Please help can't figure this out, been trying for ages

That makes sense if you have enough torque that you're limited by tire adhesion anyway. The limits to that approach tend to be cooling the rotor. You can water-cool the stator.

The torque limit is basically

highest available B field (limited by saturation) x Highest current density possible without overheating x surface area of rotor (proportional to diameter squared) x radius of rotor (lever arm length)

Since there's a lot of metal in there, you can overdrive a motor for awhile before disaster strikes, but you can do a lot more burnouts in a row with a gas engine than an electric. (Of course the use case matters.)

Sounds reasonable. Where AWD is important, you won't be sending maximum torque to the wheels anyway, and using lower torque for the front drive will improve the handling a lot. Torque steer is unpleasant.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
https://hobbs-eo.com

I think the Tesla has water cooling of the rotor aswell

ts

oltage

than

e to 5%

1%

used to select from 5%ers to improve accuracy, and while ppms of drift limi t what can be done it did get an improvement.

at you got shipped as 2% resistors didn't include any that could be shipped as 1% resistors, and a surprisingly higher proportion of parts that were r ight up against the 2% limits.

e just buy the accuracy we need.

going to have some kind of helpful distribution of values isn't always true .

e expensive, and buying the value and tolerance you need does indeed make s ense.

Gigantic waste of time! All monolithic comparators have internal feedback h ysteresis whether they specify it or not. The ones that do have hysteresis on the order of 10mV, the ones that don't should have at least a few hundre d microvolts. The internal hysteresis blurs the switching thresholds signif icantly within the ridiculous OP input specification. If you think that's d umb, try to find out his application.

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Thanks! You could've trimmed the quotes. I would've understood. :-)

It scares me too but not as much as right handed traffic does. :-)

There aren't many places in the UK where driving can be said to be a 'relaxing experience'. The only part of the UK ime, where that might be true would be in the more rural or wilder parts of Scotland.

I should think a 15 volt rated supercap of a high enough Farad value (say 30 to 50F) would be more a liability than an asset. 2.4Kjoules or more of energy released in a millisecond or so by a short circuiting fault would create one hell of a bang! Not only that but I should think it would increase the risk of the starter motor solenoid contacts welding shut.

Personally, I'd rather use the safer option of carrying a separate jump starter battery in the boot (trunk) even if it's nothing more than that

12AH SLA and a pair of home made stubby jump leads.

There is always a fatality risk in whatever activity we undertake, whether it be travelling 250 miles by car (as of Aug 2013 - it had previously been 230 miles as of Feb 2009), or 6000 miles by train (also a Feb 2009 figure) with a one micromort risk (one in a million chance of accidental death).

Even if the self driving car could increase the travelling distance to

1000 miles per micromort (making such travel "Four Times Safer"), there will always be the risk of fatality, even if such fatal accidents then become considered as 'extremely freaky' events where the actions of a human driver *may* have changed the outcome from 'fatal' to 'just seriously injured' - discounting the statistical probability by then of human intervention being more likely to result in a fatal outcome.

When self driving vehicles can offer a statistically proven reduced risk of fatal accident per travelled mile compared to human controlled vehicular mileage, the problem remains that of not being in control when you're convinced that your own driving skills are way above the 'average' which you deem to be a very low bar for the self driving car to get over but not the bar you believe you have set at a higher level than the self driving car is capable of matching.

There's probably a better way I could have stated the above BICBA trying to find one. Let's just say that if you're a married man, who can sit relaxed in the passenger seat whilst your wife does the driving[1], *and* resist the urge to offer "constructive criticism" of her driving 'style', no matter the provocation, then using a self driving car (once its micromort mileage rating is at least twice as good as the average man's) shouldn't be any more stressful an experience than being chauffeured around by your spouse. :-)

[1] I find it helps to recall the comforting fact that (according to the Insurance Underwriters' own figures) "Women are statistically lower risk drivers than men." by way of consolation for not being in the driving seat. :-)

I've also learned from bitter experience that offering 'constructive criticism' only makes the situation worse - it seems to divert SWMBI's attention away from the task of driving safely in traffic. Far safer to take mental note(s) and defer the 'constructive criticism' until safely parked up and out of the traffic.

However, most sane husbands will (if they know what's good for them) let discretion be the better part of valour and reserve any such attempted appraisal exercise *only* for those occasions when the mental note(s) just happened to include the phrase "Near Death Experience!" or similar. :-(

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Johnny B Good

Transmissions are obsolete. Who needs them?

Rick C.

Yes, electric cars still have gears, just a single fixed ratio like the rear end in a conventional car to let the engine run at the RPM it works best.

Rick C.

LOL No, the English are not that bad drivers in my limited experience.

Yes, same in most places, cities can be a parking problem..

Not so difficult to add some series resistance (wires will do).

I see posting after posting of battery horror stories, of battery paranoia. And society picks up on that it seems. If you treat the batteries normal, nothing much happens. Bad chargers, not fused loads will get you fires. physical damaging batteries too.

I have all sorts of batteries in use here, calling 'lithium' in general dangerous is silly, there are lipos everywhere, small ones with internal protection chips in headphones, where not, in many USB chargeable places.

I have been replacing 2 AAA cells in 3 V gadgets here by one lifepo4 (3.2V) AAA and one dummy AAA just for fun (and to prevent leaking AAA in expensive remotes, test equipment, wireless keyboard, etc), and also (bad bad bad I know) by one lipo (3.7V) AAA and one dummy in a wireless temperature humidity meter that hangs outside free from everything where it can go up in flames if it wants to. SLA sucks in my opinion, I have an other 12 V one that is dead, terminals corroded, always handled it according to the datasheet, after a few years its over. Lifepo4 is still expensive, and a bit lower capacity, but no fire hazard. Adding some supercaps may well be the future.

Oh well, where I used to work it was a 1 hour drive to work and then later back, in the winter you would see the car wrecks on the side of the road. Driven through Europe, never a problem.

If 'statistics' say self driving is safer, then insurance companies will no longer insure cars without autopilot, and you driving yourself will become a crime ;-) Beware of statistics, really!

:-)

And then there is that GPS thing now in almost every car, 'take next turn right' on a regular basis people drive into a river where a bridge was supposed to be, in full obedience to the voice from the machine.

Some drivers... I will not go in a car with them again. Those were male BTW.

Once down under, with some people in a hotel, decided to rent a car. I said 'I am not comfortable with driving on the wrong side, are you?' 'Oh yes, no problem'. Next thing you know we almost had a head on collision as the guy's reflexes made him evade the wrong way. Subsequenctly *I* got blamed for bringing up the subject.. I took the bus there after that. Over confident..

You're referring to the rear axle differential reduction gear in a rear wheel or all wheel drive vehicle. That's really a hybrid of mechanical transmission and a central electric motor (sometimes seperate motors for rear and front wheels using half shafts and UJs).

The box of cogs required by an ICE is typically eliminated in this electric hybrid by the use of a BFO Switching voltage converter controlled by an accelerator pedal sensor input to the microprocessor controlling the motor(s) voltage and current demands. Furthermore, the micro-controller can/will also provide traction control.

However, imho, the only sane way to electrically power a road vehicle is to go the whole hog and eliminate the excess baggage of gearbox, prop shafts, differentials and half shafts with UJs, by incorporating the electric motors into the wheels themselves.

These days, lightweight high torque pancake styled Neodymium PM BLDC motors can be integrated into each wheel with little to no net increase in unsprung mass. The transmission then takes the form of electric cables and a BFO switching converter weighing far less than the mess of mechanical cogs and shafts currently required by ICE (and still used by most of the ill thought out designs of Electric) powered vehicles.

If a job's worth doing, it's worth doing properly. :-)

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Johnny B Good