[///M 4 Life]

has anyone ever thought if its possible to modify an i3 with the range extender to charge the battery while driving it? i been driving my pops i3 for a few weeks now and keep thinking of how its not possible to make this happen using the wheel spin or the wind alone. any thoughts would be appreciated

luigi

[The Wind Breezes]

It won't charge the battery while driving? That's bullshit, come on BMW!

As far as possible, very possible. Next question, are you OK spending a shitload of money and / or do you know a bunch of bored EE friends who are interested in the car?

[///M 4 Life]

Originally Posted by The Wind Breezes

It won't charge the battery while driving? That's bullshit, come on BMW!

As far as possible, very possible. Next question, are you OK spending a shitload of money and / or do you know a bunch of bored EE friends who are interested in the car?

it will hold the battery at a certain point while driving but using gas. i want it to use anything but gas. wheel spin or wind to make the charge happen

[The Wind Breezes]

So in other words you want the car to charge off its own battery power? Good luck!

[Nkc]

Super efficient solar roof and maybe some wind energy sounds like a good idea.

[Joe240]

What you're talking about is what engineers are shooting for, but it's damn near impossible at the moment. The added rolling resistance of putting generators at each wheel would cause the batteries to discharge more energy to drive the car forward, effectively shortening the range as well.

Adding solar panel roof is a good idea, but the added weight of the panel, specially one strong enough to withstand a rollover and protect the occupants, would also cause the batteries to discharge more effectively shortening the range, regardless of how efficient the solar panel (the ones we have at the moment aren't anywhere near efficient enough for this).

Wind power would be great as well, except the window turbines with the generators for them, would add not only a ton more weight (generators that turn the motion into electricity use heavy magnets so weigh a lot), but now the aerodynamics of the car are effected so it's trapping air to turn turbines. This once again means the batteries discharge faster making your range less.

Bottom line is that the renewable energy sources aren't efficient enough at the moment to make a car that self charges to increase its range (not talking about a perpetual motion setup where it would never need to be plugged in again, that's explained here: http://mapawatt.com/2011/11/24/why-p...ines-dont-work).

[Joe240]

Oh and the chevy Volt has probably the best setup (imo) where it always runs off batteries. Sure it has a range of ~50 miles on a full charge, but the gas engine is efficient and runs a generator that charges the batteries when the batteries run out of juice. The engine doesn't connect to the driveshafts at all, only the electric motor does.

I like this setup because if you can use a really efficient motor that can generate an estimated 50+ mpg (bolt is like 42 I believe) and it doesn't pollute that bad (sorry diesels), then it can be better to run it off the gas setup than it is to plug it into the electric grid (assuming normal power plants are powering the grid, not nuclear or renewable sources). It's a good start on more environmentally friendly vehicles.

[Chihuahua]

what you're talking about is perpetual motion. If you solve that problem, be sure to clear space on your mantle for the Nobel Prize you'll receive about 5 seconds after someone confirms your findings.

[RABAUKE]

Here is an interesting story in the National Post coving a bit of a think tank or pie in the sky stuff if you prefer regarding electric vehicles and recharging ideas. I think the out of the box thinking is great, but we are a long way off for most of this stuff, that's just my two cents.

http://driving.ca/auto-news/news/mot...-vehicle-crowd

[remlemasi]

Originally Posted by Joe240

Oh and the chevy Volt has probably the best setup (imo) where it always runs off batteries. Sure it has a range of ~50 miles on a full charge, but the gas engine is efficient and runs a generator that charges the batteries when the batteries run out of juice. The engine doesn't connect to the driveshafts at all, only the electric motor does.

I like this setup because if you can use a really efficient motor that can generate an estimated 50+ mpg (bolt is like 42 I believe) and it doesn't pollute that bad (sorry diesels), then it can be better to run it off the gas setup than it is to plug it into the electric grid (assuming normal power plants are powering the grid, not nuclear or renewable sources). It's a good start on more environmentally friendly vehicles.

Isn't this exactly what the i3 REx does?

[Joe240]

Originally Posted by remlemasi

Isn't this exactly what the i3 REx does?

No idea.

[DRTMGRT]

Originally Posted by ///M 4 Life

has anyone ever thought if its possible to modify an i3 with the range extender to charge the battery while driving it? i been driving my pops i3 for a few weeks now and keep thinking of how its not possible to make this happen using the wheel spin or the wind alone. any thoughts would be appreciated

luigi

I've considered turbine derived energy. There are several aforementioned issues.

The best current solution (no pun intended ) is a generator that runs off of aquafuel.

Edit: like the ones used in formula e

[///M 4 Life]

Originally Posted by Joe240

What you're talking about is what engineers are shooting for, but it's damn near impossible at the moment. The added rolling resistance of putting generators at each wheel would cause the batteries to discharge more energy to drive the car forward, effectively shortening the range as well.

Adding solar panel roof is a good idea, but the added weight of the panel, specially one strong enough to withstand a rollover and protect the occupants, would also cause the batteries to discharge more effectively shortening the range, regardless of how efficient the solar panel (the ones we have at the moment aren't anywhere near efficient enough for this).

Wind power would be great as well, except the window turbines with the generators for them, would add not only a ton more weight (generators that turn the motion into electricity use heavy magnets so weigh a lot), but now the aerodynamics of the car are effected so it's trapping air to turn turbines. This once again means the batteries discharge faster making your range less.

Bottom line is that the renewable energy sources aren't efficient enough at the moment to make a car that self charges to increase its range (not talking about a perpetual motion setup where it would never need to be plugged in again, that's explained here: http://mapawatt.com/2011/11/24/why-p...ines-dont-work).

I'm thinking more in the aspect of using the current generator that holds the charge but instead of using gas, to use like maybe the wind flow from driving and the wheel spin to turn the generator to hold the charge. I'm not a scientist but i don't see how its not possible to get even more mileage maybe not 1:1 but why not if the gas holds it at 1:1??

[Joe240]

Originally Posted by ///M 4 Life

I'm thinking more in the aspect of using the current generator that holds the charge but instead of using gas, to use like maybe the wind flow from driving and the wheel spin to turn the generator to hold the charge. I'm not a scientist but i don't see how its not possible to get even more mileage maybe not 1:1 but why not if the gas holds it at 1:1??

For the exact reasons as mentioned. The batteries in all situations would have to discharge more energy than the generators could produce. You'd end up loosing mileage because of it, not gain mileage or even break even. Even with a break even scenario, it wouldn't be cost affective to put the technology into the car then. It would just make it heavier, cost more, for no positive gain.

[remlemasi]

Originally Posted by ///M 4 Life

I'm thinking more in the aspect of using the current generator that holds the charge but instead of using gas, to use like maybe the wind flow from driving and the wheel spin to turn the generator to hold the charge. I'm not a scientist but i don't see how its not possible to get even more mileage maybe not 1:1 but why not if the gas holds it at 1:1??

Regenerative braking is exactly what you are describing (wheel spin, not wind), which is not even close to 1:1, but very effective nonetheless. This is present in all hybrid and electric vehicles.

Unless I am misunderstanding?

[remlemasi]

Originally Posted by Joe240

No idea.

It is.

[Joe240]

Regenerative braking is indeed a thing and remlemasi is right, it's not 1:1.

[afadeev]

Originally Posted by ///M 4 Life

I'm thinking more in the aspect of using the current generator that holds the charge but instead of using gas, to use like maybe the wind flow from driving and the wheel spin to turn the generator to hold the charge. I'm not a scientist but i don't see how its not possible to get even more mileage maybe not 1:1 but why not if the gas holds it at 1:1??

Wind and wheel rotation are not free.

Wind is air resistance, generated as a by-product of propelling the car forward by converting stored battery energy into kinetic energy.

By the first law of thermodynamics, the total energy of a system is constant.
By the second law, the energy can be transferred from one form to another (battery to kinetic), but always with a loss.

Therefore, you can not recoup more power from car's motion, then it took to accelerate the car in the first place.

Google laws of thermodynamics, and the impossibility of perpetual motion machines, or finish high school, whichever goes faster:
https://en.wikipedia.org/wiki/Perpetual_motion

a

P.S.: In practice, one of the highest energy transfer efficiencies can be achieved with a simple flywheel. Attach a wheel to an electric motor, use current to increase flywheel's angular kinetic energy. To convert the wheel's kinetic energy back into electricity, attach a load to the same electric motor to use it as a generator. If the flywheel and motor are sealed in a vacuum, using magnetic bearings and aligned with the Earth's axis of rotation, you can get round trip efficiency of 85-97%. A typical lithium ion battery charge/discharge efficiency is ~80% (ignoring all other forms of entropy from electric motor heat, friction, etc).

An actual round-trip regenerative braking efficiency is at best ~65%.

https://en.wikipedia.org/wiki/Flywhe...age_efficiency
https://en.wikipedia.org/wiki/Lithium-ion_battery
https://www.tesla.com/blog/magic-tes...rative-braking

P.P.S.: Gas engines are not 1:1 anything. They are an external energy source that converts thermal energy from the heat of propellant combustion into pressure, which is then converted to angular kinetic energy by moving the pistons which turn the crank shaft. Net of all thermal and friction losses, ICE engines have an average efficiency of ~18-20%.

https://en.wikipedia.org/wiki/Intern...rgy_efficiency