Electric car conversion: Project ForkenSwift

[MetroMPG]

Skewbe says:

I'm really hoping you have good news today, metrompg.

An aside, this guy is claiming 50mph on a 36v metro, on a 6HP (at 48v) Forklift Motor, does that sound likely?
http://cgi.ebay.com/ebaymotors/ws/eB...m=260166974714

[MetroMPG]

It's legal!!

Got insurance and plates at lunch time today.

(Be back later to reply to posts above...)

[MetroMPG]

SVOboy says:

Yay!

*handsyouaprize*

[MetroMPG]

Just got back from an errand run. It's ForkenSwift weather: rainy (ie. not biking weather for me). Man, the car is slow though! Mental note: avoid driving at peak traffic times in future...

just limiting the system to 72 volts cuts costs dramatically.

From what I've read, 72v is considered the minimum practical voltage for around town conversions. It would meet your speed requirements just fine (depending on the components you pick).

An aside, this guy is claiming 50mph on a 36v metro, on a 6HP (at 48v) Forklift Motor, does that sound likely?
http://cgi.ebay.com/ebaymotors/ws/eB...m=260166974714

Hey, that car looks familiar. I think it was for sale on eBay months ago... I thought someone even posted to this thread, but I can't find the reference.

Anyway, it might get 50 mph, but not under anything you'd consider "normal" circumstances (ie. you'd need a looooooong runway). I've calculated that the Flea needs 7.7 hp just to maintain 50 mph on flat ground in no wind. Obviously it needs much more than that to accelerate to that speed. Sure, an e-motor can deliver above its rated HP for some time, but still.

[MetroMPG]

Yes, very familiar...

Found it http://cgi.ebay.com/ebaymotors/Geo-M...QQcmdZViewItem

Same car sold in July for $1k as a "fixxer upper".

[MetroMPG]

Originally Posted by skewbe

Very cool, can't wait for some real world stats (0-30 times, top speed, range, etc).

So where is the garage entry already?

P.S. what is downshifting like without a clutch (spinning the motor up on the synchros?) or do you not do much shifting or hows that work?

Right... garage entry! I should get on that.

What formula will I use for MPG equivalent though? There are 33,557 watt hours in a gallon of gas, and the FS pack theoretically (when new) holds 48v*220AH (I think) = 10,560 watt hours (less than 1/3 of a gallon of gas, equivalent energy!)

Problem is, I don't have a killawatt meter, so I don't know exactly how much I'm putting back into the pack when I recharge. Suggestions? I can estimate SOC from pack voltage... but that's kind of like estimating MPG based on where you gas gauge was before topping up.

Downshifting is pretty easy: push/pull to neutral while releasing the go pedal, no load (exactly the same way you do it in an ICE car when you don't use the clutch to get to N), then push/pull towards the gear you want while spinning up the motor. It's actually faster than upshifting.

Upshifting: go to neutral (no load), and push firmly against the synchros while the motor is spinning down. Takes maybe 1 and a half seconds to upshift.

I've been driving it like an ICE car, except revving higher (over 3k before shifting up).

I'll make a video that shows the shifting.

[MetroMPG]

Several people on the EVDL suggested today that we go to 72v for the FS. The motor can handle it, we've already got the batts & (barely) room in the hatch for 4 more. And it would make it much easier to use our 36v charger (split pack parallel string charging). The rear springs would have to be beefed up though.

Believe it or not, last week I almost bought a Curtis 48-72v 400A controller on eBay. It went for $200 . Now I'm kicking myself that I didn't grab it ("buy it now" was available). Those turn up much less frequently than the 48v golf car stuff.

I'm going to get a killawatt tomorrow. I checked the chargers today, and they're 10A & 3A @ 110VAC, so if the meter's limit is 15A, I'm good to go. That'll let me measure the car's energy consumption at the wall.

[MetroMPG]

Just for fun, I picked up 4 more batts from Ivan's. This is what the car would look like on the stock springs @ 72v with 4 more in the hatchback .

Click in, it's pretty funny in the big image.

[MetroMPG]

Originally Posted by SVOboy

Add the batts!

Well I talked about it to Ivan: we've agreed I'll watch for a 72v controller. It'll likely take a while for another cheap one to turn up, and now I'm really kicking myself for not buying that $200ish one last week. In the mean time we'll also look into doing up some kind of controller bypass. If we're really lucky, that might just be enough of an improvement to be able to sometimes drive on the grown-up streets.

Ivan had the car this weekend. Said he drove around grinning the whole time - the EV grin!

And, not unexpected by anyone, he experienced its practical limitations. The main roads are too much for the FS due to hills, traffic (speed/density), or both. This forced him to take his ICE car on one trip to his little brother's house because there's no side-street alternative.

---

In other news, I bought another Curtis 36/48 225A on eBay - got a good deal. While shopping for the FS, I got familiar with what people are paying for these, so I actually bought it just to resell and make a couple of bucks. But when I told Ivan about it, he said he wants to buy it off me to make an electric motorcycle. He's a bit of a bike nut - owned a bunch, currently has an old Triumph Bonneville & a Suzuki SV1000. He's got a non-running Yamaha RD350 donor in his shed that he wants to convert.

[MetroMPG]

Drove up to the city waste transfer station at lunch time to see if they'd weigh it for me. Drumroll please...

942 kg / 2077 lbs.