[bavarianride]

Originally Posted by jeffc42

The motor does not use permanent magnets. When there's no power, it just spins freely. So long as you do not exceed 140mph, you won't spin them too fast.

Does it mean that when power is off, the magnet-less motor has no inertia, hence there needs to be another (electro?) mechanical parking brake to hold i4 in steep terrain?

How much electricity (from 12V or main battery?) does this ebrake consume when parked to hold 4500-5000lb on 30+% gradients@SF?

[jeffc42]

Originally Posted by bavarianride

Does it mean that when power is off, the magnet-less motor has no inertia, hence there needs to be another (electro?) mechanical parking brake to hold i4 in steep terrain?

How much electricity (from 12V or main battery?) does this ebrake consume when parked to hold 4500-5000lb on 30+% gradients@SF?

An EV does have friction brakes and a parking brake just like ICE cars do. Regen braking cannot bring a car to a complete stop, because the braking force is proportional to the speed of the car. All EVs switch to friction brakes when regen braking has maxed out. It is good old fashion disc or drum brakes that hold an EV in place on a hill, same as for any other car.

"Inertia" is the wrong word. Any spinning mass has inertia, which resists spinning faster or slower, but friction is what causes a magnet-less motor to slow down when unpowered. The bearings of the motor are designed to minimize friction; friction is the same whether the the motor is powered or not.

[cruzer666]

Originally Posted by spool twice

the tricky part about BEV's with towing isn't the battery pack, its if/when the 12-14v system is down and getting it from P to N to allow the car to roll. BUT I could be confusing this with a perm magnet motor...

There's no indication what to do when the low voltage system is out. Older BMW's have mechanical releases for P to N and for the parking brake. I don't see a mention for this on the i4's. I'm sure BMW thought of this scenario though

[jeffc42]

Originally Posted by cruzer666

I'm sure BMW thought of this scenario though

It amazes me that people are worried that BMW would design a car that cannot be towed.

[techwhiz1]

Originally Posted by bavarianride

How does X5 eBrake manual disengage work when the AGM battery is drained?

It's mechanical and the drive unit for the eBrake is released.

Pads no longer make contact with the drum when released.

They are engaged by a small electric motor and a worm drive typically. When released the worm drive no longer is engaged.

[bavarianride]

Originally Posted by jeffc42

An EV does have friction brakes and a parking brake just like ICE cars do. Regen braking cannot bring a car to a complete stop, because the braking force is proportional to the speed of the car. All EVs switch to friction brakes when regen braking has maxed out. It is good old fashion disc or drum brakes that hold an EV in place on a hill, same as for any other car.

"Inertia" is the wrong word. Any spinning mass has inertia, which resists spinning faster or slower, but friction is what causes a magnet-less motor to slow down when unpowered. The bearings of the motor are designed to minimize friction; friction is the same whether the the motor is powered or not.

As you said, inertia can be resistance to spin faster or slower (i.e. resistance to change of velocity) with respect to current rpm, which can be 0 rpm while parked, right?

So what you mean is that unpowered magnet-less motor cannot resist change of velocity (since minimal friction, hence minimal inertia), so it can spin up from 0 rpm as long as friction brakes are released.

[bavarianride]

Originally Posted by techwhiz1

It's mechanical and the drive unit for the eBrake is released.

Pads no longer make contact with the drum.

I think all bimmers using ZF rely on the same mechanical pin/latch (single use?) of the ZF unit to manually move from P to N when AGM battery is drained.

That ZF pin/latch can only be accessed after removing underbody panel(s), and some local tow drivers gave up and towed by force onto flatbed (damaging ZF in the process).

The first MY of F30(2012) in the US has a special turnkey to access a knob under the shift gear panel, but someone at BMW believes that accessibility is not worthy to keep for subsequent F30.

[jeffc42]

Originally Posted by bavarianride

As you said, inertia can be resistance to spin faster or slower (i.e. resistance to change of velocity) with respect to current rpm, which can be 0 rpm while parked, right?

So what you mean is that unpowered magnet-less motor cannot resist change of velocity (since minimal friction, hence minimal inertia), so it can spin up from 0 rpm as long as friction brakes are released.

Inertia is not friction; they're completely different things. I suggest wikipedia. But, yes, an unpowered motor will happily spin up when the car is pushed, whether by gravity or something else, when the brakes are not engaged.

[bavarianride]

Originally Posted by jeffc42

Inertia is not friction; they're completely different things. I suggest wikipedia. But, yes, an unpowered motor will happily spin up when the car is pushed, whether by gravity or something else, when the brakes are not engaged.

Yeah wikipedia says similarly about inertia as my previous post:

"Inertia is the resistance of any physical object to a change in its velocity. This includes changes to the object's speed, or direction of motion."

So motor inertia is to resist moving from 0 rpm, or resist changing(faster or slower than) a specific rpm.

I remember reading EV motor spec that says low inertia(that helps with instant high rpm?) and high torque, I am not sure what are similar specs for i4(or Tesla) motors, maybe techwhiz will know.

[bavarianride]

Originally Posted by cruzer666

I'm sure BMW thought of this scenario though

BMW thinking of this scenario does not necessarily mean it is easily accessible and/or serviceable.

[JMD]

Originally Posted by Ken7

Between rest breaks, food breaks and pee breaks, most people won’t even drive 200 miles before stopping. It’s also safer. But hey, obviously most people here think you’re very wrong.

If you really ‘need’ that kind of range, get a Lucid. The $70,000 Lucid Pure (after $7,500 tax credit) won’t set you back much more than a well equipped i4. But I suspect you might have a few reasons why that too is a poor choice.

Just a final comment, why did you feel compelled to come here to tell people, in a roundabout way, that they made a bad choice? I’m always amazed at how regardless of the forum, you’ll always get a few ‘enlightened’ posters to tell everyone why they’re going down the wrong path.

By no means did I say those that chose the i4 made a bad choice. Personally, I think BMW did some good things with the i4 Series,...and for starters, the i4 Series looks damn near like a norm looking BMW. As for the choice they made,...it shouldn't make a 2-ounce difference what I thought about their purchase,...no more than what their next door neighbor,...who owns a Tesla,...thinks of their decision to purchase a BMW i4.

That said, I didn't come here to knock their purchase no more than anyone else did to praise their purchase.

Now, you can cut this cheese anyway you want, however, there are many out there in the cyberspace that have weighed in on the i4,...the iX, so, it is what it is.

Lastly, no matter what you think of my comments here,...I'm still hopeful that BMW comes through with a BEV that I want to invest in,...so I don't have to deal with the sloppy driving dynamics offered by a bunch of wanna-bees!

That said, I'm more "Pro-BMW-BEV" than you think,...however, just as we recognize the good in design and engineering, we must also identify major short-comings! And with that, I think we can agree on.

[bavarianride]

Originally Posted by JMD

That said, I'm more "Pro-BMW-BEV" than you think,...however, just as we recognize the good in design and engineering, we must also identify major short-comings! And with that, I think we can agree on.

I would like to get a BEV that is similar to a G30 330i, e.g. 3500lb, 500+ miles of range, 0-60 in 5 to 6 seconds, battery warranty (e.g. 90%) for 15 years/150k miles, charge time for 20% to 80% in 5 minutes with regular 240V dryer plug@30A.

This likely won't show up in 5-10 years (or never?), but those are the parameters that will be of value to me.

[techwhiz1]

Originally Posted by bavarianride

I would like to get a BEV that is similar to a G30 330i, e.g. 3500lb, 500+ miles of range, 0-60 in 5 to 6 seconds, battery warranty (e.g. 90%) for 15 years/150k miles, charge time for 20% to 80% in 5 minutes with regular 240V dryer plug@30A.

This likely won't show up in 5-10 years (or never?), but those are the parameters that will be of value to me.

Well what.you are asking for is not possible.
The charge time on a 240V circuit makes it not possible. You have specified 7200 watts; and at 10 minutes it's just a trickle into ANY battery.

500 miles of range moving 3500lbs means you are going to need capacity of about 110-120kwh so no way can you charge that in 5-10 on a house circuit. Even the current DC systems won't be able to charge that fast.

Even with a doubling of battery capacity you are still looking at 750lbs of battery and support structure.

You would need to reduce the weight of the current i4 by 1500lbs and even with battery tech, you can't get there from here.

Also you are asking for what 95% of people don't need.

[bavarianride]

Originally Posted by techwhiz1

Also you are asking for what 95% of people don't need.

I guess 95% of current BEV owners(with home charging) do not need these parameters, but I think most drivers will benefit from these parameters.

As far as 2x density still requires 110kWh battery to go 500 miles, my hope is that miles/kWh can further improve, say, to 6-10 miles/kWh, so 500 miles can be done with 50kWh battery, with 2x density, to drop battery weight from 1000lb+ to 200-300lb.

[techwhiz1]

Originally Posted by bavarianride

I guess 95% of current BEV owners(with home charging) do not need these parameters, but I think most drivers will benefit from these parameters.

As far as 2x density still requires 110kWh battery to go 500 miles, my hope is that miles/kWh can further improve, say, to 6-10 miles/kWh, so 500 miles can be done with 50kWh battery, with 2x density, to drop battery weight from 1000lb+ to 200-300lb.

The average mileage per year in the US is less than 15k. No matter how you slice it, less than 5% of people drive more than 200 miles a day and I would venture that 500 miles is a real rare case for all but a few on a regular basis. Mass manufacturers make cars for the masses. That's where it is cost effective. Haven't you heard of the 80/20 rule? You don't need to build a product for everyone 80% is enough and allows you to do so and keep costs under control.

With efficiency of electric motors already above 90%. Where do you think a doubling of efficiency is going to come from? You are going to reduce the car's weight by half?
That still doesn't factor in aerodynamic drag and increases exponentially with speed.

Like I said doubling the efficiency of batteries seems doable in the next 5-10 years. You just aren't going to increase efficiency in electric cars by 100%.

You could dump a huge amount of weight by going to carbon fibre and exotic composites in the structure, but then the cost is beyond what you would want to pay. You didn't factor cost.

Right now you can go buy a Lucid with 500 miles of range and a 120kwh battery. Oh, but it costs $150k-ish.

[bavarianride]

I am thinking to go a week without charging. There are lots of free charge ports at work too, but still once fully return to office, it will be rationed.

The miles/kWh is improving incrementally from 2 to 3 to now 4 miles/kWh, I am not sure how much room to push in that envelope.

BMW does have proprietary CFRP manufacturing capability that they allegedly plan/planned to make mainstream, but that effort seems to falter.

Originally Posted by techwhiz1

The average mileage per year in the US is less than 15k. No matter how you slice it, less than 5% of people drive more than 200 miles a day and I would venture that 500 miles is a real rare case for all but a few on a regular basis. Mass manufacturers make cars for the masses. That's where it is cost effective. Haven't you heard of the 80/20 rule? You don't need to build a product for everyone 80% is enough and allows you to do so and keep costs under control.

With efficiency of electric motors already above 90%. Where do you think a doubling of efficiency is going to come from? You are going to reduce the car's weight by half?
That still doesn't factor in aerodynamic drag and increases exponentially with speed.

Like I said doubling the efficiency of batteries seems doable in the next 5-10 years. You just aren't going to increase efficiency in electric cars by 100%.

You could dump a huge amount of weight by going to carbon fibre and exotic composites in the structure, but then the cost is beyond what you would want to pay. You didn't factor cost.

Right now you can go buy a Lucid with 500 miles of range and a 120kwh battery. Oh, but it costs $150k-ish.

[cruzer666]

Originally Posted by bavarianride

, charge time for 20% to 80% in 5 minutes with regular 240V dryer plug@30A.

This likely won't show up in 5-10 years (or never?), but those are the parameters that will be of value to me.

Battery size that allows for charging from 20% to 80% on a 30A circuit in 5 or so minutes is a 1kWh 🙂

Now this is a pretty impossible requirement, wouldn't you agree ? Essentially what you are saying is you'll never get an BEV without saying you'll never get a BEV, because there won't be any BEV ever made that will satisfy the requirements you mentioned.

[bavarianride]

Originally Posted by cruzer666

Battery size that allows for charging from 20% to 80% on a 30A circuit in 5 or so minutes is a 1kWh ��

Now this is a pretty impossible requirement, wouldn't you agree ? Essentially what you are saying is you'll never get an BEV without saying you'll never get a BEV, because there won't be any BEV ever made that will satisfy the requirements you mentioned.

1kWh is small for 3-4 miles/kWh(which by way is similar to ICE efficiency), how far can that front be pushed?

100x improvement appears insurmountable at this point, but I remain hopeful.

[Park2670]

After driving an EV for five years, I find it fun how many people that do not drive EVs try to solve problems that aren't really a problem.

Until I can charge my 110kWh battery at home in five minutes, its just not good enough for me. Until I can drag a gas generator to charge me, its not good enough for me. Until I can travel 1,000 miles on one charge, its not good enough for me.

I have driven well over 100,000 miles in my EVs, and never been stranded. I am honestly at the point where I cannot figure out why other people are still going to gas stations.

[spool twice]

Originally Posted by Park2670

After driving an EV for five years, I find it fun how many people that do not drive EVs try to solve problems that aren't really a problem.

Until I can charge my 110kWh battery at home in five minutes, its just not good enough for me. Until I can drag a gas generator to charge me, its not good enough for me. Until I can travel 1,000 miles on one charge, its not good enough for me.

I have driven well over 100,000 miles in my EVs, and never been stranded. I am honestly at the point where I cannot figure out why other people are still going to gas stations.

can you imagine charging a 1,000 mile capable battery? how many hours would that take?

Let's say we do get to 5 miles/kWh, that's a 200kWh battery.

Even at let's say a 240V/100A station at home (and thats almost nonexistant), that's still a 10.4 hr charge, or overnight, assuming it can sustain 19.2kW rate of charging without need to trickle down after 80% SoC. On a DC fast charger @ 350kW, that's 1.75 hrs, and that's in a non-existant scenario where it would charge 350kW across 0-100%, which we know isn't even possible.

I do agree, some of these "requirements" are a bit far fetch and even unrealistic in even future state.

[techwhiz1]

Originally Posted by Park2670

I have driven well over 100,000 miles in my EVs, and never been stranded. I am honestly at the point where I cannot figure out why other people are still going to gas stations.

This is exactly my perspective.
We are now on our third EV in my house and my daughter has been the primary driver. She comes home and plugs in and can't figure out why people still go to gas stations.

We started with a Fiat 500e because they were giving them away. My teenager needed a car and at $99 a month on lease, it was cheaper than the bus. The only real outside expense was the charging station install.

She drove almost 36k miles and I did a few of them. Now that car had crappy range. Less than 100 miles on real life. I was able to get to and from work.

We got rid of that and got a Bolt. No range anxiety and it was good enough that in 2020 when that car was going off lease we bought a 2020 Bolt.

We have never been stranded, even in the crappy ranged 500e.

In the next year I will be buying an i4 M50, Fisker Ocean and a used Fiat 500e for the new teenagers driving.

I will install a second charging station and we will be completely electric, except for a Mini project car and the X5 for those really long road trips because it seats 7.

[footie]

I’m right in thinking that the shorter mostly city journeys you make the better the range is with an electric car?