This video was exactly what I needed, I have an old phone with a dead battery and no charger, 6 minutes just saved hours of googling. Thank you!

The third pins explanation is nice, thanks. In regards to pin 4, at least on many Samsung phones, that's for nfc as the nfc coil is in the battery on those

Lithium Ion batteries not only catch fire/explode when they overheat. This can also happen at impact, short circuit and having the lithium metal react with water. It all potentially makes it go ablaze.

Battery protection is very important. A friend of mine bought a shady battery like this for his phone several years ago. The thing swelled the first time he tried to charge it. The battery was provided to me for the purpose of investigating what went wrong. Turns out the only "protection" there was a 0 ohm link where the double mosfet was supposed to be, and a no name npn transistor in place of the DW01 chip. Guess they used a PN junction of the transistor in place of a thermistor. Having said that, this third pin on cellphone batteries actually predates lithium ions. I've seen it on stuff used in the late 90's and early 2000's. I recall taking apart a Siemens C35 NiMh battery that looked almost identical to a Li-Ion battery. Inside however where 3 square NiMh cells in series, and the middle pin was nothing but a thermistor connecting to the negative pin. That was the whole electronics inside, and the thermistor played an important role in the charge of the battery, as that's how the charger was detecting that the battery is charged. When these batteries recharge to 100%, passing more current through them heats them up. That's what the charger detects, and stops the charge.

On some Canon camera batteries the fourth contact is to prevent third party batteries. The camera might still work but it may have limited functionality like not telling the remaining charge or it might just warn of the non-original battery. Some of those have been cracked though

Yeah, I'm running my "Lenovo A2010" phone from an external 4.5V power supply since a month now and the phone itself is nicely stable. 🙂 Yes, a 10KΩ resistor between negative and middle pin is required, but also... ● two parallel capacitors between positive and negative to simulate battery capacity ● one series diode on the positive connector to limit current and preventing the phone from trying to charging the non-existent battery ● connecting the USB to a charger is also required, because the non-existent battery can reach below 1% over time because of software reasons So, actually, you can try this at home. 🙂

i had always wondered why cellphone , digital camera , digital radios etc. have more than two terminals . he speaks clearly , not too fast and has the camera close to everything and it is focused good and he explains everything well

Well Done, Ron!! Awesome delivery and production. You have most likely, saved lives. 😍😍

excellent explanation which confirms what I always thought SHOULD happen, excepting cheap knock-off batteries of course. Thanks for sharing and great research, thank you.

I try to learn something new every day and here it is 8am and I've just done so already. Great content.

What? I thought it was obvious: the extra connection pads are there to keep the magic smoke inside! Jokes aside, it never occured to me there was a thermistor involved. Thank you for demistifying this concept, also there are great comments in the comment section which go into other details, overall very informative experience

Awesome video, can't believe your channel has such little attention, the quality is better than channels 40x the size!

Fantastic Ron!. I'm sure others have explained those extra terminals. But your presentation is top notch. It would be interesting to see if you could figure out the extra terminals of laptop batteries. I scavenged many and in so many instances that tiny board caused the battery to be rejected as a faulty one. But when I measured the voltage of individual cells sometimes all of them were fully charged at above 4V. beside the temperature of the battery which is reported to the laptop, I suspect that at least one terminal provides the signature of the cell because my laptop recognizes the cell manufacturer and its part number. Moreover because of the laptop internal charger, it would make sense that many pins would be assigned to function as BMS. However the laptop does not really need to know the SOC of each individual cell... or does it? Just like the power supply sends a good signal to the PC, perhaps the laptop tests the SOC of each cells when it's first turned on, to make sure the battery is not faulty. The total voltage of the pack could still be good while the voltage of individual not meeting safety spec? The laptop could easily analyse if that's true, but i doubt that's the case as a hardware approach from the internal BMS can easily handle this task. Are you up to doing one of those laptop pack demystifying? Thanks

Thermistors were present before lithium batteries were used. If you check the battery packs on power tools, even the old ones with NiMH or NiCad always had at least an extra connection. You can also find batteries with even more connections for smart charging using a BMS (Battery Management System). The BMS can be in the charger or the battery (depends on the design).

This is probably the most helpful video on batteries I have seen to date. May the algorithm spread the word.

sir, today you teached a complete stranger a couple of things about batteries. Thank you.

That's pretty interesting, although most Samsung batteries (not for newer phones, that's a separate component) have the NFC coil integrated into it, that is the case with the Samsung Galaxy s5 for example, that's probably why it has 4 pads instead of 3 pads.

Outstanding!! I'd always assumed it was for data transfer! That's a handy thing to know. I was just wondering how I could get a thermistor without ordering one. Kudos!!!

Only one sentence for this clip,brilliant and clear explanation .

I am amazed that you have only posted a handful of videos! Keep it up!

Thanks for this high quality video. Also, good explainations on the parts that might be logical for people with a technical background but are not for beginners like me :)

This just have solved the mystery about that pin incredibly well. Thanks a lot

Thanks mate! The couple of times i thought about what the pins were used for i just brushed it off and forgot about it but this video has been very informative. I liked it a lot!

Excellent video ! This is exactly why I had to use the protection board off my S4 battery to create a huge DIY battery pack 👍😆

Дякую за інформацію, все коротко і зрозуміло.

Dedicated camera batteries also have that protection feature with extra pins. Even shown at 4:30 in the video, but not quite pointed out in the dialog explaining this.

Sometimes the OEM batteries aren't that much safer! The photo you show of the protection board is a standard protection board that you'll see atop MOST batteries, its a DW01 chip and another bigger chip which is a MOSFET(switch). Their job is to disconnect the battery if its short circuited, discharged below 2.5V or charged above 4.2V. With these in place, batteries are much much safer - and 18650's often have them built in, but some, particularly lithium polymer rectangular batteries don't and these must only be used where there is another battery management system in place. None of this matters if the battery sustains mechanical damage which can then fail with spectacular results.

wow, an explanation so simple even i can understand it. well done!

Thanks for the video! I always assumed the middle connector was for charging the battery.

very informative! had this small question for years. Now I will try if my new battery has at least a thermal resistor before using it. thank you!

Magnificent. God Bless you and the all the developers of UKposts.

I subscribed.. Seriously this is just a simple video but very informative..thanks dude..

Thermistors were already present on ancient Siemens' and Nokia's battery packs when they still consist of AAA or similar-sized NiMH elements.

Thanks a lot. All mobile phone users must watch this video. Very useful and informative. Thank you once again for sharing this info. God bless you.

Thank you for this great illuminating video, all i can say is that i'm all 'Charged up' after watching this presentation 🙂

Thanks man, subbed. I wish you grow big and share more wisdom.

thank you sir for sharing your knowledge. your youtube channel is a real treasure.

What a relief. I've been asking myself this question for for years. Thank you very much for the explanation!!

Дуже влучне пояснення теми, буду його рекомендувати;)

With some phones that third pin can also be used to boot into service mode. And if someone wants to run phone using a external power supply, add some tantalum capacitors close to power pins. It will help with high power draws when cellular modem starts transmitting.

Ah yes, I remember having phones with replaceable batteries...

If I get to boot up my phone thanks to this, it would be great ! God bless this simple explanation and fix.

Short and to the point. Amazing!

As a student studying electronics and working on circuitry, this is all 100% true

2:01 What you said is indeed true for iPhone batteries over the past 5 years or so. iPhone batteries have some software mechanisms to prevent people from normally using a 3rd party battery. If you use a 3rd party battery for your iPhone, you will get a bunch of warnings and removed functionality of the battery. Apple is forcing consumers to only use official battery in their iPhones, which a serious issue for right to repair. You can’t even copy the information of the old battery and paste it onto the new one. The iPhone will still recognise the new battery as a 3rd party one. You need to buy a core battery, remove the battery management system (BMS) from the original battery, solder the BMS to the new core battery. All without frying anything. This is the only way to properly use a 3rd party battery on an iPhone. This shouldn’t be the case in this day and age. While the 3rd terminal is not use for forcing consumers to use original batteries, Apple does that by other means. There are quality 3rd party batteries in this world, we shouldn’t say no to all 3rd party batteries. But I do understand that there are unsafe batteries from China.

Every school needs him!

I've noticed this on other batteries too, thank you for addressing all of them. :)

That was really informative ❤

a video in an era where most phones have fixed-in batteries 😂

I don't know why this showed up in my feed, but I'm glad it did. That was some great info.

This explains a lot. Thank you Ron

The protection mechanism must be implemented by the mobile phone and the battery to ensure safety

All depends on the third party battery manufacturer. Some might be better than the OEM.

This is an excellent short but expressive information!

Thanks a lot to you Mr Ron Mattino, HONORS.

Fake/counterfeit batteries are indeed dangerous, but sometimes even genuine batteries can catch fire or explode if they were not built correctly: the Samsung Note 7 is a perfect example of this😮

This is why OEMs need to make parts available

You helped me figure out how to hardwire a restaurant headset to a power source instead of needing to use a battery. I can already hook it up to a speaker. This way people on the line can hear the orders easily even though we only have 3 batteries. Thanks man

I was about to conduct this investigation, your video saved me so much time, thank you, subscribed.

Was expecting maybe a 3.3v output on the 3rd connector, but of course it's a temp sensor! Really nice idea to put the teperature sensor inside the battery. Learnt something new about something I've never thought about, nice. 🍻 Thanks for this video.

Thank you for solving my childhood mystery

I'm stoked i finally know how to rum a phone without battery. thank you

Oh my.. this random video suggested by youtube will save me n my family from future mishaps. May nature bless you, sir 🙏

This is really an intuitive video and clearly explained, thank you, I was wondering why there is a third pin since I was 7 years old, now im 18, finally learnt it after 11 years, thank you

Thank you for explaining, always wondered why they have another pin on the battery

Amazing video! I never knew that batteries even had more than 2 connecters, until know, and I now I know why! Keep up the good work 👍

This video is one of the best videos i have ever seen on UKposts. Thank you!

Awesome video, one of the best video ever seen. It's not at all boring, and gave very detailed information

Short and simple, good video! :D

I worked at RadioShack back in the day. A customer lost his battery and we didn't have any. I was able to boot up his phone using 3 AA batteries but it didn't need a resistor. Strange but cool! Great video

I did like this! I've always been curious about those extra pads, but didn't know whom to ask.

I have often wondered 'Why do mobile batteries have 3 terminals'? UKposts served up this vid out of nowhere. Ty UKposts, Ty Ron. I can now safely test many questionable batts and you have instantly allowed me to power a dozen old cell phones that I can use for cams, remote speakers, etc. Wow. Yep. Awesome vid Ron. Ty.

I always assumed it was some sensor or data but never bothered to figure it out. Thanks for the interesting video

I've learned a piece of new information from this video. Thanks a lot.

I was able to start couple of phones with only plus and minus terminal, but some phone wasnt charging, of course after connecting the middle it took charge, i wasnt thinking about tempareture stuff tho, Thanks for the video.

Thanks!Very informative.that was one of my questions all time.

Ron, this was a very interesting video! Thank You So Much and Please Have a Healthy and Merry Christmas and Happy New Year!

Ron. Thank you! I am not technical but you were able show and explain so that I understand completely. I'm never buying a cheap battery again!

Thanks dude 😊 I work in this field field and i liked the way you explain with, I've just subscribed to watch and learn more 👍 good luck and thank you again ✌

Educated and very useful video... Thanks to your explanation... 🌷💟👍💪💌

Excellent explanation BRASIL

This is a great video. Thanks for making it. I've bookmarked it to watch again. I think I'll be avoiding dodgy third party battery manufacturers. Being able to power a phone from a difference source could be very handy if the battery stops working and I have to get data from my phone.

The third terminal can sometimes be a serial bus using Dallas 1 wire protocol to a gas gauge IC. This allows reading current, voltage, temperature, battery serial number, max capacity, charge level and many other things. Sepura TETRA radios have batteries where the third terminal does this.

Is there any way to connect the device directly to the house electrical oulet? I have a ProScan tablet that the batteries expanded and i wanna know if i can just remove the battery and use it directly from the oulet of my home.

Great video! Very nicely explained, great way of presenting! Keep it up!

Great video!! First I've seen of your channel, I think. I'll definitely watch more.

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I always thought it was some kind of data monitoring thing. Excellent video.

Very informative video. A million thanks to the creator and the team. Kudos.👍🇧🇩

“Most people are positive”. Nicely done!

I thought all these days those were the power in terminal..like DC power input and output 🤯 thank you 🤙🏾

Excellent explanation strait to the point thank you

You explained that very intelligently and concisely.

Hey Ron. Clear video, thanks. What is the brand/type of the amp/watt measuring device you are using (4:05)? I have only seen it as a USB tester.

It seems counterintuitive that if the battery temperature goes up, the resistance gets lower. I learned something new. Thank you.

I use these batteries on a certain side project, I added a overcurrent protection, but now I will add a temperature protection too

Thank you, never wondered about this but I'm happy to learn new things.

பாராட்டுக்கள்! Congratulations! Very Excellentastic Video! Thanks Mr.Ron Mattino!

I think that when there are 3 inputs on a battery, the middle is for the ground cable (protective cable) but it is not used everywhere

u can see on the PCB P- T P+ ez this is the reason why marking on PCB is very important