Archive for March, 2007

So much information, so little time

Saturday, March 31st, 2007

OK, the latest: lithium iron phosphate. 1 charging step as opposed to 2 for lithium-ion; much larger overcharge tolerance; four times higher energy density than lead-acid; longer cycle life than Li-Ion (up to 2000 cycles) — according to manufacturer. A lot more expensive than Pb-H2SO4. How much? Waiting to hear back…

Headlong into the design phase

Saturday, March 31st, 2007

Getting a real appreciation for how tight space will be after putting together 4 battery “dummies” made from cardboard. These are big batteries! We’ll be lucky to get 4 under the hood, and 6 in back–so we’re looking at 120V again.

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Came across this post on the EVDigest discussion board, posted by an Australian EV enthusiast:

“I have just installed 45 ThunderSky TS-LFP80AHA batteries (Li-Ion) in my car and taken it for a couple of test runs. These batteries are GREAT!!! Half the weight and at least 1.5 x the range of my old lead pack. Much less voltage sag under acceleration also. I am never gonna tow lead again… not ever! Just a matter of finishing installing and fine tuning the BMS.”

Very tempting, but I get no response when I contact Thunder Sky Ltd. in China, and they can’t be found anywhere in the US. Gotta move forward, and if they become available in the future I can always swap them out.

Stripped to the bone

Thursday, March 29th, 2007

On Friday I ordered the motor, and bought a stainless steel blank from which the coupling between the motor and clutch plate will be lathed. The motor is Advanced DC’s 9″ FB4001, the biggest one they make. I want to have enough motor if we are able to use lithium-ion or convert to it in the future. Clutch plate and blank were sent to machinist in New Hampshire. On Sat-Sun we pulled the last remaining bits of “weight” from the car–including fuel lines, rear seat belts, and various brackets which we are saving for possible adaptation.

Removing the fuel lines ended up being a real chore. There are four, and they snake around underneath the car, secured at five different places by rugged clips. We would have yanked the whole harness but they are accompanied by the two rear wheel brake lines.

Finally it came down to either removing the steering column to get them away from the last clip, or getting “medieval” with a bolt cutter and cutting them out in pieces. Medieval won out, saving time and wear on our already-battered knuckles.

It’ll be nice to be able to post something constructive

Sunday, March 18th, 2007

instead of describing the destruction we’re wreaking, as we undo the craftsmanship of the Koreans who built the car 10 years ago. And it’s built well–”Ford (Kia) Tough”. The joints line up, the parts are solid. If it wasn’t for that stinking gasoline engine they had to go and put in it. Pretty soon we get to start building things.
Today the gas tank was removed, leaving a cavity of the perfect size to accommodate 6 of our batteries. I’m pretty sure we can get 4 under the hood, but I want 11 total. So finding space for that extra battery may involve some creativity (”What happened to your glove box?”).

Transaxle, engine part company

Saturday, March 17th, 2007

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and an assault is made on fuel tank, not realizing that to remove it means disassembling the car from the inside. Two advantages to working inside the car: 1) the bolts are easier to remove 2) it’s clean.
Back seat is removed.

The ICE has been iced

Thursday, March 15th, 2007

I had some free time today so I hopped over to United Rentals, picked up an engine hoist, and an hour or two later the Internal Combustion Engine of our little Aspire had been extracted most handily. Felt good.

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Next: separate transaxle from engine block, remove back seat, and make battery mockups out of cardboard to test battery configurations. There’s a lot of space way up front, but putting weight too far forward (or rearward) can cause weird handling problems. That leaves room for four or five tops under the hood–and means at least six batteries will occupy the space formerly occupied by the back seat. I want to build the rear battery box big enough to accommodate 144 volts, or twelve batteries total; if we decide on fewer batteries, extra space in the box can always be plugged with blocks of wood. I’ve also been mulling over a way to drop the box into the floor to keep the CG low, and I think if we maintain the structural integrity of the longitudinal beams of the unibody there is a way to actually increase its strength.

The plan is this: bolt the battery box frame not only to the chassis floor, but to the beams themselves using U-bolts (no holes drilled into the beams). So in the event of a head-on collision the beams would have to fail before the batteries would come out. We’ll leave at least 9″ behind the front seats as a “crush zone” for added safety (six Trojan T-1275s weigh 500 lbs, and could be deadly without sufficient restraint).

Exhaust…gone

Wednesday, March 14th, 2007

Well Sunday came and went, and for want of an engine hoist the engine is still in the car (someone should tell rental companies to stay open on Sunday, they might make some money).

Not resting on our laurels, we dismantled the rest of the A/C and exhaust, with more landfill fodder and skinned knuckles to show for it.

Bob Batson of EVAmerica has been running calculations to figure out what motor/battery config will work best. Latest: 11 Trojan T-1275 12-volt batteries will yield 132 volts, keep the weight under the GVWR (gross vehicle weight rating) and provide as much or more range as going with 8-volt batteries. Why? I have no idea. A conversation to follow up on.

We are leaning towards a clutchless design, or actually a “clutchpedal-less” design–the clutch plate stays in the transaxle but the flywheel is gone. So to change gears you drop off the accelerator and just shift (it doesn’t do any harm because the little angular momentum of the electric motor is absorbed by the springs of the clutch plate). I want to do some more research on this, but the idea is appealing–we will be losing the weight of the flywheel and the energy required to accelerate it from every stop. According to Bob, the only gears we’ll need to use are 2nd and 3rd, and shifting occurs infrequently. And in our new EV the flywheel, the purpose of which is to translate inertia into compression in the cylinders of an ICE, would be about as useful as a catalytic converter anyway.

Nick is the best for keeping the mood up amidst setbacks. His latest contribution: any time he removes an oddly-shaped part he holds it up and (with suitable hick-mechanic-from-hell accent) says, “This here’s your problem, right here!”

We crack ourselves up.

No we haven’t given up

Saturday, March 10th, 2007

Missed blogging last week, but work is progressing. Pulled the AC and differential apart today, and with any kind of luck we’ll be able to pull the engine tomorrow.

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Our hi-tech piece of equipment today was a 10′ long 2×4, which turned out to be the ideal piece of gear for dropping the stabilizer bar on the front suspension. We wrestled last week with it, we wrestled today with it–then we took our 2×4, cut it in half and pried the sucker off, one of us on each side of the car. Worked like a charm.

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The phrase that keeps coming to mind, and what is becoming more or less our official motto, is: “Whatever Works”. We’ve been going step-by-step through the “How to Remove The Whole Freaking Engine” section of the 1997 Ford Aspire shop manual I found on ebay ($19), and I just received the 1997 Ford Aspire Electrical and Vacuum Troubleshooting Manual ($27) which will come in handy when we get to instrument wiring. Don’t know what we’d do without the manuals and the torque wrench (affectionately renamed the Dork Wrench), which takes no prisoners when it comes to removing tight nuts.