Successfully jump started a truck this morning

[phidauex]

Headed to work this morning it was 1 degree F here, and I saw a guy with a dead truck on the side of the road, he had his hood open and jumper cables out, but no other obvious options. I waved to him and swung around to line up for a jump.

Here is where I'm very glad I did the quick 12V Access Ports mod! https://www.macheforum.com/site/threads/how-to-add-access-ports-for-lvb-connection-points.4107/

I left the car on and in P, popped the frunk, pulled the two plastic caps covering the 12V points, and connected the jumper cables. I told him not to crank right away like on a normal car, but to give it a minute to charge. I quickly fired up CarScanner to collect a little data - ha.

The LVB DC/DC settled at 40A, then moved up to 70A. We waited for about 2 minutes, then I told him to give it a shot - it cranked and fired right up. Looking at the logs later, DC/DC spiked to about 170A when he cranked, and then settled back down to 70A, then 40A after we were disconnected.

I put my plastic caps back on, closed the hood, and we took off. All in all very quick and easy. It was also a good reminder for me to move my jumper cables to the frunk - never know when it might be needed, and temps like this are no joke to be stranded in.

EDIT: Quick rephrasing of the datalogs after a closer look.

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[Gimme_my_MME]

I quickly fired up CarScanner to collect a little data - ha

Haha nerd

I mean well done with the good Samaritan job

 

[macchiaz-o]

I had no idea we could jump start another car from a Mach-E. For reasons I figured I just didn't understand, I thought EVs couldn't do that.

Tesla says not to do this in their owners manual.

Ford's owners manual doesn't say not to, and even shows one Mach-E starting another:

So I'm really happy to find out we can, @phidauex -- thanks! I'll put my jumper cables back into the frunk.

 

[phidauex]

I had no idea we could jump start another car from a Mach-E. For reasons I figured I just didn't understand, I thought EVs couldn't do that.

Fortunately I've been jumping vehicles with a small 12V aux system for years (Prius). I can see why some companies wouldn't want you to do it for risk of damaging the 12V battery, but when it is cold as hell I'd happily trade a few % of my LV battery life to help someone who could be in danger.

That said, I think the trick to jumping with an EV is just to wait a little while before cranking. On an ICE you just connect the cables, rev up the donor, and give it a crank. The donor car's big battery and alternator supplies plenty of cranking current.

On an EV, the battery is smaller, not designed for cranking, and there is a DC/DC rather than an alternator, which charges slower (by design).

So you should connect the cables and then WAIT - between 1 and 5 minutes should be plenty, depending on how seriously dead the receiving car is. Then give it a crank. That should limit cranking current on the EV battery, and be most likely to start the car without any harm to the EV.

NOTE: When I say "harm to the EV" I'm thinking of premature wear on the 12V battery - not "car blows up" kind of harm.

 

[zhackwyatt]

I had no idea we could jump start another car from a Mach-E. For reasons I figured I just didn't understand, I thought EVs couldn't do that.

Tesla says not to do this in their owners manual.

Ford's owners manual doesn't say not to, and even shows one Mach-E starting another:

So I'm really happy to find out we can, @phidauex -- thanks! I'll put my jumper cables back into the frunk.

You just have to rip up plastic in your car to do it.

 

[phidauex]

You just have to rip up plastic in your car to do it.

No kidding! They really needed to put a little hatch or door above the 12V points. There are some random hatches to nowhere in the frunk, but the 12V points get nothing?

I strongly recommend the 12V access mod - $5 worth of plastic caps, a 2" hole saw, and about 30 seconds is all it takes.

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