Jump Starting a Prius II

Discussion in 'Toyota Prius Family' started by xcel, Mar 11, 2007.

  1. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    ___A Prius II owner at the MaHG yesterday told a story of recently being stranded at an out of state Airport with little to no help from Toyota’s Road Side Assistance. What had happened is she left a light on in this Prius II and the 12V went dead. The Tow Truck operator Toyota had called for her was clueless as to what should be done and she was forced to rent a car for two days until Toyota sent out a competent tow-truck operator to jump start the Prius II. Not only did it cause a lot of unneeded mental stress but also a lot of wasted time and money. Let us hope this does not happen to anyone else.

    ___I am not sure what is contained in the Prius II Owners Manual as I do not own one but a jump start should be spelled out with pictures and warnings in the manual? The 05’s like hers apparently do not have a diagram/schematic or maybe it is written poorly enough so as to create a misunderstanding? Either way, consider downloading and printing out the following pdf from Toyota’s tech line and place it in one of the glove boxes. The guide gives a very nice overview of your vehicle as well as Emergency response and the particulars about jump starting a Prius II on page 22 and 23.

    2004 Prius II - Emergency Response Guide.

    Roadside Assistance

    The Prius uses an electronic Gear Shift selector and an electronic P switch for Park. If the 12-Volt auxiliary battery is discharged or disconnected, the vehicle cannot be started or nor can it be shifted out of park. Most other roadside assistance operations may be handled like conventional Toyota vehicles.

    Toyota Roadside Assistance is available during the basic warranty period by contacting:

    United States: (877) 304-6495
    Canada: (888) TOYOTA 8 – (888) 869-6828


    The Prius is a front drive vehicle and it must be towed with the front wheels off the ground. Failure to do so will cause serious damage to Hybrid Synergy Drive Components.

    Vehicle Operation

    Refer to the Electronic Key section (page 6) for vehicle starting/stopping and (page 15) for vehicle disabling information.
    • The vehicle may only be shifted out of Park into Neutral only in the ignition-on and READY-On modes.
    • If the 12-Volt auxiliary battery is discharged, the vehicle will not start and shifting out of Park is not possible. There is no manual override except to jump start the vehicle.

    Jump Starting


    The 12V Auxiliary battery may be jump started if the vehicle does not start and the instrument cluster gauges are dim or off after depressing the brake pedal and pushing the power button.

    The 12V Auxiliary battery is located in the cargo area. The rear hatch door will not unlock or open if the auxiliary battery is discharged. Instead, an accessible remote 12-Volt auxiliary battery positive terminal is provided in the engine compartment junction block, as illustrated, for jump starting.

    • Remove the junction block cover and connect the positive jumper cable to the positive terminal in the junction block.
    • Connect the negative terminal to the ground nut.
    • The High Voltage HV battery pack cannot be jump started.
    ___Good Luck

    Last edited: Mar 26, 2007
  2. hobbit

    hobbit He who posts articles

    Re: Jump Starting a Prius II.

    Hybrids are certainly not the only types of cars with 12V batteries
    in places other than underhood. [Not even considering the nice
    handy "jumpstart terminal", which is somewhat unusual.] But
    the 12V is totally usual, so that must have been a particularly
    clueless tow operator.
  3. tbaleno

    tbaleno Well-Known Member

    Re: Jump Starting a Prius II.

    I think the problem might have been the battery is in the back, but without power you can't open the hatch on some model years of prius.

    So you have to jump from the fuse box. Or something like that. But I agree with you that he probably was clueless. Even if a manual isn't very well written you would think that he would have been able to figure it out. And he even talked with someone on the phone walking him through it but he couldn't figure it out then either.

    Poor lady had to rent a car for two days. At least Toyota was nice enough to pick up the bill.
  4. Skwyre7

    Skwyre7 Well-Known Member

    Re: Jump Starting a Prius II.

    You can open the hatch in a Prius II if the battery is dead. It involves climbing into the back, and getting into the under floor storage along with the spare tire. The manual latch is in there. Of course, it's a pain to do all that, so renting a car might be easier.
  5. tbaleno

    tbaleno Well-Known Member

    Re: Jump Starting a Prius II.

    Some years (not sure which ones) don't have that manual latch from what I hear. Am I mistaken?
  6. Dan

    Dan KiloTanked in post 153451

    Re: Jump Starting a Prius II.

    Interesting choice of telephone numbers for Canada.

    CANUTEC *666.
  7. cuchulain

    cuchulain He who posts articles

    Re: Jump Starting a Prius II.

    Hello from Japan

    A little bit off topic but the Japanese manual for the NiMH HV battery in the NHW10 (Prius 0 ) says it can be jump started using 12V battery. Is this the same for Prius 1. I was wondering about this? Did it disappear in the Prius II. I may be interpreting incorrectly( have to check with the dealer next time).

    It has a dial under the trunk showing NiMH 288V/ charge/ fault

    Thanks Andrew:rolleyes:
  8. hobbit

    hobbit He who posts articles

    Re: Jump Starting a Prius II.

    A similar thing just came up on priuschat WRT the Ford Escape.
    Yes, the NHW10 model japanese Prius had a 12V-powered boost charger
    to push a few zoobs into the HV pack in the hope of being able
    to start the car's engine. Toyota dropped that for the NHW11
    [or u.s. "Classic"] and the NHW20 we call the Prius II. Ford
    kept the clue, though, and has a hybrid-battery jumpstarter.
    I haven't heard of anyone actually needing to use it yet.
    Last spring we did a little hack-job experiment and proved that
    it's quite possible to push charge into a Prius pack with a
    suitable power supply as opposed to Toyota's magic and very rare
    charger, but the process has to be watched carefully and done
    *only* long enough to get the car started and take over. On the
    other hand, the folks working on plug-in Prius mods via boost
    converters are sort of doing the same thing on the fly while
    going down the road...
  9. cuchulain

    cuchulain He who posts articles

    Re: Jump Starting a Prius II.

    Thanks Hobbit

    I read about Mazanitro Micro conversion PHEV using DC-DC converter to charge the HV battery. :rolleyes:
    I was wondering if 12V-powered boost chargeri could be used for this.
    12V RC packs would a lot easier to build.

  10. malibucarl

    malibucarl New Member

    Re: Jump Starting a Prius II.

    You can also hook up a battery charger to the same spots under the hood. I just did it this afternoon AFTER calling dealer to verify its OK.
    It takes a relatively short time vs other cars I've owned. I left it on about 15 minutes.
    The "smartkey" outsmarted me while closing the windows--the result I left the car powered up ALL night.
  11. NiHaoMike

    NiHaoMike Well-Known Member

    Re: Jump Starting a Prius II.

    Make a power pack with two 6v lithium batteries (the kind used in old digital cameras) by connecting them in series to a connector that would parallel with the existing standby battery when plugged in. If the standby battery runs down for any reason, plug in the power pack, wait a while, and then it should power up the car without a problem. A small solar panel with a proper charge controller can be used to prevent this problem in the first place. For those who park indoors, a 15v regulated "wall wart" with two diodes in series to drop the voltage to 13.8v would make a nice trickle charger.

    I'm not sure why Toyota did not do away with the 12v battery altogether and use a large capacitor and nonvolatile memory instead. Based on the (retail) prices I've seen for similar parts, it would actually be cheaper.
  12. hecojoe

    hecojoe New Member

    Re: Jump Starting a Prius II.

    My son accidently left mine on overnight because he had to take out a cd. In the morning it was basically dead. I wanted to turn it off but for some reason when the bqttery is extremely low you can't do that. I knew it was on because the green P light was lit. So I crawled in the back and disconnected the ground wire (not an easy task), waited 8 hours, re-connected and it was good to go.
  13. Tochatihu

    Tochatihu Well-Known Member

    Re: Jump Starting a Prius II.

    Several options for 12 v helper batteries have been mentioned. Any should work as long as they present a low enough internal resistance. An example of what probably won't work is a string of alkaline D cells.

    The most important thing is to never ever reverse the polarity when connecting external 12 v. Get that wrong and expensive Prius parts become ornaments. It has happenned; don't let it happen to you!

  14. R.I.D.E.

    R.I.D.E. Well-Known Member

    Re: Jump Starting a Prius II.

    Could you use the host vehicle as a battery charger instead of jump starting?

    It's an option on non hybrids when the jumper cables aren't heavy duty enough to get the amps for a straight jump. It won't work on a bad battery.

  15. Tochatihu

    Tochatihu Well-Known Member

    Re: Jump Starting a Prius II.

    Gary, yes.
  16. New Yorker

    New Yorker Member

    Re: Jump Starting a Prius II.

    Same thing happened to me too. I was about to warn my kids to turn off the the light "we are about to get home..." But the kids are kids and left the light on anyway. For two days the 12V battery is completely drained.

    If you like electronics, as I do, it is actually very easy to jump start a Prius. Any battery set close to 12V will work (8 D batteries, 10 AA NiMH rechargeables, 6-Cell lead-acid battery of any size, or Lithium 3-cell). I used my sons' Radio Controlled airplan LiPO battery (3-cell 11.1V 4Ah) connected the positive to the fuse box as the Users Manual depicted, and the negative to any part of the car metal body. Then just turn the Prius on. The Prius just needs the computer to function. After that the high voltage pack will start to feed the 12V via the DC-DC inverter. Disconnect my own portable battery right away.

    No need for heavy duty cable, because the 12V battery is not used to start the ICE engine as all non-hybrid cars. I used household wires which became warm after jump start but OK. The computer and lights and fans, mirrors... just use a few hundred watts of electricity. In comparison, a non-hybrid car uses 20 to 50KW of electricity to start the engine which requires extremely thick wires.

    Don't turn your Prius off for at least an hour, preferrably plan a long trip of a few hours. The 12V lead-acid battery needs a long time to be fully charged from a complete drain.
    Last edited: Sep 16, 2009
  17. picstart

    picstart New Member

    The Prius has much in the way of electronics. The issue is has Toyota used common sense in applying the electronics so as to be effective. A light being left on..a hatch left open is not a rare event in this universe. Toyota lacking much in common sense leaves the battery to drain down beyond its ability to start the car or even open the hatch. Now how useful is this? Perhaps if you are stuck at night in a snowdrift you might want the next 30 mins of light and are willing to sacrifice the ability to start the car and stay warm. Common sense I am guessing is to kill the power drain before the car loses it ability to start. Further the low battery voltage makes nonsense out of any diagnostic information so why even display it.
    Common sense says brakes and gas pedals working well is something drivers might want not the ability to run the radio until you need a jump start. Sure the manual is a good index if you work for Toyota but drivers want to see the most likely things that they may need to look up prioritized. As to the tow truck incident both the tow truck operator and Toyota in letting batteries drain down lack common sense. Sure I know you can open the hood pry of the fuse box cover and jump start from there but smart battery monitoring would make it unnecessary until the battery failed.
  18. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    I've set the passenger compartment dome light on our HCHII to be always off. It's irritating to be getting into a pitch-black car sometimes, but I got tired of dealing with near dead batteries after a door was left slightly ajar. I'd do the same thing to the trunk light, if it had a switch. We also have "map" lights, and they've brought the 12 volt to near death on one occasion, I just try to be vigilant with them.

    Bottom line, I don't think I should have to disable these convenience features. There's got to be a way to prevent catastrophic voltage drain. There likely is. But it will take legislation, and/or one manufacturer taking the lead.
  19. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    There ought to be a timer circuit on all lights when the ignition switch is not in the on position. I wonder what it would take to add one for all of those lights?
  20. msantos

    msantos Eco Accelerometrist

    One way to remedy the low battery charge issues due to a light left on is to go LED all the way on the inside.

    For instance, on my 2010 Prius as well as on my HCH-II, I replaced every single bulb I could on the inside (trunk+license plate+DRL, too).
    If the dome lights are left ON, the battery will still be OK next morning since the power draw is literally a fraction of that filament bulbs counterparts. While the light they produce is comparable in effectiveness, the color is that of a cooler white and it looks good too.



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