woo hoo - first ev ride

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nazar
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woo hoo - first ev ride

Post by nazar »

gudday guys, just wanted to say that i had my first EV ride today..

i must say that i was very impressed (but then again, i knew i would be)..

was a little surprised that the "get up and go" was really good (AC motor).
i liked the quietness of the motor as well (although it had a slight knocking when starting from stop - the reason i was told, that it was an old motor)

i noticed the RPM counter did not work from the original body of the car, is there a way of using this, or even having a rev counter?? or would it be useful for a EV

i also noticed a little oil or grease on the engine supports for the motor - i am assuming it did not come out of the AC motor, but i was very confused as to why it was there

it was a front wheel drive, and looking at it (because it seemed so much easier) i wondered if it was an easier conversion for a FWD, also, i am thinking the weight would be a lot less..
do people recommend doing a FWD rather than a rear??
there is an awful lot to learn about EV's :)
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coulomb
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woo hoo - first ev ride

Post by coulomb »

nazar wrote: i noticed the RPM counter did not work from the original body of the car, is there a way of using this, or even having a rev counter??
Yes, especially with an AC conversion. The AC controller has to know (or at least estimate pretty well) the speed of the motor, so it's usually not hard for it to connect to a tachometer of some sort. For example with our MX-5, we get the speed of the motor in CAN packets, and will drive the original tacho via the Tritium Driver Controls computer. It has outputs designed to drive traditional pulse-based (e.g. tacho) and current-based (e.g. fuel gauge) instruments.
or would it be useful for a EV
It is useful, but even more useful is an amp gauge. So in some conversions, the tacho is used for current instead of motor speed, or sometimes you can switch between the two.

For a DC conversion where the top current is around 500 A and the tacho goes to around 6000 RPM, this is a good fit. For the MX-5, the tacho goes to 8000 RPM, and battery current goes to about 300 A max, so it's not such a great fit. But we'll probably end up using the bottom third of the tacho for battery or motor current.
it was a front wheel drive, and looking at it (because it seemed so much easier) i wondered if it was an easier conversion for a FWD, also, i am thinking the weight would be a lot less..
You can get light and heavy host vehicles in FWD and RWD. It does get a bit harder to find light RWD hosts, however.
do people recommend doing a FWD rather than a rear??

The reality is that there are overwhelmingly more FWD conversion candidates than RWD. So if you choose RWD, you are restricted in the choice of vehicle to convert.

If you want direct drive (no transmission but retain the differential), then you're almost forced to use RWD, since the differential and transmission are so intimately linked in a typical FWD. But most conversions retain the gearbox, so that's often not an issue.

Overall, there isn't really an agreed recommendation for FWD verses RWD; it depends so much on what you want to convert.

For beginners, I would stay away from 4WD or AWD, because the extra transmission losses eat up power, and hence either acceleration, range, or battery space and cost.
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BigMouse
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woo hoo - first ev ride

Post by BigMouse »

I'm doing a RWD conversion for simplicity, and because I wanted the option to do direct drive (though I've since decided to retain the gearbox). The major problem with FWD (in my opinion) is the question of clearance between the motor and the "long" driveshaft. You're limited on the diameter motor you can use, and often limited on the length as well due to the position of the frame rails. This makes it very difficult to choose a donor/motor combination since it's often hard to know whether there will be clearance without taking measurements on the car itself from underneath. Even then, these measurements (centre of crankshaft to axle) are hard to take as there is an oil-pan in the way and the axle is usually at an angle. RWD cars don't have many, if any, obstructions in the engine bay, and they are usually long enough to fit any standard length motor. So if you can find a RWD candidate, chances are you won't have trouble getting whatever motor you end up choosing to fit. It's also simpler to support the motor from the original engine mount points in a RWD.

I am biased towards RWD for those reasons, but I've been tempted by a few FWD cars recently.

FWD is a bit more efficient due to having parallel shafts (RWD has to convert the motion through 90 degrees in the rear diff). As coulomb said, FWD cars are more plentiful as well, and it's easier to find a light-weight one.

Some FWD cars have longitudinally mounted engines, which have all the ease of motor mounting of a RWD car, but without the efficiency benefit of a transverse FWD.

Rear engine, RWD can have either longitudinal (Porsche, supercars) or transverse (MR2) engine mounting.

A quick (probably incomplete) list of common RWD (or FWD with longitudinal engine) cars:
Any BMW (3 series are lightest of course. I'm looking for an e36 3 series Compact at the moment)
Mazda MX-5, RX-7
Nissan 300zx, 280sx, Skyline, Silvia, etc
Toyota Supra, old Celicas and Corollas. MR2 would be treated as a FWD due to the transverse engine layout.
Mitsubishi GTO
Mercedes Benz (Most except the compact ones. 190's are surprisingly light and RWD)
Porsche (these are interesting. The front engine ones usually have a rear-mounted transaxle, which means you just couple the motor to the torque tube and retain the existing clutch/flywheel. Rear engine ones are longitudinal, which is also easy)
Audi 80, 90, A4, some VW Passat (these are either FWD or AWD, but have longitudinally mounted engines)
Subarus can be converted to RWD, but the ability to get it engineered and registered is a question. From my reading, it seems like it would have to be engineered as an ICV (individually constructed vehicle), which has cost and insurance implications.
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Any ute
Falcons and Commodores

I won't list FWD cars, there's not enough room on this thread ;-)
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woo hoo - first ev ride

Post by Johny »

Good examination of RWD vs FWD Bigmouse.
It would be good repeated in a thread RWD vs FWD Considerations. There may already be a suitable thread.
nazar
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woo hoo - first ev ride

Post by nazar »

Johny wrote: Good examination of RWD vs FWD Bigmouse.
It would be good repeated in a thread RWD vs FWD Considerations. There may already be a suitable thread.


x2

yes, thanks bigmouse and columb
there is an awful lot to learn about EV's :)
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