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Old 02-28-2018, 08:46 AM   #528 (permalink)
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Join Date: Dec 2011
Location: New Zealand
Posts: 5,027

ND Miata - '15 Mazda MX-5 Special Package
90 day: 39.99 mpg (US)
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I spoke too soon about my battery - 3 days after I posted that, my IMA system shut off. I have reason to believe the MCM (motor control computer) failed, because the IMA light is off and I have a "no communication" CEL. However, rather than replace just the computer and risk another one failing in the same way, I'm planning to buy a cheap pack with failed battery cells, and swap my good ones over.

Right now at idle, the DC-DC converter puts out just enough voltage to keep the car from dying, and shuts off above 4k RPM, which I need to rev to surprisingly often.

I went back and forth on whether I might want to run an ECU fooler and gut the hatch (huge weight reduction, lots of space gained), but the Insight's engine is gutless below 3K RPM without the IMA and the gearing is wrong for driving in an area with a lot of inclines. So, for now, going to fix what's there.

In other news, I have my eye on some lithium cells which I might play around with. The 2011-2013 Hyundai Sonata hybrid had a ~1.5kwh lithium battery, 9 x 5.3Ah 30v subpacks in a series. 5 or 6 of these would result in a 150v or 180v nominal pack, with 800 or 950wh respectively. Internal resistance in LiPo is lower, and charging the pack at home would be reasonable, so long as I can figure out battery management translation.
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