Irony

This is a true story, I swear I didn't make it up ... (I've never made up things on things on this forum).

Yesterday, I drop a friend at his place, and while backing up in his driveway, a man walks towards the car, and knocks on the passenger window.
I open it, and he says :
"Hi sir, my car just died, I think that the battery is flat, do you mind if I jump start it with yours"

and I replied :

"I'm sorry, but this is an electric car"

:twisted:

Weither or not the LEAF 12V battery would have supported the load of starting a gas engine, I don't know.

hah - that's great...but it actually brings up a very good question. Can you jump a gas-guzzler with the Leaf? Does the manual have any reference along these lines?

I'd suspect that you could...maybe the real question is - would you want to? :lol:

I have jump started a Prius with a Prius. There is even special contact points under the hood for doing it. No idea if the Leaf has such contact points but since the Leaf uses a standard 12 volt system I would not be surprised it can do the same. Hopefully the solar option will prevent a Leaf from needing a jump start itself!

By the way the reason the Prius needed a jump was that the hatch was not shut all the way so the interior lights remained on until the 12 volt battery was so low the car would not start. Of course "start" in this case is really "turn on" in the Prius just like I suspect it is in the Leaf.

Why would you not let him put his boost cables to the 12v battery?
Does the manual warn against this?

BTW what are the specs on the 12v battery?
group size, CCA, Reserve minutes, etc

"Jumping" a "12v-dead" Prius takes only a LITTLE current to get the dead Prius going.

Starting an ICE typically takes hundreds of amps.

I say, do not try it (except a L&D emergency), even though it might work.

With the LEAF OFF, the HUGE discharge rate on the LEAF's 12v battery might damage it.

With the LEAF ON, you might possibly blow out the LEAF's DC-to-DC converter.

smkettner said:

Why would you not let him put his boost cables to the 12v battery?
Does the manual warn against this?

Click to expand...

I think Gudy did the right thing - unless Leaf manually specifically talks about how to use the battery for jump start - I'd not do it either.

If the manual doesn't talk about it - that is a good question to ask Nissan ...

garygid said:

With the LEAF OFF, the HUGE discharge rate on the LEAF's 12v battery might damage it.

Click to expand...

The LEAF 12v battery is a fairly standard car/light-truck lead-acid battery.
I'm certain it would have no trouble at all starting the stranded car.

The battery is probably the last part that would be damaged.
Would I jump-start an engine? No way!

While the battery would be just fine, I wouldn't want the current surge and transients going through the Leaf's circuitry and the back end of the DC-DC converter. Unless the manual specifically says "go ahead", I wouldn't try it.

In fact, if I was receiving a jump-start in the Leaf (from a tow truck or ICE car), I would ensure that the donor car is OFF to keep the power rails quiet. Automotive electricity is a nasty place.

I probably would have been fine to jump the guy's car off of the LEAF - and would have made an excellent photo op if you ask me! The battery surely has the guts to do it, and if you're worried about the electronics just pop the positive terminal connector off.

Not sure why you'd ever have the LEAF in the receiving end of a jump-start, though. :roll:
=Smidge=

Smidge204 said:

Not sure why you'd ever have the LEAF in the receiving end of a jump-start, though.

Click to expand...

I thought it was said that if your 12v battery died that the car would not start. In that case you would need a "jump start" to get some power for the car to turn on and then start using the big battery.

The battery in the LEAF is a bit small, but it is a standard PbA battery. With the LEAF off, I would have given him a jump, assuming he wasn't driving some giant diesel engine or a large V8. I probably would not try with the LEAF on due to the large transients that the DC-DC may not be expecting as others have mentioned.. Though any half decent engineer would have designed the DC/DC with protections for this, probably not worth the risk.

Gary is right. the Prius cannot jump a regular car which could need a hundred amps.

not sure that you should jump a car with the Leaf either. regular cars need enough power to crank over an engine. your Leaf only needs enough to boot up the computer.

From the looks, it is the same size battery as some ICE civics have.

Assuming the "dead" battery is just discharged, and not really "dead-dead", the other way to "jump" is to let your battery (or 12v system) charge their battery for enough time (maybe 20 minutes) to recharge it enough to be able to start their car by itself.

This method is much less risky, since you can disconnect the "jump" while they try to start their ICE.

turbo2ltr said:

From the looks, it is the same size battery as some ICE civics have.

Click to expand...

try jumping a car when your car is not running. the battery alone rarely has enough boost on its own. alternator input is almost always needed

Right.
Battery output voltage, possibly around 12.5 with small or modest current flow?

Voltage needed to charge at a "slow" rate might be 13.5 volts?

So, the 14 volts or more and "healthy" current from the alternator usually charge the batteries OK.

But, the LEAF's DC-to-DC might only produce 12.5 volts, like a battery might?

At least he didn't ask you to siphon some gasoline

I might have given it a shot, but removed all connections to the 12V before trying. Looks like a substantial enough battery for it but unless there is specific language in the owners manual I would limit the exercise to the 12V battery only.

I agree.

DaveinOlyWA said:

try jumping a car when your car is not running. the battery alone rarely has enough boost on its own. alternator input is almost always needed

Click to expand...

If that's the case, how does the battery have enough power to start the car it's installed in? Why wouldn't it have enough power to jump start another vehicle without a running engine attached?

All you're doing is hooking the batteries up in parallel. Using the donor car's engine to charge the other's battery is not actually necessary unless the stuck car has an actual fault in the charging system.
=Smidge=

GroundLoop said:

garygid said:

With the LEAF OFF, the HUGE discharge rate on the LEAF's 12v battery might damage it.

Click to expand...

In fact, if I was receiving a jump-start in the Leaf (from a tow truck or ICE car), I would ensure that the donor car is OFF to keep the power rails quiet. Automotive electricity is a nasty place.

Click to expand...

The LEAF does not have or need a starter motor/alternator. When a 12v dies it's usually dead so the LEAFs 12v system is off until it's replaced... or is it? Does raise a question of what does the LEAF do when it's 12v system fails. Will its 12v functions run off of the propulsion battery and tell you to replace the 12v??? I think it's going to be a bit of an adjustment for everyone regarding the simple anatomy of Electric Cars. The people with Owners Manuels might be able to verify more on this and if jump starting is recommended for gas cars.

Smidge204 said:

DaveinOlyWA said:

try jumping a car when your car is not running. the battery alone rarely has enough boost on its own. alternator input is almost always needed

Click to expand...

If that's the case, how does the battery have enough power to start the car it's installed in? Why wouldn't it have enough power to jump start another vehicle without a running engine attached?

All you're doing is hooking the batteries up in parallel. Using the donor car's engine to charge the other's battery is not actually necessary unless the stuck car has an actual fault in the charging system.
=Smidge=

Click to expand...

well, it all depends on how dead dead is. a very low battery will IMMEDIATELY cause a drain on the good battery that the good battery may not be able to overcome without the car running.

now, i guess i am old, but remember in the old days when alternators put out enough to say running even if you disconnected the battery? i cant tell you how many times we had to take the good battery out and put it in the car to jump it and put the bad battery back in the car afterwards.