Why do MOBILE BATTERIES have THREE terminals? A simple Explanation.

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.

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

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

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

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

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.

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

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

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

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

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.

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.

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

Дякую за інформацію, все коротко і зрозуміло.