Electric car conversion: Project ForkenSwift

[MetroMPG]

Well, just because I'm moving it doesn't mean we can't talk about the car!

I'd drive it to the east coast, but it would take me about 3 weeks to get there, going about 25 km, charging for 6 hours, another 25 km, charging for 6 hours...

I haven't sen anything new about the Poulsen Hybrid since the first flurry of info came out. You might want to head over to this thread and poke people there who were talking about it (near the bottom half): http://ecomodder.com/forum/showthrea...otor-4958.html

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Here's a ForkenSwift milestone I passed this weekend:

My parents' nieghbour was always ribbing me about the car - dubious about its real utility. "I'll believe it when I see you drive your mom up to church in it," he said.

Want to guess what I did yesterday?

And, drat, he wasn't there to see it.

[Intrigued]

LOL! Yeah, 3 weeks might start wearing on a person...or their significant other... I haven't noticed; have you talked Ivan into joining here?

I guess we CAN still talk about the car - it's been an inspiration to many. I am also on the lookout for an old forklift, which reminds me: there's one - oops, there WAS one on eBay, in Pennsylvania: Caterpillar Forklift - Electric - Model M50D - eBay (item 200258975243 end time Oct-06-08 07:53:38 PDT)
They may have chickened out from getting no bids, or listed wrong.

...and I see my Poulsen link was misspelled, so I fixed that. Thanks for the ecolink; I'll go over there after studies today!

Intrigued

[MetroMPG]

Nope, Ivan's got more pressing issues (a 1 year-old @ home) to bother spending time on the computer!

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Good news! James from the UK, designer of the incredibly useful LED battery pack monitor that is in the ForkenSwift, has just posted step by step instructions on how to build them:



See: EV Weblog: LED Bargraph battery monitor part 2

An LED monitor like this is invaluable for anyone driving an older, less-than-perfectly-balanced pack. Prevent battricide! Build a pack monitor!

[Daox]

That is awesome, and will be very handy in the future.

[Intrigued]

If I had the time I'd build one of those monitors. I can't believe I don't see something like that on eBay. (hint, hint!) If I go ahead with the Poulsen add-on to the Quad Cam, I'm gonna want one of those!

[MetroMPG]

I just got a message from an EV builder in Ottawa. He's replacing a pack on a car next weekend and asked if I wanted the old batteries - identical type to what's in the ForkenSwift now. Price: core charge.

Apparently the vehicle getting the new pack is getting 40km per charge now, roughly half what it's capable of when new (in warm weather).

Assuming similar efficiency to the ForkenSwift (reasonable assumption), we should expect similar range from the batteries, more or less doubling what we're getting from the ones we have now. Woo? Woo!

OK, maybe a bit less since we'd be taking a bigger hit from Herr Peukert because we're running a lower voltage pack with higher current draw.

[Intrigued]

Cool! Ah, the price of fame...

You say you're taking an amp-hour capacity hit from Herr Peukert, because you're running a higher current draw. Do you think you'll actually be drawing more amperage per battery than the previous car? Which reminds me: did you ever do a test to see what brush timing got you the best mileage? I remember you had to do some brush work to get the motor running in the correct direction, then did some end cap work later to get timing correct...or something like that... I'm guessing there will be some of us in the future that end up addressing that same question.

It sounds like that LED battery pack monitor is going to get a workout, for sure!

Ouch! I see my "90 day average" is down. My "best tank" has timed out. Looks like time to try another one... :-)

[MetroMPG]

Originally Posted by Intrigued

It sounds like that LED battery pack monitor is going to get a workout, for sure!

You got that right!

It's possible we're seeing higher average amp draw per battery, but then it all depends on the driver, doesn't it? I tend to drive the FS pretty conservatively. Even though the Jetta these batts are coming from is probably a 120 volt system, if it's driven faster and accelerated harder it could all work out to be the same.

I never did any brush timing vs. efficiency testing because (1) I have no easy way to hold enough other variables constant, and (2) we don't have instrumentation that would make data collection easy. Just look at the "fuel log" for this car and you can see efficiency swings pretty wildly. So there's no way I'd be able to see the effect of changed brush timing just by fiddling with it and using the car.

[Intrigued]

Wow. 120 volt. Sounds motivational to me...

Yeah, I guess I didn't consider the logic to my efficiency question. I'd better get to some of the threads and sites that deal with electric motor selection and efficiency. Knowledge is power!

[MetroMPG]

How worn out is the "good" ForkenSwift battery pack (currently in the car)?

Some simple calculations to get an estimate:

• It's a 10.56 kWh nominal pack (8 batteries * 6V * 220 Amp hours rated per battery) (V * Ah = kWh).
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• 80% of the new pack capacity is 8.45 kWh (10.56 * .8).
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• Looking @ an average of 5 similar drive cycles on the existing pack to an estimated 80% depth of discharge (W.A.G. - impossible to say without a hydrometer), it could travel 28.1 km, in warm weather (>20 C / 68F).
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• The average energy from the wall to recharge was 4.36 kWh.
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• Assuming 85% charging efficiency (another W.A.G.), then the capacity to 80% DOD of the current pack is 3.7 kWh (4.36 * .85).
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• The car's efficiency based on these figures is 132 Wh/km (3.7 kWh/28.1km), or 212.4 Wh/mile, or 158 mpg(US) equivalent energy consumption.

So, the current pack has 43.8% of the capacity compared to "new", to 80% DOD (3.7 kWh / 8.45 kWh).

So what would the car's range be on a new set of batteries?

64 km (8.45 kWh / 132 Wh/km) or about 39.8 miles. In warm weather.