Throttle attenuator for an EV

[Andy Chee]

Surely there is an existing software setting for this? rather than relying on hardware sensor trickery.

...
Do EVs not have such a thing?

Not on my economy car! Gotta pay at least twice as much for a premium EV with the "non-hairtrigger throttle" setting.

Just to clarify, is this a homebrew DIY EV build?  Or is this an EV from a global manufacturer?

[quince]

Just to clarify, is this a homebrew DIY EV build?  Or is this an EV from a global manufacturer?

It's the EV named in the pedal pinout PDF in the first post. Given that this hardware is untested, I would rather it not be searchable yet.

[tggzzz]

Can I check my understanding...

• cars are lethal pieces of machinery, that have killed and injured many people
• hence the cars and their operator and their operation are controlled by many laws, and those laws are enforced
• insurance is a legal requirement, and that requires clear statements that the cars are (or are not) roadworthy and unmodified
• you have a Chevrolet BOLT EV ?2023?
• it is difficult to control, either because you cannot control it or because the control setup is too aggressive
• you can pay more to have the car be more controllable. That implies Chevrolet is shipping a car that is, by default, too aggressive
• your solution is to add extra homebrew hardware to the car, directly between the throttle and the rest of the car
• your hardware will be temporarily connected using the existing connectors
• your hardware will modify the car's behaviour
• your hardware could equally easily make the car's control setup more aggressive rather than less aggressive

Point 6 is difficult to believe.
People are more likely to pay extra to have the option of making their car more fun to drive.
I believe there is a "hot-rodding" community that makes cars more aggressive and "fun" to drive. See point 10.
Such hot-rodding probably invalidates insurance and manufacturer's warranties.
If such hot-rodding is detected (e.g. after warranty claim or accident) then the owner has a Big Problem.
Being able to remove the evidence of hot-rodding, e.g. using a temporary removable fitting would be advantageous in that respect.

Comments?

[uer166]

Comments?

I used to work for a major EV manufacturer in engineering, this entire thread and an assertion that adding a mod board to a pedal control loop is somehow "safe" is absolutely ridiculous. OP: either replace car or get used to the pedal response, the chance of you killing or maiming someone else is way too high.

[tggzzz]

Comments?

I used to work for a major EV manufacturer in engineering, this entire thread and an assertion that adding a mod board to a pedal control loop is somehow "safe" is absolutely ridiculous. OP: either replace car or get used to the pedal response, the chance of you killing or maiming someone else is way too high.

Just so.

I wonder if "quince" has somewhat, ahem, different objectives to the ones he has stated, hence his preference that he doesn't want "Chevrolet BOLT EV" to be searchable viz:

It's the EV named in the pedal pinout PDF in the first post. Given that this hardware is untested, I would rather it not be searchable yet.

[quince]

Thanks for continuing to participate in the thread, folks.

you can pay more to have the car be more controllable. That implies Chevrolet is shipping a car that is, by default, too aggressive

The OEM acceleration is too aggressive. You should try one. In the EU/UK they're known as the Opel Ampera-E.

OP: either replace car or get used to the pedal response

If I had $40,000 laying around to buy a car with the Chill Mode feature, maybe I would.

your solution is to add extra homebrew hardware to the car, directly between the throttle and the rest of the car

It does exactly what Tesla's well-known and celebrated "chill mode" feature does. It imitates part of "snow mode" in an Ioniq.

your hardware could equally easily make the car's control setup more aggressive rather than less aggressive

Only if you expect me to solder the resistors in backwards and also fail to do any verification & validation.

People are more likely to pay extra to have the option of making their car more fun to drive.
I believe there is a "hot-rodding" community that makes cars more aggressive and "fun" to drive. See point 10.
...
Being able to remove the evidence of hot-rodding, e.g. using a temporary removable fitting would be advantageous in that respect.

Comments?

The only way to make a Bolt faster is to sell it and buy a Tesla. Steepening the throttle curve genuinely would achieve nothing. I love the conspiratorial tone, but I use my car for transportation and have no interest in making it more "fun."

Millions of cars have their speeds and throttles limited by aftermarket kits. I could probably buy one of those... perhaps I will!

https://www.rostra.com/how-to-add-speed-limiter-to-a-vehicle.php

https://www.avsgemini.com/speed-limiters.html

They're even all over Amazon: https://www.amazon.com/rev-limiter/s?k=rev+limiter

Such hot-rodding probably invalidates ... manufacturer's warranties.

Warranty expired already, mate.

[tggzzz]

Thanks for continuing to participate in the thread, folks.

you can pay more to have the car be more controllable. That implies Chevrolet is shipping a car that is, by default, too aggressive

The OEM acceleration is too aggressive. You should try one. In the EU/UK they're known as the Opel Ampera-E.

OP: either replace car or get used to the pedal response

If I had $40,000 laying around to buy a car with the Chill Mode feature, maybe I would.

You mean you didn't test drive a car before buying it? Strange, and not what I would expect from an engineer.

your solution is to add extra homebrew hardware to the car, directly between the throttle and the rest of the car

It does exactly what Tesla's well-known and celebrated "chill mode" feature does. It imitates part of "snow mode" in an Ioniq.

your hardware could equally easily make the car's control setup more aggressive rather than less aggressive

Only if you expect me to solder the resistors in backwards and also fail to do any verification & validation.

Conclusion: either you are someone that doesn't have the first clue about how components and circuits work, or you are a troll, or both.

People are more likely to pay extra to have the option of making their car more fun to drive.
I believe there is a "hot-rodding" community that makes cars more aggressive and "fun" to drive. See point 10.
...
Being able to remove the evidence of hot-rodding, e.g. using a temporary removable fitting would be advantageous in that respect.

Comments?

The only way to make a Bolt faster is to sell it and buy a Tesla. Steepening the throttle curve genuinely would achieve nothing. I love the conspiratorial tone, but I use my car for transportation and have no interest in making it more "fun."

Millions of cars have their speeds and throttles limited by aftermarket kits. I could probably buy one of those... perhaps I will!

https://www.rostra.com/how-to-add-speed-limiter-to-a-vehicle.php

https://www.avsgemini.com/speed-limiters.html

They're even all over Amazon: https://www.amazon.com/rev-limiter/s?k=rev+limiter

There are all sorts of dangerous and illegal things "all over Amazon".

In the UK there are many things which are legal to sell but illegal to operate. I learned that in 1972 w.r.t. some types of radios.

I now see such things every day on the roads, and they kill/injure hundreds of innocent passers by every year.

Such hot-rodding probably invalidates ... manufacturer's warranties.

Warranty expired already, mate.

Is the insurance also expired? The insurance is almost certainly invalidated, so when you hit someone they will suffer the health consequences and financial consequences of not getting a financial settlement.

That's selfish in the extreme.

This is correct:

Comments?

I used to work for a major EV manufacturer in engineering, this entire thread and an assertion that adding a mod board to a pedal control loop is somehow "safe" is absolutely ridiculous. OP: either replace car or get used to the pedal response, the chance of you killing or maiming someone else is way too high.

[bookaboo]

Comments?

I used to work for a major EV manufacturer in engineering, this entire thread and an assertion that adding a mod board to a pedal control loop is somehow "safe" is absolutely ridiculous. OP: either replace car or get used to the pedal response, the chance of you killing or maiming someone else is way too high.

1000% this.

What happens if the mod develops a dry joint, or gets moisture ingress?  Doesn't bear thinking about.

Besides I can't imagine that a Bolt is uncontrollable off the line at the lights. If that's  the case, how would you ever park it?

[nali]

...or crusty parts from Aliexpress or wherever.

I don't really get the logic of the OP requirement. I still want to stomp my pedal but only get 50% power? What happened to the traditional lump of wood under the accelerator method? Or good old fashioned pedal control?

[Andy Chee]

According to wikipedia the 2023 Chevy Bolt sold over 62,000 vehicles in the US.

I would imagine that if the accelerator was problematic, we'd be hearing complaints from the other 61,999 Bolt owners.

[SteveThackery]

I must concur - as an ex Reliability Engineer, I know that the effort that goes into ensuring the safety and reliability of the control systems is extraordinary. I haven't been involved in EV's, but the systems will have been subject to deep FMEA (failure modes and effects analysis), as well as being engineered as fail-safe. Two-layer sanity checking will probably be built in, and the system will have been comprehensively tested, including electrical stress testing.

The idea that some no-brand circuit board from a nameless Chinese factory will have received even a fraction of that attention is..... daft, to put it politely.

The mod board has the capability of sending any throttle opening* signal into the system. So a bug or glitch might cause it to send a "pedal is pressed to the floor" signal at any time. Waiting at a stop sign, reversing into a space, etc.

Electronics are pretty reliable these days, but the reliability requirements of vehicle control systems is much higher than typical consumer electronics. There is no way that I would install a device like this in such a safety critical system.

[quince]

I appreciate all of the feedback! From your suggestions, I'm hearing these new requirements.

• American IPC Class 3 (highest grade) PCB fabrication with e-test
• BOM restricted to AEC-Q100 or higher components
• Conformally coated or even fully potted PCB
• Extensive thermal bake-out and vibration testing to qualify each unit
• Enclosure and physical placement must be robust to user input and impact
• FMEA must be conducted
• Functional safety analysis must be conducted
• Design must be tuned from functional safety and FMEA perspective so that any number of component failures (open, short, partial) results in an immediate vehicle fault code and no unintended acceleration. If unachievable, product is not deployed.
• Limiter must be tested extensively on a closed track before shipment to customers.
• Limiter must be UL certified
• Limiter must have clear indication to the driver when active and inactive

The vehement discouragements I'm not sure I understand. If I buy a Tesla Model X, I can press a button to make it accelerate like a Prius at best. If I want that functionality on my car, why should I be prohibited from adding it, as long as my insurance is notified? If you have an idea for implementing it with fewer parts and higher functional safety, do share! Calling me a troll is unkind.

I could find a replacement throttle pedal or potentiometer module that outputs a voltage range 50% as wide as the original with the right offset. I would be surprised if that takes less than a year.

NHTSA has a helpful interpretation on throttle translators as used by leg-paralyzed drivers here: https://www.nhtsa.gov/interpretations/18185a.

A servo losing power and getting stuck at max throttle is horrifying. It's also a far cry from any failure that could occur in a passive resistor network adapting two redundant potentiometer circuits to lower voltages. I can test this, but I expect that losing any one or two components in the schematic I designed would result in mis-alignment between the two throttle signal channels sufficient to trigger an immediate fault code on the car.
 
Now, is the idea of modifying cars reasonable? Some in this thread say otherwise, contrary to the forum's motto: "Don't turn it on, take it apart!"

NTSB and the EU do not seem religiously opposed to retro-fitting cars with limiting devices as long as they are implemented safely.

• The NTSB has been asking NHTSA to mandate speed limiting devices for years: https://www.autoblog.com/2023/11/18/ntsb-again-urges-car-speed-limiter-tech-after-fatal-crash-at-triple-the-posted-speed/
• The EU is now requiring speed limiters in all new cars as of a few weeks ago. https://www.evo.co.uk/news/22326/speed-limiters-are-now-mandatory-but-you-can-turn-them-off

I would imagine that if the accelerator was problematic, we'd be hearing complaints from the other 61,999 Bolt owners.

Most of them are weirdos who like to spend excessive effort keeping their foot barely pressed on the pedal so as to accelerate as slowly as possible. I suggest you test drive one to understand what I'm talking about.

Or, try a Tesla in and out of Chill Mode. You may surprise yourself and find that a lower torque cap is actually nicer to drive.

[Monkeh]

So we've gone from 'stomp the pedal' to 'excessive effort to barely press the pedal'.

Are you, by chance, used to an incredibly oversized and slow responding engine and have never developed any degree of fine control?

[janoc]

Now, is the idea of modifying cars reasonable? Some in this thread say otherwise, contrary to the forum's motto: "Don't turn it on, take it apart!"

That doesn't mean that safety and laws go out of the window. In the US pretty much anything goes when it comes to cars, in Europe if you attempted this sort of stunt, you will not pass the mandatory technical inspection and your insurance would be void, with you being instantly on the hook for any damage or problem that happens. Regardless of any forum mottoes. That you are even bringing this sort of thing as an argument shows a rather astounding lack of comprehension.

I am not sure whether you realize how high the medical bills could be if you hit someone (regardless whether because of your hack or any other reason) - and don't have a valid insurance. Probably your kids would be still paying those debts, esp. in the US, not to mention your possible prison time for driving without insurance.

NTSB and the EU do not seem religiously opposed to retro-fitting cars with limiting devices as long as they are implemented safely.

Which doesn't mean that whatever homebrew gadgets are allowed, esp. stuff that goes into safety critical systems (I am sure you have heard about the runaway accelerator problems on some Toyotas before, right?)

E.g. in Europe any mods you put on your car have to be either generally approved or you must get your own checks and approval of them from the authorities (i.e. TüV in Germany) - and have that noted in your registration papers! Otherwise your car is illegal to drive, full stop. E.g. here in Germany even using different wheel rims than the original ones the car came with can result in a major fine from the police and your car being towed/declared illegal to drive if you didn't do the above.

The speed limiting devices you refer to are completely irrelevant to the debate - these have to be factory-fitted (plus it is a completely different, much more complex system - tied to satnav maps + reading of traffic signs). Homebrewers need not apply - as an individual you have zero chance to satisfy the regulatory requirements to make your own mod legal.

Most of them are weirdos who like to spend excessive effort keeping their foot barely pressed on the pedal so as to accelerate as slowly as possible. I suggest you test drive one to understand what I'm talking about.

Or, try a Tesla in and out of Chill Mode. You may surprise yourself and find that a lower torque cap is actually nicer to drive.

I think that simply due to statistics the probability is much higher that the Bolt owners are all fine - except for one weirdo who is hell bent on trying to kill himself by messing with something they don't understand instead of learning to drive the car they have bought.

And if you like the Tesla - why did you buy a Bolt? Buying a Bolt and complaining it doesn't drive like a Tesla (and trying to dangerously mess with it to boot) is a bit daft, IMO.

[tggzzz]

I think that simply due to statistics the probability is much higher that the Bolt owners are all fine - except for one weirdo who is hell bent on trying to kill himself by messing with something they don't understand instead of learning to drive the car they have bought.

And if you like the Tesla - why did you buy a Bolt? Buying a Bolt and complaining it doesn't drive like a Tesla (and trying to dangerously mess with it to boot) is a bit daft, IMO.

Personally I don't care if the OP kills/injures himself; that is his business. I do care if he kills/injures someone else.

Based on the arguments the OP makes, clearly he doesn't understand so many things that the daftness of the bolt/tesla thing is entirely unsurprising.

[edavid]

In the US pretty much anything goes when it comes to cars, in Europe if you attempted this sort of stunt, you will not pass the mandatory technical inspection and your insurance would be void, with you being instantly on the hook for any damage or problem that happens.

OP is in the US, so why is the European system relevant?

I am not sure whether you realize how high the medical bills could be if you hit someone (regardless whether because of your hack or any other reason) - and don't have a valid insurance. Probably your kids would be still paying those debts, esp. in the US, not to mention your possible prison time for driving without insurance.

It sounds like you don't have much knowledge of US health care or auto insurance.

Auto insurance coverage limits can be quite low.  In my state, the minimum for bodily injury is $25K.  Most engineers carry more than that, but it's very rare (and expensive) for anyone to have more than $1M coverage.  So, auto insurance doesn't really protect your net worth.

Fortunately, it's rare for an accident victim to have more than $10K in medical costs.  (Loss of income can add to that though.)

In most states, driving without insurance is punished by a small fine, not jail time.

There is no requirement to report modifications to one's insurance company, and they do not void the insurance.  In the event of a claim, the insurance company would have the burden of proving that the modification caused or contributed to the accident.

[bookaboo]

I appreciate all of the feedback! From your suggestions, I'm hearing these new requirements.

• American IPC Class 3 (highest grade) PCB fabrication with e-test
• BOM restricted to AEC-Q100 or higher components
• Conformally coated or even fully potted PCB
• Extensive thermal bake-out and vibration testing to qualify each unit
• Enclosure and physical placement must be robust to user input and impact
• FMEA must be conducted
• Functional safety analysis must be conducted
• Design must be tuned from functional safety and FMEA perspective so that any number of component failures (open, short, partial) results in an immediate vehicle fault code and no unintended acceleration. If unachievable, product is not deployed.
• Limiter must be tested extensively on a closed track before shipment to customers.
• Limiter must be UL certified
• Limiter must have clear indication to the driver when active and inactive

The vehement discouragements I'm not sure I understand. If I buy a Tesla Model X, I can press a button to make it accelerate like a Prius at best. If I want that functionality on my car, why should I be prohibited from adding it, as long as my insurance is notified? If you have an idea for implementing it with fewer parts and higher functional safety, do share! Calling me a troll is unkind.

I could find a replacement throttle pedal or potentiometer module that outputs a voltage range 50% as wide as the original with the right offset. I would be surprised if that takes less than a year.

NHTSA has a helpful interpretation on throttle translators as used by leg-paralyzed drivers here: https://www.nhtsa.gov/interpretations/18185a.

A servo losing power and getting stuck at max throttle is horrifying. It's also a far cry from any failure that could occur in a passive resistor network adapting two redundant potentiometer circuits to lower voltages. I can test this, but I expect that losing any one or two components in the schematic I designed would result in mis-alignment between the two throttle signal channels sufficient to trigger an immediate fault code on the car.
 
Now, is the idea of modifying cars reasonable? Some in this thread say otherwise, contrary to the forum's motto: "Don't turn it on, take it apart!"

NTSB and the EU do not seem religiously opposed to retro-fitting cars with limiting devices as long as they are implemented safely.

• The NTSB has been asking NHTSA to mandate speed limiting devices for years: https://www.autoblog.com/2023/11/18/ntsb-again-urges-car-speed-limiter-tech-after-fatal-crash-at-triple-the-posted-speed/
• The EU is now requiring speed limiters in all new cars as of a few weeks ago. https://www.evo.co.uk/news/22326/speed-limiters-are-now-mandatory-but-you-can-turn-them-off

I would imagine that if the accelerator was problematic, we'd be hearing complaints from the other 61,999 Bolt owners.

Most of them are weirdos who like to spend excessive effort keeping their foot barely pressed on the pedal so as to accelerate as slowly as possible. I suggest you test drive one to understand what I'm talking about.

Or, try a Tesla in and out of Chill Mode. You may surprise yourself and find that a lower torque cap is actually nicer to drive.

No you are hearing several very well qualified people tell you not to do it for your own safety and the safety of others.

I drive a Model Y Dual Motor daily. Even in normal mode it's perfectly possible to drive it like a Prius. Chill mode just takes away the real punch and top end.

[SteveThackery]

There is no requirement to report modifications to one's insurance company, and they do not void the insurance.  In the event of a claim, the insurance company would have the burden of proving that the modification caused or contributed to the accident.

That is astonishing! Is it really true? If so, wow! Here in Europe it's the exact opposite.

[tggzzz]

There is no requirement to report modifications to one's insurance company, and they do not void the insurance.  In the event of a claim, the insurance company would have the burden of proving that the modification caused or contributed to the accident.

That is astonishing! Is it really true? If so, wow! Here in Europe it's the exact opposite.

If it was true then US insurance companies are missing tricks in how to avoid payouts. (E.g. if you are stationary in a traffic queue and are rear-ended, checking to see whether your tyres are legal).

I find it hard to believe that US insurance companies are that inefficient with their shareholder's money.

[janoc]

OP is in the US, so why is the European system relevant?

Because he keeps bringing up irrelevant arguments about the EU trying to bolster his claims.

It sounds like you don't have much knowledge of US health care or auto insurance.

I know enough to know, that I don't want to drive around with an invalid insurance and get into an accident. The victim's medical (and other) expenses you will get ordered to pay afterwards are most likely to drive you bankrupt.

That your insurance covers you only up to $25k (which is, IMO, ridiculous but that's different topic) or that most people don't incur more than $10k in medical costs after an accident is not an excuse to drive around without one (or with an invalid one). That is a completely ridiculous position to take - all it takes is one moment of bad luck.

[BarrowBoy]

I guess owning a 641bhp, (478kW) 700Nm EV would not be your cup of tea then. Maybe it might be safer if your walking I guess, or best bet is stay in bed. Don't go limiting a EV just because you lack throttle control.

[tom66]

I would be very surprised if your vehicle does not have some kind of eco mode.  Or perhaps you can get the throttle map reprogrammed.  I would consider both before replacing the accelerator signal, which strikes me as very dangerous.

[quince]

The car's acceleration response is normal with a 500 ohm resistor inserted on each throttle signal line. There aren't any fault codes either. Looks good for installation!

[bookaboo]

That easy? Wow, to think the big Auto companies were wasting all that time on testing and compliance. 

[tggzzz]

That easy? Wow, to think the big Auto companies were wasting all that time on testing and compliance. 

And reliability, especially w.r.t. connectors, water, vibration.

Good luck with the response from your insurance company, when you inform them of this modification. Ditto lawyers, after an accident - whether or not you were responsible.