Remote Living > Transportation

Thinking about an EV conversion

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SparWeb:
Hi,
Apologies for having no show-and-tell.  Still just pie-in-the-sky thoughts.  Putting them down in text to hear any reactions / corrections / ridicule that my fellow members consider appropriate.

I've always wanted to built an EV conversion.  It also seems out of reach since I live so far out of town.  The only realistic EV for me would be able to get me to work every day.  That would demand at least 80 km between charges, and preferably 160 km to get to work and back home without a recharge in between.  I think to be realistic and economical I should only consider 80 km and make sure I have provisions to recharge before getting back (and 8 hours at work with the car plugged in should guarantee a charge to get back home).

I currently spend 3000+ dollars a year driving to work and back just on fuel.  Maintenance on the car is also an expense, but it doesn't seem realistic to expect the maintenance costs of a home-brew EV to be any less than a mass-produced high quality auto.  My current auto is a 9-year-old Acura TSX.  It is still in great condition; in fact, I have never had a better car than this one.  It would be a shame to screw up a good car for a dreamy project (and what would I drive in the meantime during the conversion?).  So I have to find a suitable donor car that will be able to carry the motor and battery power I need.

Complicating the means to this end, I need an EV that can clip along at 60+mph (100 kph) to keep up with highway traffic, which is 80% of my drive to work distance.  It will also have to manage 10% gravel road.  Not going to worry about the 10% city streets which is where most EV's are at home.  The gravel roads will demand a correct F/R wheel load balance otherwise the handling will be compromised.  Since I live in Canada, and we get snow here, handling would be a crucial concern whether or not I live on a gravel road.

To keep a 3000+ pound car going 100 kph, especially up a 10% grade hill, I think I need at least 80 kW in the drive motor.  Nothing cheap about these motors.  There goes 1 year of fuel cost savings.

To complete my trip to work, at this speed, it will require a battery bank that can deliver about 40 kW-hours.  Every day.  There's nothing light about such a battery bank and that will eat up the equivalent cost of 2-3 years of gasoline savings to buy the monster LiPO pack.

Plus the cost of the motor drive controller....  Any suggestions to keep all these costs under control?

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.

DamonHD:
Not that I have much to offer on this topic, but ... would you for example be prepared to sacrifice the back seat area of a vehicle to accommodate some of the 'stuff' eg the batteries?

Rgds

Damon

joestue:
33 kilowatt hours per gallon of gas is approximately $3.5 worth of electricity, which is cheaper than the price you're paying for gasoline.

potentially your savings are inversely proportional to the efficiency of your gasoline engine. if its 20 percent, then theoretically you can spend 600 canadian on your electric bill instead of 3000 on gasoline.

But the life cycle cost of the battery must be less than the difference.

33 kilowatt hours for $4.5
or 6.6 kilowatt hours for $.66
difference is about $3.84
this $3.84 works out to be $0.58 per kilowatt hour.

suppose you buy the 100 amp hour 96 volt pack here
http://www.batteryspace.com/lifepo4-prismatic-battery-charger-and-bms-package-96v-choose-from-40ah-60ah-or-100ah-w-can.aspx

that's 9600 watt hours for $6650 and at 300 watt hours per mile that gets you 32 miles or 51 kilometers.

so lets assume a 6.6 kilowatt hour battery pack costs $4580

you need to charge and discharge it $4580/$3.84 or 1192 times to break even. that's about 4 years of driving.

if your battery is twice the size you need it to be, it will take 2400 50% discharges before you break even.. that's like 8 years of driving.

note that i could have done all this math in per unit notation, and the actual figures won't matter.

I don't know if you can get reliable lithium ion batteries any cheaper than 60 cents a watt hour, which is 600 dollars per kilowatt hour. i think the hybrid car manufacturers are able to buy lithium ion batteries at 300 dollars per kilowatt hour and its projected to drop to 200 dollars per kilowatt hour in a few years. i'm skeptical of that happening in just a few years. maybe 5 years and there may be a lot of inflation between now and then.

Mary B:
I have debated this and what is needed is an ultralight enclosed 3 wheel "car" so battery requirements are less. Add a tiny electric start on board generator just in case battery capacity drops below 30%. Keep the weight under 1500 pounds(or even 1,000) and it would make a good commuter. 2 seats, small storage area... build it like the Can Am Spyders with front wheel drive, could use a front transaxle form a small car then lighten it as much as possible.

50% of my trip to town are just errands to get a few things form the store where I do not need the storage space of my truck.

george65:
It does not sound like your circumstances and requirements are suitable for an EV, unless you invest in something like a tesla that can go the distance.  I have paid less than $100 a year for fuel for 14 years and I do at least 2 interstate trips per year and and an intrastate trip of over 300 km every month or so to see my Dad. I have a 3 Ton 4WD that I can put a load of gear in to carry round and economy is not that great but when you are running on Veg oil, it doesn't really matter other than for range.

I can put 200L of oil in the back with the rest of my equipment for the interstate trips which gives me about 2500 Km range starting with a full tank as well.  People often go on about the weight of the oil failing to realise that it is less than just 2 other people in the car my size and far less than 5 average people in it even though it can carry 7.  500 pounds would be 3 people in the back seat. Unless it's some micro car, that ought not be a problem unless the car has compromised structural integrity to to start with.

An EV may not be a practical or economical Soloution for you at this time but it you wanted to save money on fuel ( and all the environmental  considerations)  A veg oil/ Bio Diesel powered car would be a very easy and practical answer......IF, you are prepared to do the bit of extra work required to produce our own fuel.

This is usually the stumbling block. Many talk the green hype but when put to the test, fall over because it requires some extra effort and time.

IF you were going to build and EV, I'd be looking at something like a Subaru Outback or Forrester.  All wheel Drive, would be easy to remove the engine and couple a motor to everything else, Take a LOT of extra weight to worry one and heaps of room for batteries, controllers etc.

The other thing that comes to mind is a Hybrid.
From what I have read I believe there are companies out there doing plug in Conversions on priarse vehicles. You can add extra battery packs and charge the things from the mains and the engine only kicks in when the batteries are depleted.... which to me sounds ideal for you.  If you ever got diverted or stuck in traffic, this would stop you getting stranded when you would be happy to pay 5 bux for fuel to get home.
Again, wouldn't  be worried about weight. If you turn the thing into a 2 seater with extra packs ( which I don't think are real heavy anyway compared to a person) it's just the same as having a couple of passengers on board all the time.

One other thing in favour of a hybrid that comes to mind is something I was reading about just the other night on Teslas......
You say you live in Canada... Where it snows.... A hybrid will give you heating from the engine in winter. I was reading reports on how using the heater in a tesla eats into the range of the thing at a very substantial rate.  With  a Pure EV you would not have a heater and while it may be considered even a Luxury where I am on an EV, For anywhere there is snow I'd say it was an essential!

I also notice Priarse has fans on the battery/ inverter so this being the case you may be able to get some heat from that. I Imagine running along at 100 would tend to get things warm so it may be possible to duct this heat to the cabin rather than just dump it to atmosphere.

It would seem to me converting a Hybrid and putting in extra battery packs would be a lot easier and cheaper with infinately fewer hassels and problems than starting with an IC vehicle and converting that.

http://www.pluginsupply.com/specs/

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