[steadfast]

Originally Posted by Raghu M

Kind of something that is almost bizarre. The manufacturer may have the right to say that the car was serviced at a repair shop outside TAMO but how logical is that? A blown headlight leads to a car catching fire? If that is the case, then these vehicles will never be a full option to Indians. Would they agree that there was a genuine fault with the vehicle if it was repaired at a TATA service center? If the vehicle is so sensitive, it doesn't deserve to be on Indian roads.

There is nothing bizarre in this. Please read comment no. 12 of this thread that will give a better idea of what the root cause of the problem is. It was not a simple headlight change and blown away, it was an accidental repair done outside for front left part of the car. The bizarre thing is what insurance company did to customer and that the customer agreed to it.

[Neversaygbye]

As anyone who has owned a Tata Vista would know, replacing any of the driver side headlamp bulbs is a royal pain thanks to the design of the engine bay. I once went to a local auto electric shop to get the bulb replaced thinking that it would be a simple thing, and the technician there screwed it up royally. He managed to short the connections and I had to go to the TASC to get it fixed. Part of the wires had burnt and I was lucky that my car had not caught fire.

Also, when the horn of my Beat conked off on a road trip to Odisha, a roadside garage just could not figure out how to change it despite having a replacement horn available.

The point I am trying to make is that not every technician outside the ASC may have the requisite knowledge or skills to fix a particular car, and in this case the reasons Tata have mentioned look absolutely genuine to me. Let's cut them some slack - just because it's Tata doesn't mean we need to bash them. At least they are trying. The same cannot be said for some of the other OEMs, at least one of which is still using Dot 3 brake fluid in some of its new cars instead of the more suitable for ABS Dot 4.

[pranavt]

Sounds like a case of someone using thinner wires to connect the bulbs to the fuses. Fuses are rated to their specifications, whatever they may be (5A, 10A, 20A, etc). And they won't blow as long as you don't pull their rated current through them. But a bad wiring job (where someone most probably used thinner wires than recommended) will cause the wires to heat up enough to cause the the insulation to melt. At that point, all bets are off. To someone above who brought up battery ratings and amperes, 35A at 12V is not the same as 35A at 5V or 220V.

If it was a simple headlight/bulb change by the owner to higher-than-recommended-specs, good riddance; One car blinding people on the roads is off. If the owner was just replacing a broken headlight, he/she/they probably placed too much faith in random labourers working on their car.

[V.Narayan]

IMHO with EV's and the higher and different safety requirements we simply cannot take our cars to friendly neighbourhood garages any longer. I know I would not.

[MT_Hyderabad]

Tata responded to this incident like lightening and the previous case last year is still under Investigation!
Will I still buy a Tata EV? No.

[TROOPER]

So the entire saga could have been avoided if the owner was ready to cough up the cash, get it repaired at TASS and then claim refund from insurance?

Must say, quite a ballsy move from the owner to get his insurance work done from a FNG, that too of an EV, under warranty.

This is also why one must spend that extra bit and buy insurance from the dealer or ensure your dealer has a tie up with the insurance co. Have had experiences with Maruti and Tata and the experience has been super smooth every time.

[shortbread]

This isn't an EV only problem!

Not too long ago a Maruti spresso caught fire in Kerala as it was running on the road, the passengers inside sadly were burnt alive and perished. It was a horrible incident caught live on camera. Investigation later revealed the fire was due to a short circuit due to aftermarket accessory installation.

There is a growing gap between the complexities ot modern automotive electronics and the competencies of roadside accessory installers. It's simply not worth it.

[navin_v8]

Interesting discussions here on this lovely forum about the infamous Tata cars catching fire, from Nano to now Nexon.

Although the aftermarket part fiddling is a valid point raised by Tata, but a thorough investigation needs to be done to rule out any other thermal problems that caused the fire.

Although not relevant to this thread, I came across an incident online where an owner of a Tata Harrier is claiming that his Harrier's bumper and grill melted while being parked in open (under Sunlight) in Bangalore. This looks like a one off case, but in my entire lifetime I have never come across anything like this. Does it have to do with QC issues or general build quality of Tata cars? I don't know.

Source: https://twitter.com/iamsauravnahata/...80503865081856

[Jeroen]

Originally Posted by chandu

My point was that the press release at minimum sounded like they were putting the blame somewhere easy and not going deeper.

Thanks for your elaborate reply, much appreciated. Just a few more thoughts and some practical examples.

Yes, manufacturers do take all kinds of precaution against fire happening due to electrical faults. Still, on all ICE cars electrical faults are the number two cause of car fires, right after fuel faults (usually leaks).

And that is before we have DIY electrician messing about with a car electrical wiring.

Using inappropriate wire, in terms of diameter (gauge), material and insulation can cause serious problem including fires. The resistance of a wire is a function of its length, but also its diameter. Half the diameter means 4 four times the resistance.

There is a reason we use different gauge wire for different currents. Just an illustration of current versus proper gauge size (and length). At a given length of wire you can hardly go one gauge down. Let alone if you half the diameter. Then of course, it can get worse, if you use inappropriate wire material as well.



I have a little less faith than you of the so called high quality of workmanship in the automative industry. Be it the car manufacturers or some of their suppliers.

Yes fuses are made to pop slightly above their rated current. But lets have a look at the chart I picked up from the link you provided>



So for most if not just about all automotive electrical circuit it is not a problem that the fuse pops at a higher rating than advertised. As you can clearly see in the graph, at anything under 1 second, the current can be quite a bit higher. But that is for a very short period of time. If you need current protection for under a second you could go for quicker fuses, but in general it is not a problem. What the graph also shows is that for anything over 1 second, in absolute terms, the fuse is supposed to pop very close to its rated value.

And I have seen to many studies and measurement where that, for a variety of reasons, simply does not happen. E.g. a 10Amp fuse would not pop at a continuous 15-20 amp current.

Here is an interesting example of a poorly executed wiring fix I found some years ago in one of my cars. I pulled out the cable and keep it as a Lucky memento. It could have easily caused some serious fire.

the 25Amp fuse never popped!!

As you can see the insulation has (partly) melted and exposed the core in several places.







By and large electrical circuits in cars tend to be designed and installed correctly of course. It is not as if we have cars going up in flames left right and center. But it does happen. More often it happens when people have been messing with the electrical system. On some cars, replacing a simple light bulb can require quite a bit of work. It is easy to damage electrical wires, to get them stuck and squeezed into something.

That is before we consider the option that people make modifications without installing a proper fuse! I have come across those modifications. Radio directly wired into the battery. Foglight directly wired into the battery etc.

It has happened many times and we have a number of members who can testify to that as well.

I think we both agree we just don’t know what happened in this case. It would be better if more detail was provided. Although I am not sure some of our esteemed members would have believed that either.

My point is just this: A fused circuit is not a iron guarantee of the respective circuit not overloading.

Here is an interesting fuse I pulled out of my Mercedes some years ago At the time we discussed it in another thread. The fuse was still working, but as you can see the body of the fuse had actually melted. Go figure!!



Jeroen

[kaps454]

Originally Posted by PratikPatel

What’s so bizarre about this? I have spent a number of years in UAE, and anyone who has stayed there will vouch for what I am about to say:

In summer, tens of cars just go up in flames just standing parked.

True, seen that happen, new cars too. Don't know if mods were done though.

My dad's first car there was a honda civic shuttle, had loads of better cars but never sold this one even after 2 lakh kms. Honda service costs and parts costs were huge, almost merc range, but he got that little car service at honda for sentimental reasons.
regards kaps454

[mayd85]

I have to deal with fuses sometimes, as a part of my job. We were once testing with a 10A fast blow blade fuse from a reputed manufacturer, and the fuse was blowing pretty much as per the I2t characteristics. Later, our testing got extended for some reason and we ran out of fuses. One of us had a bright idea of buying a lot from local spares shop. To our surprise, more than half of those fuses did not blow even after passing more than 100A of current for almost 10 seconds (that's 1000 sqA.s, 10A fuse is rated around 150-200 sqA.s, IIRC). We stopped because our wires started heating up. So much for the quality of aftermarket 'protection' devices. God knows what these FNGs use when they do the repairs

[Tucker48]

Would this have happened in case of ICE cars? If not, then EV's definitely are still in their infancy. Or, if this is the case going forward, I have no hopes of EV's becoming mainstream.

Also, who takes such cashless insurance which can't get it fixed at the authorized service center.

I'm all in for "Right to Repair", means diagrams and spares will have to be made available to everyone and any capable person is able to fix the car. And the companies are doing exactly the opposite and making it tougher and tougher for people to get them fixed themselves.

[electric_eel]

Originally Posted by Tucker48

Would this have happened in case of ICE cars? If not, then EV's definitely are still in their infancy. Or, if this is the case going forward, I have no hopes of EV's becoming mainstream.

Also, who takes such cashless insurance which can't get it fixed at the authorized service center.

Yes this is a bad insurance that the user has taken. But then Dealers often quote exhorbitant insurance premium and I had to bargain hard with them to get matching
quotes (at least 50K more).

I'm all in for "Right to Repair", means diagrams and spares will have to be made available to everyone and any capable person is able to fix the car. And the companies are doing exactly the opposite and making it tougher and tougher for people to get them fixed themselves.

I am all for "right to repair" it is actually a pity that companies are trying hard to go the other way. In fact a traditional car company like Tata motors can get a serious advantage in the EV space if they become more open with the specs. EVs are in the future likely to have a significant software footprint.

1. At the heart of a BEV is the complex BMS (battery management system) particularly
for Chemistries like LFP.

2. Software for routing and range prediction taking into account elevation gains, traffic
density etc.

Opening up this would mean more open source software. This will definitely improve both the quality of the software as well as documentation; open source products sustain better with better documentation; which in turn simplifies training of service staff.

All this and more can be got with less investment. It makes lot of sense for TML which cannot compete with the likes of Tesla on the software side.

[guptad42]

This incident shows that at least for EVs, insurance companies should insist on all electrical and thermal/cooling systems repairs to be limited to the company authorised workshop.

For the next 3-5 years, restricting all EV repairs to company workshops is also an option, as the tech is very new in the Indian market and the aftermarket technicians do not have the training to deal with EVs.

Will the insurance company accept Tata Motors analysis in this case, and take care of the loss and trauma to the vehicle owner?

[chandu]

Lots of good points. Let me try to answer these properly.

Originally Posted by Jeroen

Thanks for your elaborate reply, much appreciated. Just a few more thoughts and some practical examples.
Yes, manufacturers do take all kinds of precaution against fire happening due to electrical faults. Still, on all ICE cars electrical faults are the number two cause of car fires, right after fuel faults (usually leaks).
Using inappropriate wire, in terms of diameter (gauge), material and insulation can cause serious problem including fires. The resistance of a wire is a function of its length, but also its diameter. Half the diameter means 4 four times the resistance.

However, I will point out that all fuses are designed to continuously run at the rated current, they will only fuse when the current is significantly above rated value (as you can see in the chart you have attached). Fuses typically are meant to open in a fault condition, not if something minor is wrong or a device draws slightly higher current. Fuses are typically meant to open if a major fault or short circuit occurs. This is a very common misunderstanding of how fuses work.
The tables that you see normally which give the ratings of the current carrying capability of wires, are generated using a safety factor for the max temperature of safe continuous operation of the insulation used for the wire. Typically you can go way over for short periods without any problems.

I have not really said anything about the fact that it was an EV that caught fire as the fire location had nothing do do with the fact that it was an EV.

Originally Posted by Jeroen

I have a little less faith than you of the so called high quality of workmanship in the automative industry. Be it the car manufacturers or some of their suppliers.
Yes fuses are made to pop slightly above their rated current. But lets have a look at the chart I picked up from the link you provided
in absolute terms, the fuse is supposed to pop very close to its rated value.
And I have seen to many studies and measurement where that, for a variety of reasons, simply does not happen. E.g. a 10Amp fuse would not pop at a continuous 15-20 amp current.
Here is an interesting example of a poorly executed wiring fix I found some years ago in one of my cars. I pulled out the cable and keep it as a Lucky memento. It could have easily caused some serious fire.
the 25Amp fuse never popped!!

All systems designed for automotive use will have a significant amount of FMEA work done so that typical failure modes are identified and taken care of, obviously, things do escape and get out in the field. which is why there are so many recalls in the automotive field. Plus, frauds do happen as we all found out in the Toyota Airbag supplier case.

Originally Posted by Jeroen

By and large electrical circuits in cars tend to be designed and installed correctly of course. It is not as if we have cars going up in flames left right and center. But it does happen. More often it happens when people have been messing with the electrical system. On some cars, replacing a simple light bulb can require quite a bit of work. It is easy to damage electrical wires, to get them stuck and squeezed into something.

That is before we consider the option that people make modifications without installing a proper fuse! I have come across those modifications. Radio directly wired into the battery. Foglight directly wired into the battery etc.
I think we both agree we just don’t know what happened in this case. It would be better if more detail was provided. Although I am not sure some of our esteemed members would have believed that either.
My point is just this: A fused circuit is not a iron guarantee of the respective circuit not overloading.

Yes, none of us know what happened in this particular case and which is why this whole thread got started.

Fuse manufacturers should do more about educating design engineers about their limitations (maybe there are design guidelines that give this information). I also used to think that fuses should blow at the rated current and only found out more about it when i was designing a component that included a fuse and I started asking questions.
Yes, you are correct, a fused circuit is not a guarantee of the circuit not overloading, this is upto the designer to ensure that the circuit is designed properly and will fuse in the anticipated fault conditions.

Originally Posted by Jeroen

Here is an interesting fuse I pulled out of my Mercedes some years ago At the time we discussed it in another thread. The fuse was still working, but as you can see the body of the fuse had actually melted. Go figure!!
Jeroen

Wow, this does look bad. A fuse should never be able to get hot enough to melt its housing without fusing.