester features an LCD display to indicate the results. It has a menu tab and clips to connect the battery tester to the vehicle’s battery.
How to Use Battery Testers
Each model comes with an instruction manual or manufacturer’s guidelines. We recommend always referring to it before getting started.
Additionally, ensure the tester is fully functioning and compatible with the type of battery you own. After these few pointers, the actual process is relatively simple, with only two steps.
First, insert the battery into the tester. Make sure the positive and negative contacts on both the battery and device match up. Next, secure the battery firmly in place, then take the reading.
After use, store the device in cool, dry conditions such as within your toolbox. This helps maintain and prolongs its lifespan while minimising the risk of damage.
Tip: Do not use a wet cloth when cleaning as this could damage the battery tester. Instead, use a clean cloth or specialised electronics cleaning wipes.
How To Take a Meter Reading?
Once the battery is correctly positioned, you should be able to take a voltage meter reading. Depending on the model you have, the output may vary between different result formats.
If your tester displays a graph or chart, it should be easy to assess the battery’s remaining capacity. But as a general rule, batteries in the green or pointing towards the higher end of the scale are in good working order.
In contrast, batteries with results around the middle of the scale may still be usable for use in sole lower-power applications. Even so, close monitoring will be required.
At last, batteries in the red section or lower end of the scale need to be changed or recharged. They are most likely to have little remaining capacity.
Different Types of Battery Testers
There are different types of battery testers, each suited to varying battery types and sizes.
Electronic battery tester
The electronic and digital types are the most common ones used for testing the remaining capacity of a battery. Most digital models feature an LCD, showing the result in a clear and easy to read format.
Depending on the model, the result is displayed in the form of bars or a graph. This enables quick reading and analysis of the test results.
Domestic battery tester
Also known as the household battery tester, this type is usually used for testing cylindrical batteries. This includes double and triple A batteries and 9V PP3 batteries.
A domestic battery tester covers the majority of everyday household batteries. It is also suitable for testing a combination of battery types, such as C and D batteries.
These battery testers units are a great example — and are worthy of investment if you are looking for one!
All in One Battery Tester – AAA/AA/C/D/Lithium Button Cells – No longer available
The All-In-One Battery Tester can test the battery strength of more than 12 types of batteries. Suitable for standard AA/AAA/C/D/9V batteries, button cells, and lithium batteries, e.g. in digital cameras.
Features an easy-to-read LCD indicating the battery level capacity.
Mini Battery Checker AA, AAA, C, D, 9V Coin Cells
An inexpensive, compact and convenient battery testing solution. This unit accommodates AAA, AA, C, D and 9V battery sizes and makes testing your batteries a snap.
Universal battery tester
Universal battery testers are suitable for batteries in a range of different sizes. Similarly to domestic battery testers, they are primarily used for cylindrical batteries.
Universal Battery Tester
This lightweight, easy to carry Universal Battery Tester is a simple yet effective model. It works with standard and rechargeable household batteries, including Lithium-based batteries.
With this unit, you can test voltage, capacity, and internal resistance. Plus, it also works with alkaline and various other non-rechargeable batteries.
Car battery tester
Car battery testers are intended for use with lead-acid batteries. These testers connect to vehicle batteries to provide a clear sign of the following:
Battery testers for automotive applications are important. It is crucial as high currents are drawn during start-up. Ensure that your tester is compatible with lead-acid batteries before use for safe testing conditions.
Have a look at this 12VDC lead-acid battery tester for vehicles below!
12VDC Lead Acid Battery Tester including SLA, AGM, GEL – No longer available
This battery tester works on all automotive 12V lead-acid batteries. Suitable for testing various battery types, including:
- Ordinary lead-acid battery
- AGM flat plate battery
- AGM spiral battery
- GEL battery
It can quickly and accurately measure the alternator’s charging and starter’s cranking conditions. Plus, it can identify batteries with bad cells.
With reverse polarity protection design and meets major battery testing standards such as:
Additionally, this battery tester features an LCD display to indicate the results. It has a menu tab and clips to connect the battery tester to the vehicle’s battery.
How to Use Battery Testers
Each model comes with an instruction manual or manufacturer’s guidelines. We recommend always referring to it before getting started.
Additionally, ensure the tester is fully functioning and compatible with the type of battery you own. After these few pointers, the actual process is relatively simple, with only two steps.
First, insert the battery into the tester. Make sure the positive and negative contacts on both the battery and device match up. Next, secure the battery firmly in place, then take the reading.
After use, store the device in cool, dry conditions such as within your toolbox. This helps maintain and prolongs its lifespan while minimising the risk of damage.
Tip: Do not use a wet cloth when cleaning as this could damage the battery tester. Instead, use a clean cloth or specialised electronics cleaning wipes.
How To Take a Meter Reading?
Once the battery is correctly positioned, you should be able to take a voltage meter reading. Depending on the model you have, the output may vary between different result formats.
If your tester displays a graph or chart, it should be easy to assess the battery’s remaining capacity. But as a general rule, batteries in the green or pointing towards the higher end of the scale are in good working order.
In contrast, batteries with results around the middle of the scale may still be usable for use in sole lower-power applications. Even so, close monitoring will be required.
At last, batteries in the red section or lower end of the scale need to be changed or recharged. They are most likely to have little remaining capacity.
The Bottom Line
The easiest way to check a battery is to use a dedicated battery tester. Suppose you are checking your vehicle battery, use a unit made for automotive testing.
And when purchasing a unit, you must ensure that the tester is compatible with the batteries you have. Additional features will also largely come down to personal preference and requirements.
Some key factors to keep in mind when looking for the best battery tester include:
As for car battery testers, the unit must be dependable and reliable.
In a nutshell, a battery tester will help you determine if your battery (or car’s) is nearing the end of its usefulness and whether you need to replace it or not.
© Wiltronics Research Pty Ltd 2022
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