Are there certain necessary specs for a portable jump device?

[prius2pony]

There seem to be 100 brands & models of small jump start devices, and no two "Top 10" list I've looked at have the same winners. Most devices list what size ICE engine it will turn over. If our MME 12v battery is dead, my understandings the portable jumper can bring that back to life. Am I right to assume that under no scenario are we actually charging the HVB via these handheld devices (i.e. putting a couple of miles on in an emergency)?
What minimum specs do you think are required to get the MME 12v up and running?

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[phidauex]

It wouldn't be much - maybe 40A for up to 10 seconds to allow the contactors to close and get the DCDC charging? I suspect even the smallest jump packs intended for scooters and motorcycles would be plenty.

Personally I bought a Noco Boost Plus, which is overkill for starting the MachE, but would cover most small and midsize vehicles I might come across on the road.

 

[prius2pony]

It wouldn't be much - maybe 40A for up to 10 seconds to allow the contactors to close and get the DCDC charging? I suspect even the smallest jump packs intended for scooters and motorcycles would be plenty.

Personally I bought a Noco Boost Plus, which is overkill for starting the MachE, but would cover most small and midsize vehicles I might come across on the road.

"DCDC"? Please spell out for this non-automotive guy. Thanks.

 

[generaltso]

"DCDC"? Please spell out for this non-automotive guy. Thanks.

Direct Current to Direct Current. It’s what uses the high voltage battery to charge the 12V battery. Kinda like the alternator in a gas car.

 

[prius2pony]

Direct Current to Direct Current. It’s what uses the high voltage battery to charge the 12V battery. Kinda like the alternator in a gas car.

SO I've found a couple of other, similar threads. Do I have this right...A dead LVB needs the "jump" so it can wake up the systems in the car, which in turn will allow the Main 88kwh battery to start restoring the charge to the LVB. Is that right?

 

[RickMachE]

Yes

 

[generaltso]

SO I've found a couple of other, similar threads. Do I have this right...A dead LVB needs the "jump" so it can wake up the systems in the car, which in turn will allow the Main 88kwh battery to start restoring the charge to the LVB. Is that right?

Correct.

 

[AKgrampy]

Yes

I am going to have to do some reading on this. I accept that this is accurate; however, I thought the HVB will charge the LVB whenever the LVB hits a low voltage threshold (even when the vehicle is not operating.) My curiosity is how does the DCDC start operating correctly after if failed to keep the LVB in the proper charge state? I am sure there is a bunch of info on this topic and I will read it later.

 

[generaltso]

I am going to have to do some reading on this. I accept that this is accurate; however, I thought the HVB will charge the LVB whenever the LVB hits a low voltage threshold (even when the vehicle is not operating.)

It does. But not if the LVB is completely dead.

 

[Tom L]

SO I've found a couple of other, similar threads. Do I have this right...A dead LVB needs the "jump" so it can wake up the systems in the car, which in turn will allow the Main 88kwh battery to start restoring the charge to the LVB. Is that right?

I look at this a little differently based on my experience with my PHEV (Honda Clarity) and a small portable charger as referenced by the OP. I think the portable charger does not charge the Mach-E's 12V LVB but provides the current necessary for the HVB to start and operate the car. Once started, the electrical system (HVB?) starts charging the 12V LVB to the extent it can hold a charge. In my case, my 12V battery would not hold a charge so I would have to repeatedly use my little portable charger until I replaced the 12V battery. It doesn't take much juice to actually start an EV because you are not spinning a starter motor until the gasoline catches fire.

 

[Mach1E]

Yes

I thought there are multiple threads that ended in a flat tow because it wouldn’t take a jump unless the HVB was plugged in.

 

[generaltso]

I thought there are multiple threads that ended in a flat tow because it wouldn’t take a jump unless the HVB was plugged in.

Those were caused by issues other than a dead LVB.

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