You can drive an electric car with only two 12v car batteries!

[txlibdem]

This guy is chronicling his electric conversion of a 1986 Dodge. Sometimes funny, but very instructive to see him driving around with only two car batteries powering his electric vehicle.

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And it's kind of a cool looking electric car, too. IMO.

[TheWraith]

1. Standard car batteries contain roughly 80 amp-hours of electricity.

At 12.6 volts, that's 1,008 watt-hours per battery. Two batteries means 2,016 watt-hours. Typical battery-to-wheels efficiency for an electric vehicle is around 250 watt-hours per mile at 35 MPH. So yes, you can drive an EV on two regular car batteries as long as you don't need to go more than 8 miles, round trip, at low speed.

[txlibdem]

8. The battery pack in the Chevy Volt is 400V (IIRC)

It's definitely both voltage and watt-hours that determine top speed and range. I agree that this will be no speed demon.

But he seems to be having a blast trying out different things to make it work.

[TheWraith]

15. Watt-hours determine range, voltage determines potential torque.

Although the voltage is a lot less important than the watt-hours in terms of overall performance, since you can eke a lot more power out of that kind of pack than the Volt does. Case in point, the Tesla Roadster runs on basically the same voltage range. It all depends on the engineering. Theoretically the most rawly efficient means would be electric motors directly in or attached to the wheels, allowing for the least waste of power in transmission, but with four wheels that gets expensive and it potentially exposes the electric motors to things like road salt that could damage them.

[dmallind]

16. that efficiency is a tad low

I'm averaging 4.6m/kwh at considerably more than 35mph (my work commute is almost all free moving highway or 50mph trunk roads), and I'm far from an efficiency leader. Some folks are getting high 5s even low 6s for entire charge cycles.

But your conclusion is sound of course - he will not go very far or very fast. EVs have about 80kw output batteries on average with 16-80kwh capacity

[TheWraith]

17. You're right, it probably is, at least for 35 MPH.

I was ballparking it based on battery-to-wheels efficiency numbers for dedicated electric vehicles. The Tesla Roadster is officially rated at around 265 watt-hours per mile, for instance (although in real-world use it's actually somewhat more efficient, capable of running as low as 194 watt-hours per mile under ideal conditions) and the Nissan leaf is rated at 242 watt-hours per mile (again, potentially going as low as 191).

My assumption was also that a converted car is going to be slightly less efficient on electricity than a dedicated EV, because of not as much attention being paid to the weight of the vehicle, and also less efficiency in a drive train built on the assumption of running off a gas engine rather than an electric motor. So I pegged it at the higher end of the potential estimates.

[dmallind]

18. The bugger with EVs is "it all depends"

Certainly ICEs can get varying mileage too due to driver variation, but our "fun car" Mustang GT convertible (kinda blows the "green cred" of the Leaf) will never get more than 25 or so on even the gentlest cruise, and my wife's Hyundai can never realistically get less than that as a tank average even driven by the most aggressive driver. Most drivers regardless of habits are going to average about 18-22 on a tank in the GT, 27-30 in the Sonata. Pretty small range. But Leaf drivers? EPA says 2.9 m/kwh. God knows they must have the Stig to get that low. Typical driver results are reported from 3.3-5.7 on an average charge over time on the Leaf forums, with hypermiling experts who can get in the 6s now andagain. A much greater range as a ratio.

I don't know if it's because not everyone has standardized the "EV drive" yet with its emphasis on reducing braking and quick acceleration followed by coasting, or because of the technology (although you would think gearless consumption would be more linear) but for some reason YMMV has never been more true than with EVs.

[immoderate]

2. Does it only work on snow?

--imm

[zipplewrath]

3. Just not very far

And not very fast. Golf cars usually have at least 4. They only go about 8 miles.

[txlibdem]

9. And his car is a lot heavier

Golf carts weigh less than a Dodge. I think he'd be lucky if he could get very far at all with only two batteries.

[zipplewrath]

14. Do better with bigger cables

He kept commenting on the "discoloration" of the main cables. On a cold day like that, he shouldn't be seeing ANY. With some bigger cables, he'll have smaller losses and get more work out of his batteries.

[txlibdem]

20. I know what you mean. He's gonna need cables 5 times as big.

Take a look at the photos on the chevy volt website, the Nissan Leaf site, the Mitsubishi i site, etc. All EVs have big beefy cables.

[MADem]

4. Ha! Very cool, indeed. I like the dog, too! nt

[tinrobot]

5. I had a converted MGB for a while.

It had 16 6v golf cart batteries and a range of about 50 miles.

This guy will not get very far, but it's just a test drive, so I suspect there will be more batteries in the car when it is done.

[txlibdem]

10. sweet

My commute never allowed for that. I'm so jealous.

Did you get "the EV grin" when you pass by the gas stations?

[tinrobot]

19. Absolutely got the grin...

It was a fun car to drive, and I was a little sad to see it go.

It's been replaced by something a little better, however, a BMW Active E. That car is definitely a smile inducer.

[txlibdem]

21. Congrats on the Active E

I recently saw a youtube video for the i3 and i8 EV concept cars. Such sweetness.

[txlibdem]

22. So now you've got an even bigger EV grin?

I'll bet and I wouldn't blame you.

[OKIsItJustMe]

6. You could drive a standard car with a single battery…

A disabled manual transmission car, without a “clutch safety switch” could be put into gear, and driven a short distance at a slow speed using the starter motor. (Eventually, the starter will burn out. I had a woman confess burning out her starter in exactly this way, after I mentioned it in passing.)

[txlibdem]

7. Well... I wouldn't try my commute like that I'll tell ya that much

[Dead_Parrot]

11. I'll confess to doing that...

...in an old mini: I ran out of gas near the top of a hill, and cranked it far enough to get me onto the coast down (at the bottom of which was a supply of gas).

Not something I'd want to do twice, It didn't sound too happy...

[joshcryer]

12. Worth it for the captions for the dog.

[txlibdem]

13. He just wanted to come along for the ride

I think so anyway...