Jump starting another hybrid vehicle with the RAV

[Yugguy1970]

I have had a search but can't find a definitive answer.

Can I use the +ve fuse box point in the RAV to jump another hybrid (my inlaws Cross), or do I need to use a good old fashioned petrol car?

Cheers

[Roy124]

I have read you should not use a hybrid but not sure if that meant HEV to ICE.

[Tee_J]

1 hour ago, Roy124 said:

I have read you should not use a hybrid but not sure if that meant HEV to ICE.

Really...? Good to know! Thanks!

[Yugguy1970]

Aye that's what I read, you can start another hybrid but not an ice.

Ironic really, we ended up using their ancient Peugeot 206 to jump their 2021 YC.

[Roy124]

IIRC, on a conventional jump start you run the live car.  During the jump process the live Battery is fed by the alternator which can supply sufficient power to run the other car starter motor.

With the HEV, even with its engine running,  it is not designed to provide that power.

[Tee_J]

11 hours ago, Yugguy1970 said:

Aye that's what I read, you can start another hybrid but not an ice.

Yikes!! 😱

8 hours ago, Roy124 said:

With the HEV, even with its engine running,  it is not designed to provide that power.

Double crikey!! 😱 😱

Last year...or maybe 2022, I helped a neighbour jump start their ICE car - a Mercedes Benz.

If I remember right, even with the jump, their car did not immediately start - seemed to still struggle....so much so that the chap asked me to rev the engine! 😁 Of course with a hybrid when not rolling but in Park, you can try to rev the engine but it doesn't - at least mine didn't. The engine simply cut out.  I did put it in Drive and then tried revving again - having forgotten to engage both the "hand" brake and normal brake, and ended up nearly ramming the chap into his car and slamming into his car to boot! Quick reactions saved the day! (pheew!)

So I guess now I can see why it wasn't as smooth as I expected it to be. Very good to know. Does this apply to all ICE vehicles or is it ok where the vehicle to be jumped is of the smaller/lighter variety...?

Many thanks for the information folks!

[Rav Rob]

Had this issue recently when my daughter managed to leave the lights on on her ICE car, I was about to dash off to rescue her, then remembered I couldn't, so had to grab the wife's ICE car instead.

I since then got the Halford's 6-1 jump pack which is really good and I keep it charged up (once a month or so) so its ready to grab and go, its a hefty jump starter, self contained tyre compressor that works well, light, USB power bank, even has a small 240V mains output & 12V lighter socket in a chunky unit. for £99 I love it.

[Rhymes with Paris]

I thought it would be a good idea one summer to park up my old lexus 200 in town and watch the world go by for a bit.

With it being a bit hot, I left my 12v fridge box in the boot running for cold drinks and pork pies for refreshments.

This fridge had previously run for 8 hours plus without the engine running in my diesel Citroen, no problem.

So after a couple of hours watching the local wildlife screeching and jumping up and down, I got bored and tried to start the engine,of course the dreaded click click,dead.

So I rang my pal Denzel, and he turned up eventually,a bit tricky as my car was on a one way, and he had to go bonnet to bonnet to reach.

Well he had a " breakdown do-it- thyself" box containing very short jump leads,a few odd spanners, and a pair of pliers.

Now this box never had the word "top" written on it with marker pen, so every single time it was deployed it would deposit all of its contents on the road.

His habit was to turn off his engine prior to jump starting another, I presume in an attempt to flatten both batteries, so after turning his engine back on ,we got going.

The local wildlife took a few minutes off from pointing at passing aeroplanes to enjoy this pantomime, I believe it's still talked about to this day amongst those customers of the Spoon's that was opposite at the time.

[Roy124]

50 minutes ago, Tee_J said:

Yikes!! 😱

Double crikey!! 😱 😱

.....

If I remember right, even with the jump, their car did not immediately start - seemed to still struggle....so 😁 

Connecting your good (12.5v) Battery in parallel with the duff (9.5v) Battery will result in an applied voltage to the dead starter motor of 11v.

Reving your good ICE car will generate 14.5v, the output 12v, and your dead car starts.  It might hiccup but it should start.

Your HV will provide that additional 1v too but as soon as the dead starter tries to draw that 12v the output from the HV will drop and possibly not recover.

Will it wreck the HV?  I don't know, but there may be protection circuits that think the HV is at fault and may cut the system. 

I might be talking crap, but it's just my rationalisation.

 

[Tee_J]

6 minutes ago, Roy124 said:

Your HV will provide that additional 1v too but as soon as the dead starter tries to draw that 12v the output from the HV will drop and possibly not recover.

Will it wreck the HV?  I don't know, but there may be protection circuits that think the HV is at fault and may cut the system. 

"...gulp...!" 😱 Thank God I didn't do any damage to my Battery... Car still runs like a dream... 🤗

[Roy124]

1 hour ago, Tee_J said:

Yikes!! 😱

Double crikey!! 😱 😱

 😁 

So I guess now I can see why it wasn't as smooth as I expected it to be. Very good to know. Does this apply to all ICE vehicles or is it ok where the vehicle to be jumped is of the smaller/lighter variety...?

You might manage with a smaller diesel.   My E Class Battery was enormous.   It was specified for stop/start* though mine did not have SS.  I don't know it's rating but it was about 3 times the size of a Yaris or Corolla Battery.

*while the Toyota hybrid has stop start this is an entirely different process from the ICE stop/start.

 

[Tee_J]

Well..this sucks! I hate to now not be in a position to help family and friends - and other folks, with jump-starting their cars... 😳

My previous MPV (hate the term "SUV"!) was a Sharan 2.8 VR6 and with that I could jump-start anything...well nearly anything... 😅 trucks, buses...any large vehicle was out of bounds! Lol!

[Rhymes with Paris]

What I do know,is if you go the jump leads route, it's well worth getting the expensive ones, longer and heavier than the cheap ones, around £30 then early 2000s as opposed to around a tenner.

Easier to reach in tricky situations, and tend not to start smoking and melting the insulation when connected.

Always carry them now, but I might be behind the times a bit as I have now become invisible due to ageing.

[Yugguy1970]

The issue is pure ice cars have strong batteries that have to power a starter motor, whereas we have basically a duracell 12v for the computer and it can't really drive an ice Battery.

 

[Mjolinor]

Best way to do it is both cars off

connect jump leads

start the good car

leave it for 10 minutes or so

then engine off

disconnect.

start the other car

That way you are not likely to damage anything but there is always a risk with modern cars.

 

[Derek.w]

Its a lot cheaper just to call at Halfords for a jump starter pack or booster pack if you prefer.

[Roy124]

14 hours ago, Rhymes with Paris said:

What I do know,is if you go the jump leads route, it's well worth getting the expensive ones, longer and heavier than the cheap ones, around £30 then early 2000s as opposed to around a tenner.

Easier to reach in tricky situations, and tend not to start smoking and melting the insulation when connected.

I bought mine in a French Autoroute service area in the 70s.  They are suitable for a 24v Truck.   Still have them, testament to the accumulation of car bric-a-brac one collects over the years.  Don't need them now though.

My 19 cents snow scrapper, bought 60 years ago was fletched by a daughter.

The snow chains had to go as wheels got bigger.   

Still have my oil can etc etc