3 ms·

I wonder what the efficiency numbers are. The retrofit will add weight to the car, but won't remove any in the form of a lighter engine. There is also no rege

I wonder what the efficiency numbers are. The retrofit will add weight to the car, but won't remove any in the form of a lighter engine. There is also no regenerative breaking, and presumably no way to disengage the engine to run purely on electric power. I also wonder, speculatively, if the power assist will interact degenerately with the existing automatic transmission--perhaps running the car in a less than optimally efficient gear.

tocomment 14y ago
Actually I don't see why they can't put regenerative braking in. The motors double as generators and they already have a connection running to the battery. And the motors are right next to the brakes so they could easily detect when the brakes come on. Anyone know?
- pdonis 14y ago
  To do regenerative braking the motors have to know when you're braking. That means hooking into the car's controls to detect when the brake pedal is pressed. It also means preventing the normal mechanical brakes from engaging while regenerative braking is being done. And it means being able to engage the mechanical brakes if the batteries can't accept incoming energy fast enough. All this is a highly non-trivial controls problem, which requires close integration with the car's control computers. I don't see how that can be done with a retrofit.
  - rcvassallo 14y ago
    You're making the problem harder than it needs to be. Knowing when the car is braking is trivial - the vast majority have a dedicated brake switch wire. Why do you want to prevent the normal brakes from engaging when regen braking is happening? Since the electric motors are on the rear wheels, braking traction will be severely limited. The majority of braking needs to happen up front due to dynamic weight transfer. Instead, use a simple brake balance controllers to reduce the mechanic braking effort at the rear and make up for it with the regenerative braking. Brake balance controllers are readily available in the aftermarket, so this is a solved problem.
    - jack-r-abbit 14y ago
      The way the video describes the controller in the trunk, I believe it is not interfaced directly to the car. I kind of assumed it uses an accelerometer to notice the car is moving forward and engages the DC motors. If this is true, I would imagine that the same accelerometer could notice that the car is braking.
      - rcvassallo 14y ago
        Not sure why the trunk mount is relevant for interfacing with the car. The brake switch signal activates your brake lights, those are typically at the rear of the car :) Admittedly, for a universal application you want to interface with as little of the car as possible. That said, in the US all cars made after 1995 comply with certain On-Board Diagnostics protocols (OBD-II) so you can interface with several standard systems. One such sensor available in OBDII is the VSS or the Vehicle Speed Sensor. Check out a device like the Scan-Gauge[1] to get an idea of other sensor that can be interfaced with universally. It would be trivial to run some wire under the carpet and plug into the OBDII port to give the hybrid system access to all kinds of engine & sensor info. [1] http://www.scangauge.com/products/scangaugeii/ http://www.scangauge.com/products/scangaugeii/
        jack-r-abbit 14y ago
        > Not sure why the trunk mount is relevant for interfacing with the car. I wasn't saying that. Let me rephrase: The way the video describes the controller (the one in the trunk)...
      - ars 14y ago
        > I would imagine that the same accelerometer could notice that the car is braking. It would not be able to tell the difference between braking and simply slowing down, for example going uphill - or worse, driving in water - hitting the brakes when going through standing water can be disastrous. As for the accelerometer detecting moving forward it has some nasty feedback going on there, since it detects its own motion. Plus imagine going downhill and the read engines think you hit the gas so they cause you to go even faster. That said, it should be possible to interface with the engine there are plenty of signals that can be used (throttle, rpm, etc).
tocomment 14y ago
Also I don't see why you can't put the engine in neutral and drive with these motors (I guess you'd need a separate throttle though?)
rocky1138 14y ago
We don't have numbers, so this is all speculation. Still, I think we can agree it's a neat idea that definitely deserves exploration. With regards tot he transmission question: my car (and many others) allow me to select the gear even though it has an automatic transmission. In my car it's called Autostick, other cars it will be something else; sportshift maybe. In this way, I can ensure the gear will be optimal for gasoline consumption. Also, perhaps in the future, a model can be made to incorporate regenerative breaking.
adjwilli 14y ago
Yeah, they say it gets between 50 and 100% better gas milage, but are those "savings" spent at the electrical outlet?
- altcognito 14y ago
  http://www.scientificamerican.com/article.cfm?id=electric-cars-cost-per-charge http://www.scientificamerican.com/article.cfm?id=electric-ca... Depending on the efficiency of the implementation I'm sure (as well whether or not this is a valid study at all), but it seems that electric cars are able to do it significantly cheaper than gas. So those savings are probably not spend at the electrical outlet.
polshaw 14y ago
>perhaps running the car in a less than optimally efficient gear. A properly designed solution would enable the opposite; keeping the car in an optimal gear for longer. A hybrid works best when the batteries run where they have the greatest advantage against the fuel.

tocomment 14y ago

Actually I don't see why they can't put regenerative braking in. The motors double as generators and they already have a connection running to the battery. And the motors are right next to the brakes so they could easily detect when the brakes come on. Anyone know?

pdonis 14y ago
To do regenerative braking the motors have to know when you're braking. That means hooking into the car's controls to detect when the brake pedal is pressed. It also means preventing the normal mechanical brakes from engaging while regenerative braking is being done. And it means being able to engage the mechanical brakes if the batteries can't accept incoming energy fast enough. All this is a highly non-trivial controls problem, which requires close integration with the car's control computers. I don't see how that can be done with a retrofit.
- rcvassallo 14y ago
  You're making the problem harder than it needs to be. Knowing when the car is braking is trivial - the vast majority have a dedicated brake switch wire. Why do you want to prevent the normal brakes from engaging when regen braking is happening? Since the electric motors are on the rear wheels, braking traction will be severely limited. The majority of braking needs to happen up front due to dynamic weight transfer. Instead, use a simple brake balance controllers to reduce the mechanic braking effort at the rear and make up for it with the regenerative braking. Brake balance controllers are readily available in the aftermarket, so this is a solved problem.
  - jack-r-abbit 14y ago
    The way the video describes the controller in the trunk, I believe it is not interfaced directly to the car. I kind of assumed it uses an accelerometer to notice the car is moving forward and engages the DC motors. If this is true, I would imagine that the same accelerometer could notice that the car is braking.
    - rcvassallo 14y ago
      Not sure why the trunk mount is relevant for interfacing with the car. The brake switch signal activates your brake lights, those are typically at the rear of the car :) Admittedly, for a universal application you want to interface with as little of the car as possible. That said, in the US all cars made after 1995 comply with certain On-Board Diagnostics protocols (OBD-II) so you can interface with several standard systems. One such sensor available in OBDII is the VSS or the Vehicle Speed Sensor. Check out a device like the Scan-Gauge[1] to get an idea of other sensor that can be interfaced with universally. It would be trivial to run some wire under the carpet and plug into the OBDII port to give the hybrid system access to all kinds of engine & sensor info. [1] http://www.scangauge.com/products/scangaugeii/ http://www.scangauge.com/products/scangaugeii/
      - jack-r-abbit 14y ago
        > Not sure why the trunk mount is relevant for interfacing with the car. I wasn't saying that. Let me rephrase: The way the video describes the controller (the one in the trunk)...
    - ars 14y ago
      > I would imagine that the same accelerometer could notice that the car is braking. It would not be able to tell the difference between braking and simply slowing down, for example going uphill - or worse, driving in water - hitting the brakes when going through standing water can be disastrous. As for the accelerometer detecting moving forward it has some nasty feedback going on there, since it detects its own motion. Plus imagine going downhill and the read engines think you hit the gas so they cause you to go even faster. That said, it should be possible to interface with the engine there are plenty of signals that can be used (throttle, rpm, etc).

tocomment 14y ago

Also I don't see why you can't put the engine in neutral and drive with these motors (I guess you'd need a separate throttle though?)

rocky1138 14y ago

We don't have numbers, so this is all speculation. Still, I think we can agree it's a neat idea that definitely deserves exploration. With regards tot he transmission question: my car (and many others) allow me to select the gear even though it has an automatic transmission. In my car it's called Autostick, other cars it will be something else; sportshift maybe. In this way, I can ensure the gear will be optimal for gasoline consumption. Also, perhaps in the future, a model can be made to incorporate regenerative breaking.

adjwilli 14y ago

Yeah, they say it gets between 50 and 100% better gas milage, but are those "savings" spent at the electrical outlet?

altcognito 14y ago
http://www.scientificamerican.com/article.cfm?id=electric-cars-cost-per-charge http://www.scientificamerican.com/article.cfm?id=electric-ca... Depending on the efficiency of the implementation I'm sure (as well whether or not this is a valid study at all), but it seems that electric cars are able to do it significantly cheaper than gas. So those savings are probably not spend at the electrical outlet.

polshaw 14y ago

>perhaps running the car in a less than optimally efficient gear. A properly designed solution would enable the opposite; keeping the car in an optimal gear for longer. A hybrid works best when the batteries run where they have the greatest advantage against the fuel.