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Old 12-12-2013, 08:06 PM   #540 (permalink)
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Okay, seeing the IMW Seven and talking to Kevin Smith and to some of the folks at the MIT Electric Vehicle Team has got me thinking more about the main electric drivetrain for CarBEN EV5. I like the looks of the BRUSA SSM1-6.17.12 ( BRUSA SSM1-6.17.12 | Metric Mind Corporation ) along with the Getrag GX629 6.4:1 EV Transaxle assembly ( GX629 6.4:1 EV Transaxle assembly | Metric Mind Corporation ). That puts the ~5500RPM which is the peak efficiency of the motor right about 55-60MPH (depending on the tire diameter you use).

No rare earths used and lower cost (though certainly not inexpensive), and a compact package (roughly 11" x 20"?) with no 90 turns - we may have a winah!

The batteries used in Seven are the Thundersky (now CALB) 100Ah cells: CA100FI 100Ah, 3.2V, 0.3-2C CALB EV LiFePO4 Lithium Battery

I can fit 106 of these (Seven has 99) and Kevin Smith swears by them and their ruggedness. That would be ~35.3kWh and cost roughly $16,000. They use no BMS and do a "bottom balance" and have stopped seeing stress that occasionally caused the cells to swell.

I had used the EiG 20Ah pouch/prismatic cells in my planning: EIG Cells and I could probably fit about 50kWh into the compartments in the floor. FVT has an innovative BMS system that shunts the excess from one cell to another cell that is still charging; rather than to ground - as I understand it.

I looked briefly at the A123 cells, and these are wider than would easily fit. And they are very hard to find, if not impossible.

A choice for charger is still vague. Seven has a Manzanita, and it works well. They disconnect it on the inside, so that regen doesn't blow it out.

One of the MIT EVT people has put me in touch with their Porsche guy, and I have asked about getting the rear suspension. He is a busy person (postgrad?) and I will wait and see if he can help me. I'm also going to look at the Neon front suspension that Seven uses (in the front and back), though I don't think it could fit in the back of CarBEN, and I don't need the Prelude rear wheel steering; as the wheelbase of CarBEN is significantly shorter.

It looks like all this hardware will cost $35-40K, which is actually about what I was expecting.
Sincerely, Neil

Last edited by NeilBlanchard; 12-12-2013 at 08:23 PM..
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