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Old 02-06-2018, 02:48 PM   #8 (permalink)
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Originally Posted by jamesqf View Post
And yes, it is a design flaw because it would be simple to make the DC/DC converter provide current from the traction pack.
It's not quite that simple because the traction battery must be disconnected when not used for safety. This means the 12v battery is necessary to actuate the contactor that connects the traction battery to the rest of the vehicle circuitry.

My thought was a momentary switch that can be manually operated that closes the contactors. Hold the switch long enough to charge the 12v battery, a minute or 2, and then the 12v battery can take over holding the contactor closed.

The power required to "start" an EV is very low compared to an ICE. A very small 12v source is all that is needed to provide just enough to run the computer and close the contactor, then the traction battery takes over.
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