Why not jump start?

Valid question given the wording in the manual - it gives a couple of vague warnings about the care required but does not mention that if it goes even slightly wrong lots of expensive electronics gets fried

There are several threads here about seeing X in the gear indicator display for example

 

Jump starting can destroy your gauge cluster. Old threads and a very recent one had someone’s garage jump start his car and blew out the display, proving that it can (will) happen.

That’s just one (major) potential issue I’ve seen.


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The manual states to hook an aux battery to the battery terminals. This is no different than putting a new battery in. The manual does caution about using any type of charger. Jumping using a running car is not the same as just connecting another battery.

 

Can anyone explain why not in scientific terms, i.e. not just talking about spikes and surges?

For me, the running car has a regulated DC output at around 13.8V. If this is connected to the 'dead' car, there will be some voltage drop across the jump leads due to non-zero resistance and the current flowing. This means the dead car's battery voltage will be increased, from some volts, to less than 13.8V. Why should this be bad?

I can understand that if a Boost-type jump charger is used which gives more than the max tolerated by the tolerated components on the dead car, then damage can occur. But I don't see damage occurring when the voltage is increased to within the limits. Sure, there is a 'surge' in voltage but you'd also get this when you turn the Ignition on normally, but from lower voltage, i.e. 0V.

 

Quite simply the ecus are not sufficiently protected from the extremes experienced during a jump start. Simply don't do it. There is enough body of evidence which proves it damages ecus on the 360s. What more do you need?

 

He is asking a very technical question that he probably doesn't have sufficient knowledge about electronics to understand the answer (if he did, he wouldn't be asking). In short, he is describing a steady state response and ignoring the transient response. Dang, go study up on transient response of LRC networks and you will get a good idea.

 

A running car regulated at 13.8v can not guard against high voltage spikes lasting microseconds. You can design the eltronics to guard against spikes, but it starts adding costs. In my past automotive experience the industry counts pennies and nickels . Our ECU hardware comes from Bosch which is high volume, so Bosch like everyone else is watching their pennies. If you desire you can guard against it, meaning re engineering. Ferrari using Bosch for ECUs is a cost savings, as the overhead to design an ECZU for such low volumes would be huge. Now Ferrari could have worked with Bosch , demand a ruggedized design, which would not be susceptible to voltage spikes, but who knows, Bosch could have even said they were not interested, or wanted too much in Engineering costs. I have personally worked on designs for military where we ruggedized the design to protect from potential lightening strikes. The component cost increases even at low volumes , is only a few dollars, but depending on the PCB layout and how tight the board is, it could also require newer packaging if a larger board is required. It all starts adding $$$. Is it a Significant amount per car? No. But it is automotive, and they count their pennies.

 

On the contrary I have a degree in Electronic engineering, and I am quite familiar with the concept of inductors, resistors and capacitors, plus a whole lot more. So why don't you hit me with the pure facts? So if you believe that "it is because it is" then fine. I wasn't asking you the question. Neither was I saying that I didn't believe damage could occur from jump-starting. What I was doing is asking how the damage occurs.

So without getting emotional, nor insulting, can anybody answer the question? Those that don't know the answer, please back off with your derogatory comments.

 

OK, I doubt anyone has done full FA on the failed components. It is very expensive and time consuming, particularly if you don't own the design and aren't going to make changes to the design. BUT, the most likely causes are punch through of the dialectic layers or transient latch up causing overheating and thermal damage. TLU is one of the most common failure mechanisms in semiconductors, even more common than SLU (static latch-up). There is very little you can do about it. I guess you could create a filtered charging port that would filter out the transients but that is a bunch of cost and complexity for a very rare occurrence.

 

Ok so lots of jargon there. You are implying there is some increase of voltage to provide the energy for this punch-through? What causes this increase in voltage? The charging system of the live car would respond to the extra load from the dead car. The voltage would collapse initially and then recover. Are you saying the recovery is under-damped and overshoots the regulator setpoint? What happens under normal conditions when the live car has a sudden load increase, like switching on headlights? Why doesn't it destroy its own electronics?

Perhaps I didn't pose the initial question clearly enough, I wasn't asking what dies in the ECU and other electronics, rather what causes the components to die.

 

You could go borrow a fancy storage scope from work, start, probing all the power and input lines on the ecu, Speedo, and other assemblies that are known to fail, start jump starting your car from different sources over and over again and I'm sure you will find some spikes that could do damage to susceptible circuitry. I'm heading to the factory next month, and meeting some suppliers. I will see what they have to say. I'm betting the answer will be about saving $$$$

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I get you bro, same here, I wanted to ask the question long time ago

its like asking "why does animals grow old", many people would laugh at such questions but it is really a valid and very very scientific question.

waiting for answers for why jump start would spike voltages too.

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.littelfuse.com/~/media/Electronics_Technical/Application_Notes/Varistors/Littelfuse_Suppression_of_Transients_in_an_Automotive_Environment_Application_Note.pdf&ved=2ahUKEwjBj7TGoJrkAhWFdd8KHZ7eCDAQFjARegQICBAB&usg=AOvVaw0UmZUYDGX-Kl6Dhhqb1lKi&cshid=1566606706754

 

I'm in electronics also, but really, the only explanation needed is "You'll **** it up, don't do it".

 

It was quite a simple question and I'm glad at least 24000rpm got it. The rest of you rely on folklore and hear-say. I have an open mind, I can fully believe jumpstarting is bad for your car, literally where there's smoke there's fire, but I want to know the cause. Why does the supposed transient voltage kill the dead car and not the live car - surely both are exposed and the live car even more so as the dead car is down-stream of the resistance of the jump leads? What causes the transient?

So no, I'm not going to hook up my 'scope and do the tests - I'm not donating my car to science. But I'd still like to know if anybody is fortunate to have the scientific explanation. Having an open mind also lets in the possibility that this jumpstart myth is just that and damage is only caused when external high voltage chargers are used.

 

again, let me repeat what dang2407 mean.

1. we do not jump start our ferraris, just like we don't jump from 10th floor's balcony.
2. while we know how jumping from 10th floor would kill a human being(buildup speed---- sudden deacceleration----force upon our body ---- impact big enough to crush vital organs..... death) , we do not know how jump start a ferrari 360/430 would kill its electronics via voltage spikes. How is that spike generated specifically?

 

There's a parallel on this forum like the question dang2407 raised.

Hill Engineering throw out bearings. Everybody says it is superior than OEM ones. I am asking specifically how Hill engineering TOB is better? Is there any specific engineering explanation?

Don't get me wrong. I use Hill throw out bearing and timing belt tensioner bearings on 3x of my 360s, so I am not against them. I just want to know why.

I personally do not see any difference between OEM and the Hill unit, bar cosmetics. Why am I buying from Hill if I doubt its superiority? because it is cheaper and in my eyes the same as the OEM units.

 

I’m a luddite but even I’d rather carry around a handy jump start box like a Noco Genius GB 40, than a bulky clumsy set of heavy gauge jumper cables.

 

There is no jargon whatsoever in my answer. There are a lot of EEs on this board and this is basic circuit analysis stuff combined with some basic FA so I am not sure why it is so hard to understand. Despite what you keep implying, we are not talking about the steady state. We are saying that the connection itself causes an arc that contains extremely high frequency components. Those easily travel through the system and dissipate their energy in the circuits, often causing TLU. Why can't a relay start a motor that is 10% above it's operating current? Why do the contacts on a 30A relay fail and fuse shut on a pump that draws less than 10A? Why did the points in an old ignition system wear away and fail? It is all the same thing, transient response. Again, this is basic stuff for any EE so you can either do the research or take our word for it.

For the record, every engineer knows that analyzing it from a V perspective is folly. Voltage is potential to do work and the Current (I) is what actually does work. THAT is why they teach everything in terms of I, or an alternate domain like the S domain.

 

What if Hill is merely equal quality, but cheaper?

 

that's be great. The thing is, almost everybody says Hill units are better. I need some proof. at least tell me which part of the unit is superior, material is superior?
machining accuracy?

 

You missed the point of my question and you came in with some low-level semi-conductor jargon in an attempt to be condescending (at least to me, and I take insult from your reply). You still have not managed to explain the reason that jump-starting may damage the dead car's ecu. You keep on about transient states and high frequency, and random references to currents and voltages. Please explain the mechanism of how the damage is instigated. All you've said up to now amounts to "bad stuff will happen". If you can't, then lets leave it at that. I didn't come here to argue, I asked a civil question and I expect a civil answer, even if it is "I don't know", but instead I get a bunch of inflammatory responses - nice forum.

 

So here is the simple truth, you claim to be an EE and clearly are not so this is over your head. I warned that it was technically beyond you if you aren't educated as an EE but you insisted so I explained. Now you are upset that your ignorance is showing and you don't understand (per my first response). You justify it by saying it is 'jargon' when I have explained the mechanism in as simple terms as possible. There is a reason they don't even tell you how a resistor works until 2nd year - IT IS COMPLICATED. Further explaining isn't going to get you educated sufficiently to understand how electronics work so I will leave it there and you can live on in your belief that everyone else just isn't smart enough and it isn't a problem. Good luck with that.

 

What I don’t understand is even if you figure out exactly why and where it happens in the loom/circuit... what will you do differently? Rewire an ic? Add a capacitor in? From a functional standpoint and practical standpoint it doesn’t matter.

From a personal standpoint, anyone who does jump it and blow the cluster... I just laugh, it’s not my car.