Possible mild hybrid conversion using alternator?

[nyoom]

Hello,

I'm not sure if I should post this here or with the hypermiling threads, but I have seen a couple videos where people convert alternators into electric motors. I was thinking, since we already have an alternator, and it already does some regenerative braking, what if somebody attached a motor controller to it and use it as a (very weak) assist motor, converting the alternator into both an alternator and a motor and therefore the car into a mild parallel hybrid? Would a larger alternator be needed for any reasonable result, and/or will a high-voltage system be needed to run the motor? Would the OEM battery be able to hold enough charge to do this, or would a larger battery be required?

Sorry for the many questions, I'm just brainstorming possibilities.

Thanks :)

[mohammad]

there is no gain in trying to use the alternator to propel the car. there is no excess power being generated. in north america the alternator does not do regen braking. there is a thread on here about converting the car to a plug in hybrid with alternator delete.

Having a mild hybrid that propels the car is normally for preformance reasons not fuel savings. The mild hybrid can help start the gas engine faster if you have auto start stop and can make the car feel more preformant.

Plenty of other ways to save gas: Foma has articles on reducing cold engine fuel consumption and isolating the heater core. You can also do aero mods, tire changes, over inflate your tires, add a grill block or engine off coast if its a standard.

[Eggman]

Other companies have done it, why not try it on the Mirage? Seems to me it would surely help, just nobody has done it - not that we know of. All it takes is one enterprising individual (or group) to develop it for the Mirage. And who knows - maybe it could be applied to other gas-burning engines too, like a add-on cruise control.

I mean, why not?

[nyoom]

the alternator is rated for 85A, so 85A×15V = 1,275W = 1.7HP. not great, but maybe it'll be noticable because of how light the car is?

the largest motor controller that I can find that operates on 12V is a 3kW (≈4HP) controller for an e-bike (how do I add links and on mobile?), which is better. this would need at least a 200A alternator, but I'm relatively certain they make those and adapting it to a mirage shouldn't be that hard.

but using a regular automotive battery like this will almost certainly reduce it's lifespan. would a deep cycle battery help? or will it not like the large load? i'm pretty sure a lithium ion battery might work better for this, but they're expensive and I doubt the drop-in replacements will be able to withstand large current draws for long periods of time, and I definitely do not want a premature failure of a $500 battery.

as for controlling the hybrid system, I was thinking that we could hijack the throttle pedal with our own signal generated by a circuit with some logic and stuff. if I'm not mistaken, the throttle pedal is just a potentiometer? if so, it shouldn't really need an actual computer to do it, you could probably just do it with some analog electronics. and we can probably just ignore when the ECU demands charging.

FYI I doubt I'll actually physically do this anytime soon, I'm more or less just brainstorming and creating plans. perhaps when I have more time on my hands and I gather enough money I'll get this done, and possibly sell it as a product?

[Tommyptr]

I always thought a great hybrid idea was to create an all electric car, and then have a tiny 1 cylinder engine connected up to an alternator/generator something or other most efficient in creating electrical power. The engine could run when you are driving down the road to extend the range... run when you are not driving the car (aka self charging and would shut off when either low fuel or fully charged conditions occur)... or you could keep that function off and just charge with wall power (if so desired). It might not exactly have a range of a Prius, but it would eliminate most problems with current electric cars. Heck, the gas motor might just be able to keep the car moving at 30 or so MPH if the battery did go completely flat... to get you to a charging station/home or other safe place off the highway instead of just dumping you where you sit. (*ps, i am fully aware of videos existing where people attempt to charge electric cars with a little generator and the results were not great, taking longs times with only short distances added... I'm talking about a dedicated electrical solution tailor made which would perform considerably better).

[mohammad]

I have looked into the feasibility of this in the past. My idea was to use a cheap ass battery with a long ass warranty that I could get replaced as needed and to wire up my own controller that would keep nominal operating voltage slightly below normal and force maximum voltage when the fuel injectors and or spark plugs stopped operating as I would know that DFCO is occurring.

In reality the economics of this are horrible, when i realized I would make the car less reliable and have to drive over a million km before breaking even I gave up on the idea. Much more gas can be saved cheaply by doing Daox's alternator delete: https://mirageforum.com/forum/showth...for-better-MPG


post 15 here talks about alternator upgrades: https://mirageforum.com/forum/showth...l=1#post144029


In my opinion it would make more sense if you figured out how to bring the auto stop and go and built in regenerative braking from other markets to your car.


If I had a huge youtube following I would consider this but otherwise the economics are bad.

[mohammad]

Tommyptr cars like the BMW i3 offered a range extender. What you are describing is basically just a plug in hybrid with a really small engine. Toyota offers the prius, and RAV 4 as plug in hybrids. I am also almost certain that it is illegal to offer a car in canada that cannot reach a top speed greater than our highway speed limits during normal operation. the BMW i3 could do 105kmph while powered by its gas generator and there is a famous lawsuit about it.

[nyoom]

Making a strictly series hybrid would probably be really expensive, as I would need to convert the car to an EV first, adding on a full-size motor, but then another motor and engine powerful enough to power that motor. There also probably will be inefficiencies in converting the mechanical energy to electrical energy and then back to mechanical, instead of just using the mechanical energy directly in a parallel hybrid.

What I'm looking to do is something similar to Honda's IMA system, where there is only one motor, connected directly to the engine, which acts as both propulsion and charging.

[7milesout]

I like this thread. Lots of out of the box thinking. I can't remember exactly, but my old electric golf cart ran an electric motor and I believe it was something like 2 hp. Could have been anywhere in the 2 to 4 hp zone. But you know, gearing and how it is coupled to the drivetrain makes a difference. Mine wasn't stock (of course), and it would move pretty good.

Even if our alternator could put out 2 hp, I don't think it would be as effective transmitting it to the drivetrain as a golf cart's motor does. But I don't really know any of this, just speculation. I bet the people behind me at a traffic light would appreciate something giving me a boost to get rolling...

[Tommyptr]

I should make a quick mention, that the RPM of the Alternator is not the RPM of the car, in general its about 3x the speed.. im not sure what it spins in a Mirage, but 3x is generally what it does in the average automobile. Wonder if that throws a monkey wrench in any of the figures.... just as an example, if the car is doing 1000rpm, the alternator is churning at 3000rpm.