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Toyota Highlander Hybrid Battery Pack Questions

ulevulev Posts: 57
Since I purchased my HH 4wdi non-Ltd vehicle I have noticed that my traction battery status has fluctuated from time to time.

As I read my owners manual, I noticed several apparent anamolies.

1.)my status has never gone higher than level '6'..

2)often when starting up in the morning, my status level has been @ 5 or even level 4....
I have heard a sound from under the hood similiar to a motor whine after shutting down the vehicle.

I do not leave the vehicle in 'N', always in Park and do not leave any lights on.

Why would there be an apparent 'loss' of battery 'status'?? :confuse:

Ken, care to input ?


  • toyotakentoyotaken Posts: 897
    Couple of answers for you.

    1. The traction batteries (3 banks of them btw) are Nickel-metal-hydride, which to clarify for those who think that there is a large environmental impact for building these, there isn't. They are non-toxic and recyclable even with the non-toxic compounds. They are designed to be charged and discharged millions of times in their life cycle. They are not like a "convential" battery in that you don't charge them to "full charge" then discharge them fully. My understanding is that they work optimally between 60%-90% charge and the electronics on the HH and Prius automatically keep it in optimal charge state for life of the batteries. So answering your question, I wouldn't worry too much about not having "a full charge" on the screen as this is what is needed to have the batteries work optimally.

    2. NIMH batteries discharge themselves over time and even if your status indicator showed "6" when you stopped, they will slowly discharge just from sitting. Hence the recommendation that you don't leave the vehicle sit for months at a time without starting it occasionally.

    2b. The HH is similar to the Prius in that the coolant, once hot, and when you turn off the vehicle gets pumped into, for lack of a better term, a "thermos" inside of the engine compartment. This will keep the coolant hot/warm for a period of up to 3-5 days from my understanding. The reason for this is that cold starts are the worst time for any ICE (internal combustion engine) for both gas milage as well as emissions, so by pumping the warm/hot coolant into the engine when you start up the vehicle, it GREATLY shortens the time needed for the ICE to warm up, reducing emissions, and improving milage while allowing the engine to shut off sooner as it stays on to get it to operating temps as soon as possible.

    What you're probably hearing is either the pump shuttling the coolant, or these vehicles also test for "evaporative emissions" from the gas tank and there is a mechanical noise, normally several hours after it is turned off when it's doing that test. This is common on most Yotas, and if you go onto the dealer lot, look on the shift lever of vehicles which have just come off the truck and you'll notice a white tag on an elastic band explaining this for the customers as it can be disconcerting if you haven't heard it before.

    Hope this helps.

  • ulevulev Posts: 57

    Thanks so much !!

    Valuable info that I did'nt know before.

    Especially enlightening was item 2b...

    This vehicle is truly a tecnical marvel ! :blush:

    Thx again
    Al :shades:
  • toyotakentoyotaken Posts: 897
    You're welcome!

  • stevedebistevedebi LAPosts: 3,788
    "The traction batteries (3 banks of them btw) are Nickel-metal-hydride, which to clarify for those who think that there is a large environmental impact for building these, there isn't."

    You'll have to speak with Toyota corporate on this item; it is their own charts that show the higher pollution costs to manufacture the Prius over an ICE car, though they don't break down the reasons. One would assume it is the batteries, though I suppose it could be the electrical components...

    "he HH is similar to the Prius in that the coolant, once hot, and when you turn off the vehicle gets pumped into, for lack of a better term, a "thermos" inside of the engine compartment."

    I have read in these forums that the HH does not use the "thermos" system, for some reason.
  • toycashtoycash Posts: 139
    That's good information, but the Highlander Hybrid does not have the coolant storage tank like the Prius.
  • toyotakentoyotaken Posts: 897
    Thanks for the update, I'll keep that in mind and confirm. If I find out differently, I'll be sure to post it here. We all learn things every day.

  • dunebuggydunebuggy Posts: 4
    This weekend AAA had to jump start my new HH in my garage! My wife had left the passenger side door ajar overnight. Now you would think with as many batteries there are in this car you
    should never have to jump start it! I traded a Landcruiser for this HH and not once did I have to jump start it! I don't know if this has been a problem for anybody but it sure sucks! :lemon:
  • molokaimolokai Posts: 313
    The traction batteries have NOTHING to do with the lights when the vehicle is off. The only battery you are relying on is the little battery that boots the computer. I think that Toyota should have a safeguard against this. I once left the reading light on one night, but nothing happened.
  • tomslycktomslyck Posts: 70
    I bought a little inverter to plug into the outlet by the back hatch. Does anyone know whether this is powered by the big battery or the small one?
  • waltrdewaltrde Posts: 26
    If you are going to use an inverter I'd recommend using it sparingly when the HH is not running or buying the largest battery that will fit under the hood to replace the smallish stock 12 volt battery. All 12 volt accessories, including the power outlets are powered by the small 12 volt battery under the hood. The big traction battery packs only power the wheels. I'm surprised that people are running this battery down so frequently. The Highlander battery has to be twice of that in the Prius and I've read relatively few reports of people needing jump starts because the 12 volt had gone dead in the Prius.
  • phoebeisisphoebeisis Posts: 121
    Which battery energizes the gas motor starter-the small 12 volt?Hmmm,it does seem odd that the battery power would be so marginal.It takes a pretty stout battery to start a gasoline motor.I'm surprised that a door light (couple of watts)could discharge a battery like that in just 24-48 hrs.
    Now if the "traction battery" pack starts the motor,then I could see using just a tiny battery for "other stuff".
    What circuit runs the electric steering?I know the regen brake energy is sent to the battery pak.Does the battery pak run nothing but the wheels??Where does the electric steering get power?Same for the AC fan?Is the AC compressor run by an electric motor-?Does the major electric drive motor "run" anything else-you know,like driving a compressor like a gasoline motor?
    Lot of questions.Just let me know what works the starter and the power steering?Thanks.Charlie
  • I'm curious if anyone knows whether running the traction battery down is hard on it or will reduce its lifespan? In slow traffic and by driving carefully I can run on electric only until the battery indicator bottoms out, at which point the gas engine automatically kicks in. I admit it's hard to get it this low unless you're actually trying to, but its novel to run only on electricity when you can get away with it. Any opinion on whether this is bad for the battery?

    (ps - I never park it and leave it in a 'run down' state)
  • toyotakentoyotaken Posts: 897
    The 12v battery is primarily for getting all of the electronics up and running when you turn the key. It is also to keep the background electronics running when the vehicle is off. Such as the clock, radio presets, etc.

    The traction battery is used to power the vehicle when moving, the A/C, the PS motor, etc.

    Because the 12V battery does so little on the hybrids, they use a smaller one than in the conventional ones. Leaving the lights (headlights or interior) in most vehicles will drain the battery within 8-12 hours anyway, it takes about the same amount for the ones used in the hybrids. No difference there.

  • waltrdewaltrde Posts: 26
    Probably not something you want to do all the time, but the hybrid system wont let you abuse the traction battery. The computer control systems in the Toyota hybrids are programmed to keep the traction battery within an ideal range of charge and will not allow the traction battery to discharge below or charge above a certain safe point while the vehicle is in operation. This is to maximize the life of the battery. If the charge falls too low, the ICE will run to recharge the traction battery as you've noticed. The only way I know of to reduce the life of the traction battery in operation would be to block its airflow, causing it to overheat, so always keep the floor of the second row seats clear.

    The only way I know of to discharge the traction battery below the safe range is to park it for a very long time in a "run down" state.
  • Be carefull using an inverter in the HH. The max is 120 watts for the whole system. I bought an iGo from Radio Shack to power my laptop. It didn't seem very efficient to power an inverter and then step it back down to power the computer. The thing works great and also has a plug to charge my phone. What are you using the inverter to power?
  • ulevulev Posts: 57
    Ken, or others in the know, what company is the source for Toyota's traction motor batteries ??? :confuse:
  • toyotakentoyotaken Posts: 897
    I'm not at work right at the moment, but as far as I can recall, they're built by Panasonic. I also believe that Toyota is a large stock-holder in Panasonic as well. If I find out differently Monday, I'll be sure to post it here.

  • jackson4jackson4 Posts: 2
    I just bought a hybrid ten days ago, and had to go out of town for five days. This morning when I tried to start the car, the battery was dead. When I called Toyota service, the rep told me to jumpstart it, then bring it in to the dealership. He acted like he thought it was a common problem and seemed ticked off when I told him I didn't want to babysit a car so that its battery wouldn't die. I already have a Highlander and have loved it, but I don't want a temperamental car that I have to have someone come in and start for me if I go away. The tow truck driver said there was no reason that the battery should have died, as nothing in the car was left on. Has anyone else left their Hybrid for an extended period of time, and had this problem?
  • phoebeisisphoebeisis Posts: 121
    I have seen two other reports of having to jumpstart the HH.After checking around one found the dome light switch had been put on ON,and the other's wife had left the door ajar.The "standard" 12 volt battery is apparently kinda dinky-absolutely no bigger-heavier than it needs to be.It doesn't have a lot of reserve.Mess 9369or so) is one of the jumpstart victims.Luck,Charlie
  • Makes sense.

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