FOXWELL BT705Plus Car Battery Tester

Consistently Reliable

I purchased the Foxwell BT-705 Plus after getting wildy different battery test results from my Topdon BT100 and was skeptical that it was giving accurate readings. One day it said the battery was good, the next it said it was bad and to replace it.

Once I received the Foxwell however, it was consistently giving the same test results, over multiple tests. In this case it was testing my battery as good, and the state of health measured nearly 60 percent over the Topdon's results.

Needless to say, I will no longer rely on Topdon BT100 nor would I recommend it, but I can definitely say with certainty that the Foxwell BT-705 Plus is worth the extra cost if accuracy and reliability are important to your battery tests.

don't buy

Piece of junk. Bought it 11/2025, less than a year old, and still under warranty.. Stopped working after use 5-6 times (looks new still, with plastic cover on screen) would not power up with a blank screen. manufacturer wanted to ship it to China for repair. It would be a hassle to ship, and it could take a month or two before receiving it back.. So I purchased a different battery tester made by Topdon, model BT600Plus (made in USA).

The hardware is solid, but the automated logic has a programming blind spot

The hardware is solid, but the automated firmware logic has a major programming blind spot. If your alternator's internal diodes are healthy, the screen will display 'NO PROBLEMS' even if the total DC output voltage is dangerously low (e.g., 11.9V) and your charging system is actively failing. Do not rely blindly on the text verdict—manually verify that your 'LOADED' and 'NO LOAD' values are strictly above 13.5V. Also, keep an eye out for the funny 'REPPLE' spelling typo on the dashboard screen! The price of the unit, it would also be great to be able to upgrade the firmware and a detachable cable to use longer ones.

M. Funk

June 30, 2025

LASTED 1 DAY AND DIED ☠️ (Red Button Clarification)

As far as my experience goes, I've been wrenching for over 40 years.

I tested three different batteries on the first day. Two in the vehicle’s and one out of vehicle. It did great in the testing and results.

The second day I went to test 3 additional batteries and the screen wouldn't light up, but oddly the last clamp attached would cause a slight spark when touching the terminal. Yes, I verified the correct polarity when attaching the cables.

For as expensive as this unit is I would expect a better build quality!

NOTE: The red 'link' button on the tester has no function. Seriously, After multiple emails with the company support they confirmed by saying "...we have confirmed that this button has no function", with the last email stating, "This button is designed to connect to Bluetooth, but it has not been developed yet."

Nice tester that seems to error on the side of caution

This is a very nice battery tester. It came with a hard plastic carrying case that makes it nice to store and pretty portable. I tested a brand new battery that I was installing for my trailer winch and, as expected, the test came back good. I also tested a few car batteries and charging systems and the results were as expected. The "one off" I will say is when I tested a known bad battery that was only at about 11.7v, the tester came back with "good - charge and retest". After throwing the charger on the battery for a few hours I retested and the tester came back with it as a bad battery. I'm not sure what triggered it to say good vs bad honestly. I'm hoping this is just the charger erroring on the side of caution and not just declaring a battery bad because it couldn't test something with that low of voltage. I plan to continue to use this as my primary tester so I'll see if there are any other anomalies.

My first professional car battery tester

Although it is a professional car battery tester it is very simple to use as there’s instructions on the screen showing every step. Just a kind reminder. The tester itself doesn’t have power supply (no batteries). So no way to turn it on without hooked up to the battery terminals. But it will light up instantly as soon as hooked up to the battery. So far so happy with it.

Too large for what it does.

This would be a decent tester if it were not so huge. I already own another brand of battery tester that is approximately half the size and half the price. Using the two units' side by side, they have remarkably similar features and capabilities. I do not know what is inside this thing, but it is just too big and bulky to not offer any more than devices half its size. The only thing I can attribute to the difference in price is that the Foxwell does come in a nice protective case versus my other unit that just has a cheap pouch it slips into, but I am not buying a case I am buying a battery tester.

When testing these units' side by side with a multimeter, my old testers voltage reading seems to align more with the readings on the multimeter. The results between the two testers are close, but not as close as I would have expected. For instance, a known discharged good battery was used for a test subject. The voltages were close, but the tested CCA, SOH, and resistance were not. I am not sure if the voltage measurement is used to calculate these other readings or not. One tester said to charge and retest the battery and the Foxwell said to replace the battery. This could result in someone spending money to needlessly replace a good battery. Seeing the variances in testing with the Foxwell, I just do not trust it like I do the other brand I own. The construction of the Foxwell tester seems rugged and the clamps and cables do not feel flimsy. The Foxwell BT705Plus does offer 24v testing capability that my old tester does not. Had I not had another tester to compare against, I may have favored the Foxwell a little more, but I even prefer the display of my old tester over the Foxwell. If this could be repackaged into a smaller form factor and priced more competitively, it could certainly be a contender.

Very nice way to test batteries charging system and cranking, that’s simple to use with good quality

The BT705 Plus Car Battery Tester by FOXWELL, is an effective testing tool that can easily providing useful data from a reputable diagnostic tool company. Here are some of the things I’ve learned while owning it and things to consider before buying.

I. Quality – This tester is nicely made out of good quality materials. I’d put it in the lower side of the upper tier of the quality scale for battery testers.

II. Performance – This little machine works great in many ways with a lot of capabilities for a battery tester. The screen is easy to read and use, with simple buttons. The clamps are strong and appear to be copper. The machine is a good size that’s easy to hold, comes with a protective coating around the edge and has a nice plastic case to store everything. This is a very useful tester that’ll check your battery, cranking ability, charging, SOC, SOH, and even attempt at a heath check of the battery. It would be nice if it could also check Lithium batteries, but it can hand most others.

Overall, this has been a great tool to have, that’ll get me needed information quickly, easily and most importantly accurately. I’ll be sure to update this review, if I ever start to have problems with it.

If you’d find it helpful to see an up-close visual inspection of this product, I recommend you watch my included video in full screen or landscape. They say a picture is worth a 1000 words, well it’s video!

You can trust that this review is simply my honest opinion that is attempting to provide you with helpful insight that I wish I had before I picked this product. Hopefully it was helpful in your decision.

2:49

Know your battery condition before it becomes a problem

I got this to test the batteries in my cars, trucks, tractors, etc. I have quite a few vehicles and recently found out that even though I keep all my vehicles on battery charger/maintainers, some of the maintainers I have don't indicate battery health and I was stuck with a no-start away from home because of it. This is also capable of starting and charging diagnostics as well. Hopefully, this will eliminate problems in the future by giving me better insight into when to replace a battery before it becomes a problem.

The Countess

July 9, 2024

Great

Needed a good battery tester.

Impressive, this battery tester doesn’t only test battery but your alternator as well and can test your starting power, as well as some other things.

It can test multiple types of batteries including gel batteries. It can also test a variety of voltages too.

I’m impressed by this product.

James

July 8, 2024

Easy diagnosis

This couldn't be easier to use. Hook it up, turn it on and follow the promts. Thats it! Even if you have very little experience in working with an automobile, you can use this. And, I have tested it against my other testing equipment and its as accurate as they are. And, the price is way less than my other testing equipment so its a deal!

1:25