Remote Living > Transportation

Thinking about an EV conversion

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SparWeb:
I remermber Jerry fondly!
His truck was lead acid powered, a direction I don't want to go.
A little comparison calculating shows that lead cells add many pounds of weight more per km you want to go than LiPO cells do.
My number crunching may be of interest, so I will post up a few graphs that really were an eyeopener for me.

Warpspeed:

--- Quote from: SparWeb on March 12, 2017, 03:38:26 PM ---Hi,
One more of the not-so-simple problems, is getting a donor car that can handle the increase in weight without overloading its chassis and suspension.  It would be nice to grab any old Honda Civic or a Ford Focus, but there really isn't much weight in these cars to begin with - not much fat to trim after pulling out the engine and fuel tank.  My first estimate is that the EV conversion would increase the weight of the car by at least 500 pounds.  Not likely to be safe without beefing up the suspension and wheels. 
Whoops... that will add more weight.

--- End quote ---
Five hundred pounds is only like having three average sized passengers, and quite often many basic commuter cars have a "sports variant" with upgraded brakes, wheels, and suspension to make any upgrade a straight bolt on.
I think I would like to keep the original manual gearbox. Most of your power consumption will be when accelerating or climbing hills. A manual gearbox would greatly reduce the peak load on the electric motor, and I am sure would offer enough advantages to offset the weight penalty.

I have never owned an Alfa Romeo, but those are reasonably small cars, without being tiny, and have the engine at the front, and the clutch and manual gearbox at the back which is pretty unique and may simplify things. They are also now old enough and affordable enough to do really radical things to.
They have pretty good original weight distribution too for a small car, and a bunch of batteries at the front instead of the engine would probably not change that a whole lot.

Just unbolt the front of the bell housing and remove the clutch, and fit an electric motor right there.... Done.

SparWeb:
Indeed, lowering the seat can solve the headspace problem of virtually any car.  Lightening the driver's seat (if the donor car has powered seats, for example) may be necessary anyway.  Considering my purpose for the car, the back seats will simply go, to make space for batteries.

George, you aren't wrong about diesel fuel efficiency, although in Canada, diesel is more expensive than gasoline.  Only about 1/2 of the fuel stations carry diesel around here.  The choices of car from the OEM are limited, seemingly, to Volkswagens and their tarnished reputation, and trucks larger than 1 ton.  I have already considered other fuel conversions, such as natural gas, but there are no businesses offering the conversion in Canada or a home fueling station (I have NG service at the house) and the economics seem to save me very little money.  The cost of the conversion itself won't be recovered for years.  To rephrase my goals, I am trying to USE NO CHEMICAL FUELS at all.

I started to figure out what to expect from an EV, bearing in mind that I want to go minimum 50 miles, preferably 100 miles, on a single charge.  I collected stats from the EV's on the market (Ford, Chevy, Mitsubishi, BMW, and, of course, Tesla) and they were very interesting to compare.  The first thing I noticed (and it's obvious on the graph below) is that the Tesla's are in a class all their own.  Basically, a Tesla gets 3x the range of any other type of EV available for sale from a major manufacturer.  The green dot near the red Tesla dots in the Chevy Bolt, closing in on Tesla territory.  Most of these can meet my minimum range, but few of them can do more than 100 miles (Chevy Bolt, BMW i3, all Teslas).  Price of admission into the long-range EV club starts at 40,000 CAD.

Looking at vehicle conversions, I got more surprises.  Would you believe that there are many auto conversions on the DIY EV forum and EV Album that have BETTER range than the OEM cars on the market?  I was encouraged to see that.  Admittedly, these are just builder claims, not as scientific as CAFE test trials.  But I don't expect that the OEM claims are exactly what I would get either.  Temperature always affects battery range, so I'm more likely to believe the range claim of a DIY builder in Oregon state than the OEM official numbers from California as representative of range in Calgary.

LiPO cells make all the difference in DIY conversions.  Compare the LiPO conversions to the lead-acid battery powered cars, and there's no competition.  There are plenty of LiPO battery conversions that meet my minimum range requirement.  Looking more carefully at the examples that do, and I find some other things in common.  Two of them are Honda Civics, converted using Advanced DC series-wound motors.  To get the range they obviously need to a LOT of batteries inside.  Apart from that, I can't see any other components or equipment that have strong advantages.  So I think a lot of choices are wide open to me, to use use what I think I need as I dig deeper into the design.



I was expecting to see some kind of advantage, given all the claims being made, for the AC motor conversions.  No sign of it in the numbers I collected of DIY EV's.  I doubt that AC regeneration braking will help me, since my goal is to run on highways, where I tend to not touch the brakes for 10 - 20 minutes at a stretch.  That is one cost and complication that I can avoid.

Warpspeed - that's a neat idea.  It brings up another way to choose a candidate for conversion - saving a rare auto from the wrecking yard.  Plenty of cars go to scrap for the simple reason that their engine quit and isn't worth the repair.  This appears to be a factor in the number of Mazda RX-7 conversions out there.  The average shop isn't interested in tampering with those funny engines, and owners are stuck with big repair bills.

Warpspeed:
I am only half joking when I suggest you could always mount a Honda gasoline standby generator in the boot.

SparWeb:
Hmmmm
300 VDC battery pack  <->  240VAC output from generator, rectified.

Yeah, I think I see it.

 8)

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