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Old 05-04-2010, 05:27 PM   #124 (permalink)
RobertSmalls
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Join Date: Aug 2008
Location: Buffalo, NY, USA
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Prius C - '12 Toyota Prius C
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I built a DC/DC converter toggle switch, which pretty much works the same way as an alternator kill switch. Hit the switch to disable the Insight's charging system and deep-cycle the 12V battery. My 12V battery is an Optima yellow top with half the energy content of my traction battery, so I may as well take advantage of it when grid charging is convenient.

Building the switch was easy. Short DC/DC converter pin 6 to ground to disable the converter. I extended that wire through the dash, to a toggle switch, and then to ground.

I could run my 12V battery down to 20% SoC and grid charge it with my 62% efficient charger, allowing me to use the traction battery for propulsion instead of electrical accessories. That would save about 0.02 gal of gas, and use .26KWh of electricity instead. Using the 13.4KWh/gal conversion factor that I favor, that's ... 0.02 gal of gasoline equivalent. Huh.

I probably won't be using the toggle switch much, eh?

The math works out only slightly better for grid charing the traction battery pack.
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