Jump starting another car....

AAF?

or

FAA?

Nope.....i't's.......

Automobile and Touring Club of Finland (AL)

International Clubs | AAA Exchange

 

I can't think of a reason not to jump start a car with a 12 volt battery from another car with a 12 volt battery if both are negative ground, which most are. The fact that a Prius has a separate 200 volt electrical system is irrelevant. You're not using that. The Prius 12 volt battery is part of the 12 volt electrical system just like every other car out there. I've jumped my Harley Davidson from a car but I wouldn't do the reverse because of the difference in battery size (and therefore capacity) but the Prius 12 volt battery is similar to most any car battery out there. I don't have a Prius anymore so I can't check the owner's manual to see what Toyota says but someone else might be able to check that and report back.

 

Really BAD idea.
If neither vehicle is "running" then if you make a mistake with the cables there will just be a big spark.

HOWEVER......if the donor vehicle is running and you make that same mistake, some of the electronics in the donor vehicle could be damaged and that might cost you more than the price of a tow.

Nothing wrong with jumping to or from a Prius.......if the disabled vehicle still has any life in it at all......and IF neither vehicle is running.

The biggest real problem is clear access to good connection points.

Having said that, I will never do any jumping with either of my hybrid cars because there are always better options........in my opinion.

 

There is a difference between connecting up jumper cables and trying to start another car and connecting them and just charging the other car without starting. I would only do the ladder if it was me, strictly to charge the other car battery.
There were specific instructions on the Gen 2 and I don't remember the details, something about blowing a 30 Amp fuse if I remember right. I haven't even checked out my Gen 4 yet.

This video shows no restrictions on a Gen 4.

 

When I do it on my gen 3 and 4 I just turn my car on, hook my cables to the dead car, and leave it running for a while. I then disconnect the cables and try to start the dead car. I never attempt to start the dead car while connected to my Prius.

 

If you insist on continuing to do that........connect the cables FIRST then start your car.
IF you get a HUGE spark when the last connection is made, STOP and disconnect.

Connecting to a disabled vehicle with an unknown problem while your vehicle is running can result in TWO disabled vehicles.

 

Tips? Sure…
Tip 1: If you don't know what you're doing, definitely NO!
Tip 2: If you do know what you're doing, YES, but take great care!
Tip 3: If you're not sure, read all you can about jump-starting Prii (Prius Chat is a great resource and has dozens of threads on the subject)
Tip 4: …er that's it, there is no Tip 4!

 

I don’t really jump random cars, just family or my lawnmower. I usually measure with a multimeter first to verify it’s just a little too low.

 

The Prius owner manual says not to jump any cars.

They do not say you cannot use the Prius to jump family. I do not know where you would connect the cables though,

 

When I had my Gen 1, I was content to do this:

1. Make my car READY.
2. Unplug my battery + cable at the battery. (Gen 1 and 2 have an unpluggable plug there. Went away in Gen 3.) In an ordinary car, you would never disconnect the battery while the car's running because it plays an essential role with the alternator and voltage regulator, but there's no such problem in a Prius.
3. Jump from my battery (now not connected to my car) to the other vehicle.
4. Disconnect the jumper cables, reconnect my battery to my car, and drive away.

Since moving to a Gen 3 and losing the convenient unpluggable battery cable, I've switched to just carrying a lithium ion jump pack in the glove box, and of course that turns out to be even more convenient, and takes up less space than cables.

I liked the looks on the faces of the family stranded in their lumbering old van as I walked up to them with a little box-with-clamps sticking out of my pocket. I also liked the looks on their faces when it started the van.

 

The Prius battery is not designed with the capacity to start an engine though.

 

My technique was generally to leave the cables connected for a while, that is, more about transferring charge to the other vehicle's battery first, rather than trying to directly crank the other engine from my battery.

Anyway, never had a problem. The Prius battery doesn't need more than about thirty "cold cranking amps" for its normal job in a Prius, but ends up able to provide a few hundred anyway, and much more if it isn't super cold.

One can probably find an engine too big, or a day too cold, for success to be guaranteed, I just never did.

I'm pretty sure a Prius aux battery will start just about anything my pocket LiIon pack will start....

 

That isn't necessarily true.
It has plenty of capacity to HELP start one if the resident battery is just a bit weak.
It also has plenty of capacity, if healthy, to turn over a small engine that is also healthy.

It was not designed with enough capacity to REPEATEDLY run a starter but that doesn't mean that it won't do it once.

P.S. I do NOT believe that it a good idea to jump to or from a Prius to another vehicle no matter how you do it.
But that doesn't mean that it is not possible.

 

At the risk of encouraging what may be a terrible idea, I have jump started two vehicles from my 2017 four touring. The first was a late 90s Ford Ranger. I don't know if I got lucky, but I took zero precautions and just hooked up positive to positive and negative straight to the Ranger' negative with total disregard for the order in which I attached to each terminal. I believe the Prius was still running during this time. I'm also fairly certain that the Ranger just had a low battery, because we didn't wait hardly 30 seconds before cranking it over and it started right up. After reading this forum for the last half hour, I decided to go ahead and jumpstart my 2016 eco two after it has been sitting for a few months. This time I was very careful. With both cars completely turned off, I started by attaching the negative cable to a ground on the '16 (dead car), then attached to the negative battery terminal of the '17 (donor car). I then connected to positive terminals, '16 first. With both cars hooked up, I started the '17 and let it sit for about 15 to 20 minutes. I turned off the '17 before disconnecting from the terminals in the reverse order. The '16 fired right up although with quite a bit of shaking/vibrating initially. The shaking/vibrating had been noticed previously - it was just a little bit worse than normal from sitting. I'm concerned that this may be due to head gasket failure... but at any rate, neither car appear to have suffered any negative effects from the jump start.

 

The second (jumping another Prius) probably wasn't much of a risk. The Ranger, with your Prius running (I assume you mean READY), that was probably a bad idea and you got lucky.

Part of the luck was that the Ranger only had a low battery, and started easily, and you didn't have any oopsies hooking up those cables while your Prius was READY. When READY, your Prius is supplying 12 volts through its DC/DC converter. There are a couple fuses on the path from there to your battery, and one of them (if earlier generations are any indication) is a PITA to replace if it blows.

The fuse, ideally, protects the DC/DC converter itself. The wild card is not knowing whether your particular DC/DC converter ever read that old Murphy's law corollary that went "an expensive semiconductor device protected by a fast-blowing fuse will protect the fuse by blowing first."

 

yessir - ready… and likely with the engine running seeing as how I had my 5 yr old nephew in the car and it was bitter cold so the heat was cranked up as far as it’d go to warm him up.

Thanks for weighing in…

After doing some homework before jumping my dead ‘16, I realized that it was very reckless to just dive in head first like that. The only thought running through my mind at the time was that it was a great opportunity to set an example for my nephew by showing him that it’s important that we always keep our eye out for random acts of kindness, especially when we see others that need help and we’re in a position to offer it.

It had been my experience for the past few years that Luck wasn’t something I’d seen much of. I think maybe I’ll rethink that though. Like the footsteps in the sand, I’ve probably just been blind to it.
-Always much to be thankful for. I appreciate you for confirming that fact for me.

*I’m pretty sure you’re saying that I was lucky that I didn’t accidentally touch the live cables to one another after hooking up the donor car - but thought maybe I should ask for clarification so I know exactly how to go about jumping someone safely in the future.

 

One way to stay out of trouble with jumper cables is to separate them (if possible).

start with just the red (positive) cable, connect it to the dead car positive post, then to helper car positive post.

then get black (negative) cable, connect to helper car negative post, and finally to dead car ground point (bare, substantial metal of car body, bolt or engine).

disconnect in reverse order.

 

Certainly you want to make darned sure the free ends of the cables never bonk into each other while the other ends are on a battery (donor or the donee). Sometimes I figure out a way to hold them in one hand between different fingers so I completely prevent them from knocking together.

Back when I did carry cables, they were a brand called Safe-T-Plug and they came apart in the middle with a big heavy insulated plug. Each plug side had an LED that would only light up green when that end was installed to its respective battery with correct polarity. You'd make sure both LEDs were on and then shove the plugs together. Even if there's a spark, it's there in the middle, well away from both batteries.

Most pocket jump packs come with the equivalent functionality built right in. They have an LED that shows when you have the clamps on the right way, and won't perform the jump until then.

(Some of them have an override button in case you're jumping a battery so dead the box can't even tell if the polarity's right or not. Before using that button, of course, it's on you to double/triple check you've got the clamps the right way.

 

I fondly remember Scotty Kilmer (YouTube car maintenance guy) using old-style jumper cables, connected both pos and neg at the helper car, then rambling around (while rambling verbally), holding the other two ends perilously close. Subliminal teaching.