How much 12v power can we pull continuously thru 12v connections from HV battery?

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dtbaker61

dtbaker61

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You've contradicted yourself here. I think the latter is correct and you will not need to have the Mach E on to keep running 12v power off the battery access jump points and the dc-dc system should keep it topped up. There's only one way to find out for sure.

This would be different that doing this same operation on my Leaf. The Leaf definitely has to be turned on to keep the 12v battery topped up.
I don't KNOW that the MME checks 12v when 'off' since it apparently shuts down all the parasitic 12v loads it can once the car is turned 'off'. I am only guessing that it checks once in a while to take care of the LV battery when MME is parked for 'long periods'.

For my purposes, knowing that I want to run significant 12v loads while parked, I am GUESSING I'll have to leave MME turned on so that main contactors stay closed, dc-dc is powered up, etc.
 

louibluey

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I don't KNOW that the MME checks 12v when 'off' since it apparently shuts down all the parasitic 12v loads it can once the car is turned 'off'. I am only guessing that it checks once in a while to take care of the LV battery when MME is parked for 'long periods'.

For my purposes, knowing that I want to run significant 12v loads while parked, I am GUESSING I'll have to leave MME turned on so that main contactors stay closed, dc-dc is powered up, etc.
If Dan can get to 75A to 100A continuous load on the 12V bus, I think the DC-DC converter will either be running 100% duty cycle, or it will be operating at a very high duty cycle. I think MME will need to be ON (and getting it to stay ON for hours will be another issue for later, if it works).
 

ChasingCoral

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I don't KNOW that the MME checks 12v when 'off' since it apparently shuts down all the parasitic 12v loads it can once the car is turned 'off'. I am only guessing that it checks once in a while to take care of the LV battery when MME is parked for 'long periods'.

For my purposes, knowing that I want to run significant 12v loads while parked, I am GUESSING I'll have to leave MME turned on so that main contactors stay closed, dc-dc is powered up, etc.
I'm guessing the opposite as Ford has said in a number of places that the system keeps the LVB topped off from the HVB when it is parked or stored. You'll find out when you test your rig!
 
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dtbaker61

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I'm guessing the opposite as Ford has said in a number of places that the system keeps the LVB topped off from the HVB when it is parked or stored. You'll find out when you test your rig!

I wouldn't want to force the main contactors to cycle open/closed under load more times than needed if I can avoid it by leaving the MME 'on'.
 

ChasingCoral

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I wouldn't want to force the main contactors to cycle open/closed under load more times than needed if I can avoid it by leaving the MME 'on'.
Good point.
 

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