The best video I've seen so far on battery safety design. Awesome job, happy to have discovered your channel!

Thanks for a great video, 3 years down the road and its still very useful and insightful for folks entering the Li-Ion space.

Hi. I am amateur attempting to design my first device with Li-ion cell. Really thanks for doing good job explaining the approach. I think people who would watch this video would appreciate even more information, so absolutely don't worry about the length. You have saved me a ton of effort with less than half an hour of video. Again, THANK YOU!

Thanks for this. For all the hints and tips.

Excellent. Very clear information, thank you!

your videos about li-ion is a must-be for anyone that want to know how modern devices have implemented the charge circuit, there is a lot of things for more fancy functions, but for a simple low power battery design this is a complete solution.

Background video with audio listening became foreground attention. Thank you for pointing out these considerations.

Excellent video!

Very good! keep it coming!

As always, great video. Safety and regulation considerations are what distinguish ok from great design, IMO. Also really like the final part about testing.

As usual, timely and very informative.

Job well done sir. Job well done. Thank you very much for a great lesson.

Great video! Crisp and clear! We have a similar circuit but we're having issues with reverse-polarized batteries. Our 18650 battery holder does not mechanically prevent reverse insertion of the battery. When inserted the wrong way with the charger enabled we have 2 voltage sources in series, smoking up the charger as its first victim. The MCP73871 from your schematic has "Integrated Reverse Discharge Protection". Does this suffice for batteries that are inserted the wrong way? I think it means the battery cannot discharge back to the USB/AC side. What are your recommendations on reverse battery protection in this kind of scenario?

Awesome stuff! Would it be possible for you to have a video discussing what it takes to start up a design firm? The path you went down. How you built clients.

Extremely well articulated on this important topic so easily overlooked by DIYers. Clear and concise, good job!

Good job!

Thank you for making this video. Great information and well explained.

That was really helpful, I really needed to know all of this. It really hurts low power design right, even the fuse taxes every joule the product uses. Maybe I'll include some jumper wires and instructions to let my customers decide on the safety/performance trade off, although even then, I'll probably not mention the fuse. If you use better components this is less of a problem right? I thought you could have it on only while it is being charged, but if UL are going to bypass the normal charging chain that's not going to work is it? Almost at the point of adding a primary cell so the mcu can manage battery fault states without drawing from it. Certainly not an option most of the time.

Man I love your videos

Thank you for the video and the information, i have a question, if you don't find a charging ic with power path due to shortage or any other reason, how we can build one using basic components? Any useful link for that? Thank you again.

Battery design, let's go!

Nice - welcome back

Do you also have a video with a more advanced IC that you have used in the past?

Hello. Did you miscalculate the resistor values to get the voltage on the VPCC pin? 4.7V * R6/(R6+R5) should equal 1.23V according to the MCP73871 Datasheet. But I might not be understanding the Datasheet... Thanks great video!

Great video, Very informative. Would you consider doing one on multi-cell ? How would you change the charging and battery protection design?

What will OD and OC pins be low or high? When over charge and discharge protection is active.

The world's best teacher

In the automotive world, the engineers told us that the charge voltage to shut off was 80% and discharge was 20%. I didn’t design them, just fixed them using best practices and their diagnostic flow chart. I truly enjoy the learning process but I am at a basic level somewhat as I ended my career teaching in 2 day classes and 4 hr seminars. Out of 30+ subjects, electrical was 6 levels ending with lab scopes, but starting with just simply knowing how to be comfortable with a digital multi meter and how to use them and what they seeing. Most did not know what voltage drop was in a series circuit even though they were doing it across a component. Question; I want to create printable schematics for each circuit and did not know if software is out there for a low cost or free. I am installing a fuel injected engine into a 55 year old truck for myself. But having a schematic for a tech to use is an owner worst fear they don’t know about until it breaks. My son(s) will end up with the vehicle and very few who retro-mod a vehicle never think of the wiring, connectors, color, location etc. I do because I worked on them. Without photos, colors or circuit design, a shop could spend days chasing a problem instead of 20 minutes doing basic checks then replacing a part or fixing a circuit fault. I stumbled onto this channel because of my range of interest and started watching. I enjoy your discussion style and use to visual tools. I am subscribing and hope the best for your efforts. In 38+ years of repairing auto’s, it is a physical task w/o A/C and poor heat and fitting the clock as dealer techs and good shops pay by flat rate, based of warranty time for pay. Start early and stay late, burn 6,000 calories per. Retire and bring home tools and the tool boxes, fill the home garage then nurse the worn elbows, arthritic fingers and get buy on disability, SS, + a 401k if lucky. But the children were feed and had some things but no one to use the tools. $10k today gets an empty tool box with wheels & keys. Another $150k in hand and air tools. Pennies on the dollar to sell but if able, build that classic car or truck and has value since they don’t make them anymore. Besides, 1/3rd the cost of new, paid for and no tags or taxes as they are antiques, but with modern features. This industry is huge! Thanks much! Cert Auto ASE Master tech since 1978, retired.

I'm testing this protection chip AP9101CAK6-BVTRG1 with the DMN2029USD N-MOS but can't get it to work. My main problem is that it doesn't recover from overdischarge test. I connect a lab power supply to simulate a battery and when I set it under 2.8V it protects from overdischarge but increasing the voltage back to > 3V doesn't return to normal operation. Any ideas why? I've tried testing the AP9101 with the FS8205 MOSFETs from the chinese protector DW01A with no success. Thanks!!

Do you have a GitHub for these examples? I’d love to have this as a starting point without the risk of copying it wrong. Amazing presentation. Thx.

This is a good video but it does not go into detail about why it is important to avoid an undervoltage condition for some types of lithium cells. Information on this subject is hard to find but the following is what I have discovered. Lithium metal does not have good mechanical properties so many lithium cell manufacturers coat the working material onto a copper substrate. That works fine as long as the cell is above a certain minimum voltage. If the cell potential ever drops below that voltage the copper substrate can dissolve in the electrolyte and contaminate it. When the cell is recharged the copper does not plate back evenly and copper dendrites can grow across the cell until it eventually shorts. That can cause the cell to vent or even explode. There are plenty of videos showing how to "jump start" an undervoltage cell but they do not mention that the contaminated cell becomes a little bomb with a random time fuse. Lithium cell contamination may be the primary cause of lithium cell fires. Some chargers from China will slowly charge a contaminated cell as if that would somehow fix the problem. It probably wouldn't and there may be no simple way to detect the contamination or uncontaminate the cell. It is better to recycle undervolted cells than risk using them

I just came across this video and cringe when someone generalises by saying Li-ion. Mixing different chemistries as if they are the same. My check of 18650 and I get Lithium Iron Phosphate (LiFePO4) but mobile phone/tablet batteries are Cobalt based such as Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2) - These chemistries have different voltage requirements. --- Otherwise, I like your videos. The UL explanation is great.

👍🏼

BTW: Curious about the latching circuit mentioned at @19:10 to suppress the firmware infinite loop state.

i love you

Sorry, I'm not really following one part. Could you explain what you mean around @16:19 when you said that the shunt/sense resistor will "overwhelm the FET variances"? Oh, and where does the value "10" come from in your equation when solving for the current threshold?

why not use resettable fuse?

Ok excuse me but if you use a sensing resistor, why not bypass the FET's completely? R4 straight through pin 6 (Vss) and 2 (Vm)

Has someone said to you before that you look like Steve Jobs?