# Can you jump start a Prius?
**URL:** https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795
**Category:** Factual Questions
**Created:** [October 6, 2009, 9:04am UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795 "2009-10-06T09:04:56Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)
#### Post date: [October 6, 2009, 9:04am UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/1 "2009-10-06T09:04:56Z")
I assume you can’t jump start a Prius, but they just did it in this awful movie I was watching so I thought I would ask. I wouldn’t think the battery voltages would be compatible or that the power requirements would be in the right ballpark.
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### Author:  [@Broomstick](https://boards.straightdope.com/u/Broomstick)
#### Post date: [October 6, 2009, 9:19am UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/2 "2009-10-06T09:19:56Z")
The Prius does have a gas engine of some sort in it, it’s not entirely electric - could you jump start that?
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### Author:  [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)
#### Post date: [October 6, 2009, 9:28am UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/3 "2009-10-06T09:28:03Z")
Presumably, the gas engine is started by the weird Prius battery and there is not a separate starter battery just for the gas engine.
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### Author:  [@N9IWP](https://boards.straightdope.com/u/N9IWP)
#### Post date: [October 6, 2009, 11:21am UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/4 "2009-10-06T11:21:26Z")
The Prius has a 12v battery. It is used mostly to keep the computer running. The 12v battery is in the back but there is a terminal under the front hood for hooking it up.
If the 12v battery was dead you could boot up the computer by jump starting - but to get the engine running you need the big battery pack. If that is dead you prerty much have to go to the shop.
Brian
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### Author:  [@Turek](https://boards.straightdope.com/u/Turek)
#### Post date: [October 6, 2009, 12:11pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/5 "2009-10-06T12:11:20Z")
From the Prius manual:
> [@](#):
>
> The following procedures may be used to start the hybrid system if
> the vehicle’s 12 volt battery is discharged.
> You can call your Toyota dealer or qualified repair shop.
>
> If you have a set of jumper (or booster) cables and a second vehicle
> with a 12 volt battery, you can jump start your Toyota following
> the steps below.
>
> Open the hood and fuse block
> cover.
>
> Open the exclusive jump starting
> terminal cover.
>
> Connecting the jumper cables.
> Exclusive jump starting terminal on your vehicle
> Positive (+) battery terminal on the second vehicle
> Negative (-) battery terminal on the second vehicle
> Connect the jumper cable to ground on your vehicle as shown in
> the illustration.
>
> Start the engine of the second vehicle. Increase the engine
> speed slightly and maintain at that level for approximately 5
> minutes to recharge the 12 volt battery of your vehicle.
>
> Turn the “POWER” switch to ACCESSORY mode.
>
> Maintain the engine speed on the second vehicle and turn
> the “POWER” switch to ON mode, then start your vehicle’s
> hybrid system.
>
> Make sure the “READY” indicator comes on. If the indicator
> does not come on, contact your Toyota dealer.
>
> Once the vehicle’s hybrid system has started, remove the
> jumper cables in the exact reverse order in which they were
> connected.
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### Author:  [@Maastricht](https://boards.straightdope.com/u/Maastricht)
#### Post date: [October 6, 2009, 12:20pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/6 "2009-10-06T12:20:06Z")
When we just got our new Prius, we didn’t know yet that you have to drive it at least once every two weeks, or the battery will empty itself. So when I had once left the car stand still for a month (we do most of our stuff by bike) the battery turned out to be dead, and a mechanic had to come and jumpstart the car, and then I had to drive at least twenty minutes without stopping.
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### Author:  [@GaryM](https://boards.straightdope.com/u/GaryM)
#### Post date: [October 6, 2009, 12:35pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/7 "2009-10-06T12:35:50Z")
> [@Maastricht](#):
>
> and then I had to drive at least twenty minutes without stopping.
Sounds like the plot of a “B” movie! Good thing you didn’t get pulled over by the cops.
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### Author:  [@Philster](https://boards.straightdope.com/u/Philster)
#### Post date: [October 6, 2009, 12:40pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/8 "2009-10-06T12:40:29Z")
**Maastricht** , I would think you had to drive and keep the engine running when stopped… and that stopping was actually creating some of the electric charge required for the batteries.
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### Author:  [@Maastricht](https://boards.straightdope.com/u/Maastricht)
#### Post date: [October 6, 2009, 1:08pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/9 "2009-10-06T13:08:53Z")
> [@Philster](#):
>
> **Maastricht** , I would think you had to drive and keep the engine running when stopped… and that stopping was actually creating some of the electric charge required for the batteries.
:o This is correct, of course. I could stop the car, but not the engine.
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### Author:  [@Driver8](https://boards.straightdope.com/u/Driver8)
#### Post date: [October 6, 2009, 1:17pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/10 "2009-10-06T13:17:51Z")
As Turek shows, the owners manual does indicate you can do this.
I can tell you first hand that you can do this the other way round - just last week we used our Prius to jump start a Chevy Trailblazer.
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### Author:  [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)
#### Post date: [October 6, 2009, 5:53pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/11 "2009-10-06T17:53:44Z")
> [@N9IWP](#):
>
> The Prius has a 12v battery. It is used mostly to keep the computer running. The 12v battery is in the back but there is a terminal under the front hood for hooking it up.
>
> If the 12v battery was dead you could boot up the computer by jump starting - but to get the engine running you need the big battery pack. If that is dead you prerty much have to go to the shop.
>
> Brian
This is interesting. Why wouldn’t they design the system so that the big battery pack could jump the 12 volt by pressing a button. Why bother with a 12V at all? Wouldn’t more space for the big battery pack be better?
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### Author:  [@Gary\_T](https://boards.straightdope.com/u/Gary_T)
#### Post date: [October 6, 2009, 6:05pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/12 "2009-10-06T18:05:19Z")
> [@WarmNPrickly](#):
>
> This is interesting. Why wouldn’t they design the system so that the big battery pack could jump the 12 volt by pressing a button. Why bother with a 12V at all? Wouldn’t more space for the big battery pack be better?
A number of electrical devices – light bulbs are one example – are much more feasibly run on 12 volts than on the much higher voltage of the battery pack. Having a 12-volt battery for these is simpler and less expensive than incorporating a transformer (or whatever the appropriate component is) to provide 12 volts.
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### Author:  [@YogSothoth](https://boards.straightdope.com/u/YogSothoth)
#### Post date: [October 6, 2009, 7:22pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/13 "2009-10-06T19:22:53Z")
Yes you can jump start it, I’ve done it before. The procedure’s pretty much the same: Open the hood, hook the cables to the battery and a ground, hook the other end to another car, run that for a minute then turn the Prius on. Good as new.
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### Author:  [@Snickers](https://boards.straightdope.com/u/Snickers)
#### Post date: [October 6, 2009, 7:30pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/14 "2009-10-06T19:30:33Z")
> [@Driver8](#):
>
> I can tell you first hand that you can do this the other way round - just last week we used our Prius to jump start a Chevy Trailblazer.
Yep - we had to use my husband’s Ford Escape hybrid to jump my '85 Corvette just this weekend. Mr. Snicks wanted to take pictures.
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### Author:  [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)
#### Post date: [October 8, 2009, 12:12am UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/15 "2009-10-08T00:12:32Z")
> [@Gary\_T](#):
>
> Having a 12-volt battery for these is simpler and less expensive than incorporating a transformer (or whatever the appropriate component is) to provide 12 volts.
Transformer wouldn’t work – this is DC, not AC, and transformers only work on AC. You’d need an even more complicated \* expensive component.
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### Author:  [@coremelt](https://boards.straightdope.com/u/coremelt)
#### Post date: [October 8, 2009, 12:21am UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/16 "2009-10-08T00:21:29Z")
> [@t-bonham@scc.net](#):
>
> Transformer wouldn’t work – this is DC, not AC, and transformers only work on AC. You’d need an even more complicated \* expensive component.
there are plenty of dc-dc converters and they’re no more complicated or expensive than an ac-dc transformer.
> **[DC-to-DC converter](https://en.wikipedia.org/wiki/DC_to_DC_converter)**
>
> A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter. Power levels range from very low (small batteries) to very high (high-voltage power transmission).
> Before the development of power semiconductors, one way to convert the voltage of a DC supply to a higher voltage, for low-power applications, was to convert it to AC by using a vibrator, then by a step-u...
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### Author:  [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)
#### Post date: [October 8, 2009, 8:55am UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/17 "2009-10-08T08:55:25Z")
Wouldn’t a resistor act as a simple DC to DC converter. It would be very inefficient, but wouldn’t it be effective for a long enough to jump start the small battery with the big battery? It seems like such an obvious function. Why should you have to find another source of power to start your car when you’ve got a massive NiMH battery right there?
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### Author:  [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)
#### Post date: [October 8, 2009, 11:35am UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/18 "2009-10-08T11:35:39Z")
It sounds as if the designers have taken care that the car can be recovered from a blackstart situation. That is where there is no power in anything. Thus they have designed it so that you can start the car, with a totally dead main power store, with just the secondary, seperate, standard 12 volt system. And further, they have ensured that that subsystem can be started when it is dead with normally available (i.e. another car) power. One might argue about avoiding a subsiduary battery, but you could easily end up in a very difficult to recover from situation. So, if the designers didn’t do it this way, I would be asking very hard questions.
As mentioned, a lot of conventional car electronics are alreday designed to work off 12 volts. I can’t see Toyota suddenly deciding to go out and specially craft new electronics for the higher voltages for no good reason, and at great expense. The electornics of a modern car is a very complex place when it comes to electronics. There can be dozens, if not more, processors, many communication busses, and a wide variety of critical sensors and actuators. All of these are designed around 12 volts. Most, if not all, are not made by the car manufacturer.
A big DC-DC converter would be a solution, but it adds expense, complexity, and you end up back with the very nasty failure mode whereby the car is not jump-startable.
The beauty of the Prius, in many ways, is that it is a conventinal car in all respects except for the add-on electric genemotor, its power controller, and batteries. A total failure of that system leaves you with a perfectly useful conventional car. It makes a great deal of sense to keep the two halves well seperated.
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### Author:  [@natural](https://boards.straightdope.com/u/natural)
#### Post date: [October 8, 2009, 4:13pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/19 "2009-10-08T16:13:34Z")
Yes, but can you PUSH START it? 😉
Roger
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### Author:  [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)
#### Post date: [October 8, 2009, 4:33pm UTC](https://boards.straightdope.com/t/can-you-jump-start-a-prius/512795/20 "2009-10-08T16:33:54Z")
> [@Francis\_Vaughan](#):
>
> It sounds as if the designers have taken care that the car can be recovered from a blackstart situation. That is where there is no power in anything. Thus they have designed it so that you can start the car, with a totally dead main power store, with just the secondary, seperate, standard 12 volt system. And further, they have ensured that that subsystem can be started when it is dead with normally available (i.e. another car) power. One might argue about avoiding a subsiduary battery, but you could easily end up in a very difficult to recover from situation. So, if the designers didn’t do it this way, I would be asking very hard questions.
>
> …
I thought it was mentioned upthread that if the big battery pack were dead, you had to take it into the shop. I thought that jump starting only worked for the little 12V battery being dead.
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