Project: The Electric Booger (budget EV conversion - '92 Mazda MX-3)

[Daox]

Originally Posted by mechman600

Your Paseo would make a perfect one!

Yeah it would, if I still had it. Current thought for something EVish is I still have a 1993 Tercel, and I'd love to hybridize it for 20 miles or so of EV range. But I'd want to go with lithium and that means $$$, and I don't have a lot of excess at the moment.

[mechman600]

For the very few of you with a DIY EV conversion, allow me to describe the virtues of a functional tachometer.

It's amazing. I cannot believe I didn't do this before. It makes driving 100% more enjoyable. Downshifting without a clutch is slicker than goose $*&# because you precisely know your "blip RPM". Try blipping the throttle on a motor that you cannot hear. That was me before.

I now have figured out my power curve and shift points. I used to guess before. Now I do not have to. Peak power is at 3400 RPM. I can tell because of the sudden slight lurch of power and drop in battery voltage when the Alltrax reaches peak output voltage and goes into bypass (which is another reason I love the Alltrax, because it has a bypass making it nearly 100% efficient at peak output). It is pretty much out of steam by 4000 RPM. I can now shift by RPM and not vehicle speed.

As you can tell, the Electric Booger is running better than ever and I am very happy with it. Thanks again to MetroMPG for giving me this series wound motor. Well, "giving" is a strong word because the deal was that I now owe him a case of home made beer. So in my garage is 6 gallons of a very dark, highly hopped ale.

Here is my helper helping me mash the grain, making delicious, sweet, fermentable wort:

[nemo]

Electric car builder, home brewer, and an assistant, can life get any better?

Oh yea the tech, so the 3400 RPM is also your best efficiency.

[MetroMPG]

That's very exciting news!

The info about the car is interesting too.

[War_Wagon]

Whoa whoa whoa...you trade with beer?? Ahhh, step into my office here, have I ever got some sweet deals on eco rides for you!

[mechman600]

Originally Posted by War_Wagon

Whoa whoa whoa...you trade with beer?? Ahhh, step into my office here, have I ever got some sweet deals on eco rides for you!

Careful what you wish for! If I ever am forced into a commute longer than the eBooger can handle I will be knocking on your door!

[mechman600]

It was time to figure out the best gear to use when accelerating from a stop. So I took a video with my (cough...hands free...cough) cell phone to make this:

http://www.youtube.com/watch?v=OpbHJPgcVIY

That folks is what 30 peak HP pushing 3000 lbs (est.) looks like. And exactly the same 0-50 km/h (31 mph) time when starting off in first and shifting to second vs. simply starting off in second.

[puddleglum]

were you able to tell if you used more watts in one run than the other?

[mechman600]

Originally Posted by puddleglum

were you able to tell if you used more watts in one run than the other?

Nope. I don't have fancy instrumentation that can measure interesting stuff like that.

Today I did a 19.6 km trip and short shifted a lot, shifting at 2500-3000 instead of 3000-4000 and cruising at 2000-2500 instead of 3000+. You can see in my fuel log that I achieved the best efficiency I have ever done at 394 Wh/mile. I did baby it though, so it might have been just a coincidence.

I have always been under the impression that higher revs with an EV is more efficient. Weird. I will try it this coming week of commuting to see what happens.

[thingstodo]

For a DC motor, I don't think that the speed has a lot to do with the efficiency.

I have read (somewhere ..) that using higher revolutions (less than 'redline') is good for the motor, since the built-in fan moves more air and the motor runs cooler. It makes sense to me.

I guess the fan moving air would be more load, but it would likely not be measurable.