# Wierd Hybrid? EV + Gas GEO METRO



## DavidDymaxion (Dec 1, 2008)

*Re: Weird Hybrid? EV + Gas GEO METRO*

There was a guy that did this with a Subaru Justy, and another with a Subaru BRAT. An all wheel drive car is easier since you just hook up an electric motor to the rear differential.

Most hybrids work the other way, use electric to accelerate, and use the gas motor for steady cruising.

A potentiometer that could handle EV levels of current would be huge and get extremely hot. What some EVs have done is start out with a huge power resistor just to get rolling, and then switch directly to the batteries.


CinVT said:


> Hi,
> 
> I have this idea and I want to know how crazy or impossible it sounds.
> 
> ...


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## dimitri (May 16, 2008)

You will run into a weight issues, since you want it cheap I assume you will use Lead Acid batts and since you aren't removing anything, just adding more metal parts, you will likely exceed gross weight limit.

If you use LiFePo4 cells and say 7" DC motor, it could probably work, but you also need to figure out gear reduction between the motor shaft and rear differential, or you will be burning amps and heating up the motor too much.

Its a doable project, but needs lots of planning and calculations. Also need to design a control to turn ICE on and off while driving and prevent turning full pack to the DC motor unless its already spinning.


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## CinVT (Oct 29, 2009)

So, it is possible to go from the batteries to the motor in this case that the car will be in motion then?Something else I should consider for this project?


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## CinVT (Oct 29, 2009)

*Re: Weird Hybrid? EV + Gas GEO METRO*

Instead of a gear reduction, can I use a lower RPM motor instead?


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## dimitri (May 16, 2008)

*Re: Weird Hybrid? EV + Gas GEO METRO*



CinVT said:


> Instead of a gear reduction, can I use a lower RPM motor instead?


You should figure out RPM range of the differential input shaft which corresponds to your desired min-max speed where you will use electric assist. Max speed will be your max traveling speed ever, so you will never overspeed DC motor, otherwise it will splatter over the road 

Once you know desired RPM range, you can look for motors, then everything else to match the motor.


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## CinVT (Oct 29, 2009)

*Re: Weird Hybrid? EV + Gas GEO METRO*

Thank you both for the answers.I will figure out the shaft's RPM. As I'm going to have to find a rear axle from another car, I suppose I can get the RPM from the transmission tail for that car and go from there, and for the speed I suppose should consider something in the range of 75/80mph, maximum speed of the Metro with the gas motor.


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## rmay635703 (Oct 23, 2008)

*Re: Weird Hybrid? EV + Gas GEO METRO*



CinVT said:


> the speed I suppose should consider something in the range of 75/80mph, maximum speed of the Metro with the gas motor.


A 7" motor will never get you that fast without burnt smell with a single gear range req. the series electric to go that fast will be tough. Not enough low end on most where you will need it geared like that.

Cheers
Ryan


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## vpoppv (Jul 27, 2009)

It would seem to me that if you are after fuel efficiency, you would be better off using the electric motor for takeoffs and lower speed driving and save the ICE for the higher speeds. I think that's how a Prius does it, and for good reason: electric motors have torque from 0 RPM and ICE works more efficiently at higher RPM's. I know that in my case, in a Geo Metro, I got pretty bad gas mileage going in the 25 MPH range, stop and go, and did GREAT above 50 MPH. With the electric, it loves getting up to 25 MPH, then it isn't so happy anymore.....


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## dimitri (May 16, 2008)

Those are all excellent points, and CinVT, let me clarify everything I said was just to support your theory of ICE first , then electric and keeping it cheap. However, for reasons above I would not recommend doing it this way if you are after fuel efficiency. Unfortunately, if you do it right way, it ain't going to be cheap. Proper DIY hybrids are never cheap or easy, that's why you don't see many of them around.


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## vpoppv (Jul 27, 2009)

I forgot to post that someone did do a hybrid setup. There's some of details at the webite:

http://metroxfi.com/geo-metro-xfi-hybrid-project-page/

and there's a video:

http://www.youtube.com/watch?v=ggtvqmhj3Tc


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## dogstar74 (Dec 6, 2008)

Doesn't a Geo Metro Get about 55 miles per gallon anyway? 2.50/gallon is way cheaper than even a motor!


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## vpoppv (Jul 27, 2009)

dogstar74 said:


> Doesn't a Geo Metro Get about 55 miles per gallon anyway? 2.50/gallon is way cheaper than even a motor!


That is certainly a very valid point. Before I did the conversion, I gave some serious thought about making a sort of semi-hybrid. I still plan on doing it some day. I would remove the alternator and replace it with an electric motor that would be powerful enough to handle turning the water pump constantly and the A/C compressor when needed. Using a deep cycle battery should give you decent range before discharging from the distributor. I figure it should make it good for 10 more MPG.....


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## ForkenSwift (Feb 3, 2008)

dogstar74 said:


> Doesn't a Geo Metro Get about 55 miles per gallon anyway? 2.50/gallon is way cheaper than even a motor!


True!

But EV projects aren't necessarily about saving money. Rick - the owner of that hybrid Metro project car - is an inveterate tinkerer. He pursues efficiency the way many (most?) other gearheads spend money on power & speed. Meaning: without losing sleep over cost/benefit analysis!

FYI, here's the build thread for his hybrid Metro.

Another experiment at hybridizing a small car I've seen used a chain drive to one rear wheel in a Ford Aspire. The project was ultimately abandoned - chain noise being one issue (he could have used a belt).


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## toddshotrods (Feb 10, 2009)

I've been toying with a similar idea for a while now,it was actually the catalyst for my race rod EV project. The problem I have yet to figure out a solution for is weight. I originally wanted to turn my 91 Accord into a performance hybrid. The problem is carrying the weight of two powertrains (ICE front-drive / EV rear-drive), plus enough batteries. Even with lithium I'd be looking at a 4000lb vehicle - minimum.

Of course a Geo is much lighter to start, and by not going for performance you can keep the weight down somewhat, but you still have two setups. The ICE isn't going to be as fuel-efficient dragging the EV-powertrain around, and the EV-powertrain is going to have less range and performance because it is pushing an extra ICE around.


I haven't given up completely yet, but have changed my goals. I am toying with the idea of a much lighter EV rear setup in the FWD Accord, designed to provide clutchless creeping ability in city traffic; as well as a possible mileage boost by helping get the car moving from a stop. The hurdles I haven't given serious thought to yet are a switchable single/dual throttle control with one gas pedal, and computer control for cooperation between the two powertrains. Drive-by-wire would be the ultimate because a computer could tell the appropriate powertrain when and how much work to do, depending on what "mode" the driver selects (e.g. Traffic, Stop-n-Go, Highway). Just thinking out loud, in case my madness can actually help someone someday...


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