TOPDON BT100W – Bluetooth Battery Tester Review

Here at TheCarStuff, we have had the opportunity to test and review various tools designed to maintain and troubleshoot vehicles. One such tool that has recently caught our attention is the Topdon BT100W Battery Tester. This compact, handheld device is designed to assess car batteries’ health and performance. It is a straightforward, no-fuss tool that in my opinion, every household should have. Why? Read on.

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3 reasons why you should own a battery tester

You might wonder why you would need a personal battery tester when many auto parts stores offer battery testing services.

The first answer lies in the potential conflict of interest. When the person testing your battery is also trying to sell you a new one, there is always a chance that their assessment might not be entirely unbiased. Having your own battery tester like the BT100W provides an independent second opinion, ensuring you only replace your battery when it’s truly necessary. I am not saying all car part shops or garages are bad, but when working on commission, the temptation might be there.

The second reason is when you buy a second-hand car; the seller might try to tell you that the battery is new, the car is charging fine, etc. etc., thus inflating the car’s price. Devices like this TOPDON quickly assess the battery’s condition and prevent you from buying a car that needs a new battery right away. On this alone, the device literally pays for itself.

Lastly, it’s about proactive maintenance. Knowing the state of your battery, particularly before extreme winter or summer conditions, can be crucial. These seasons can put significant strain on your battery’s ability to start your car. If you’re aware that your battery is nearing the end of its life, you can preemptively replace it and avoid the inconvenience of being stranded in severe weather. If you had known your battery was on the brink of dying, you might have avoided getting stuck in that blizzard and needing to be towed…

TOPDON 100W overview

On the outside, the body of the unit is made of sturdy plastic, the display is clear and data visible, the cables and clamps give an impression that they should last a while. There is not really much else to it on the outside – sturdy plastic “box” and manual/specs on the back side. 

Inside is where the magic happens – the Topdon BT100W Battery Tester is not just a battery tester but also a cranking tester, and a charging system tester. The cranking test measures the power your car’s starter motor is drawing from the battery, while the charging test assesses the performance of your car’s alternator, the component responsible for recharging the battery and powering the electrical system when the engine is running.

The BT100W is powered by the battery it is testing, eliminating the need for an external power source. It features a super user-friendly interface with a few buttons: enter, up and down buttons for navigating through options, and indicators for good, charging, and bad states. It does not get much easier than that.

Downloading the app

TOPDON has both iPhone and Android apps available for the 100W. Best is to search for “BT100W” and you can’t miss it. 


TOPDON 100W app

Once downloaded, the app’s home screen allows you to select the test. 

Screenshot 20230712 124611 BT100W

It also allows you to create a profile so you can save the results for the future reference. 

TOPDON 100W app - home screen


There are 2 ways – one using just the unit and hooking it up directly to your car’s battery, and the other – using the app.

Option 1 – all manual

Using the BT100W is straightforward. First, you connect the device to the car battery using the provided clips. Once connected, the BT100W powers up the main screen with several options.

The first option is the battery test. This test allows you to select the type of battery being tested, including regular flooded, AGM (Absorbent Glass Mat – a type of lead-acid battery that delivers high currents), and other types. You then input the battery’s cold cranking amps (CCA – a measurement of the number of amps a battery can deliver at 0°F for 30 seconds and not drop below 7.2 volts), which can be found on the battery itself.

The BT100W quickly returns a result, indicating the battery’s health and charge. For instance, in one of my tests, it showed a battery with 79% health and recommended charging it. This way I know that the battery is in an OK condition so no need to replace it. In another test, it indicated a battery in bad condition with 10% health and 60 CCA – an example of “too far, too late”. This one was quite dead.

The next test that the Topdon does is the cranking test. Here it gets a bit tricky as you will need to be in a car or have a buddy (or use the app, read on). The device instructs you to start the engine within 30 seconds (if you don’t have a buddy, make sure you position it safely so it doesn’t fall into the engine bay once the engine starts), after which it performs the test and provides a result. This test can help identify if your starter is pulling too much or too little energy, which could indicate a need for a new starter.

The final test is the charging test. You start the engine and increase the RPM for five seconds. The BT100W then performs a Ripple test, which tests the rectifiers in the alternator (the rectifiers convert the alternator’s AC output into DC to charge the battery), and provides a result.

Option 2 – W for “wireless”

Now we come to the part where the BT100W is different to its predecessor (BT100), and makes the process really easy as the unit connects to your phone via Bluetooth!

Topdon has both Android and iPhone apps that you can download from the respective app store. Once installed, make sure your phone’s Bluetooth is on, and wait for the two to pair up. This is quick, and once done, you will see the range of tests in the app.

So what does the app allow you to do?

Essentially the same thing, but you will see some additional information in the app.

Remote Testing: The app allows you to conduct all the tests above but from inside the car, eliminating the need for a second person to assist with the testing. This is particularly useful when performing the starting or cranking test, as you can initiate the test from the app and then start the vehicle.

Detailed Readouts: The app provides a detailed readout of the battery’s health, including the state of health, cold cranking amps, battery voltage, and internal resistance. This information is presented in a clear and easy-to-understand format.

Test Selection: The app allows you to select and initiate different tests, including the battery test, starting test, charging test, and system test, while you sit in the car. This gives you the flexibility to choose the most appropriate test for your needs without the need to run back and forth between your car seat and the engine bay.

Test Results Storage and Sharing: This is super-handy – the app allows you to save the test results for future reference. You can also share the results via various platforms, which could be useful if you need to share the information with a mechanic, or somebody else. It can also be used by mechanics when reaching out to customers when they find out that the battery is not great while servicing the car (see point 1 above, beautifully eliminated).

Guided Testing Process: The app guides you through each step of the testing process, providing instructions on what to do next. This makes the BT100W battery tester easy to use, even for those who aren’t familiar with battery testing. You just can’t go wrong as it tells you step by step what to do and when.

Our tests

We have tested the tool with the Android tool and an older battery. 

We have downloaded the app, turned on the bluetooth, hooked up the BT100W to the battery and let the phone find the battery tester. Make sure that the unit is on (the display goes on), if the screen is blank, check the clamps and make sure they connect well to the car battery terminals. 

Screenshot 20230725 111343 BT100W

Once synced, you can leave the BT100W on the battery or somewhere safe (keeping it connected) and move to the car. 

In our first test we have tested the car battery health. 

Battery health test

The battery health turned good, but needed charging. We had a bit of a drive ahead of us the same day so the battery got a top up. Which leads us to the second test: charging.

Charging test

Yet again, the app walks you trough what it needs you to do.

In this case, the charging voltage was normal so nothing wrong here with the battery either. We had a bit of a drive ahead the same day so it was a good opportunity to charge the battery a bit. 


Cranking test

The last test was the cranking test. 

The BT100W will lead you through the process as you need to turn off all the systems that drain power such as aircon or radio. Once done, you will see the results in the app. 

What we really like are the Save and Share functions. 

The save function allows to to save and retrieve the historical testing in an easy to navigate user interface. 

Screenshot 20230725 133225 BT100W

The “Share” feature is what it says on the tin – you can share the result via email, social media app, or any other apps that allow sharing images that you have in your phone. The good thing is that the test results remain in the app/phone so the BT100W doesn’t need to connected to a car battery for you to be able to share the results.

Screenshot 20230725 133411 Android System


In my experience, the BT100W has proven to be a reliable tool for testing car batteries. It provided accurate results for both good and bad batteries and the cranking and charging tests. Its compact size and ease of use make it a valuable tool for both DIY enthusiasts and professional mechanics, and the app supercharges its usefulness and ease of use. Whether testing weak or faulty batteries, assessing the health of a good battery, or testing the starter, the BT100W’s results have been consistent and reliable.

What really stuck out was how is the BT100W incredibly user-friendly. Even if you are not familiar with automotive jargon, the device makes it easy to understand the health of your car’s battery. It provides clear, easy-to-understand results, and the user interface is intuitive and straightforward. Going back to point 3 above, I do really think that something this simple to use is a great piece of tech for literally anyone owning a car.

Where to buy


The TOPDON BT100W is a battery tool that provides the efficiency of a plug-and-play tool and the robust data analysis of a high-tech digital tester. It can function as a standalone battery tester and run a variety of tests.

Users can tap into the device’s app for more advanced functions, enhanced data analysis, and view or save battery test reports in a separate folder.

The BT100W device operates in eight languages, and the BT100W app supports nine languages.

The BT100W can perform battery tests, cranking tests, charging tests, and system tests.

By monitoring the cranking time and cranking voltage, a cranking test helps to check the health and service life of a battery.

The charging test helps to determine whether the charging system is working properly and the car is ready for the road.

The system test function enables technicians to perform a battery test, cranking test, and charging test, with only one click.

The BT100W’s battery library allows for easy access to key battery information such as battery standards, CCA, specifications, and more.

Yes, the BT100W can create test reports to compile important battery status information in one spot.

The test reports include data such as state of health, state of charge, internal resistance, and more.

Data synchronization between the BT100W tester and the mobile application is performed seamlessly to ensure accurate information is displayed across both platforms.

The device supports English, French, Spanish, German, Italian, Portuguese, Russian, and Japanese.

Yes, the BT100W can operate on a variety of battery types and analyze the battery’s state of health, state of charge, and cold-cranking amps.

The app allows for more advanced functions, enhanced data analysis, and the ability to view or save battery test reports in a separate folder.

The battery tests help to find and mitigate potential issues by analyzing the battery’s state of health, state of charge, and cold-cranking amps.

The state of health indicates the overall condition of the battery and its ability to function properly.

The state of charge indicates the current battery capacity as a percentage of its maximum capacity.

Cold-cranking amps (CCA) is a measure of a battery’s capacity to start a car at 0 degrees Fahrenheit.

Yes, the BT100W can function as a standalone battery tester, providing versatility to every garage.

Martin Shaw
Martin Shaw

Martin is an automotive enthusiast with a deep passion for all things cars. He has spent the last decade immersing himself in the industry, reading up on the latest models, attending car shows, and tinkering with his own vehicles. Loves: family, all things cars (apart from selling them), pizza.

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