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Old 03-24-2017, 03:07 PM   #20 (permalink)
cajunfj40
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Hello thingstodo,

Quote:
Thanks for the pointer!

I drive by a wrecker on my way home. They are closed for the day by the time I drive by, but I could maybe drop by on Monday and see what they have, or what they can get.

These are the vehicles that Wikipedia lists under BAS hybrid. Any others that I could cross-reference ... or would I rely on the wrecker to do that cross reference?

2012-2014 Buick LaCrosse w/ eAssist
2012-2014 Buick Regal w/ eAssist
2013 Chevrolet Malibu w/ eAssist
2014 Chevrolet Impala w/ eAssist
It looks like they go up to 2016, possibly 2017. Not sure. Best get the part number off a GM parts website and use for comparison if you go look at it. The wrecker cross-reference may or may not adequately dis-ambiguate between eAssist and regular vehicles.


Hello foxgrockefeller,

Quote:
Found one from 2013 malibu for $100, did all 2013 malibu's have this system?
I would be super excited to get this thing working, would be very cheap EV drivetrain for anything light.
Not all had it, just the ones with eAssist. Only 2.4L engines had eAssist, but not all 2.4L engines do. I have not exhaustively researched it.

General:

I did some note-taking:

All numbers in *engine crankshaft RPM*:

Engine has horsepower peak at 6,700RPM, so redline is probably 7,000-7,500 or so?

Generator output is 15kw(20.1hp) from 1570-3180RPM
Max cranking torque is 110lb-ft(150N-m), so call that from 0RPM or so.
Max motor torque during assist is 79lb-ft(107N-m) at 1,000RPM
Max motor power output is 11.2kW(15hp) from 1,000-2,200 rpm

Poking around I found an OK picture, so I stuck a ruler up by the screen to try and figure out the pulley ratio. It looks like a 2:1 reduction from motor to crank. Could be more, but that's an easy number to math with. Hmm. Need to divide peak torque by 2 as well, I think, to make the math work. Yes, that checks out.

So I did some quick math.

All numbers below here in *motor/generator rpm*:

So, we have a motor that has a stall or pull-up torque of 55ft-lbs, falling to 39.5ft-lbs that it can carry up to 2,000rpm where it goes to constant-power of 15hp, steady up to 4,400rpm (torque has fallen to 17.9ft-lb), and falling off in an unknown manner after that.

As a generator, it can absorb 15kw/20.1hp from 3140-6360rpm, falling off in an unknown manner above and below that range.

Stock, this thing would be a stump-puller with top speed potential roughly that of a 200-250cc gas 4-stroke. Great city/dirt bike.

If I recall correctly, the transition from roughly constant torque output to roughly constant power output happens when the back EMF equals the battery voltage, so in this case 2,000rpm. Doubling the voltage (230VDC) will roughly double the RPM (4,000rpm) to which the motor can make roughly constant torque. This will double the output power to 30HP, which will then be roughly constant to ~8,800RPM. If the winding insulation can handle it, going to triple voltage (345VDC) would net 45hp from 6,000-13,200. All at the stock max currents, so no additional I^2R losses, and still under the assumed motor redline of ~14,000-15,000rpm.

Of course, if you want to shove more current in, you can increase the power even more, or with less voltage, at the expense of more heating/losses.

If one could nab the voltage buck/boost circuit out of a later Toyota HSD system and control it, that'd allow more drive/regen voltage out of a smaller battery made from Leaf or Volt modules, or one could hack said modules to make them all series, rather than series/parallel, but I think that's more work.

I'm interested in an inexpensive controller circuit that can take single-phase 240VAC and make 3-phase power to run this motor. All I need is soft-start - variable speed is a bonus. I have a snowblower that wants converting...
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freebeard (03-25-2017), thingstodo (03-24-2017)