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Which EV's charge the batteries as you brake?

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  • 02-10-2018 4:38pm
    #1
    Registered Users Posts: 11,794 ✭✭✭✭


    which (if any) EV's out there charge the batteries when you brake like the Toyota hybrid cars do ?

    And also, do any EV's have any kind of dynamo/alternator or inverter system to charge the batteries as the car is moving ... even if its putting a trickle charge into the batteries?


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Comments

  • Registered Users Posts: 682 ✭✭✭galvo_clare


    Pretty much all of them have regenerative braking I’d say.
    The idea of trickle charging the batteries as you’re driving wouldn’t work as it would rob the drivetrain of energy, defeating the whole purpose.

    which (if any) EV's out there charge the batteries when you brake like the Toyota hybrid cars do ?

    And also, do any EV's have any kind of dynamo/alternator or inverter system to charge the batteries as the car is moving ... even if its putting a trickle charge into the batteries?


  • Registered Users Posts: 21,964 ✭✭✭✭ELM327


    I don't think there is an EV on the market that doesn't have Regen Braking
    It varies for each EV wrt the amount of Regen available. AFAIR the Zoe has very little regen whereas the leaf40 and Ioniq have variable regen where the user can select how much (or no) regen they want


  • Registered Users Posts: 12,116 ✭✭✭✭KCross


    And also, do any EV's have any kind of dynamo/alternator or inverter system to charge the batteries as the car is moving ... even if its putting a trickle charge into the batteries?

    There are Plugin-Hybrids (aka PHEV) which have a normal petrol engine which charges the battery while driving and it also can power the wheels.... parallel hybrid.

    There is also the likes of the BMW i3 which has, basically, a generator in the car which is not connected to the wheels whose sole function is to charge the battery when it gets low.... series hybrid


  • Registered Users Posts: 3,284 ✭✭✭cros13


    When you hear "self-charging hybrid" from toyota it's a deceptive statement. They present it as if it's a point in favor of the car when it's really a point against.

    If the car doesn't have a plug, all your energy to move the car is ultimately coming from a petrol pump at six to twelve times the cost of electricity from your sockets at home.

    Yes, the hybrid is recovering energy that would otherwise be lost as heat in the brake discs... but you are also carrying 150-250kg more weight everywhere.
    For the capacity of the battery they have in those cars (25 to 200 times lower capacity than a full EV) you're also paying quite a lot of money.
    That tiny battery can't supply enough power to run a powerful electric motor so you lose out on many of the performance advantages of a real EV as well.


  • Registered Users Posts: 21 Baller23


    Really looking forward to the Kona EV and Niro EV getting here too, although I could definitely hold out for a Tucson EV if they ever get around to producing it


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  • Registered Users Posts: 8,295 ✭✭✭n97 mini


    All EVs have re-gen. The traction motor becomes a generator when the wheels are turning the motor (i.e. when decelerating) as opposed to the motor driving the wheels.


  • Registered Users Posts: 6,638 ✭✭✭zilog_jones


    cros13 wrote: »
    Yes, the hybrid is recovering energy that would otherwise be lost as heat in the brake discs... but you are also carrying 150-250kg more weight everywhere.

    Do you know what also weighs a lot? Diesel engines. The 1.6 diesel manual Auris weighs 10 kg more than the 1.8 petrol hybrid. Toyota's hybrid transaxles are also very efficient in terms of mass, just taking the weight of the batteries and assuming that's some extra burden on the car is a bit silly really.

    You're paying extra for the two motor-generators, inverter, and all the other gubbins under the bonnet that a normal ICE car doesn't have. Stuff which rarely breaks, unlike modern diesels, i.e. maintenance costs will be lower.


  • Registered Users Posts: 81,220 ✭✭✭✭biko


    On the Outlander there are 5 regen settings.
    It may seem like too much but I actually use them all.
    I notice that I brake much less now, saving on brake pads too lol

    https://www.youtube.com/watch?v=ASsq-y2t5-s


  • Registered Users Posts: 65,324 ✭✭✭✭unkel
    Chauffe, Marcel, chauffe!


    biko wrote: »
    I notice that I brake much less now, saving on brake pads too lol

    It's a common misconception that only if you use regen, the car doesn't apply the conventional brake system (pads and discs)

    Depends on the EV (PHEV) but a lot of them use a lot of regen for a fair bit of use of the brake pedal itself too. I've never payed that close attention myself, but regular poster here liamog saw -100kW on the energy consumption meter, so extremely high regen, going back into his battery when he had to brake hard :eek:


  • Registered Users Posts: 11,794 ✭✭✭✭Andy From Sligo


    so - does regen kick in automatically .. or do you have to turn the knob manually to the level or regen you need?


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  • Registered Users Posts: 2,299 ✭✭✭PixelTrawler


    biko wrote: »
    On the Outlander there are 5 regen settings.
    It may seem like too much but I actually use them all.
    I notice that I brake much less now, saving on brake pads too lol

    https://www.youtube.com/watch?v=ASsq-y2t5-s

    Kinda wish at the higher settings it activated the brake light. E.g. using B5 coming into a roundabout.


  • Closed Accounts Posts: 2,471 ✭✭✭EdgeCase


    In a Toyota hybrid you basically put the car into D and drive.
    If you brake, the regenerative system does the first part of the braking - slowing down the car and the mechanical brakes do the rest. It's totally seamless and you just press the brake pedal like you would on any car

    There's less wear on brake pads, especially in traffic.

    If anything the braking is smoother than you'd experience on a normal car.

    They also have a "B" mode on the "gear lever" (they don't have gears really). If you select that it engages the regenerative system and it will operate like a drag. It's a similar feeling to changing down gears on a manual car to slow down.

    It's handy if you're going down a hill or if you're just gently slowing down and as you become more familiar with the car you tend to use it more.

    Other than that - you just turn on car, drive car, turn off car and everything happens entirely seemlessly and automatically.

    Hybrids also tend to be very very easy to drive in traffic. There's no "biting points" - stalling is just technically impossible and you have no need to rev. The system is just totally smooth. You can just nudge along at any speed from 0.25km/h to full motorway speed.

    What I've really noticed as a big difference, even compared to traditional automatic cars is the smoothness of the power at low speeds. You can smoothly adjust your position in a tight space with a degree of calm and accuracy that can only be delivered by an electric motor. You've huge torque at low speed which an engine can't really deliver.

    You really don't have any reason to interact with the nuances of the hybrid system that you would interact with the engine management system on a traditional ICE car. It just works.


  • Registered Users Posts: 21,964 ✭✭✭✭ELM327


    so - does regen kick in automatically .. or do you have to turn the knob manually to the level or regen you need?
    In my Ioniq there's a setting you can set from 0 to 3
    If you just set it to 2 constantly there will always be regen. But i use the paddles to set it to 0 when I want to coast (and boy does it coast) and 3 when i want to stop.
    The new leaf has a similar system.


  • Closed Accounts Posts: 2,471 ✭✭✭EdgeCase


    OP : I'd suggest you just test drive one. The controls vary a bit. The likes of the Prius has a lot of unique approaches to doing things whereas the cars like the C-HR use control that look more like a traditional automatic, even through they're using the same drive system as the Prius under the hood.

    Toyota / Lexus, Honda and Hyundai also do things slightly differently so again, just test drive.


  • Registered Users Posts: 1,470 ✭✭✭denismc


    So can someone explain the actual mechanical parts in these systems?
    So you have normal disks and pads but is there a separate set of pads driving a little generator for the regen?
    I am just wondering is there an extra failure point there that can go wrong or do they last the lifetime of the car?


  • Registered Users Posts: 81,220 ✭✭✭✭biko




  • Registered Users Posts: 11,794 ✭✭✭✭Andy From Sligo


    so with this high torque and the regen 'braking' am i right in saying these EV's have got to be better on icy/snowy roads are they? whereas in an ICE car they always do say use the engine as a brake in snow and ice rather than your brake pedal.


  • Registered Users Posts: 65,324 ✭✭✭✭unkel
    Chauffe, Marcel, chauffe!


    My Ioniq was very good in the heavy snow earlier this year. Which in a way surprised me as the car is heavy and has skinnier than average tyres. The throttle control is pretty good though and you would have high torque at very low speeds, which makes it easy to control the traction quite precisely, particularly compared to a manual gearbox ICE car

    That said, don't take my word for it, most of my previous cars have been rear wheel drive, which is not great in snow / ice. Let's see what other EV owners have to say.


  • Registered Users Posts: 11,794 ✭✭✭✭Andy From Sligo


    on another point how do EV cars batteries cope in the cold/icy temperatures. normally with a load of types of batteries ranging from mobile phones to camcorders to even ICE 12v batteries can be very affected by discharging in cold weather , so i am wondering how EV batteries cope? - do they suffer? ... plus of course you have the added drain of having the heater on/ lights on/ heated seat on etc ...


  • Closed Accounts Posts: 2,471 ✭✭✭EdgeCase


    denismc wrote: »
    So can someone explain the actual mechanical parts in these systems?
    So you have normal disks and pads but is there a separate set of pads driving a little generator for the regen?
    I am just wondering is there an extra failure point there that can go wrong or do they last the lifetime of the car?

    They have disc brakes just like any other car.
    Regenerative braking works by basically running the drive motor(s) as a generator. The car’s control system applies an electrical load to the motor/generator. That effectively makes it resist against the turning motion of the wheels as that energy is being used to generate electricity which is fed back into the battery.

    So when you press the brake pedal you’re sending a command to the management system to start generating electricity from the motion of the wheels. This is used in conjunction with normal mechanical brakes which do the final stop and would also do an emergency brake just like any normal car if you put your brake pedal to the floor.

    The engine is also integrated into the hybrid system. It’s just not just bolted onto the side of a normal petrol engine. The system manages ignition and sparking and all of that to tightly coordinate with the electrical drives. One of the motor generator units also starts the engine, replacing a starter motor. The engine is also run at optimal speed for maximum efficiency.

    Toyota’s approach uses a power split device which basically is system of planetary gears that allow the mechanical power from the engine and two motor/generators to be combined seamlessly. It’s a little bit like a differential, but more complex and gives the car continuously variable speed. There are no gear changes.

    It’s actually an extremely elegant piece of mechanic engineering.



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  • Registered Users Posts: 6,638 ✭✭✭zilog_jones


    so - does regen kick in automatically .. or do you have to turn the knob manually to the level or regen you need?

    When you use the brake pedal it will be applying some amount of regen blended with friction braking (traditional brake discs) - the ratio of how much is regen and how much is friction braking depends on various factors like speed, brake pedal pressure and velocity, etc.

    Generally, light use of the brake pedal at moderate speeds will be mostly or entirely regen, very hard/sudden braking will be mostly friction braking (also during an ABS/VSC event, it'll be 100% friction braking), and slowing to a stop (like 10 to 0 km/h) will be 100% friction braking.

    Some hybrids and EVs have further controls for regen, but this is mostly to control how much regen occurs when you're not on the pedals - this is there to replace engine braking in a traditional ICE car. Shifting to "B" mode will also increase regen (combined with ICE engine braking in hybrids).
    so with this high torque and the regen 'braking' am i right in saying these EV's have got to be better on icy/snowy roads are they? whereas in an ICE car they always do say use the engine as a brake in snow and ice rather than your brake pedal.

    I found it very easy to drive my Prius Plug-in in the snow (in EV or hybrid mode) on summer tyres, the "Eco mode" reduces throttle sensitivity and gives finer control of gentle acceleration, using the brake pedal lightly didn't cause any drama, and if I tried to do anything silly the traction control would kick in kill power to the wheels. I was able to climb hills (in Cork city) without hassle if I was going slow enough.


  • Registered Users Posts: 11,794 ✭✭✭✭Andy From Sligo


    so , am i right in saying that the only way the batteries in the car can be topped up with charge is by means of the regen braking and then at all other times the batteries are discharging? and the motor can only be in a mode of either driving the vehicle or charging the vehicle (as in when braking) ?

    So no other topping up of the batteries occur when the car is going forward and driving unless its braking?

    Where is the engine on the EV, normally in the front is it? - if so , why could they not have put some kind of generator/dynamo/alternator on the back axle and through some kind of inverter to boost the charge so that as the car is driving forward it can send some kind charge to the battery even if it works out a trickle charge ?


  • Closed Accounts Posts: 2,471 ✭✭✭EdgeCase


    No. They charge when you’re going down hills and inclines and also when the engine is running at maximum efficiency. For example, it makes more sense for the car to use electrical power at low speeds and capture that power while the engine is working at optimal speeds as ICEs are very inefficient at low revs.

    In general it’s smoothing out the energy consumption and capturing energy that’s normally wasted.

    Full EVs can do the same, just without the engine management requirements.There’s no need for extra motors on the back axel. The whole thing is done from the drive train (the equipment driving the front wheels.)

    The control systems on these vechicles are very sophisticated and it’s small, reliable, robust computing technologies that have made them possible as well as solid state power converters and inverters.


  • Registered Users Posts: 18,984 ✭✭✭✭Del2005


    so , am i right in saying that the only way the batteries in the car can be topped up with charge is by means of the regen braking and then at all other times the batteries are discharging? and the motor can only be in a mode of either driving the vehicle or charging the vehicle (as in when braking) ?

    So no other topping up of the batteries occur when the car is going forward and driving unless its braking?

    Where is the engine on the EV, normally in the front is it? - if so , why could they not have put some kind of generator/dynamo/alternator on the back axle and through some kind of inverter to boost the charge so that as the car is driving forward it can send some kind charge to the battery even if it works out a trickle charge ?

    I've a Lexus hybrid and it'll charge the traction batteries when driving if they are low. If you want to know what it's doing turn the energy display on and it will show where the power is being generated and used, just don't look at it for too long when driving.


  • Registered Users Posts: 1,648 ✭✭✭bp_me


    EdgeCase wrote: »

    They also have a "B" mode on the "gear lever" (they don't have gears really). If you select that it engages the regenerative system and it will operate like a drag. It's a similar feeling to changing down gears on a manual car to slow down.

    You shouldn't use B mode. B mode simulates engine braking by actually providing engine braking and this uses some amount of fuel to first spin up the engine to the rpm necessary.

    Either use cruise control and it will use regen braking to maintain speed (newer cars with "full range" adaptive cruise can use the friction brakes too) or use the brake pedal gently yourself and the initial stages will use only additional regen (up to about 12kW worth).

    Fun fact on models other than the prius having more conventional controls... the CHR has a kickdown button under the throttle :D

    Video posted above is not a bad intro but very out of date. Gen 3 onwards removed the drive chain and added the speed split device which was the limiting factor in the speed at which you could drive in 'golf cart' mode in favour of gearing. Gen 4 went totally mad from there.


  • Registered Users Posts: 6,830 ✭✭✭Alkers


    Does lifting off the accelerator illuminate the brakes in EVs or is the deceleration only similar to coasting in an ICE?


  • Registered Users Posts: 65,324 ✭✭✭✭unkel
    Chauffe, Marcel, chauffe!


    Simona1986 wrote: »
    Does lifting off the accelerator illuminate the brakes in EVs or is the deceleration only similar to coasting in an ICE?

    Good question. It depends on the EV

    i.e. in Ioniq you have 4 settings of regen:

    0 - no regen
    1 - mild regen
    2 - strong regen
    3 - very strong regen

    If you use 2 or 3, as soon as you lift of the accelerator, the brake lights come on


  • Registered Users Posts: 6,638 ✭✭✭zilog_jones


    Where is the engine on the EV, normally in the front is it?

    When talking about cars, "engine" usually specifically means an internal combustion engine (ICE), so there is no "engine" in an EV, only electric motors. Of course, "motor" on its own can be a bit ambiguous, but when talking about hybrids or EVs it usually refers to the electric motors (not the ICE).
    why could they not have put some kind of generator/dynamo/alternator on the back axle and through some kind of inverter to boost the charge so that as the car is driving forward it can send some kind charge to the battery even if it works out a trickle charge ?

    It wouldn't make sense to be putting energy back into the battery that you've just taken out - with extra losses. It would lead to the vehicle being less efficient.

    If you engage a dynamo on your bicycle it creates additional resistance, and you need to work slightly harder. You don't get anything for free.

    A "generator" in an EV would be a petrol engine that is only there to charge the battery, i.e. not connected to the drivetrain. The BMW i3 REx and some others have this.


  • Registered Users Posts: 21,964 ✭✭✭✭ELM327


    When talking about cars, "engine" usually specifically means an internal combustion engine (ICE), so there is no "engine" in an EV, only electric motors. Of course, "motor" on its own can be a bit ambiguous, but when talking about hybrids or EVs it usually refers to the electric motors (not the ICE).



    It wouldn't make sense to be putting energy back into the battery that you've just taken out - with extra losses. It would lead to the vehicle being less efficient.

    If you engage a dynamo on your bicycle it creates additional resistance, and you need to work slightly harder. You don't get anything for free.

    A "generator" in an EV would be a petrol engine that is only there to charge the battery, i.e. not connected to the drivetrain. The BMW i3 REx and some others have this.


    +1


    This idea of using a dynamo on an EV for some sort of perpetual motion comes up a lot when people new to EV ask me about it.
    I generally explain it by comparing how hard you have to cycle with a dynamo up a hill compared to without one. Then you can see the lightbulb illuminate, energy isn't free.


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  • Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 7,943 Mod ✭✭✭✭liamog


    Reminds me of the people who suggested a wind tunnel/turbines to capture passing air.

    https://alcse.org/the-american-wind-powered-car/

    On the one hand, yep captures energy, but the drag is increased so no free power.


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