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!
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.
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
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! 🔧👑
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.
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.
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.
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).
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.
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
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.
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!
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.
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%.
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
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.
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.
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!
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.
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.
This is an awesome video, great details , and especially useful to understand better what happens behind those owner's manual instructions. Great to especially know the self-protection features to hopefully never have to replace the LV battery again! (I'm stuck with replacing my lead-acid every ~3-4years..) Hope many tow truck companies get more familiar with Tesla and other EV low-voltage jumpstart procedures, especially as more rental car companies provide them and folks are not as familiar as real owners, and might run the HV battery down to 0 and need a tow... then they get very confused when by the time they arrive at the supercharger, they still can't charge the HV battery, as often the LV 12/16v batt has run down. Just a quick jumpstart by the tow truck as you demonstrated, can get them going again!!
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.
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.
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.
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!
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.
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 TH-cam 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!
Professor, we need your help. You’re the only person who knows what they’re doing. I have a salvage 2023 Tesla model Y which does not start. Service mode doesn’t load when opened, stuck on loading. Do I need to replace the vc-front or should I buy Tesla’s software “toolbox 3” to clear the codes. Any help would be greatly appreciated, thank you!
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.
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...
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.
We have new lithium battery for our forklift, they seems to degrade over time but slower then the lead acid ones we had, seems to take longer to charge too , although this might be the cold, we work in giant freezers -30C ( -22 F) that damage them prematurely. I also notice that when slowing down or breaking, the battery get recharged by the motors, that did some overcharge before the tech fiddled with the setups.
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!
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
Great video! Just for an FYI the old lead acid battery voltages, at the terminal posts, were about 14.5V while charging/topping off the battery after reaching a low of 12.5V. The float voltage was around 13.4V after charging was completed and driving down the road. Has anyone recorded these three voltage states for the new 16V battery battery?
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 BMS is controlling the negative of the battery, and you still sense some volt(maybe something like 10v ) even is the BMS is cut off the power
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.
Thanks Professor John, excellent work as always. The Reconnect LV Battery in service mode runs the same routine as Toolbox does from my experience. I tried using that option on my Model 3 with a lead acid battery where I received an error that the task couldn’t be completed. This is how I am arriving at my conclusion. I did notice that there is an option to reconfigure the vehicle’s LV battery in Toolbox switching it from the Lead Acid to Lithium Ion. I haven’t pursued this yet but I will research it in the near future and see what it would take to make the switch. I’ll keep you posted.
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.
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.
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.
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.
Thank you again, great video as usual. I do have one suggestion to make as supplementary information that may help. The missing piece. How do I access the low voltage battery when it has died and the frunk is closed? The latch on the frunk is electric and requires power from the low voltage system to unlock it. How this is achieved is an important step to enable repairs to be completed.
Thank you so much for explaining these batteries! As a Tesla technician myself its so great so see your videos! Though I did notice that you keep calling the VCFront/LefT/Right a "Voltage Controller" Tesla calls them Vehicle Controllers tho :D
At 15:35 it was stated that you could get that battery replacement message during random driving. I do not believe that would be at all possible as I don’t believe the car would be functional if that 16 V battery ever went off-line.
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.
Great to see you back. Love the mislabelling of the battery ! And the only other way to see if you have a Li battery is on the vehicle data screen which won't work as the battery is flat LOL. Isn't the song for this "There may be trouble ahead"...........................
Thanks for all your presentations Prof Kelly. Engineers sometimes baffle us techs. The 12V battery has been around for a century and 12V accessories are the norm whereas 16V or 5V USB accessories are the exception. I cannot think of a justification for migrating to the 16V battery other than a poke in the eye to Tesla's clients. Until the ;late 1980s all cars in US had 1 of 6 different headlamp models, and then hundreds of varieties blossomed, and the cost of replacing a lamp jumped from a few $ to several hundreds of $. Any of the 6 could easily be found at the local auto store, but none of the newer, costlier styles. Lithium batteries also need costly charge management circuitry, whereas lead, NiCd,... are far more tolerant of charging style variations without added circuitry.
^ This + they can make thier own batteries in house, put data line in there check is it original tesla battery? see HP inkjets... As much I like the tech goes into Tesla's, I despise the company and owner ...
The accessories are still 12v, this battery is within the range of a 12v battery that they work fine. 12v nominal is not possible with lithium, since we're talking 3.6v nominal per cell and not 2v like lead, you can do either 3 series to get 10.8v, or 4 series to get 14.4 nominal (3.6v per cell) and 16v at 4.0v per cell. Seems when the car is running it maintains 15.5v which would be 3.87v per cell. It'll likely live a very long time minus any defects that fail early. Running at a maximum of 4.0v and normally at 3.87v will significantly increase lifespan over charging up to 4.2v. They will be going to a 48v system soon though to reduce wire size, as well as 800v for the high voltage platform likely going into the cars instead of just the trucks.
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.
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
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.
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
Great to see Dr Kelly back on TH-cam! 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.
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!
Yes the "reconnect LV battery" button in Service mode does the same thing as the toolbox 3 procedure.
Good to know. Thank you
There are no such advanced courses here and everything is still very unknown, thank you
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!
The amount of research and great work that goes into these videos is simply outstanding.
THANK YOU!
Thank you very much!
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!
When I went to engineering school over 40 years ago, we never had professors this good.
Thank you!
No one explains EV systems like the doc. Weber must be the best training centre in the US.
Thank you very much!
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?
Thanks for your great videos, sir!
Thank you very much Fred!
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!
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
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.
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.
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!
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.
Terrific video and clear, logical presentation with excellent graphics. Thank you from Virginia.
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!
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
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!
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 know what I'll be watching tonight! Great to see you professor. 👍🏻👍🏻
Thank you so much!
Glad to see you back professor, and congratulations for the video graphical information that pop-up on sometimes, they are very helpful.
Much appreciated!
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.
I was been missing this videos.
Thank you
Thanks
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
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
Exceptional video. Thank you for taking the time to make it.
Glad you enjoyed it!
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
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 for your awesome teaching style and incredibly clear videos! Please more Telsa repair videos!
Thanks, will do!
It's about time. Seemed so archaic to put a lead battery in something like that. Good explanations
Thank you.
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).
Thank God you back
Thank you very much!
Excellent observation @4:35 with wrong battery voltage labeling ! Thank You !
Thanks for watching
Wow! That was fantastic! Nobody does videos like this! Thanks!!
Glad you liked it!
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.
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!
Thanks!
Thank you so much!
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!
Who’s here because their having aftermarket stereo issues? Your a great researcher and teacher! 👏
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!
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!
Always enjoy watching your videos sir. Thank you again for the information overload.
My pleasure
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!
With muscular dystrophy this man makes things happen. Don’t make excuses for not doing the same. Great video, as always!
Thank you!
Super information, Prof Kelly, as always! We are all a step closer to understanding this new technology!
Thank you very much!
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.
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.... th-cam.com/video/fJH1r1s8B6Y/w-d-xo.html
This is an awesome video, great details , and especially useful to understand better what happens behind those owner's manual instructions. Great to especially know the self-protection features to hopefully never have to replace the LV battery again! (I'm stuck with replacing my lead-acid every ~3-4years..)
Hope many tow truck companies get more familiar with Tesla and other EV low-voltage jumpstart procedures, especially as more rental car companies provide them and folks are not as familiar as real owners, and might run the HV battery down to 0 and need a tow... then they get very confused when by the time they arrive at the supercharger, they still can't charge the HV battery, as often the LV 12/16v batt has run down. Just a quick jumpstart by the tow truck as you demonstrated, can get them going again!!
Thank 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!
Incredible detailed knowledge that is unlikely to be found anywhere else..Thank You .. John for this 1st class lesson as always !
Thank you!
So pleased to watch this broadcast and full of interesting information as usual from WeberAuto.
Thank you!
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
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
Sir, you are a unique person.
Sincere love and respect from Turkey.
So nice of you
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!
A great video as always! Thanks for the deep dive into the Tesla 16v battery. Many thanks.
Thanks for watching!
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.
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 TH-cam 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! 🤝
Professor, we need your help. You’re the only person who knows what they’re doing. I have a salvage 2023 Tesla model Y which does not start. Service mode doesn’t load when opened, stuck on loading. Do I need to replace the vc-front or should I buy Tesla’s software “toolbox 3” to clear the codes. Any help would be greatly appreciated, thank you!
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!
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...
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
We have new lithium battery for our forklift, they seems to degrade over time but slower then the lead acid ones we had, seems to take longer to charge too , although this might be the cold, we work in giant freezers -30C ( -22 F) that damage them prematurely. I also notice that when slowing down or breaking, the battery get recharged by the motors, that did some overcharge before the tech fiddled with the setups.
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
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
Thank you for this video ☺️
You’re welcome 😊
Great video! Just for an FYI the old lead acid battery voltages, at the terminal posts, were about 14.5V while charging/topping off the battery after reaching a low of 12.5V. The float voltage was around 13.4V after charging was completed and driving down the road. Has anyone recorded these three voltage states for the new 16V battery battery?
Thank you. The voltage with the car ON is almost always 15.5V
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 BMS is controlling the negative of the battery, and you still sense some volt(maybe something like 10v ) even is the BMS is cut off the power
Great information. Thanks!
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
Thanks Professor John, excellent work as always. The Reconnect LV Battery in service mode runs the same routine as Toolbox does from my experience. I tried using that option on my Model 3 with a lead acid battery where I received an error that the task couldn’t be completed. This is how I am arriving at my conclusion.
I did notice that there is an option to reconfigure the vehicle’s LV battery in Toolbox switching it from the Lead Acid to Lithium Ion. I haven’t pursued this yet but I will research it in the near future and see what it would take to make the switch. I’ll keep you posted.
Thank you Scott! That is good information.
I love these videos
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.
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.
I am enjoying the Tesla video series. I have not worked on one yet. Some fantastic information.
Glad you like them!
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.
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.
Nice sir 😁
Thank you!
WeberAuto, where those in the know, come to know more
You're a legend John
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 again, great video as usual. I do have one suggestion to make as supplementary information that may help. The missing piece. How do I access the low voltage battery when it has died and the frunk is closed? The latch on the frunk is electric and requires power from the low voltage system to unlock it. How this is achieved is an important step to enable repairs to be completed.
Thank you for this opportunity to learn more about TESLA technologies! 👍
Thank you so much for explaining these batteries! As a Tesla technician myself its so great so see your videos! Though I did notice that you keep calling the VCFront/LefT/Right a "Voltage Controller" Tesla calls them Vehicle Controllers tho :D
Thank you. I was wrong about the name.
This video was so informative and precise. Thanks and keep up the good work.
At 15:35 it was stated that you could get that battery replacement message during random driving. I do not believe that would be at all possible as I don’t believe the car would be functional if that 16 V battery ever went off-line.
That is correct, the message would occur long before the battery totally fails
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.
Great to see you back.
Love the mislabelling of the battery !
And the only other way to see if you have a Li battery is on the vehicle data screen which won't work as the battery is flat LOL.
Isn't the song for this "There may be trouble ahead"...........................
Thank you!
So great to see you back! 🎉❤
Thank you!! 😊
Great content as always! Much respect.
Thanks for all your presentations Prof Kelly. Engineers sometimes baffle us techs. The 12V battery has been around for a century and 12V accessories are the norm whereas 16V or 5V USB accessories are the exception. I cannot think of a justification for migrating to the 16V battery other than a poke in the eye to Tesla's clients. Until the ;late 1980s all cars in US had 1 of 6 different headlamp models, and then hundreds of varieties blossomed, and the cost of replacing a lamp jumped from a few $ to several hundreds of $. Any of the 6 could easily be found at the local auto store, but none of the newer, costlier styles. Lithium batteries also need costly charge management circuitry, whereas lead, NiCd,... are far more tolerant of charging style variations without added circuitry.
^ This + they can make thier own batteries in house, put data line in there check is it original tesla battery? see HP inkjets...
As much I like the tech goes into Tesla's, I despise the company and owner ...
The accessories are still 12v, this battery is within the range of a 12v battery that they work fine. 12v nominal is not possible with lithium, since we're talking 3.6v nominal per cell and not 2v like lead, you can do either 3 series to get 10.8v, or 4 series to get 14.4 nominal (3.6v per cell) and 16v at 4.0v per cell. Seems when the car is running it maintains 15.5v which would be 3.87v per cell. It'll likely live a very long time minus any defects that fail early. Running at a maximum of 4.0v and normally at 3.87v will significantly increase lifespan over charging up to 4.2v.
They will be going to a 48v system soon though to reduce wire size, as well as 800v for the high voltage platform likely going into the cars instead of just the trucks.
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.
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