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Because there appears to be a limit at which the energy can be converted and stored in the battery that is much lower than that needed to slow quickly.
A bad example, but my LEAF30 only has an 80kW motor and a 30kW limit on regeneration to save the battery. Stopping its lardy 1600kg (ignoring any passengers etc) at 70mph at 1G is conveniently close to 500kW ignoring friction - not something that it is remotely close to capable of.
Yes there are less lardy EVs with bigger electrical systems, but even the hypercars will have a similar issue given their higher speed until you reach things like the Lotus Evija with its 1500kW capability and sub 1700kg target weight.
 

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Renault Zoe 50
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Because there appears to be a limit at which the energy can be converted and stored in the battery that is much lower than that needed to slow quickly.
Shunt the excess power to a large resistor then. :)
 

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Because there appears to be a limit at which the energy can be converted and stored in the battery that is much lower than that needed to slow quickly.
A bad example, but my LEAF30 only has an 80kW motor and a 30kW limit on regeneration to save the battery. Stopping its lardy 1600kg (ignoring any passengers etc) at 70mph at 1G is conveniently close to 500kW ignoring friction - not something that it is remotely close to capable of.
Yes there are less lardy EVs with bigger electrical systems, but even the hypercars will have a similar issue given their higher speed until you reach things like the Lotus Evija with its 1500kW capability and sub 1700kg target weight.
There is also the reliability aspects. Failure rate for an electric retardation system will be lower than a split hydraulic system ( we hope).
 

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Failure rate for hydraulics lower than electrics ....
You have evidence to back that up?

Aircraft have moved to electro-mechinical systems now, mainly because of the ability to build in redundancy, reduce weight and lower the MTBF.
 

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Shunt the excess power to a large resistor then. :)
Isn't that what they do using a technology called brake pads? :devilish:
I'm not sure that a resistor would be any lighter or lower maintenance once a cooling system was introduced.
 

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You have evidence to back that up?

Aircraft have moved to electro-mechinical systems now, mainly because of the ability to build in redundancy, reduce weight and lower the MTBF.
Haha, any ideas at all about how aircraft are maintained?
 

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Isn't that what they do using a technology called brake pads? :devilish:
I'm not sure that a resistor would be any lighter or lower maintenance once a cooling system was introduced.
The difference is the resister wouldn’t wear out like a brake pad. You also reduce the parts count and weight.

Cooling of the resister would just be a fan, or ducted air.
 

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2017 Golf GTE
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You have evidence to back that up?

Aircraft have moved to electro-mechinical systems now, mainly because of the ability to build in redundancy, reduce weight and lower the MTBF.
Surely you mean that aircraft have moved to electro mechanical systems to apply the brakes instead of hydraulic ones.

The actual brakes are still friction disc brakes not regenerative brakes. No monster resistors etc
 

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The difference is the resister wouldn’t wear out like a brake pad. You also reduce the parts count and weight.

Cooling of the resister would just be a fan, or ducted air.
Just have tungsten resistance wire brake lights - the harder you brake, the brighter they glow....
 

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At motorway speeds my ZS peaks 410V/130A regen, so around 53kW.

The main benefit discs have over drums is the ability to dump heat acquired by repeat braking. I suspect on most non-high performance EVs even front drums would be adequate (or at least non-vented discs reducing cost and unsprung weight).
 

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(or at least non-vented discs reducing cost and unsprung weight).
ps. The last car I owned with solid front discs was a 1987 Fiesta Pop Plus around 1995 - a spirited drive from Crieff to Aberfeldy had the brakes nearly failing from overheating at Aberfeldy after a substantial drop in altitude.

Not fun!
 

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The reason you still have to have friction brakes is that the regen is proportional to the car's speed. If you stamp on the brakes at 30 because a kid runs out in front of you, you still need to stop. Regen won't do that for you.
 

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The reason you still have to have friction brakes is that the regen is proportional to the car's speed. If you stamp on the brakes at 30 because a kid runs out in front of you, you still need to stop. Regen won't do that for you.
But I can stop the car if I put the motor in reverse. :unsure:
 

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The reason you still have to have friction brakes is that the regen is proportional to the car's speed. If you stamp on the brakes at 30 because a kid runs out in front of you, you still need to stop. Regen won't do that for you.
technically it is possible to make the electric motors stop the car faster and to a complete halt. There are machines out there which spin fast and have electric braking by doing funky stuff with the motor, BUT the concept isnt about regen its about stopping. HOWEVER, I dont think it would pass the current legislations.
 

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ps. The last car I owned with solid front discs was a 1987 Fiesta Pop Plus around 1995 - a spirited drive from Crieff to Aberfeldy had the brakes nearly failing from overheating at Aberfeldy after a substantial drop in altitude.

Not fun!
Yeah, I remember brake fade being quite easy to achieve in cars from the ‘90s.
 
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