What is the Tesla HVIL?

[@Leftplayer1]

Great video! I had to learn a lot about the HVIL because my Mercedes B250e, which uses a Tesla drivetrain and battery, threw a HVIL fault out of the blue. Turns out the magnet closing a Reed switch in the plate of the charger had lost its magnetism so the HVIL was randomly opening. Mercedes dealer wanted $7,000 to replace the entire charger. I fixed it with a $10 soldering iron. HVIL is a liability-avoiding mechanism more than a safety system. If you’re working on HV you should know to make sure there isn’t any voltage.

[@SupremeRuleroftheWorld]

its not just liabillity. its bad press when joe the redneck mechanic that only knows GM and doge sticks his fat fingers in a charging module or HV compressor and dies a pretty horrible death. the company does not care about the guy dying but they do care about the bad press.

[@mikeselectricstuff]

It's also about preventing the risk of arcing and fire if a connector becomes dislodged.

[@SupremeRuleroftheWorld]

@@mikeselectricstuff agreed, but mostly because of idiots poking fingers in shit they should stay away from.

[@GreenDriveIndia]

Can you please make a video, where did you soldered

[@Ingineerix]

Yes, this is a known problem on Gen 1 Tesla chargers. Also, the HVIL pins on the DC-DC side can sometimes get bad connections, even with the connectors fully latched. So an HVIL system can become a reliability issue if not properly implemented. You may well be right about liability, but I know if I am an engineer in charge of a system containing lethal voltages, I would not sleep at night if I didn't implement a safety system like this. All it takes is one death! Also, it's really easy to create a lot of damage even if someone doesn't get electrocuted. Removing and reconnecting these connections can create arc-over, and permanent damage if done while energized.

[@Shiftheads]

Appreciate you putting out so much content lately and having a setup for the presentation. Learning a lot!

[@LawpickingLocksmith]

Very nice! Thank you very much. Always reminds me that HV DC has issues. The Italian trains still use 3kV on many railroad lines. No skin effect but endless galvanic issues. At this stage 60 Ohms does a lot but I can see in future they will brobably use data lines so engineers brains will never come to a rest.

[@tommills2097]

Excellent video on a very important topic. All of us DIYers (especially EV builders!) need to be aware of the need to build this stuff into our projects. The lives of our loved ones and first responders may be in the balance... Thank you.

[@janholland2224]

Not my field but you explained it so I could understand it which is very much appreciated, thx!

[@mikeselectricstuff]

How would local sensing help module diagnosis? - if the loop is broken, none of the modules will see current. Might be useful if they could sense if the loop common-mode voltage was high or low though. I wonder why they used a non-standard resistor value.

[@DummyLooks]

The device with the broken connection would see the full voltage, wouldn't it? I assume there is 12V power going in as well to run the brains so it could report the unusually high voltage. Edit: Actually, it would only work if the resistor itself burned out, if the wire broke then you're right, there would be limited information available.

[@justinmallaiz4549]

I seems only the first hvil sensor can trip (with high voltage ) before it all goes dead

[@davefiddes]

I think you're right. The TI paper covers it. You can interrogate each module in the chain and find the one which isn't able to report the source voltage and infer where the break is. The odd value looks to be because of the expected worst case fault current if the loop is miss-wired. The Tesla M3 inverter implements the 60R with 5 x 300R 2512 1W SMT resistors. Should be able to handle a direct short across the battery if my maths is up to it.

[@Ingineerix]

Yes, the local diagnostics can sense the HVIL voltage as well as current in those cases. I think they chose a non-standard value to make it harder to spoof.

[@danieltroger]

Dude that system is so ingenious, thanks for showing us!

[@iitool]

Great vid. Thanks! I was just about to ask about the fireman's loop but you covered it. Interesting that they can cut it or disconnect it

[@Ingineerix]

Tesla instructs them to cut it in 2 places (so the cut can't accidentally touch and reconnect). Probably because with fireman's gloves on, there's no chance of releasing the connector locking tab. It's hard to do bare-handed even!

[@iitool]

@@Ingineerix Does power get automatically restored if the loop is reconnected? Or is there a timeout or soft/hard reset switch as well?

[@Ingineerix]

@@iitool Sometimes. Worst case you have to reset the BMS. On 3/Y the easiest way is to disconnect the data cable on user the back seat, right side, then reconnect it. You can also disconnect the 12v battery, wait about 30 seconds, then reconnect. This is also the easiest way on the Model S/X.

[@ke6gwf]

@@Ingineerix as a former FF, I suspect that the reason to make it something to cut, rather than a simple to unplug connector, is because firefighters want to cut things! They are all trained to cut battery cables, and so this just gives them a focus point, something familiar with bright colors and pretty pictures on it so they can feel like a hero, but not have to learn something new! Lol But seriously, I think it's also because if they just unplugged a connector, you can be sure that some tow truck driver (I did that too ;) ) is going to come along and plug it back in to see if they can drive the car on instead of having to get dirty using the winch, and if there is actually damage to the vehicle, that means that the FD might have a secondary incident on their hands, so if they decide that it warrants disabling, it's going to STAY disabled until it's off their scene. As it is, I won't be surprised if some tow truck drivers begin carrying a cut link that they spliced back together, because it's certainly something I might consider for the times when the FD is a little too zealous in cutting the cables after a minor accident, and it's pretty obvious that there is no serious damage...

[@StevenYoungcaptual]

Very interesting indeed! Please keep the videos coming! Thank you👍

[@ruaraidhmcdonald-walker9524]

We have HVILs on the first KERS systems in F1 back in 2009! Seemed like a good idea when the car could come to bits in a crash!

[@eccoseasea5107]

Wow! Very interesting! Thanks so much for explanation!

[@grettirgrattmards2348]

Man I grabbed my bong before clicking on this. I knew this was gonna be interesting. Quality content!

[@Ingineerix]

LOL!

[@emceh]

Happy Thanksgiving to you too. Thanks for educating us :-)

[@raviteza8]

What i also learned is there are so many variations on how to implement HVIL. Sometimes the HV connector has just a shorting pin and the actual HVIL loop is in the 12V LV connector for some components. In other cases like you have shown, the HV harness has also 2 extra wires running to the next device. It's kinda of confusing why they do that. Also sometimes its passive and sometimes active HVIL.

[@evjedi4061]

I am not easily impressed. But however I am always impressed by your videos. I just wanted to let you know I am thankful for your videos I learn and I appreciate that. So I just wanted to say thank you. Have a great holiday.

[@Ingineerix]

Wow, thank you! Consider making a small donation to support the channel. Link is at the bottom of my Channel's "about" page: kzbin.infoabout

[@heinzreichert1042]

Really well and understandably explained. Many thanks!

[@Ingineerix]

Glad you enjoyed it! Consider making a small donation to support my channel. Link is at the bottom of my Channel's "about" page: kzbin.infoabout

[@EpicSpaceflight]

Great explanation, in short HVIL makes sure the high voltage output is disabled before the large main connectors are fully unplugged.

Fantastic videos and well articulated. Thank-you.

[@desidude006]

Very good video. I actually had error on my 2020 model Y while on road trip, The car threw up any error saying "Vehicle might not restart, service required". It turns out to be an issue in the HVIL system and they have to order new harness for "front" and "rear" of the car. Tesla service also ended up changing my 12v battery. The car only had 37k miles on it. Honestly surprised i got this error.

[@raywalker7683]

Thank you, much appreciated

[@truthfulaudit2326]

Thank you, that was very informative and easy to understand

[@savagesarethebest7251]

First thought about the first responder Loop, "What a genius idea" Second thought, "Why is that even necessary?" The car can detect that it has been in an accident and should cut the power by itself. So I guess that it is either an extra failsafe or a psychological reassure for the first responders 💭

[@ke6gwf]

As a former first responder, BOTH! lol We like cutting things, it has pretty pictures and bright colors, gives us a sense of control, and ensures no secondary incidents. Remember that a cable can be damaged, the insulation cut, etc, without unplugging a connector, so you could have the car still powered up and have a hv cable drag on the deck of a tow truck and electrocute the guy when he steps out of the car. So it's very useful and important in cases of wrecks, and to make us feel powerful... Lol

[@savagesarethebest7251]

@@ke6gwf Thanks for your reply :)

[@mikeselectricstuff]

Not all accidents would be detectable, e.g. a fire or chemical spillage incident

[@Ingineerix]

Yes, peace of mind, and also the FR loop cuts 12v power to the airbag system, so there's no way any un-exploded airbag could go off. This has been known to happen when the RCM (Restraint Control Module) gets wet.

[@paycheckvomitthorax]

Excellent Presentation

[@Ingineerix]

Thanks! Consider making a small donation to support the channel. Link is at the bottom of my Channel's "about" page: kzbin.infoabout

[@bobqzzi]

Thanks very much for providing such useful information,

[@Ingineerix]

You're welcome! Consider making a small donation to support the channel. Link is at the bottom of my Channel's "about" page: kzbin.infoabout

[@domenicdefrancesco]

Thanks so much. I really enjoy these videos.

[@Ingineerix]

Glad you like them! Consider making a small donation to support the channel. Link is at the bottom of my Channel's "about" page: kzbin.infoabout

[@domenicdefrancesco]

@@Ingineerix Already did.

[@abhib1955]

Hi Sir, Thank you for great explanation. Can you make video on Isolation monitoring, Precharging circuits, kl30 and Pyrofuse part and other vehicle safety operations/ Components.

[@carlosfranchi5043]

What a class thank you sir greetings from Brasil central

[@retrodraggin5540]

Comments good for the algorithm too

[@diamond_h0us]

My 2 week old Model 3 is in the shop apparently due to the HVIL system. After 11 days of ownership, while plugged into the Tesla wall plug, it stopped charging after about 1.5 hours then the low voltage battery rapidly drained. I jumped it and the car powered back on. The next day after work and plugging it it to charge, it happened again. Again, at around 85% charge and around 1 - 1.5 hours of charging.

[@diamond_h0us]

Just want to add that the codes I found in diagnostic mode were: HVP_w026_Hvilfault, VCFRONT_a548_HVFaultLoadShed, VCFRONT_a192_vehicleLoadShed

[@Ingineerix]

Tesla has great engineering, but the quality is really poor, especially in the Fremont plant. (The Chinese plant seems to have consistently WAY better quality!) This is a result of a quality. They'll fix it on their dime, but be prepared to wait.

[@HelmutTschemernjak]

Another great Video, thank you so much. I like to connect a solar inverter to the 400V system for powering my house or other devices. What is the best location to take the power from? I was thinking about the heat pump which properly can also eat up to 4kW. The Idea is that Tesla should tolerate or just don’t figure out that I steal some power.

[@Ingineerix]

Yes, this would work, but your solar inverter cannot be "transformerless". It must support 100% isolation from the DC input to work properly. For instance, I was able to use this unit: on a Model 3 connected as you indicate: www.belfuse.com/product-detail/power-solutions-custom-value-added-solutions-emobility-350invch150-inverter-charger?navCategory=eMobilityPowerSolutionsTransportationindustry

[@ping-wenhsieh8450]

It is really a great video. There is a question about the HVIL cable, will the HVIL cable(the LV one)be shielded? It seems that the HVIL circuit forms a very huge loop in the system of the vehicle.

[@Ingineerix]

No it's not shielded. Why would it need to be? It's a current loop.

[@ping-wenhsieh8450]

Hi Sir, I had noticed that there would be some noises coming from the HVDC terminal, if I plugged out the HVIL connector from the PCBA, some frequencies spectrum may become lower than plugged in in the certain component-level EMC test, so that is why I asked about this question, but anyway, thanks for your kindly reply.

[@Ingineerix]

@@ping-wenhsieh8450HVDC on any EV is extremely noisy, which is why they almost without exception use shielded cables, and route to minimize loops. I'm sure some noise will be coupled into the HVIL, but it's probably not enough to worry about.

[@jbienz]

Another great video Ingineerix. I'm curious, if you're driving along and a cover switch goes bad (breaking the HVIL), will the drive motors immediately lose power and the vehicle roll to a stop?

[@Ingineerix]

No. It will wait until you turn off the car.

[@ภาคภูมิลีลาคชสีห์]

Hello, I know that the screen shows contactors open and the fuse is not broken, the two contactors are not broken. please know🙏🏻

[@hubmartin]

Why there the loop don't go to the PTC heater, coolant heater and A/C comp cables? Is there a fixed cable on the other side? Thanks for these great and frequently published videos.

[@Ingineerix]

Yes, it's part of the unit, so nothing to disconnect.

[@jawdropperch]

hello, my model 3 died in the middle of the road, tesla wants a new battery pack which I know is not the problem. they didnt share the diagnostics only that the pyrofuse need it replacement and the parts needed it werent serviceable. I opened the penthouse and replace the none damaged pyrofuse but theee is a Loop error. do you know how can I start testing penthouse components with a regular multimeter? any help is gladly appreciated, thank you

[@Ingineerix]

The first step is to put the car in service mode and see what alerts are set. The car has amazing self-diagnosis capability. I'm available for consultation if you need help. You can contact me directly by using a full browser: www.youtube.com/@Ingineerix Then click the right arrow (">") next to where it reads "Engineering and Electronics Exploration". My email is shown below.

[@yon2004]

Neat. Thanks for a great video.

[@jamesengland7461]

If the pyro fuse is fired, does that accomplish the same result as the HVIL being triggered?

[@Ingineerix]

No, the Pyro is only triggered in a serious fault. HVIL will only open the contactors, so when you reconnect the loop, it can be reset without replacing the pyro.

[@volodumurkalunyak4651]

End result is the same (high voltage only remains within high voltage battery). Pyro fuse is there for interrupting fault current and will blow in case of battery overcurrent. HVIL is there for opening contactors where connector is unplugged. Contactors have very small interrupt capacity and may not break fault current.

[@flienky]

The MEB platform has eliminated the pilot line. The connectors are specially designed so that even if removed, you can't touch the contacts.

[@Ingineerix]

It's not about touch (as much). If you disconnect a HV connector under load, you can have an arc flashover. If you disconnect it with no load, and it's ok, then you wait a bit and try to reconnect, you can have an explosion and melt the contacts. There has to be some type of interlock to prevent this. Some EVs will open HV is the hood/bonnet is opened.

[@petepetess]

I mean, if you reconnect the connector this would be with contactor or contactors open. So not cause an arc since not connected to HV battery. Not going to charge capacitor or could draw a load on this circuit. Will mention that HVIL pins in connector dont always pull power fast enough/open contactors fast enough. If someone pulls connector fast enough, even with HVIL there will still be an arc flash in the connector. Depends on sampling rate and rationality check of BMS SW, takes time to react. As well as how long HVIL pins compared to HV power contacts. Not instaneous. This is where HVIL has been something that seems like it helps, but in practices not super helpful or can just be a voltage check and good HV connector design.

[@danyelectronics6932]

hi, can you tell me what IC is responsible for the 20 mAh HVIL signal? Thank you

[@Ingineerix]

There is no "IC". It's implemented discretely using op-amps, etc, which the TMS-320 DSP reads using it's ADC.

[@dandil]

excluding someone tampering, is there any issue with just having a short that completes the circuit for the contactors?

[@Ingineerix]

This would result in an explosion and the BMS would open the pyrofuse. You cannot close contactors until the precharge of the high-voltage bus is completed. Even if you did all this manually, the BMS would sense the contactor failure and blow the pyrofuse and disable drive.

[@MarekReinsch]

Legend!

[@michalfoksa3698]

What happens when that "first responders loop (in red cable guard and with orange sticker)" located in Model 3 frunk is cut? Does it blow battery pyro fuse. Or just HVIL is opened?

[@Ingineerix]

Neither, it cuts contactor and RCM (Airbag) power.

[@michalfoksa3698]

@@Ingineerix How to recover from it? Replace harness? Where is this harness in Tesla EPC?

[@Ingineerix]

@@michalfoksa3698 On older cars you have to replace the entire frunk harness. Newer it's just a connector. If I were you, I'd just re-splice it.

[@michalfoksa3698]

@@Ingineerix it is 2021 M3, do you know part number? What about RCM, is there a need to reset it?

[@michalfoksa3698]

@@Ingineerix Thank you for your time, your content is very helpful.

[@davidtheswedishtechguy]

Hello from Sweden! I don't know if you are able to help me a bit but I hope you can give me some guidance maybe 🙂 My Tesla model S p85 (2013-14) just started acting up and I'm going to try to make this as short as I can but still give as much information I can🙂 It started last week when I drove 150 miles straight and pulled up to a supercharger and it charged fine at +-120kw to full and after it was "fully charged" at ~ 95% I returned to the car but on my way I got a message in my app that the car couldn't charge and when I tried to start the car it wouldn't let me drive and it blocked the charging port. Got toed to a dealer and the car drove it self of the tow truck..the dealer change the 12v battery that had a date on it ( 12-06-04 ) and the car was fine for another 2.30 hour drive but died again as soon as I left the car... called the dealer and he told me to pull the 12v for a while and I did this several times but the car still wouldn't go in drive or charge... called a new tow truck and when he came and tried to put the car in drive it did and it charged fine...🤷🏼‍♂️ he recommended me to keep going to my destination due to the late hour and I did.. Drove the car 4-5 times and charged two times at our hotel there and 3 days later we drove home but the car still died 2 times on the way home and every time I disconnected the 12v battery and it took 1-2 hours with that every time before the car jumped into life again.. Have driven the car 5 days after that but 3 days again I took the car and drove for 2min but forgot something at home and drove back and when I got back to the car it didn't let me drive away yet again... did notice my fans in the front run at almost max when I hade the door open so I let the car be for 5-10 min and I could drive away... I get the same error messages every time ( BMS_w036_sw_HVIL / BMS_f008_HW_HVIL )

[@Ingineerix]

The 2013's have a problem with the HV connectors on the DC-DC converter lose their HVIL or it becomes intermittent. Chose those first, sometimes it can also be the pack rapidmates (either HV or data) becoming loose.

[@davidtheswedishtechguy]

@@Ingineerix will check it this weekend... when I take it in the morning to work at it sat all night it drives just fine and after 8 hours of work it works too... it's "cold" in the morning " 16c degrees " and it sits in the shadow at work "22c degrees " but when I come home at it sits 5 min into the sun the car won't drive and it shows no temp in the dash and the AC shuts off after 2-4 min... if I wait 5-10 min it usually starts and I can drive away 🤷🏼‍♂️the fans always got on to full in the front for a while so I'm thinking maybe I have a temp sensors fault maybe? Or is it that some connector may flex when it gets hot

[@dustingoffron2252]

Does supercharging degrade LFP batteries?

[@Ingineerix]

Yes, all charging or discharging activities degrades all chemistries. The rate varies, and it's affected by many factors, but in-general LFP is more rugged. History has shown supercharging isn't really a big deal even on the ternary chemistry. In general the batteries outlast the cars for most intents.

[@vergule11]

What should be the purpose of an “optional charger”?

[@Ingineerix]

On the original Model S and X, you could get an optional second on-board charger unit, upping the AC charge capability from about 10kW to 20kW. This is no longer an option. Long range cars have about 11.5kW capability, and the others 7.7kW.

[@imadabualia4843]

HVIL has been a nightmare in the past couple of days. My model 3 is throwing an HVIL fault and I just can’t find the bad connection. Pyro and drive unit is good. Idk where to go after

[@Ingineerix]

Pyro doesn't have anything to do with HVIL, I suggest you look at the wiring diagram, it's pretty easy to troubleshoot with a meter and by following the diagram. The #1 fault is people don't know about the penthouse bolts (2 by the data connector must be fully tightened).

[@imadabualia4843]

@@Ingineerix thanks for the reply. Wow. You just blew my mind with bolts. I broke one in the process (near the charge port). I’m going to go re-tighten the ones you are referring to.

[@Ingineerix]

@@imadabualia4843 Donations are always appreciated! www.paypal.com/donate?hosted_button_id=DT4S6DVGSBX3W

[@imadabualia4843]

@@Ingineerix hello again. I found the circuit diagram and got a multimeter. Do I check the current, or voltage, or resistance? What are the expected readings. Thanks again

[@Ingineerix]

@@imadabualia4843 The HVIL is a current loop, so it comes out of the BMS at 5v and travels through the loop and comes back to the BMS where the current is checked. If there's a break, it will be 5v all the way to the break. Follow along on the circuit diagram stopping at all the connectors. #1 HVIL fault is someone forgetting to tighten the 2 bolts on either side of the penthouse data connector.

[@BlazerRox]

So is the first responder loop the same circuit as the HVIL? Why is the wire so thick?

[@unitrader403]

To the Question "Is it the same loop for first reponders or a diffrent loop?" i got a simple "Yes." in the last Video as reply. but i assume he meant its the same. For why the Wire is so thick: probably two reasons: Psychological and Practical: Its hard for people to believe cutting an ultra-thin wire will disable a dangerous High-power system completely. Also it might be hard to locate for First responders, especially if they are in their full Gear. I think for these two reasons the Cable is far thicker than it needs to be in these two short sections.

[@koeniglicher]

It is not the same. They are actually separate safety mechanisms. The HVIL does not go through the First responder loops on Model 3, if the wiring diagram is correct and complete. On Model 3, the first responder loops cut a 12V supply line to the HV contactors (with the intent for them to open, in case they were closed before) and it cuts power from the 12V battery to the Restraints Control Module (controlling the airbags and pretensioners). The HVIL itself stays intact during this. The first responder loop cable is so thick due to cable coating (as it is prone to all sorts of physical interference) and some 12V power supply wires in there, like 1 mm^2 (AWG17) to the HV contactors.

[@TimLF]

Ubuntu :)

[@coredumperror]

"HVIL" makes me think of HFIL: the Home For Infinite Losers. Anyone else?

[@王跃恒]

沙发

[@ReevansElectro]

A little more CAREFUL STUDY is needed for a complete understanding of the HV safety system. Try again.

[@Ingineerix]

This was only about the Interlock loop, it definitely is not meant to be a "Complete understanding". Hopefully you don't watch a video about how to read a pulse and then think you are qualified for open-heart surgery.