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Old 11-22-2013, 07:52 AM   #13 (permalink)
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The Mistress - '88 Bmw 320i Touring SE
Team m8
Last 3: 27.17 mpg (US)

Germany Beadle - '91 Mercedes 300td (estate, N/A)
90 day: 24.63 mpg (US)

The Bloodylingo - '05 Citroen Berlingo Multispace Desire
90 day: 39.77 mpg (US)

Shanner Scaab - '03 Saab 9-5 estate Vector
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Originally Posted by Daox View Post
This is basically what you want:
He still spent $11k on batteries.
That’s a lot of pennies!

Originally Posted by mora View Post
70 miles at 50 mph is no big deal. Get a big motor (11") and have external cooling so it will stay within temperature limits. More mass absorbs more heat. Use as high voltage as you can. Your contoller selection will likely limit voltage. If I'd go DC motor route I'd get something from Soliton series and use 250-300V pack. Those controller can limit motor voltage. You can use thinner cables as pack currents should stay low. Or then you could get suitable AC setup with controller from HPEVS for example. Voltage will be limited to 144V or something like that but then you can use batteries with bigger Ah rating. This will solve regen braking issue at the same time (can't do it using DC easily).
Oh, cost. Assuming your vehicle consumes 0.3kWh per mile (300Wh / mile) as mentioned before. 70 miles * 0.3 kWh/mile = 21 kWh. CALB batteries (LFP chemistry) cost about 440$ / kWh, so your pack alone will cost 9240$. You don't want to run the pack empty every time you run the car so let's leave some margin. 80 pieces of 100Ah cells make a good pack (25.6kWh). Price bumped to ~11k$. This pack will allow you to do ~70 miles in one go and still have 20% left. Your cells should last well over 100 000 miles this way. Even double that is within reality, though no-one using these cells hasn't driven that much yet. No real life evidence on that yet. But looking good so far.
This is not to shoot your idea down. Just to give some thoughts about it. Sometimes driving and owning an EV is not about money saving or being green. Heheh.
I've driven my EV for about 3 years. I calculated it takes less than 25 000 miles for me to "break even". About three years of driving. Almost there, heheh. Battery cost vs. gasoline cost I mean. But here gas goes for over 8$ per gallon.
These figures seem to suggest that there may be an argument for a diesel car in the interim, until battery tech and cost becomes better

Originally Posted by Ryland View Post
I agree with going with as high of voltage as you can, at some point speed controllers start costing more for higher voltage, but 144 to 300v is becoming more and more common, but up to 144v can be bought or made cheaper.
It's important to remember when building your car that you want it to last 100,000 miles, that is, if it's worth building for a 65 mile per day range.
Even if you have a 65 mile range, it's worth asking your work place about being allowed to plug in, if you can offer to take the least appealing parking space, 40 seconds of extra walking per day is good for you and it could save you a ton of money or at the very least give you a full charge on your way home.
I hear you re work charging- means I could build for a 40 mile range instead
My Blog on cars- Fu'Gutty Cars

US MPG for my Saab 9-5 2.0t Estate


Last edited by 320touring; 11-22-2013 at 07:58 AM..
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