Jump starting another car using a Prius

[EricS]

Does anyone know how to jump start another car from a Prius? The manual tells how to jump start a Prius from another car, but not how do do the reverse. Since the engine will be off when the car is stationary, the 12 volt battery won't be being charged. Doesn't this mean that the Prius' 12 volt battery will quickly be drained by the other car?

[N9IWP]

The 12v battery on the Prius is probably not beefy enough to start a conventional car.

But, If you set it up in the jump start configuration, with ready on, the ICE will come on to charge the 12v battetry (or will come on to chare the big battery which charges the small battery)

If you levae it hooked up lang enough, you will charge the other cars battery. *Unhook the cables* and then start the other car.

At least that is how I think it would work.

Brian

[bookrats]

As I understand it, other cars can jump-start your Prius, but the opposite is not possible (or not practical, one of the two.).

There's a section in the Owner's Manual -- pages 238-241 -- that talks about how to jump-start your Prius.

[randalla]

Has anyone attempted using those jumpers that work from the cigarette lighter?

[DaveG]

Originally posted by bookrats
As I understand it, other cars can jump-start your Prius, but the opposite is not possible (or not practical, one of the two.).  

There's a section in the Owner's Manual -- pages 238-241 -- that talks about how to jump-start your Prius.

The only way to "jump" another car from the prius is to hook the other car's battery up to the prius (probably with the front jump-start lug in the fusebox), and let the other car's battery charge for a few minutes.

Then disconnect the prius before trying to crank the other car over.

If you try and crank with the prius still connected, you can blow the master fuse and then you're not going anywhere either until it's replaced.

Dave.

[tmorrowus]

I'd be careful trying that.

The other car's battery could be low enough that it'll pull the voltage on the Prius 12V battery so low it won't be able to run the computers and electronics in the Prius, so the Prius would shut down.

Maybe everything would be fine in the Prius if you disconnected the other car battery and started up, but you may have discharged the prius battery enough that it won't start the computers. That's unlikely unless you leave them connected a long time, but possible if the Prius battery is marginal to begin with. You might lose computer settings (e.g. front window auto-up) and it seems possible but unlikely that running the computers at too low a voltage could cause them to corrupt their EEPROM or other memories.

If there were other cars around I'd try using them to jump rather than the Prius. And if there were no other cars around, I might be afraid enough of damaging the Prius (and then having all cars disabled) that I might forgo trying this.

If I were in the middle of a desert and needed to start both cars, I might try the following MacGyver maneuver:

1. Disconnect the dead car battery from its car by removing the negative clamp.
2. Disconnect the Prius battery from the car by undoing one or both clamps.
3. Connect the Prius battery + to the dead battery + with jumper.
4. Connect the Prius battery - to the chassis on the dead car.
5. Start the dead car off just the Prius battery (note you'll need beefy jumper cables for this).
6. While car is running, connect the car's own battery back by reattaching it's negative clamp. Note that this will cause a spark and needs to be done with a gloved (insulated) hand, and that this is dangerous since you can shock yourself or cause an explosion with the spark.
7. Disconnect the Jumper cables, negative then positive.
8. Run the car until the car charges it's own battery.

This would avoid having the other car's battery bring down the Prius system voltage while engaged.

I'm not suggesting this since I've never tried it, just brainstorming here. In fact, there is a danger in that the other car likely depends on it's battery to act as a capacitor and smooth the spikes in voltage from of the alternator. It is possible the Prius battery may be too small to do that effectively, resulting in damage to the other car's battery.

[DOC]

I asked a Prius mechanic whether or not one could use those "cigarette lighter" gizmos to jump-start another car. He said probably not, but wasn't sure.

Regarding a Prius jump-starting a regular car, he indicated it probably could be done but the problem is that the Prius battery is not as powerful as regular 12 volt batteries on the road and so it just might not work.

A general rule of thumb, however, is that if you are going to use your car to jump-start another car, during the period when your car is charging the other car's battery, be sure and have your motor running to not totally drain your own battery.

[RobertO]

I really believe that, for the time being, we need to err on the side of prudence.

I routinely jump start folks in parking lots using heavy duty jumper cable connected to my Toyota T-100 3.4 Litre V-6.

But not my Prius. Most shopping centers have a security team that may/may not have a portable jumper kit. Then there's AAA, or "somebody else".

A few years back I bought a rechargeable jumper/battery kit from Costco for about 60 bucks. They still sell them. The newer ones have some "improvements".


I kept it in back of my truck or Mercedes depending on which rig my wife was going to drive out of town. She never had to use it, but I did (on both rigs and manyh other cars and trucks) It will turn over a big displacement engine easily.

Notwithstanding the weight factor, that may be your Good Samaritan "out" when driving your Prius and you come upon somewon in need of a jump start.

Bob

[DaveG]

Originally posted by tmorrowus
I'd be careful trying that.

The other car's battery could be low enough that it'll pull the voltage on the Prius 12V battery so low it won't be able to run the computers and electronics in the Prius, so the Prius would shut down.

You'd have to have the Prius in power-on mode to make this work effectively. When it's in "on" mode, the 12v system can draw from the high-voltage system so there's no chance of it draining the battery (it would just use the generator to keep the current up).

That said, I keep a big jumpstart-pack in the trunk of my Prius so I can jump other cars from that, in addition to providing me with a 110v inverter and a worklight. Works like a charm.

I wouldn't be keen to jump another car off of the Prius itself, but if it was an emergency, I wouldn't have a problem with it.

Dave.

[inventor00]

Just ran across this Toyota Prius 2004 Emergency response manual- mentions how to jump start (the Prius) , key issues, fire, etc. Very nice info- 26 page pdf.

http://techinfo.toyota.com/public/main/2ndprius.pdf