Why do MOBILE BATTERIES have THREE terminals? A simple Explanation.
2024 ж. 5 Мам.
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In this video I am conducting a simple experiment that demonstrates the purpose of the 3rd terminal in cell phone Li-Ion batteries.
0:00 The rule of two wires in electronics.
0:43 How is mobile phone powered?
1:55 The purpose of the 3rd terminal.
3:08 Change of resistance.
3:50 Powering the phone from an external supply.
4:43 Why are 3rd party batteries dangerous?
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!
hours really? probably one search
Right
Just a reminder. Not all people are tech and Google savvy as you guys. Just respect it as it is his opinion.
@@SelectStart89 Non ironically saying the commenter would have found the answer faster from search engine than the commenter spend on typing the comment.
@@SelectStart89 Are you the one called Mountainmaker? Because I didn't even see a molehill before you showed up.
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
Thank you! I was wondering for quiet some time now what the 4th pin is used for.
@@sternenschauer in fact if you look closely at Samsung phone batteries you might be able to see thr nfc coils under the foil cover
oh thanks
No it's not you clearly haven't seen the inside of the Samsung nfc antennas they have the coils inside them
@@pinklightninggacha not all Samsung phones are the same, i am basing it on the ones i had like the galaxy note 2-4 and the xcover pro. And you cannot see an nfc coil in there just bare but you can see the outline of one on the battery. It might be different for those with a fixed battery.
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.
They have a protection board (BMS), so when a short circuit condition occurs, the BMS will cut power off. As for reacting with water, Li-Ion cells have aluminum case and are basically water proof. The only possibility to catch fire -- like you said already -- overheat or physical impact.
@@RonMattino BMS also can cause short circuit - in a case of ic failure (happened to me once). Good batteries has also regular fuse for last resort.
And puncture
Yes they can, I had a Toshiba laptop that had a built in Lithium battery and when it eventually broke down I was breaking the case up into smaller parts to throw in the trash and the battery literally exploded and caught fire and it was like a blow torch, literally a jet of fire was bursting out of the laptop from the battery compartment, it almost burnt the house down the fucking dangerous thing
Lithium-ion is not the same as lithium metal. The batteries don't have lithium metal in them.
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.
You can use a 2 pin diode as a temperature sensor and is very linear unlike the thermistor which has a curve. But NEVER in place in a circuit that needs a thermistor.
Battery starting to swell on charge means that's it's very old. Some shady sellers just relabel the batteries to reflect a more recent date to trick the buyer.
@@RonMattinohat needs to be fucking criminal if it isn't already. They're gonna burn someone's house down. Not like anyone would enforce it though. Sign...
No need to write to much
STOP PROMOTING SHIT. THERE'S NOTHING WRONG WITH 3RD PARTY BATTERIES. EVEN MANUFACTURER BATTERIES HAVE PROBLEMS. SAMSUNG AND APPLE BATTERIES HAVE EXPLODED. BUY FROM REPUTABLE SOURCES. NOTHING WRONG WITH THIRD PARTY BATTERIES
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
Sometimes my canon camera tells me to check if i use an original battery. I'm always confused bc i only use original ones.
@@UnboxingTVofficial the chip that checks might be worn if you are using original
So basically an iPhone
Canon crippled hammer just play the role there. Now they banned all 3rd party lens.
@@AdminTechnopedia just jailbreak the device FFS
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. 🙂
2nd and 3rd points are understood, by why do you need the parallel plate capacitors?
@@puspamadak Those are kinda simulating the capacity of the non-existent battery, buffer for the incoming voltage. Maybe not every phone needs those, I don't know.
You are right about the capacitor. But it's actually needed to provide peak currents that occur when the phone transmitter boots up. As for the diode, no you don't need it. You don't connect a charger to the phone powered like that, why would it want to charge the battery? ;) Also, you can't limit current with the diode, and you don't want to limit it (see above why). Battery charge is monitored by voltage also, it won't go down to 1%.
@@RonMattino Okay, not every phone like that, but my phone went down under 1% and turned off over an afternoon, so, if the battery % starts to decrease over time, just add a series diode to the positive pin and connect USB to a charger... The diode is simply prevents the phone from trying to charge the non-existent battery and eliminates the possibility of the phone heating up because of the unnecessary charging attempt.
@@zsombor_99 is that save, bruh??
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
I try to learn something new every day and here it is 8am and I've just done so already. Great content.
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.
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).
Cool! Thank you for this information. :)
A 'BMS on a charger' is known as a cell balancer, balanced charger, or 'charger with built in balancer'. The term 'BMS' should only really be used if it is mounted on the battery itself, if the circuitry is on the charger, then you should use the term balancer - that way when designing the electronics you know where the balancing occurs and whether to specify a balanced or regular charger. As an example, model aircraft almost always use batteries with no BMS, and instead specify you need a balanced charger. This is because the BMS would be dead weight in the air (until someone invents mid-air inductive recharging!), so you have the protection circuitry on the ground as a balanced charger. E-bike batteries on the other hand are almost always constructed with a BMS, that way you can use any charger you find that has the correct voltage to charge from, and dont have to worry about finding one with balance leads - handy if you are in the middle of nowhere, low on juice, and you can just pop into a bar and ask if anyone has a charger with them.
@@Debbiebabe69 Mostly (probably 99.9% of the time in modern batteries) the BMS will be integrated in the battery. That's what we call a "smart battery". But I don't think that anything dictates that the BMS has to be inside of the battery or battery pack. I think that if you design a system that monitors a battery pack (or even a single cell) and protects it against over-charging/discharging, over-current, over-temperature, over-pressure (for NiMH, Lead acid batteries ... etc) ... etc. You have the right to call it a battery mangement system. We have "devices" at work that we call chargers but the manufacturer calls it a battery management system. Of course that system is "tuned" for a specific battery but it can be re-programmed for a different battery (which happened in the past because the "old" cells were discontinued). The reason we call them "chargers" is because in the on older rolling stock, and some more recent, they are indeed simple chargers but on some machines they are far more advanced and control/monitor the batteries at cell level (voltage, current, temperature and pressure).
hi ppdan have you become a flat earther yet? If not I suggest watch a 13 part series called _What on earth happened_ by Ewaranon to learn that the earth is not a globe. I got it in my about tab.
Well Done, Ron!! Awesome delivery and production. You have most likely, saved lives. 😍😍
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
Due to the capacity of Li-ion battery there is an excessive amount of magic smoke inside, so you have to be careful, but just like any other electrical thing - once the smoke escapes the equipment no longer works...
Excellent video ! This is exactly why I had to use the protection board off my S4 battery to create a huge DIY battery pack 👍😆
Awesome video, can't believe your channel has such little attention, the quality is better than channels 40x the size!
His voice sounds like one generated with a TTS program, ESPECIALLY when """""he"""""'s pronouncing "kilo-ohm".
This just have solved the mystery about that pin incredibly well. Thanks a lot
I don't know why this showed up in my feed, but I'm glad it did. That was some great info.
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
It's true that laptops have a much more complex BMS's. The BMS, however, cannot read any extended information from the cells besides voltage. But what it does do, is _compare_ cell voltage to each other, and if it does not match, it flags the battery as defective. So, in some cases (this esp. works with power tools batteries), it helps to level the cells' voltage. This _might_ trick the BMS into believing the battery is ok. As for the manufacturer and part no. info -- this comes from the EEPROM on the BMS PCB. There is no way to extract this info from the cells. If you replace _all_ the cells, the BMS will report the same info. As for figuring out extra pins of laptop batteries, thing is, all of them are different. There isn't actually any standard that manufacturers stick to. There isn't, I believe, also much point in doing that, since laptops -- contrary to cell phones -- _can_ run off the charger w/o battery pack.
@@RonMattino Thanks for the fast reply, Some great infos you gave there. I agree, it's not worth it. The connectors have shrunk to SMD standard now. It's just impossible to probe anything. Moreover, you're right and I've been using the charger for quite a while on some of my laptops with dead batteries.
@@francoisguyot9770 Yep. Strange fact, btw. These days you can find full schematics for most laptops and smartphones online, including Apple products. However, you can't find diagrams for laptop batteries or chargers. I once tried to repair an Apple Magsafe charger with a damaged (shorted) cable, turned out charger is run by the microcontroller which blocks the device if a short-circuit condition occurred _once_. So, it was dead not due to the damaged parts but just because the MCU locked up.
@@RonMattino Yeah, that's very much like Apple to lock peripherals into the EEPROM itself. This way you're out buying another of their product because the laptop won't acceptt anything less than Apple stuffs. To be honnest, I hate the way they use the backspace even to erase forward letters. But PC have their share too, that's why i stick to Linux. All that prompted people to believe in conspiracy of programmed obsolescence. Merry Christmas and happy new year! Cheers!!!
@@francoisguyot9770 Yes, Apple is notorious for working against the consumer's interests; proprietary cables, slowing down iPhones via software updates, lobbying congress against right to repair laws, etc. I also use Linux on everything, just wish Android was closer to regular Linux.
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.
Yes, exactly, that's NFC sensor output. The battery also has the "near field communications" message on.
@@RonMattino It is not 'NFC sensor', but NFC antenna. To be honest one end of it, because second is grounded internally.
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!
This is probably the most helpful video on batteries I have seen to date. May the algorithm spread the word.
May the algorithm spread the word -- love that! ;)))
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.
Only one sentence for this clip,brilliant and clear explanation .
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!
Thanks for the video! I always assumed the middle connector was for charging the battery.
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 :)
sir, today you teached a complete stranger a couple of things about batteries. Thank you.
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.
A DW01 + two MOSFETs connected in series actually, because current needs to be cut both ways: during charge and during discharge. And MOSFETs, as we know, conduct current if reverse-biased. Original branded 18650, in fact, do not have BMS's, but 3rd party Chinese made 18650s do. As for mechanical damage, most Li-Ion cells have a security valve that is supposed to let the gas out in case a short circuit occurs. Unfortunately, it doesn't always work as intended.
You are very wrong in that later part. Most 18650 or any Li-Ion cell in general doesn't have any protection besides pressure release valves or such mechanical measures. The class of batteries that come with Protection circuit are called Protected cells and are rather uncommon. Li-po batteries almost always come with Protection circuits due to the size and possible danger except when the Li-pos are intended to be very high drain or used in a battery pack.
n7
Or you accidentally charge a hobby lipoly pouch cell on NiMH settings and drive 5-6 volts into a 4.22V cell (AKA, the typical "Absolute maximum rating" for many kinds of lithium cell chemistries). :P I had one the size of a couple pennies go up once. From sitting on my desk, the fireball licked the roof and the fireball filled my *entire* peripheral vision on the left side. I'm a big fan of iron phosphate for bigger packs, to say the least. :)
wow, an explanation so simple even i can understand it. well done!
Thanks a lot to you Mr Ron Mattino, HONORS.
Short and to the point. Amazing!
I am amazed that you have only posted a handful of videos! Keep it up!
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!!!
Well, yes, but they are really cheap actually. ;) If you look on Aliexpress, for example.
Some batteries include wiring/contact for NFC antenna. So in some cases, there is some data transfer. (most knockoffs will advertise NFC antenna, and have nothing tho)
@@IvnSoft True, but those are 4 terminal batteries, like Samsung Galaxy S6. And they still do have the NTC thermistor pin.
@@RonMattino NTC Negative Temperature Coefficient temperature goes up -> resistance goes down (I couldn't spot an explanation about the meaning of NTC in the vid)
Technically it is data transfer, it transfers data about the temperature of the battery. Also there are some batteries with a 4th contact that is actually used for data transfer. My Canon camera batteries, in the camera can tell me the batteries serial number, state of charge, and battery health.
If I get to boot up my phone thanks to this, it would be great ! God bless this simple explanation and fix.
I've noticed this on other batteries too, thank you for addressing all of them. :)
Thermistors were already present on ancient Siemens' and Nokia's battery packs when they still consist of AAA or similar-sized NiMH elements.
That was not only for protection, but to terminate the charge as well. Ni-Cd and Ni-MH get hot as they are fully charged
Well yes, and also some old Nokia batteries used a resistor on 3rd terminal to designate cell type/capacity. They used this method for some time, but not in newer Nokias.
I subscribed.. Seriously this is just a simple video but very informative..thanks dude..
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!
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
As a student studying electronics and working on circuitry, this is all 100% true
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.
3rd pin is never used to activate service mode. It's usually pins on PCB. You are right about extra capacitor though -- that's a valuable addition! Some phones may even fail to boot w/o it.
@@RonMattino ah maybe they remove it from production devices. I worked several years in Nokia and did some testing and flashing tools. 3.bp.blogspot.com/-L7dOBv0aTGo/TyL5EjuwMxI/AAAAAAAAAV0/1hdakauri44/s1600/Nokia+C1-01+Loca.jpg
@@RonMattino SOME (do you know every phone and battery ever produced?) -- and at least the sony PSP uses that pin too (see Pandora Battery)
I was about to conduct this investigation, your video saved me so much time, thank you, subscribed.
This video is one of the best videos i have ever seen on KZhead. Thank you!
thank you sir for sharing your knowledge. your youtube channel is a real treasure.
Thanks man, subbed. I wish you grow big and share more wisdom.
Thank you for this great illuminating video, all i can say is that i'm all 'Charged up' after watching this presentation 🙂
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
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.
Are there any batteries not from China?
That's Apple.
@@danielch6662 China makes most things, which is the only way that western nations can pretend to be 'carbon neutral', because all the fossil fuel use and mining are done overseas.
That was really informative ❤
Thank you for explaining, always wondered why they have another pin on the battery
Magnificent. God Bless you and the all the developers of KZhead.
The protection mechanism must be implemented by the mobile phone and the battery to ensure safety
right, the phone needs to do monitor those temps using that 3rd pin.
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😮
They're only dangerous if not properly protected with a thermistor, not by default. It's not unheard of for an OEM battery manufacturer, which is just some generic company sticking an official label on one of its batteries, to just release basically the same thing as generic, but without any official labels or branding.
Actually the battery compartment was too tight and as batteries expand while charging, the increase of pressure caused the problem.
Дуже влучне пояснення теми, буду його рекомендувати;)
I always assumed it was some sensor or data but never bothered to figure it out. Thanks for the interesting video
Ah yes, I remember having phones with replaceable batteries...
If you're in the EU new phones in like... 2025 will be required to have user replaceable batteries.
@@ayoCC Hopefully if the OEM's have to comply with EU rules they'll just sell the same models over here.
Every battery is replaceable, only opening and closing smartphone takes time and tools
@@SekretyZdrowiapl Sure, just not a job for a rank amateur.
@@civildiscourse2000 Yeah. Modern phones are glued together and require heat guns/special equipment to pull apart (especially if the phone was advertised to have some form of water proofing like the iPhones). it's why I don't really offer to try and repair/replace screens on people's cell phones on the rare occasion they wanted me to. I used to work on stuff like that as a hobby and today's phones are too much of a pain in the a** to open up these days. So I just say no. :P
a video in an era where most phones have fixed-in batteries 😂
The internal batteries also have a temp sensor, and you also can power such a phone like that if you take it apart.
Every school needs him!
This is an excellent short but expressive information!
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.
All depends on the third party battery manufacturer. Some might be better than the OEM.
Or identical.
Oh my.. this random video suggested by youtube will save me n my family from future mishaps. May nature bless you, sir 🙏
This explains a lot. Thank you Ron
This is why OEMs need to make parts available
Thank you, never wondered about this but I'm happy to learn new things.
I did like this! I've always been curious about those extra pads, but didn't know whom to ask.
I've learned a piece of new information from this video. Thanks a lot.
I have often wondered 'Why do mobile batteries have 3 terminals'? KZhead served up this vid out of nowhere. Ty KZhead, 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.
Awesome video, one of the best video ever seen. It's not at all boring, and gave very detailed information
It seems counterintuitive that if the battery temperature goes up, the resistance gets lower. I learned something new. Thank you.
I'm stoked i finally know how to rum a phone without battery. thank you
Excellent explanation strait to the point thank you
“Most people are positive”. Nicely done!
多謝分享
You explained that very intelligently and concisely.
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.
Дякую за розповідь )
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.
Thanks!Very informative.that was one of my questions all time.
u can see on the PCB P- T P+ ez this is the reason why marking on PCB is very important
Excellent explanation BRASIL
Wow thats all, years long mystery in my head is solved. Thanks 😊
Thanks for explaining. Now I'm keeping the knowledge of this.
Educated and very useful video... Thanks to your explanation... 🌷💟👍💪💌
I always thought it was some kind of data monitoring thing. Excellent video.
Awesome and educative video, just what I needed to know and have always wondered.
Nice one Ron. Very informative. And very important.
thank you for sharing!
The best and simplest explanation ever thank...🙌
Thanks for this clear explanation.
Thank you. Very usefull explanation, everybody must learn about this because the danger .
Ron, well done and thank you.
Great video!! First I've seen of your channel, I think. I'll definitely watch more.
Thank you for the significant information
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.
Dzięki ❤
Amazing video, thank you so much!!🙂
Great video! Very nicely explained, great way of presenting! Keep it up!
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
Well done. Good job ! Precious information!