I would be more confident of not damaging my Leaf's electronics if the Leaf's battery +ve was disconnected first. It's a normal 12v battery so can support jump starting. Once the other car has started, leave the donor battery connected for a few minutes to charge it back up, especially if the ICE required a lot of cranking.

Also, if you don't disconnect the battery from the Leaf's wiring, the BMS will start the DC-DC converter when the 12v battery voltage drops. A cranking load on it, may overload the converter as well as draining the LiOn battery more than you'd want. (the BMS is not expecting the 12v battery voltage to drop suddenly to well below 12v so you may have warning messages and fault codes logged)

 

I'd say avoid it, would be my personal thought. No point having two cars out of commission as a result!

 

Isn't it it the case that the best ICE is an ICE that's not running? So why bother?

 

Just need to start it up so it can get to the breakers yard.

 

I’d say yes, I’ve used my Niro to jump start my Leaf, and my Leaf to jump start my Insight.

 

But have you tried the riskier jump start of an ICE? Different kettle of fish from starting an EV

 

A bit risky if you fry some of the eNiro's electronics.

You might get away with it, but if you do it wrong, what then?

 

You won’t have done because you started it up and therefore the DCDC converter is chucking out a kilowatt at 12V

 

I'd combine 2 of the above.... run my eNiro for half hr, THEN disconnect the 12v battery, jump the ICE. Leave the ice connected for a few mins, then disconnect it, and re-connect the 12v battery.

One caveat though - do we know if disconnecting the 12v causes problems on the Niro? Will you need to put in radio codes etc?

 

One caveat though - do we know if disconnecting the 12v causes problems on the Niro? Will you need to put in radio codes etc?

Good question. Out you go and try it.

 

I’ve done this on a Kona (so practically the same as the eNiro) to a Mazda MX5 🙂
Worked no problem... think I’ve done it three times, no issue

 

Just buy a lithium ion "car jump starter for £35 of Amazon.
Keep it in the glovebox for a useful back up in case the e-Niro battery throws a sulk too.

 

Good idea, especially for MG owners as it would double the range

 

Also for detail, I did this live, with the Kona fully on/ready to drive, but in P, with the handbrake on. Red cable first, direct from the Kona battery 1st to the dead car battery, then black cable, direct from the Kona battery 1st to the dead car engine lift eye or something else metal... I didn’t really leave it much time & just started the other car.
Then carefully removed the leads & moved the cars 🙂

 

Very risky, you were lucky.
The problem is that when the ICE (assuming it was an ICE) starts, it's alternator will try and charge both batteries and disconnecting whilst this is happening can cause spikes.
Given the amount of electronics in an EV, it's a risk I will never take.
Just disconnect the EV's +ve battery cable from it's battery before jump starting and leave the jump leads connected for a few minutes after the ICE starts for it to charge up again.
Then switch off the ICE before disconnecting the leads.