Charging Electric Cars

Big Nasty

Here's a question with all this buzz about electric cars. At the moment the range is pretty low so they wouldn't be practical for a drive from Dublin to Galway for example unless you were prepared to stop at least once for a charge up. Would it not be possible to fit some sort of advanced dynamo system in order to partially charge the batteries while the vehicle is in motion, therefore giving in better economy and longer range?

biko

Some EVs has a dynamo that kicks in when you brake. The rotation of the braking wheel is used to recharge the battery again, or something to that effect.

Mr Benevolent

MCMLXXV wrote: »

Here's a question with all this buzz about electric cars. At the moment the range is pretty low so they wouldn't be practical for a drive from Dublin to Galway for example unless you were prepared to stop at least once for a charge up. Would it not be possible to fit some sort of advanced dynamo system in order to partially charge the batteries while the vehicle is in motion, therefore giving in better economy and longer range?

That's getting something for nothing and is not allowed under the laws of thermodynamics! As biko mentioned, there is a brake regenerate function, but I'd guess it adds 5% max to the range.

Eric Cartman

the extra friction created by the dynamo would make the motor consume as much if not more power than the dynamo was putting out, it works while braking because the motor is not doing any work,

mawk

you could leave a suitcase generator in the boot. make it a hybrid?

rebel.ranter

You could fit pedals for the passengers to use to charge the car as you drive!

Big Nasty

Well they have to (and will) manage to coax more life out of the batteries as time goes on, much like the brick mobile phones in their day. How many people are going to buy a car with only 100 miles range? not too many i would imagine.

Eric Cartman

MCMLXXV wrote: »

Well they have to (and will) manage to coax more life out of the batteries as time goes on, much like the brick mobile phones in their day. How many people are going to buy a car with only 100 miles range? not too many i would imagine.

100 mile range would serve most city dwellers for a day without needing to be recharged, they are working to extend it but in reality they need to make electric cars bigger and not look like something out of a childrens sci-fi book before theyll catch mainstream appeal

Big Nasty

Eric Cartman wrote: »

100 mile range would serve most city dwellers for a day without needing to be recharged, they are working to extend it but in reality they need to make electric cars bigger and not look like something out of a childrens sci-fi book before theyll catch mainstream appeal

I know it's technically enough for most city dwellers but not everyone lives 'in town'. Even if you did, most people would have the odd country drive so 100m is hardly adequate. I don't see how EV's can take off (he, he) until their range is at least 250m.

Seweryn

biko wrote: »

Some EVs has a dynamo that kicks in when you brake. The rotation of the braking wheel is used to recharge the battery again, or something to that effect.

It is not a dynamo. It is the electric motor that drives the car. The same motor that sends the power to wheels during braking works as a generator (like any electric motor) and produces energy.

Hellrazer

I had an idea a while back about putting a small wind turbine on one to see if it would charge as it was driving.

Never got around to testing it out though since I turned down the franchise opportunity.

Prototype I had designed was a house hold turbine mounted on the roof or sticking out of the boot but I was hoping to refine it so that the turbine was behind the grille and out of sight ie the wind produced by driving would turn a motor to charge the existing battery or a second one that could be changed over once one ran out and then swop it back and forward.

Surely someone could try extend their battery life in a quirky way like this.

Even the old school dynamos that were on your old school bicycles could be used to trickle charge the battery albeit very slowly.You`d probably need something a bit more heavy duty though.

Mr Benevolent

Hellrazer wrote: »

I had an idea a while back about putting a small wind turbine on one to see if it would charge as it was driving.

Never got around to testing it out though since I turned down the franchise opportunity.

Prototype I had designed was a house hold turbine mounted on the roof or sticking out of the boot but I was hoping to refine it so that the turbine was behind the grille and out of sight ie the wind produced by driving would turn a motor to charge the existing battery or a second one that could be changed over once one ran out and then swop it back and forward.

Surely someone could try extend their battery life in a quirky way like this.

Even the old school dynamos that were on your old school bicycles could be used to trickle charge the battery albeit very slowly.You`d probably need something a bit more heavy duty though.

It's a good idea and does warrant some practical examination, especially in Ireland! The one issue is drag from the the spinning blades - the drag is almost as high as an equivalent sized plate held perpendicular to the wind stream. This will increase frontal area significantly, and I'd guess that the drag increase would more than cancel out the power gains.

Another practical idea would be to use solar cells, especially now that the power conversion ratios are creeping above 50%. I'd go with solar cells over wind turbines anyday tbh.

Hellrazer

Confab wrote: »

It's a good idea and does warrant some practical examination, especially in Ireland! The one issue is drag from the the spinning blades - the drag is almost as high as an equivalent sized plate held perpendicular to the wind stream. This will increase frontal area significantly, and I'd guess that the drag increase would more than cancel out the power gains.

Another practical idea would be to use solar cells, especially now that the power conversion ratios are creeping above 50%. I'd go with solar cells over wind turbines anyday tbh.

That was my other idea--Cover the roof and bonnet with solar panels.If I could get one of these things cheap I`d experiment on it.

As for the drag--If the turbine was behind the grille and using the air thats already being channeled in there it wouldnt have as much drag.The roof mounted one was just to see if the concept would work.

You could also do it in such a way that the roof mounted one folded down and you only used it to charge when the car was parked.

freighter

MCMLXXV wrote: »

Well they have to (and will) manage to coax more life out of the batteries as time goes on, much like the brick mobile phones in their day. How many people are going to buy a car with only 100 miles range? not too many i would imagine.

As you say about phones look how advanced they are now compared to the old maxon:D of the day. Look at what another 5-10 years will do. Modern technology will take its course..:)

Big Nasty

freighter wrote: »

As you say about phones look how advanced they are now compared to the old maxon:D of the day. Look at what another 5-10 years will do. Modern technology will take its course..:)

Agreed! Anyhow, I love petrol (sniff) and I consider diesel to be the fuel of the devil so I'll be staying petrol until I am completely forced to do otherwise.

Unfortunately I reckon I probably will see this within my lifetime. :mad:

Absurdum

Hellrazer wrote: »

That was my other idea--Cover the roof and bonnet with solar panels.If I could get one of these things cheap I`d experiment on it.

the newest Prius has that available as an option, I think it runs the aircon to keep the car cool when it's parked...which is a total waste :pac:

frex

The main challenge with electric car design at the moment is that people expect similar performance to current vehicles, but the power density available in battery form is still way off that of petrol and diesel engines. Regeneration and solar inputs will assist slightly, but cant match the demands of propelling a 1000kg vehicle as well as running air con, lights, etc. In fact, the energy required to lug the batteries themselves is considerable, as they weigh much more than an engine in many cases.

Emissions laws are placing very aggressive demands on the motor industry, to the point that many vehicles, such as the Prius, are actually less efficient that some of the efficient diesels. Its a shame actually, as currently, diesel technology is by far the most efficient on the road in terms of energy density vs emissions.

Still - the mobiles we have today were huge bricks only 15 years ago so the more ideas that are put forward, the more rapidly the technology will advance.

FergusF

frex wrote: »

the more ideas that are put forward, the more rapidly the technology will advance.

One interesting idea is the Opel Ampera (http://www.opel.ie/vehicles/future-models/ampera/highlights/technology.html), it uses an electric motor to provide the drive, and the batteries are charged by a petrol engine. They claim 370NM torque, 160km/h top speed, range of 500KM and fuel consumption of 1.6l / 100km.

No idea of their plans for production, or the proposed price. I believe a prototype was driven over 400km from Opel's German HQ to the Geneva Motor show last year by one of the company bosses, so it seems proven to work.

As you mention, I think the technology will be advancing quickly in the next few years.

I would consider buying something similar if prices start to approach those of internal combustion systems, and battery life concerns were addressed...

reboot

Seweryn wrote: »

It is not a dynamo. It is the electric motor that drives the car. The same motor that sends the power to wheels during braking works as a generator (like any electric motor) and produces energy.

Akaik with my Zoe its not braking,(Maybe engine braking?) ie not putting your foot on the brake,but simply going slightly down hill.I can leave the mountains and arrive in the town of Newcastle,say 6 mile away,sometimes driving at 50mph and the dash is telling me I am charging! upon arrival I find I have 4 mile more than I started out with.
Its a different way of driving,much more relaxed,quieter of course,slower and very relaxing. With cruise control, most of the driving ,even in the country roads is done with the two thumbs. I remember those cars that made a big noise and had smoke coming out the back.

reboot

reboot wrote: »

Akaik with my Zoe its not braking,(Maybe engine braking?) ie not putting your foot on the brake,but simply going slightly down hill.I can leave the mountains and arrive in the town of Newcastle,say 6 mile away,sometimes driving at 50mph and the dash is telling me I am charging! upon arrival I find I have 4 mile more than I started out with.
Its a different way of driving,much more relaxed,quieter of course,slower and very relaxing. With cruise control, most of the driving ,even in the country roads is done with the two thumbs. I remember those cars that made a big noise and had smoke coming out the back.

Regen is fine when you're going down hill or want to slow down but it's a waste of energy when regen comes on every time you life off the throttle because you can never get back what you take out.

I drove Zoe on Friday and the regen annoyed me, I could probably adjust to it but I found it slowed down too much to the point I needed to use more energy to build up speed again.

Costing when you lift off would be far more efficient and relaxing.

I would love to hack into the motor controller and disable regen on the throttle and only have it when you press the brake.

But most likely I would learn to lift off the accelerator later than I normally would.

reboot

Deleted User wrote: »

Regen is fine when you're going down hill or want to slow down but it's a waste of energy when regen comes on every time you life off the throttle because you can never get back what you take out.

I drove Zoe on Friday and the regen annoyed me, I could probably adjust to it but I found it slowed down too much to the point I needed to use more energy to build up speed again.

Costing when you lift off would be far more efficient and relaxing.

I would love to hack into the motor controller and disable regen on the throttle and only have it when you press the brake.

But most likely I would learn to lift off the accelerator later than I normally would.

I have grown to love the regen, and don't need anything replaced re the brakes after a year service.I have always been light on the brakes and used engine braking as far as comfortable.
I find the only menu I look at is "Direct consumption" ie KW in and out.This is on the right,wiper stalk.
Folk need to go easy with comments after a test drive compared to a years driving in all sorts of Winter/Summer and Mountain areas.People may be put off a very serious decision they have to make,
ie Leaf / Zoe./BMW I3,or I8 even. Personally I fear for the entire EV project,with cars that are way too expensive for someone to consider changing to EV.
I can only answer the odd question if asked ,based on my own experience with one EV.

reboot

reboot wrote: »

I have grown to love the regen, and don't need anything replaced re the brakes after a year service.I have always been light on the brakes and used engine braking as far as comfortable.
I find the only menu I look at is "Direct consumption" ie KW in and out.This is on the right,wiper stalk.
Folk need to go easy with comments after a test drive compared to a years driving in all sorts of Winter/Summer and Mountain areas.People may be put off a very serious decision they have to make,
ie Leaf / Zoe./BMW I3,or I8 even. Personally I fear for the entire EV project,with cars that are way too expensive for someone to consider changing to EV.
I can only answer the odd question if asked ,based on my own experience with one EV.

Regen is fine, but not when you lift off the throttle, I could probably get used to it and adjust but the fact is it's more efficient to coast than use regen to slow you down where you could otherwise keep rolling without using power or wasting power through regen.

reboot

Deleted User wrote: »

Regen is fine, but not when you lift off the throttle, I could probably get used to it and adjust but the fact is it's more efficient to coast than use regen to slow you down where you could otherwise keep rolling without using power or wasting power through regen.

If you want to slow down,not only are you not wasting energy,you are making it?Its a whole new way of driving ,I get into Newcastle with 5 miles more on the clock than when I left home.Driving at fifty mph,I am charging, watching the Kw clock as I go.

reboot

reboot wrote: »

If you want to slow down,not only are you not wasting energy,you are making it?Its a whole new way of driving ,I get into Newcastle with 5 miles more on the clock than when I left home.Driving at fifty mph,I am charging, watching the Kw clock as I go.

Yes you are making energy when you "want" to slow down. So energy goes back to the battery than wasted through friction.

However because regen isn't 100% efficient you can't replace what's taken out.

So when your driving along and you are driving down a descent and you don't need to use the brakes or regen and you could Coast you'll actually save more energy than using regen when you don't need to.

When your coasting you're not using energy, there is no point in regen coming on when it doesn't need to, when you put your foot on the brake or are going down a steep hill this is ok because at that point you'd be using the brakes anyway.

reboot

Deleted User wrote: »

Yes you are making energy when you "want" to slow down. So energy goes back to the battery than wasted through friction.

However because regen isn't 100% efficient you can't replace what's taken out.

So when your driving along and you are driving down a descent and you don't need to use the brakes or regen and you could Coast you'll actually save more energy than using regen when you don't need to.

When your coasting you're not using energy, there is no point in regen coming on when it doesn't need to, when you put your foot on the brake or are going down a steep hill this is ok because at that point you'd be using the brakes anyway.

I just stick it in Cruise, and forget about it.

reboot

Mr Benevolent wrote: »

It's a good idea and does warrant some practical examination, especially in Ireland! The one issue is drag from the the spinning blades - the drag is almost as high as an equivalent sized plate held perpendicular to the wind stream. This will increase frontal area significantly, and I'd guess that the drag increase would more than cancel out the power gains.

Another practical idea would be to use solar cells, especially now that the power conversion ratios are creeping above 50%. I'd go with solar cells over wind turbines anyday tbh.

The Leaf comes with a Solar PV, 5 watts, useless fashion item?

reboot

reboot wrote: »

I just stick it in Cruise, and forget about it.

Cruise is not efficient, a steady throttle position is much more efficient but then you'll loose speed.

reboot

reboot wrote: »

The Leaf comes with a Solar PV, 5 watts, useless fashion item?

Yes useless, it's only use is for keeping the 12v lead acid topped up. Not worth an extra few hundred.

If indeed it is only 5 watts, you can buy one these days for less than 50 Euro's.

Most solar panels today are about 1 Euro per watt when bought in about 5 Kwp quantities.

reboot

Big Nasty wrote: »

Here's a question with all this buzz about electric cars. At the moment the range is pretty low so they wouldn't be practical for a drive from Dublin to Galway for example unless you were prepared to stop at least once for a charge up. Would it not be possible to fit some sort of advanced dynamo system in order to partially charge the batteries while the vehicle is in motion, therefore giving in better economy and longer range?

Zoe motor is also a generator, also check regenerative braking. I regularly drive along at 50 mph and the battery is charging. Good point .

reboot

Mr Benevolent wrote: »

That's getting something for nothing and is not allowed under the laws of thermodynamics! As biko mentioned, there is a brake regenerate function, but I'd guess it adds 5% max to the range.

There is also going slightly downhill without the brakes on, not to get into heat pumps.

reboot

Hellrazer wrote: »

That was my other idea--Cover the roof and bonnet with solar panels.If I could get one of these things cheap I`d experiment on it.

As for the drag--If the turbine was behind the grille and using the air thats already being channeled in there it wouldnt have as much drag.The roof mounted one was just to see if the concept would work.

You could also do it in such a way that the roof mounted one folded down and you only used it to charge when the car was parked.

Typical EV battery is 24 kwhrs, back of an envelope, solar, forget it.

reboot

Seweryn wrote: »

It is not a dynamo. It is the electric motor that drives the car. The same motor that sends the power to wheels during braking works as a generator (like any electric motor) and produces energy.

Charging while going downhill doesn't involve braking?

reboot

Big Nasty wrote: »

Agreed! Anyhow, I love petrol (sniff) and I consider diesel to be the fuel of the devil so I'll be staying petrol until I am completely forced to do otherwise.

Unfortunately I reckon I probably will see this within my lifetime. :mad:

I agree about you.

Bruthal

Eric Cartman wrote: »

the extra friction created by the dynamo would make the motor consume as much if not more power than the dynamo was putting out, it works while braking because the motor is not doing any work,

Its not really friction from the dynamo as such, its an electromagnetic drag or braking effect.

As a dynamo generates electric current, this generates a magnetic field. This field opposes the rotation of the dynamo. In simple terms, the higher the current generated, the harder the dynamo is to turn. To charge a battery takes a little more kilowatt hours input than what the battery can then output, so charging with a dynamo will consume more energy than it generates, during normal driving.

reboot

Bruthal wrote: »

Its not really friction from the dynamo as such, its an electromagnetic drag or braking effect.

As a dynamo generates electric current, this generates a magnetic field. This field opposes the rotation of the dynamo. In simple terms, the higher the current generated, the harder the dynamo is to turn. To charge a battery takes a little more kilowatt hours input than what the battery can then output, so charging with a dynamo will consume more energy than it generates, during normal driving.

I agree regarding the Back EMF, but I don't see any charging during "Normal driving", but when taking my foot off going down a slight hill. Surely if I end up with say 4 more miles more than when I set off, which regularly occurs at my location, the dynamo must have charged the battery over the distance?

There is no charging during normal driving, only when you back off the throttle and the regen kicks in.

Regen isn't as efficient as coasting when you lift off the throttle because of inefficiencies, so in other words it's more efficient to have 0 regen unless you actually "want/need" to slow down, the idea is you roll using energy used for as long as you can.

reboot

Deleted User wrote: »

There is no charging during normal driving, only when you back off the throttle and the regen kicks in.

Regen isn't as efficient as coasting when you lift off the throttle because of inefficiencies, so in other words it's more efficient to have 0 regen unless you actually "want/need" to slow down, the idea is you roll using energy used for as long as you can.

I see regen with my foot on the throttle on a daily basis?

reboot

reboot wrote: »

I see regen with my foot on the throttle on a daily basis?

You have to lift off the throttle for regen to engage.

Thank god at least the leaf has the option of much stronger regen in Eco and not strong in normal, the zoe regen is far too strong when you lift off the throttle, at least give people an option for low med or high regen or no regen at all or only regen when you press the brake.

Again my point is that coasting is more efficient than regen because during regen there are losses in the conversion of kinetic energy back to electrical.

Coasting uses no extra energy. Regen is ideal where you want / need to brake not when a computer decides you want to brake.

reboot

Deleted User wrote: »

You have to lift off the throttle for regen to engage.

Thank god at least the leaf has the option of much stronger regen in Eco and not strong in normal, the zoe regen is far too strong when you lift off the throttle, at least give people an option for low med or high regen or no regen at all or only regen when you press the brake.

Again my point is that coasting is more efficient than regen because during regen there are losses in the conversion of kinetic energy back to electrical.

Coasting uses no extra energy. Regen is ideal where you want / need to brake not when a computer decides you want to brake.

When you say "Lift off the throttle' do you mean simply reduce, I find regen still occurs when I simply reduce, not completely lift off.

reboot

reboot wrote: »

When you say "Lift off the throttle' do you mean simply reduce, I find regen still occurs when I simply reduce, not completely lift off.

Maybe it does on the Zoe, that's even worse, this means that you're always either using power or using regen which also has losses.

The regen I found on Zoe horribly strong and annoying, I really do not like that forced hard slow down when you lift off the throttle. I want the car to brake when I want it to not when the computer or renault tell me the car should.

I think they should have had different regen strengths or variable regen like the E-Golf via flappy paddles on the steering.

With the leaf, regen is much stronger in eco but you can get netural or very close to it via a certain throttle position much the same as the prius but in the prius it only works up to 71 Kph.

In the leaf one pedal driving is a lot more comfortable when you can keep the car going via momentum in neutral then lift off the throttle altogether and you got good braking.

I did not have enough time in the Zoe to find out if there is a certain throttle position that gives you neutral.

Dexter1979

There is a neutral throttle position and it's a very light rolling car when you coast. You can change the dashboard display to an arch with different sections. The small section between Blue (regen) and Green (eco power use) is neutral. Combine this with changing the right information side to Direct Consumption and you will see it stay at 0kW while coasting. I have seen regen as high as 20kW when lifting off the accelerator and just let the car decide.

That's something at least that you can get neutral with a certain throttle position on the zoe.

reboot

Deleted User wrote: »

Maybe it does on the Zoe, that's even worse, this means that you're always either using power or using regen which also has losses.

The regen I found on Zoe horribly strong and annoying, I really do not like that forced hard slow down when you lift off the throttle. I want the car to brake when I want it to not when the computer or renault tell me the car should.

I think they should have had different regen strengths or variable regen like the E-Golf via flappy paddles on the steering.

With the leaf, regen is much stronger in eco but you can get netural or very close to it via a certain throttle position much the same as the prius but in the prius it only works up to 71 Kph.

In the leaf one pedal driving is a lot more comfortable when you can keep the car going via momentum in neutral then lift off the throttle altogether and you got good braking.

I did not have enough time in the Zoe to find out if there is a certain throttle position that gives you neutral.

Are you seriously suggesting
driving an automatic at speed in Neutral?

reboot

reboot wrote: »

Are you seriously suggesting
driving an automatic at speed in Neutral?

It isn't an automatic, there's no gearbox in an ev.

There is a single fixed reducer gear to reduce the high rpm of the motor.

But I wasn't referring putting the car into neutral but more finding the neutral position from the accelerator while the car is still in drive/eco.

Dexter1979

reboot wrote: »

Are you seriously suggesting
driving an automatic at speed in Neutral?

If you position your foot to get 0 kW direct consumption you are effectively driving in a controlled version of Neutral. And I do this regularly. Let gravity accelerate the car instead of my battery

reboot

Deleted User wrote: »

It isn't an automatic, there's no gearbox in an ev.

There is a single fixed reducer gear to reduce the high rpm of the motor.

But I wasn't referring putting the car into neutral but more finding the neutral position from the accelerator while the car is still in drive/eco.

You are both right of course , and I agree,just wasn't very clear.My fault for not reading it closely enough, you did say throttle.