Hi ,I just wanted to take a moment to let you know how impressed I am with your teaching skills in the area of EV vehicles. Your lessons are always engaging and informative, and you have a real talent for breaking down complex concepts into easily understandable terms. Your passion for the subject really shines through in your teaching, and I feel so lucky to have you as my teacher. Thank you for everything you do! Best regards, Reza
I recently took Prof. Kelly's Hybrid/EV hands on bootcamp. It was one of the greatest learning experiences I have ever had! I would recommend it and I would do it again in a heartbeat!
Wow, thank you so much. I had always been worried about this. I heard about the old 12 V batteries having issues constantly. And when they jump to the lithium, am I on it was a better life. Thank you for pursuing this important topic.
You keep wearing a great gentle smile while explaining the deep technology things. That attracts your student's attention and helps to understand the topic quickly. Keep it up professor.
In October we have the 10th anniversary of Tesla Australia. I own one of the 11 Model S P85+ Signatures with now 383000km on the screen. Thank you from Coonabarabran, Australia.
@@theaustralianconundrum I am very glad to have switched 5 years ago. Much more comfortable and way cheaper to run. I do 30.000km/a incl. regular 900km trips. But Aussies love their oversized utes and cruisers and there is a lot of hate including vandalised charging station.
There is nobody better with EV technical information than the GREAT Professor Kelly! No other person would be able to notice an incorrect voltage label than John! 🔧👑
Highly appreciated from Germany, too. As an Ampera-e/Chevy Bolt driver I'm watching every video since your deep dive in Ampi's electric engine. Learned a lot about all the functions of parts in automobiles
Hello professor, I want to tank you very much for what are doing, continue education very detailed explanations about those amazing vehicles and technology associated with them. I've been watching you for a very long time and the informations you provide are extremely valuable. Watching your content convince me to buy a brand new Tesla Model X recently and you gave me the confidence that this vehicle is far more superior compared with any other EV's currently available. Even though Tesla is not to be perfect technology, they are working hard on getting there. Thank you for that. I hope you stay healthy and well and continue doing what you're doing. We need you and I hope there is way of supporting your channel and your work. You should be nominated for an Oscar in education when it comes to cars and EV's.
I've watched you for a couple years professor and you are the best. I just recently bought a 2025 model y long range, so now I'm watching you again and re-watching you again and really enjoying it.
How powerful is the DC DC converter that charges up the 16V battery? What power can you pull from it? How can you take substational 12-16V power out of the car?
Great to see you again Dr. Kelly. I am very impressed with your mechanical and electrical expertise as it relates to these vehicles. Looking forward to see more of your videos in this channel.
MOS is open on positive side,(from memory) you can still measure the voltage of the battery with the MOS open if you use a meter , since there is a capacitor inside the battery, you'll measure the voltage stored in the cap. Briefly You can also measure between the LIN and ECPA pins and get the voltage. If the voltage is 10.5v or more, the vehicle can recovery the battery, if it's lower, it'll need charging using a an off board charger
I now have 3 (Dead) 16V batteries. No or very low V from positive to lin. I open two of them and tried charging them at the cell connection with no luck. I used a computer charger 14V 2 amp. Any advise?
@@patricksughrue1313 yout computer (charger) is not a charger. It's a power supply. Since it's only 14V it will not be able to charge the battery to 15.5-16V.
It's been a while and glad to see you back. As always, I love this channel and just learned a lot about my model Y LV battery. I didn't even know it was 16V as opposed to 12V. Thanks for the information.
By the way, it's not 16V as opposed to 12 V: it is 14.4 V (nominal for 4S lithium-ion) as opposed to 12 V (nominal for 6S lead-acid), or 16 V (float voltage for 4S lithium-ion) as opposed to 14 V (float voltage for 6S lead-acid).
The same battery protection functions that you describe in this video are built into some - possibly many - small lithium battery packs for cordless tools, test equipment etc. They have a MOSFET with a controller that looks at many of the same variables to protect the batteries. Interesting stuff, and very thoroughly presented!
Many have two. One for charge, one for discharge. Many people incorrectly assume the "charger" is the thing with all the brains, but they almost never are. (the most advance one I've ever seen is a 4 bank gang charger for craftsman packs. it only charges on pack at a time, so it has a very tiny analog logic "brain".)
What you mention some of these protections are in the cordless tools itself but NOT in the battery. So be careful to not use the battery for something else which may destroy it because of NO protection with these usecases.
Good morning Dr Kelly, thank you very much for your explanetion. I'm Italian and a Tesla owner (MOD Y RWD), you explain in very simple way, thank you. Max
i am so glad you take the time to give us this information. makes me so proud that i am 66 years old and drive a 1994 Ram 2500 4WD gas burner and plan on it being the last vehicle i ever own don't need special tools or have to use the special gloves that i have to be safe. thanks
Professor John D. Kelly, Thank you very much for wonderful explanation of the Tesla 16V Li-Ion battery. MOSFET brought back my Grad school memories (I have Masters in Applied Electronics). My 2023 Model 3 Tesla had 0% battery when I returned back from July 4th vacation. The car is brand new with 5900 miles on it. Weather was so hot ( I am in Washington DC area) the automatic cabin temperature control kept running and drained the battery. Your video helped to understand the Li-ion battery and now the car is charged from 0% to 70%.
You are a very good at teaching others! So happy to have you in my youtube world. I am a EE and love your videos! I can not say enough! Keep the ball rolling!
As usual another great automotive video from the prof. As a slight side comment there will likely be two sets of FETs in the BMS since a typical FET has a body diode in its structure which means the FET can only block current in one direction. Opposing FETs are needed to block current in both directions. As a result the BMS can typically block charge, discharge, or both. It wouldn't surprise me if the BMS is acting on the negative side of the battery.
Fantastic job explaining the LV system and the pesky battery issues. My MY is at the Tesla Doctor for this very issue. Hoping they watched your videos.
Fantastic lesson on Tesla's Li-ion system. Thank you so much for this. I am coding refreshed Model S/X cars for tilt screen and Matrix headlights retrofits and have encountered several LV battery drain issues, not always, but often. Another option that has worked for me is using another Li-ion Telsa to jump start and close the HV contactors (LV disconnected).
I love the depth and detail. Working on mostly German cars for 20 years, this LV system is unlike anything I have ever seen. The F80 M3/M4 Li-Ion LV system is the closest but still ICE architecture
@@WeberAutoAlso, thank you for explaining the open and re-closing procedures so thoroughly. There were piles of replacement lead-acid batteries (and empty boxes) at my service center. The older system must be very failure-prone
@@carholic-sz3qv Not for 12 V loads though, only for high current loads like electric A/C. Using 48 V for everything requires changing every solenoid, motor, relay, light bulb, and control module in the car. Big PITA and costly for to switch. However, after doing the work and investment, the wiring harness and other components will be lighter and less expansive, using a lot less copper.
I don't even own a Tesla just watched the video out of interest, but have to say It is very handy information to have should I come across a Tesla owner with LV battery issues. The video is explained very well
At 6:55 , Just to bring new verified informations: These are laser welded prismatic cells made by CATL and are not pouch cells. These are capable of an insane 10c recharge and 50c discharge (345A for 10 sec) but probably limited to lower value by the BMS. Cell model number is probably: HY-3769c from CATL
@@rkan2 problem is 4s of NMC cells is way higher volt than conventionnal 12V lead acid. Higher than 15 or 16V might damage the car on 12V battery. OR.. by the voltage difference, the current that goes from the Tsla battery to the 12V battery will be very high and not have any current limiting control except protections cut off from the BMS.
@@Doctorbasss Most 12V systems should be fine at 15-16V when the 12V spec is up to 14,2V charging voltage. There is probably at least 10% margin upwards on most vehicles on the voltage. After that you might start doing damage.
Thankyou for the little educational video. The chances of me working on an EV is slim to none but I try to keep up to date. Most of my customers drive rolling scrap yards.
I have trouble saying Weee-ber. I'm a fan of Weber Grillls and I've never heard it pronounced like that. I am loving these Tesla videos. I've learned a lot.
Hello Dr. Kelly, Thank you for another fantastic and informative video. I am still learning about BEV's and the "jump start" had be very confused until I watched the full video. Watching more BEV/Tesla content P-Chi
not just that you make awesome videos, you are an inspiration to me! and even though i dont want to mention it i just feel like i have to, being in a wheel chair i guess is really hard and fact that you managed not only to overcome it but to be such a guru! rock on my man! amazing content!
While charging at a level 2 ChargePoint charger, another Tesla owner was having a problem with his LV 16 volt battery. The Tesla service tech was guiding him over the phone. I keep a small jump start battery in my trunk to help ICE drivers jump start their cars. It’s also a handy USB charger. We used it to open the frunk of his car, so he could do the second procedure you described.
Your explanation of how the Tesla battery works also described the normal actions performed by any BMS designed to work with 4 LiIon batteries connected in series. Besides all the features you mentioned, most BMS boards also have an automatic battery balancing function that works whenever the battery is charging. They also have BMS boards that work the same way with the lower voltage, longer life, LiFePO4 batteries. In that case they are equivalent to the voltages obtained by a conventional lead acid car battery, but have 3000 to 4000 full charge/discharge cycles before they drop to 80% capacity...
12:00 case: My MYLR with odometer just 8K, 4 days ago suffers an electrical system failure, vehicle may not restart message. I believe pyro fuse cuts off high voltage battery upon drive unit failure. The low battery supports the screen, emergency light trunk etc for a few minutes before dies too (at this time, the car was totally dead) while waiting the tow. How likely this Li-Ion battery battery is totally drained? I wonder if I have to press the service center to replace the battery too (still in the shop, never get back to me on any progress since Sun).
The battery protects itself by shutting off at a 10% state of charge. It is probably not bad and can be recovered by Tesla. Sorry to hear of your troubles. Best wishes.
Dear Prof. Kelly and the whole team: I'm aways happy, when I got a notification, that you have uploaded a new video, because I KNOW, there will be another superb content for the starving brain. 🙂 BUT I couldn't stand watching your high quality videos for free all the time, so I donated 100 USD. 😉 You do got the juice, Prof. Kelly, to jumpstart anybody with your energy and skills! Greetings from Germany - SkyPower Wind Energy - CEO PS: If you add a PayPal link in the video description, this would make the donation much faster and easier. PS2: Would a teardown of this 16 v battery be possible? I can't imagine what cells Tesla is using for those extreme high C ratings way over 50 (BMS cut off) . 🤔
The Ingineerix RUclips channel has a 2 part video from over 1 year ago, called Tesla Plaid - 12 volt Lithium Battery where he tears down this low voltage battery pack and goes into detailed explanation on each of the components inside.
@@KCautodoctor Thanks a lot for the info! I must have missed that. Those CATL cells are really rated for 50 C peak, stated in the data sheet shown in that video. Amazing!
Thanks for making this video. I have always wondered how you would "jump" a Tesla with a "dead" 16V battery. I hope I never have to do it, but it is great to know how.
The most common form of Mosfet power switching is negative side. So the positive is connected to the terminal and the negative is switched on or off by the Mosfet. They typically have a very high resistance off so that's why not very much voltage can leak through. I can't say for certain that they're doing this there is also positive side switching, but not used as often.
Looks like that 16V system creates some confusion even with Tesla employees. Wrong sticker and you get a faultcode to replace the 12V battery when you need to replace the 16V battery.🫣 Great content John, thanks for sharing.
Good and informative video again Professor! I did not know 16V low voltage battery is used on Teslas. Thank you for informing us. Keep the videos coming!
4.2v x 4 (4.2v in series of 4)=16.8v 3.7v x 4 (3 7v nominal voltage)=14.8v 2.5v x 4 (2.5v depleted voltage)=10.v Manufacturer's use voltages anywhere in that spectrum from depleted to full charge voltages on their products. That is why ryobi has the 18v tools and dewalt has 20v fir example. If you look inside either cell they are both just 5s battery packs. 4.2v in series of 5. Which ranges from 12.5v fully depleted to 21v. I hope this clears up the confusion on the voltage.
Very helpful and clear, I have been using this almost same type of battery for years and am very familiar with the cells voltage, capacity and charge and discharge rate. I fly model airplanes.
I love your education videos, it is crystal clear and you focus on bringing the important information to the audience. Regards from Hannover/Germany. Danke.
Thanks for the video. Does have any thermal protection ? i think, It should, considering that in hot summer, and charging conditions the LI-IO, can get pretty hot. BMS inside the LI-IO might monitor the temperature and command the MOSFET as well. Not sure.
Did not have any idea my Model Y has a 16 V battery. Thank you. You went through this so well I could do thias but am not going to. At my age I do not do any automove work anymore. Used to be a semi-shade tree mechanic. LOL
Very informative video! If the Tesla vehicle in question does indeed have a 16V Li-Ion battery how does one open the Frunk to access the battery? Can you still supply 12V to the connectors located in the front bumper to open it? Thanks again for supplying a great video!
Power MOSFET is negative disconnected. N channel mosfet is more common and cheaper than P channel. No need to do both polarities. I can not concur but I am sure they switch on the negative side. I am an expert on power tool lithium pack repair range from 12v, 18v, 40v, 56v. all negative switch. Positive is a direct connection without going through the mosfet. I am searching for a damaged used Tesla to buy for my own use. I am learning all about all the system in the car. Electric car is way easier and cleaner to work on providing the resources are there. I am also more than proficient on battery repair both lead acid and lithium and NiMH so EV is a natural and easy migration for me from ICE car which I also know how to work on at a deeper level. I learn quite a bit from your Utubes. Thank you. My intention is to work on all aspect of Tesla as I know they will not fix salvaged damaged car that is resurrected by me. I don't intend to let them fix anyway with their rip off charge. I do it myself if need to i can tear the battery pack apart and fix at cells level. I had processed thousand and thousand of lithium cells for the last 6years to build solar pack storage so that gave me plenty of experiences and know how. Once you understand the basic it is not hard to figure out the rest. EV is the future. Learn now or learn later and pay to the nose for repair if not knowing how to fix.
Interesting as usuall. There will be also a new jump in voltage from 16 to 48V on some model like the cybertruck which is in my opining excellent. this was anounced in the investors day recently from TESLA. This will also be compatible to the popular 48V DC supply on many "powerwall" or off the grid systems for home in case of emergency etc... even phone lines work on 48Vdc... 48V win! . Also The 99Wh on the label of the 16V battery is I guess limited to 99Wh rating to make easy the shipment of these as they dont enter to the "over 99Wh" CLASS 9 Hazardous goods transportation regulations.
Lots of others have already said it, but Professor John Kelly's through research and clear presentation style make complex technology easy to understand. I really appreciate his videos here at WeberAuto.
Great video again! I think they are great for reuse in other cars/motorbikes because of their lightweight and their self protection. You might wreck some stuff not being able to run above 15v though. I think at 400A discharge limit, it can crank quite a lot of small petrol engines, even though it will seriously decrease its lifespan. Do you know if the negative is always connected to the battery casing? That might give a clue over which one the mosfet opens
@@WeberAuto I opened a VW 48v mild hybrid battery, and the battery negative was just connected to the battery casing. The contractor was on the positive side. So 12v and 48v have common ground, and only positive switched. But of course, that is a different system.
@@WeberAuto The vehicle has a negative ground for the low voltage system. That means that either the battery negative is connected to the case (either internally or via an external connection), or the case is floating. A floating case for an electrical component seems unlikely to me.
Usually, battery management system MOSFETs disconnect the negative side. This enables the use of N-Channel MOSFETs which have a lower internal resistance than the P-Channel ones.
Great video as always. You have a very nice way of explaining things. I wonder why Tesla didn't go along the LFP route for the low voltage system? I guess there must be reason!
I could be wrong, but I read that LFP voltages do not change very much as the state of charge decreases. That makes it difficult to determine state of charge and state of health.
@@WeberAuto That's true, LFT have a very particular SOC curve which make the BMS algorithm to work harder on both end to determine the SOC, however, a 4s LFP cells is EXACTLY the same voltage range LVC and HVC as a lead acid which is also excellent and also the discharge curve as also very flat on both... it is like that 4s LFP and 6s Lead acis have been made to coexist together...
@@WeberAuto that certainly makes sense and one of the reasons Tesla recommend 100% charging on their LFP cars. I run LFP batteries for my 4WD fridge etc and they certainly run a very flat curve from about 95% down to 20% or so. I assume the 85% charging limit is Tesla's way of extending the life of the cells.
Hey Kelly, welcome back! Kind of surprised they "only" went for 16 volts- 24 volts would have had further improvements in efficiency but would share parts with milspec and semis, so I'm wondering why. Also of note- I've seen some owners find that the Teslas really hammer their 12v lead acids, or at least used to in the old S's. Mine was replaced recently, so I guess i'm gonna see.
The whole purpose of moving to a 16V Li-Ion battery is to improve the reliability of the low voltage system. This battery and a late 2019 change in the power conversion system with a "Standby Power Supply," will keep the low voltage battery maintained with the contactors off.
They will be moving to 48V systems shortly with all modules of their own design according to their latest open house day. Refer to a Munro interview on Autoline this week.
So Tesla brings a 16 volt system into a 12 volt world and does not tell anybody or even label the power receptacles correctly. I foresee no possibility of anything going wrong with this at any time under any circumstances.
Awesome. A few years back, I watched you breakdown a Prius hybird system. I had a Prius and now a Tesla. Just coincidence, I came across your video on the model Y.
Hi ,I just wanted to take a moment to let you know how impressed I am with your teaching skills in the area of EV vehicles. Your lessons are always engaging and informative, and you have a real talent for breaking down complex concepts into easily understandable terms. Your passion for the subject really shines through in your teaching, and I feel so lucky to have you as my teacher. Thank you for everything you do! Best regards, Reza
Thank you very much Reza!
yeah man. im hooked and this is my first video ive every watched from him
I recently took Prof. Kelly's Hybrid/EV hands on bootcamp. It was one of the greatest learning experiences I have ever had! I would recommend it and I would do it again in a heartbeat!
@@TheDisgruntledMechanic Thank you Mike! It was great to have you in class.
Wow, thank you so much. I had always been worried about this. I heard about the old 12 V batteries having issues constantly. And when they jump to the lithium, am I on it was a better life. Thank you for pursuing this important topic.
Wow I can’t believe this is the best informational video I have ever seen on youtube. Internet should be full of this stuff! Thank you sir!
You keep wearing a great gentle smile while explaining the deep technology things. That attracts your student's attention and helps to understand the topic quickly. Keep it up professor.
So nice of you
I take notes on the slow mellow tone and mindful word choice
No one explains EV systems like the doc. Weber must be the best training centre in the US.
Thank you very much!
Yes the "reconnect LV battery" button in Service mode does the same thing as the toolbox 3 procedure.
Good to know. Thank you
Great to see Dr Kelly back on RUclips! All the best from Australia sir.
Many thanks!
@@WeberAuto Ditto from Australia, love your presentation style, watch every video all the way thru !
In October we have the 10th anniversary of Tesla Australia. I own one of the 11 Model S P85+ Signatures with now 383000km on the screen. Thank you from Coonabarabran, Australia.
@@moestrei ICE only for me.
@@theaustralianconundrum I am very glad to have switched 5 years ago. Much more comfortable and way cheaper to run. I do 30.000km/a incl. regular 900km trips. But Aussies love their oversized utes and cruisers and there is a lot of hate including vandalised charging station.
There are no such advanced courses here and everything is still very unknown, thank you
The amount of research and great work that goes into these videos is simply outstanding.
THANK YOU!
Thank you very much!
When I went to engineering school over 40 years ago, we never had professors this good.
Thank you!
There is nobody better with EV technical information than the GREAT Professor Kelly! No other person would be able to notice an incorrect voltage label than John! 🔧👑
LOL, Thanks Dave!
Highly appreciated from Germany, too. As an Ampera-e/Chevy Bolt driver I'm watching every video since your deep dive in Ampi's electric engine. Learned a lot about all the functions of parts in automobiles
Great to hear!
Hello professor,
I want to tank you very much for what are doing, continue education very detailed explanations about those amazing vehicles and technology associated with them.
I've been watching you for a very long time and the informations you provide are extremely valuable. Watching your content convince me to buy a brand new Tesla Model X recently and you gave me the confidence that this vehicle is far more superior compared with any other EV's currently available. Even though Tesla is not to be perfect technology, they are working hard on getting there. Thank you for that. I hope you stay healthy and well and continue doing what you're doing. We need you and I hope there is way of supporting your channel and your work.
You should be nominated for an Oscar in education when it comes to cars and EV's.
I've watched you for a couple years professor and you are the best.
I just recently bought a 2025 model y long range, so now I'm watching you again and re-watching you again and really enjoying it.
He’s back!! Yay!
Thank you!
WeberAuto • We appreciate you very much, professor Weber!👍👍✌️
@@masbestiaquetu I have muscular dystrophy.
@@masbestiaquetu if you feel ignorant right now, it’s because you are
How powerful is the DC DC converter that charges up the 16V battery? What power can you pull from it? How can you take substational 12-16V power out of the car?
Excellent observation @4:35 with wrong battery voltage labeling ! Thank You !
Thanks for watching
Great to see you again Dr. Kelly. I am very impressed with your mechanical and electrical expertise as it relates to these vehicles. Looking forward to see more of your videos in this channel.
Thank you kindly!
Thanks for your great videos, sir!
Thank you very much Fred!
MOS is open on positive side,(from memory) you can still measure the voltage of the battery with the MOS open if you use a meter , since there is a capacitor inside the battery, you'll measure the voltage stored in the cap. Briefly
You can also measure between the LIN and ECPA pins and get the voltage.
If the voltage is 10.5v or more, the vehicle can recovery the battery, if it's lower, it'll need charging using a an off board charger
Great info. thanks!
I now have 3 (Dead) 16V batteries.
No or very low V from positive to lin. I open two of them and tried charging them at the cell connection with no luck. I used a computer charger 14V 2 amp. Any advise?
I disagree. It makes zero sense to use a P-FET because of the losses.
@@patricksughrue1313 yout computer (charger) is not a charger. It's a power supply. Since it's only 14V it will not be able to charge the battery to 15.5-16V.
@@patricksughrue1313...I'd try charging the cells individually with 4v
Thank you Professor Kelly, great to see you again. And thanks to your assistant as well. Cheers from Comox Valley.
My pleasure! I will.
It's been a while and glad to see you back. As always, I love this channel and just learned a lot about my model Y LV battery. I didn't even know it was 16V as opposed to 12V. Thanks for the information.
Thank you. I am glad it was helpful
By the way, it's not 16V as opposed to 12 V: it is 14.4 V (nominal for 4S lithium-ion) as opposed to 12 V (nominal for 6S lead-acid), or 16 V (float voltage for 4S lithium-ion) as opposed to 14 V (float voltage for 6S lead-acid).
@@brianb-p6586 you are correct sir!
Terrific video and clear, logical presentation with excellent graphics. Thank you from Virginia.
The same battery protection functions that you describe in this video are built into some - possibly many - small lithium battery packs for cordless tools, test equipment etc. They have a MOSFET with a controller that looks at many of the same variables to protect the batteries. Interesting stuff, and very thoroughly presented!
Many have two. One for charge, one for discharge. Many people incorrectly assume the "charger" is the thing with all the brains, but they almost never are. (the most advance one I've ever seen is a 4 bank gang charger for craftsman packs. it only charges on pack at a time, so it has a very tiny analog logic "brain".)
Thank you, good point
Yes, small lithium-ion batteries normally have an onboard BMS, including those in power tools.
What you mention some of these protections are in the cordless tools itself but NOT in the battery. So be careful to not use the battery for something else which may destroy it because of NO protection with these usecases.
Good morning Dr Kelly, thank you very much for your explanetion. I'm Italian and a Tesla owner (MOD Y RWD), you explain in very simple way, thank you.
Max
Glad it was helpful!
i am so glad you take the time to give us this information. makes me so proud that i am 66 years old and drive a 1994 Ram 2500 4WD gas burner and plan on it being the last vehicle i ever own don't need special tools or have to use the special gloves that i have to be safe. thanks
Thanks for your feedback
I was been missing this videos.
Thank you
Professor John D. Kelly, Thank you very much for wonderful explanation of the Tesla 16V Li-Ion battery. MOSFET brought back my Grad school memories (I have Masters in Applied Electronics). My 2023 Model 3 Tesla had 0% battery when I returned back from July 4th vacation. The car is brand new with 5900 miles on it. Weather was so hot ( I am in Washington DC area) the automatic cabin temperature control kept running and drained the battery. Your video helped to understand the Li-ion battery and now the car is charged from 0% to 70%.
Both batteries were dead? How did you solve it which solution worked? Thanks
Glad to see you back professor, and congratulations for the video graphical information that pop-up on sometimes, they are very helpful.
Much appreciated!
You are a very good at teaching others! So happy to have you in my youtube world. I am a EE and love your videos! I can not say enough! Keep the ball rolling!
As usual another great automotive video from the prof. As a slight side comment there will likely be two sets of FETs in the BMS since a typical FET has a body diode in its structure which means the FET can only block current in one direction. Opposing FETs are needed to block current in both directions. As a result the BMS can typically block charge, discharge, or both. It wouldn't surprise me if the BMS is acting on the negative side of the battery.
Great information, thanks for watching
Fantastic job explaining the LV system and the pesky battery issues. My MY is at the Tesla Doctor for this very issue. Hoping they watched your videos.
I know what I'll be watching tonight! Great to see you professor. 👍🏻👍🏻
Thank you so much!
Fantastic lesson on Tesla's Li-ion system. Thank you so much for this. I am coding refreshed Model S/X cars for tilt screen and Matrix headlights retrofits and have encountered several LV battery drain issues, not always, but often. Another option that has worked for me is using another Li-ion Telsa to jump start and close the HV contactors (LV disconnected).
Exceptional video. Thank you for taking the time to make it.
Glad you enjoyed it!
I am enjoying the Tesla video series. I have not worked on one yet. Some fantastic information.
Glad you like them!
Always happy to see a new video
Thank you
Best techinical content around. Waiting for them to put together a EV only workshop (no hybrids).
I love the depth and detail. Working on mostly German cars for 20 years, this LV system is unlike anything I have ever seen. The F80 M3/M4 Li-Ion LV system is the closest but still ICE architecture
Thank you. I agree; unlike anything I have ever seen too.
@@WeberAutoAlso, thank you for explaining the open and re-closing procedures so thoroughly. There were piles of replacement lead-acid batteries (and empty boxes) at my service center. The older system must be very failure-prone
It's not just BMW 12v lithium but also the 48v mild hybrid battery pack too I'll like to see that analysis
Alot of European manufacturers have been using 48 v Batterie for years already
@@carholic-sz3qv Not for 12 V loads though, only for high current loads like electric A/C. Using 48 V for everything requires changing every solenoid, motor, relay, light bulb, and control module in the car. Big PITA and costly for to switch. However, after doing the work and investment, the wiring harness and other components will be lighter and less expansive, using a lot less copper.
Great video,I wasn’t even looking for info on EV’s but your teaching style is compelling, had to watch it.
Glad you liked it!
Thank you for your awesome teaching style and incredibly clear videos! Please more Telsa repair videos!
Thanks, will do!
With muscular dystrophy this man makes things happen. Don’t make excuses for not doing the same. Great video, as always!
Thank you!
I don't even own a Tesla just watched the video out of interest, but have to say It is very handy information to have should I come across a Tesla owner with LV battery issues.
The video is explained very well
At 6:55 , Just to bring new verified informations: These are laser welded prismatic cells made by CATL and are not pouch cells. These are capable of an insane 10c recharge and 50c discharge (345A for 10 sec) but probably limited to lower value by the BMS. Cell model number is probably: HY-3769c from CATL
Thank you for the clarification.
Yeah, it should jump charge another vehicle no problem :P Not really that different from some jumppacks..
@@rkan2 problem is 4s of NMC cells is way higher volt than conventionnal 12V lead acid. Higher than 15 or 16V might damage the car on 12V battery. OR.. by the voltage difference, the current that goes from the Tsla battery to the 12V battery will be very high and not have any current limiting control except protections cut off from the BMS.
@@Doctorbasss Most 12V systems should be fine at 15-16V when the 12V spec is up to 14,2V charging voltage. There is probably at least 10% margin upwards on most vehicles on the voltage. After that you might start doing damage.
Finally! I’ve been waiting patiently for this latest video. So glad you are well and still educating us all! 🎉❤
More to come! Thanks for watching
Sir I'm from India I can understand your classes so easily
Thank you very much!
Thank God you back
Thank you very much!
Thankyou for the little educational video. The chances of me working on an EV is slim to none but I try to keep up to date. Most of my customers drive rolling scrap yards.
Glad to help. Thanks for watching
Always enjoy watching your videos sir. Thank you again for the information overload.
My pleasure
Who’s here because their having aftermarket stereo issues? Your a great researcher and teacher! 👏
Wow! That was fantastic! Nobody does videos like this! Thanks!!
Glad you liked it!
I have trouble saying Weee-ber. I'm a fan of Weber Grillls and I've never heard it pronounced like that. I am loving these Tesla videos. I've learned a lot.
Thank You Dr Kellly for your passion and skills for the subject , you make my day, wishing you a pleasent time and greeting from Sweden,
You are so welcome!
This video was so informative and precise. Thanks and keep up the good work.
Hello Dr. Kelly,
Thank you for another fantastic and informative video. I am still learning about BEV's and the "jump start" had be very confused until I watched the full video.
Watching more BEV/Tesla content
P-Chi
You are so welcome!
Incredible detailed knowledge that is unlikely to be found anywhere else..Thank You .. John for this 1st class lesson as always !
Thank you!
not just that you make awesome videos, you are an inspiration to me! and even though i dont want to mention it i just feel like i have to, being in a wheel chair i guess is really hard and fact that you managed not only to overcome it but to be such a guru! rock on my man! amazing content!
While charging at a level 2 ChargePoint charger, another Tesla owner was having a problem with his LV 16 volt battery. The Tesla service tech was guiding him over the phone. I keep a small jump start battery in my trunk to help ICE drivers jump start their cars. It’s also a handy USB charger. We used it to open the frunk of his car, so he could do the second procedure you described.
John are you going to disassemble that battery in another video?
I have been thinking about that. I might
@@WeberAuto I'd like to see the inside of the battery. I'd also like to see what sort of communication protocol the LIN uses.
Ingineerix did it on his channel if you can't wait.... ruclips.net/video/fJH1r1s8B6Y/видео.html
Your explanation of how the Tesla battery works also described the normal actions performed by any BMS designed to work with 4 LiIon batteries connected in series.
Besides all the features you mentioned, most BMS boards also have an automatic battery balancing function that works whenever the battery is charging.
They also have BMS boards that work the same way with the lower voltage, longer life, LiFePO4 batteries. In that case they are equivalent to the voltages obtained by a conventional lead acid car battery, but have 3000 to 4000 full charge/discharge cycles before they drop to 80% capacity...
Super information, Prof Kelly, as always! We are all a step closer to understanding this new technology!
Thank you very much!
Great content as always! Much respect.
A great video as always! Thanks for the deep dive into the Tesla 16v battery. Many thanks.
Thanks for watching!
12:00 case: My MYLR with odometer just 8K, 4 days ago suffers an electrical system failure, vehicle may not restart message. I believe pyro fuse cuts off high voltage battery upon drive unit failure. The low battery supports the screen, emergency light trunk etc for a few minutes before dies too (at this time, the car was totally dead) while waiting the tow. How likely this Li-Ion battery battery is totally drained? I wonder if I have to press the service center to replace the battery too (still in the shop, never get back to me on any progress since Sun).
The battery protects itself by shutting off at a 10% state of charge. It is probably not bad and can be recovered by Tesla. Sorry to hear of your troubles. Best wishes.
Dear Prof. Kelly and the whole team:
I'm aways happy, when I got a notification, that you have uploaded a new video, because I KNOW, there will be another superb content for the starving brain. 🙂 BUT I couldn't stand watching your high quality videos for free all the time, so I donated 100 USD. 😉
You do got the juice, Prof. Kelly, to jumpstart anybody with your energy and skills!
Greetings from Germany - SkyPower Wind Energy - CEO
PS: If you add a PayPal link in the video description, this would make the donation much faster and easier.
PS2: Would a teardown of this 16 v battery be possible? I can't imagine what cells Tesla is using for those extreme high C ratings way over 50 (BMS cut off) . 🤔
The Ingineerix RUclips channel has a 2 part video from over 1 year ago, called Tesla Plaid - 12 volt Lithium Battery where he tears down this low voltage battery pack and goes into detailed explanation on each of the components inside.
Thank you for your donation Ste Da, I appreciate your kindness.
@@KCautodoctor Thanks a lot for the info! I must have missed that. Those CATL cells are really rated for 50 C peak, stated in the data sheet shown in that video. Amazing!
@@WeberAuto You're welcome! 🤝
Thank you for this opportunity to learn more about TESLA technologies! 👍
So pleased to watch this broadcast and full of interesting information as usual from WeberAuto.
Thank you!
Thanks for making this video. I have always wondered how you would "jump" a Tesla with a "dead" 16V battery. I hope I never have to do it, but it is great to know how.
The most common form of Mosfet power switching is negative side. So the positive is connected to the terminal and the negative is switched on or off by the Mosfet. They typically have a very high resistance off so that's why not very much voltage can leak through. I can't say for certain that they're doing this there is also positive side switching, but not used as often.
Thanks for the information
Looks like that 16V system creates some confusion even with Tesla employees.
Wrong sticker and you get a faultcode to replace the 12V battery when you need to replace the 16V battery.🫣 Great content John, thanks for sharing.
Thanks Dan! I imagine there was some confusion :)
Thank you very much, your informative video helped us revive our Tesla
Good and informative video again Professor! I did not know 16V low voltage battery is used on Teslas. Thank you for informing us. Keep the videos coming!
Thanks for watching!
4.2v x 4 (4.2v in series of 4)=16.8v
3.7v x 4 (3 7v nominal voltage)=14.8v
2.5v x 4 (2.5v depleted voltage)=10.v
Manufacturer's use voltages anywhere in that spectrum from depleted to full charge voltages on their products. That is why ryobi has the 18v tools and dewalt has 20v fir example. If you look inside either cell they are both just 5s battery packs. 4.2v in series of 5. Which ranges from 12.5v fully depleted to 21v. I hope this clears up the confusion on the voltage.
Thanks for watching.
Very helpful and clear, I have been using this almost same type of battery for years and am very familiar with the cells voltage, capacity and charge and discharge rate. I fly model airplanes.
Glad it was helpful!
Sir, you are a unique person.
Sincere love and respect from Turkey.
So nice of you
I love your education videos, it is crystal clear and you focus on bringing the important information to the audience. Regards from Hannover/Germany. Danke.
I appreciate that!
omg prof i never felt that exactment for long ago , your way in teaching is awesome !!!
Thanks! 😃
Thanks for the video. Does have any thermal protection ? i think, It should, considering that in hot summer, and charging conditions the LI-IO, can get pretty hot. BMS inside the LI-IO might monitor the temperature and command the MOSFET as well. Not sure.
Yes it does, 65 degrees C
Did not have any idea my Model Y has a 16 V battery. Thank you. You went through this so well I could do thias but am not going to. At my age I do not do any automove work anymore. Used to be a semi-shade tree mechanic. LOL
Thank you for this video ☺️
You’re welcome 😊
Interesting video, thanks for teaching us so much about these cars!
Very informative video! If the Tesla vehicle in question does indeed have a 16V Li-Ion battery how does one open the Frunk to access the battery? Can you still supply 12V to the connectors located in the front bumper to open it? Thanks again for supplying a great video!
Yes, that will work
WeberAuto, where those in the know, come to know more
You're a legend John
I love these videos
Thank you!
Power MOSFET is negative disconnected. N channel mosfet is more common and cheaper than P channel. No need to do both polarities. I can not concur but I am sure they switch on the negative side.
I am an expert on power tool lithium pack repair range from 12v, 18v, 40v, 56v. all negative switch. Positive is a direct connection without going through the mosfet.
I am searching for a damaged used Tesla to buy for my own use. I am learning all about all the system in the car. Electric car is way easier and cleaner to work on providing the resources are there. I am also more than proficient on battery repair both lead acid and lithium and NiMH so EV is a natural and easy migration for me from ICE car which I also know how to work on at a deeper level.
I learn quite a bit from your Utubes. Thank you. My intention is to work on all aspect of Tesla as I know they will not fix salvaged damaged car that is resurrected by me. I don't intend to let them fix anyway with their rip off charge. I do it myself if need to i can tear the battery pack apart and fix at cells level. I had processed thousand and thousand of lithium cells for the last 6years to build solar pack storage so that gave me plenty of experiences and know how. Once you understand the basic it is not hard to figure out the rest. EV is the future. Learn now or learn later and pay to the nose for repair if not knowing how to fix.
It is actually on the positive side on these batteries
Is there a way to charge this 16v battery out of the car? Say with a makita 18v charger?
Во многих BMS мосфет находится в минусе, но в Тесле шунт в минусе, а мосфет в плюсе.
Interesting as usuall. There will be also a new jump in voltage from 16 to 48V on some model like the cybertruck which is in my opining excellent. this was anounced in the investors day recently from TESLA. This will also be compatible to the popular 48V DC supply on many "powerwall" or off the grid systems for home in case of emergency etc... even phone lines work on 48Vdc... 48V win! . Also The 99Wh on the label of the 16V battery is I guess limited to 99Wh rating to make easy the shipment of these as they dont enter to the "over 99Wh" CLASS 9 Hazardous goods transportation regulations.
Thank you. Great point about the shipping.
European manufacturers already have 48v systems in many of their cars too! I'll like to see a teardown and analysis of that thanks!
Isn't 48v pretty dangerous? 4 times the Standard voltage
@@meki___6881 No, 60V DC and above is considered dangerous according to the NHTSA FMVSS 305.
@@WeberAuto didnt know that ty very much
Good to see you back Prof 👍
Thank you kindly
Lots of others have already said it, but Professor John Kelly's through research and clear presentation style make complex technology easy to understand. I really appreciate his videos here at WeberAuto.
Thank you very much George!
Great video again! I think they are great for reuse in other cars/motorbikes because of their lightweight and their self protection.
You might wreck some stuff not being able to run above 15v though.
I think at 400A discharge limit, it can crank quite a lot of small petrol engines, even though it will seriously decrease its lifespan.
Do you know if the negative is always connected to the battery casing? That might give a clue over which one the mosfet opens
Good point on the lifespan. I do not know if the negative is connected to the battery casing. I suspect it is not. I will check. Thanks for watching!
@@WeberAuto I opened a VW 48v mild hybrid battery, and the battery negative was just connected to the battery casing. The contractor was on the positive side. So 12v and 48v have common ground, and only positive switched. But of course, that is a different system.
@@WeberAuto The vehicle has a negative ground for the low voltage system. That means that either the battery negative is connected to the case (either internally or via an external connection), or the case is floating. A floating case for an electrical component seems unlikely to me.
Usually, battery management system MOSFETs disconnect the negative side. This enables the use of N-Channel MOSFETs which have a lower internal resistance than the P-Channel ones.
Great video as always. You have a very nice way of explaining things.
I wonder why Tesla didn't go along the LFP route for the low voltage system? I guess there must be reason!
I could be wrong, but I read that LFP voltages do not change very much as the state of charge decreases. That makes it difficult to determine state of charge and state of health.
@@WeberAuto That's true, LFT have a very particular SOC curve which make the BMS algorithm to work harder on both end to determine the SOC, however, a 4s LFP cells is EXACTLY the same voltage range LVC and HVC as a lead acid which is also excellent and also the discharge curve as also very flat on both... it is like that 4s LFP and 6s Lead acis have been made to coexist together...
@@WeberAuto that certainly makes sense and one of the reasons Tesla recommend 100% charging on their LFP cars.
I run LFP batteries for my 4WD fridge etc and they certainly run a very flat curve from about 95% down to 20% or so.
I assume the 85% charging limit is Tesla's way of extending the life of the cells.
LFP unable to handle large current discharge something like 10c
@wenhaowong5549 I guess especially in a 4S1P setup.
Thanks
Nice sir 😁
Thank you!
Thank you for the video. I didn't know there were electric cars that had "non-standard" low voltage.
Hey Kelly, welcome back!
Kind of surprised they "only" went for 16 volts- 24 volts would have had further improvements in efficiency but would share parts with milspec and semis, so I'm wondering why.
Also of note- I've seen some owners find that the Teslas really hammer their 12v lead acids, or at least used to in the old S's. Mine was replaced recently, so I guess i'm gonna see.
16V was probably chosen because it is sufficiently compatible with 12V... which upper range is just 1-2V lower than 16V.
The whole purpose of moving to a 16V Li-Ion battery is to improve the reliability of the low voltage system. This battery and a late 2019 change in the power conversion system with a "Standby Power Supply," will keep the low voltage battery maintained with the contactors off.
They will be moving to 48V systems shortly with all modules of their own design according to their latest open house day. Refer to a Munro interview on Autoline this week.
@@WeberAuto With the contactors off!? How do they manage that?
@@oznerol256 Through a special DC-DC converter connected directly to two sections of the HV battery. I hope to show it in a future video.
well explained step by step .... thnxxx prof.from Toronto canada
So Tesla brings a 16 volt system into a 12 volt world and does not tell anybody or even label the power receptacles correctly. I foresee no possibility of anything going wrong with this at any time under any circumstances.
I find this really puzzling as well. And not being able to jump start another vehicle from it. It seems like an odd stopgap between 12v and 48v.
Thanks for your feedback! The information is on the owner’s manual, but how many people
read that?
Thank you Professor. It was pleasure.
First time finding your channel. I love it !
Thank you!
Awesome. A few years back, I watched you breakdown a Prius hybird system. I had a Prius and now a Tesla. Just coincidence, I came across your video on the model Y.
Tnx proff for all your effort to introduce us Ev and hybrid