You should've lowered the voltage all the way to zero, this should give us an idea of how the ADC and reference voltage is set up.

Sometimes you can see erased numbers if you use an infrared or ultraviolet camera.

I was shocked that it was a packaged chip, and not a "blob chip" under a blob of epoxy! I'm pretty sure they have these "new-fangled" battery testers now that don't have a huge load resistor in them. I think they apply a load, but only for a very short duration, and take all the measurements needed very quickly. I wonder how much the response of the battery changes over the first millisecond second of applying a load though, vs a continuous load of multiple seconds when starting a car. I guess they'd have to take that into account in the analysis

Maybe you can do anything you want using microcontrollers the straight forward way today... But as soon as anything in this new clean digital world goes wrong, people are asked and needed again who know about analouge stuff and didn't switch away from channels like this ;) By the way: Thanks for the teardown, I once was tempted to buy such a thing but it seems it´s just a voltmeter with a few more colorful LEDs. I device like this should contain any simple way to also check for ESR of the battery, especially if you already have clamps of that size.

I literally did this same task last week. My Father passed away and he had one of these in his boat stuff. I had to tear it down to see whats going on. 😂 Great minds think alike.

These electronic Car battery testers will leave someone stranded in the middle of nowhere, guaranteed. The battery and alternator need to be tested while working (under load). Ideally, everyone would have their own carbon pile load tester in the garage to properly characterize the states of the charging/starting systems of their vehicle. The electronic tester can still be used as a stop gap tool, but should add load to the charging system ( headlights, interior lights, everything with a switch turned on) then see what the measured voltage is. For the battery, a substantial dummy load is necessary for an accurate cranking amps test, but in a pinch, hook up the $0.99 store battery tester and make a note of the displayed voltage while cranking. Secondary ignition or fuel system should probably be disabled to get a few good revolutions of the motor. Otherwise, today’s vehicles light to fast so you’d never get a good measurement. Save the trouble and buy an inexpensive carbon pile or equivalent battery tester. The very first time you test the cranking amps of the battery by holding the little load switch,the shear heat that pours out of the tester will show just how ineffective the $0.99 store testers are. Thanks for the great video!! I still don’t see how you publish one everyday. I can’t remember the last time there was a day in between. Keep em coming

I was looking for an analog meter to build an esr meter around so I went to the local big box hardware store. They only had two analog meters, one a cheap dvm and the other a battery meter similar to this. I reached for the simple battery meter thinking it would be cheaper but then realized it was almost double the price of the analog dvm.

Let's say you paid $0.99USD for it, as it was a deal/throw in... In that case, you got a nice project box, connectors, display and keyboard, for a DIY project. That's not bad, IMHO...

That noname chip is probably a clone of the LM3914

Yeah, a black box teardown. I found a vintage unit with same functions, a big circuit board with hand-drawn trace patterns. I'll go study that. Please build an electronic load. See how much functionality you can get without any software. Demonstrate logic circuit capabilities. I've been studying a high voltage electrophoresis PS from the early 90's. All linear with several features to safeguard unit, circuit and user. I was lucky to find the schematic. Great unit.

RANT OF THE WEEK! :)

Wonder how accurate that voltmeter is

How does it know if your alternator is bad? You didn't test that part of it...

The "DEAD" light in the alternator column is interesting. Is it also battery status?

Does this battery tester know the remain Ampere-hour that saved in a battery? Thanks

some people say if you have this battery tester you should visit area near or not that far from tallest building in the world because ............... sir the distance may 500 km or more with green LED or green color roof

Or…..you could just take your DVM out to your car. 😮

Interesting. Wonder if it detects alternator ripple.

Micro-controlers have taken the fun out of electronics.

Microcontrollers are not the problem, its engineer wannabes that are afraid to use classical design concepts and years of training to put into them for better ideas. It's laziness and lack of reading thats the real problem. 😮