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The Great Hybrid Battery Debate

SylviaSylvia Posts: 1,636
edited April 2014 in Toyota
The great battery debate is on!

What is the replacement cost? Is there a replacement need? How does this impact the total cost of ownership over the lifetime of the vehicle?
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Comments

  • Panasonic Prismatic HV NiMH battery used in 2004 Prius is rated for about 10,000 recharge cycles until capacity(amount of charge that hold) is reduced to about 80%(1.2KW) of the original(1.5KW). I would assume, you can still drive the car with 1.2KW battery but efficiency(mpg) would be less.

    image

    Panasonic Prismatic HV NiMH battery module.

    image

    Typical consumer electronic cylinderical NiMH battery. Note: Recharge cycle is only 500.

    Dennis
  • The latest generation NiMH battery used in 2004 Pruis are prismatic(rectangle) shape. It has higher power and energy density.

    image

    Prismatic Module Spec:

    Nominal Voltage: 7.2V
    Nominal Capacity: 6.5Ah
    Speceific Power: 1300W/kg
    Speceific Energy: 46Wh/kg
    Weight: 1040g

    Cylindrical Module Spec:

    Nominal Voltage: 7.2V
    Nominal Capacity: 6.0Ah
    Speceific Power: 800W/kg
    Speceific Energy: 40Wh/kg
    Weight: 1090g

    Dennis
  • First, let me clear up the vague use of "battery". There are many types of batteries. The most polluting types are lead-acid, Nickel Cadmium(Ni-CD)and button(Mercury) batteries. Lead, Cadmium and Mercury are heavy metal that pollutes the environment if they make contact with human directly or indirectly.

    Ni-Mh battery used in Prius is much more environmental friendly. Nickel and Metal Hydride are not heavy metal or toxic. Nickel can be found in 5 cents literally. There is still the need to recycle Ni-Mh batteries because Nickel recovered from recycling pays for itself! This is not true for other batteries.

    Dennis
  • 2004 Prius has 1.5 KWH(kilowatts/hour) battery and Civic Hybrid has about 1 KWH battery. How big is HV battery capacity compare to pure electric vehicle(EV) battery?

    Toyota Rav4 EV had 28 KWH EV NiMH battery to achieve 87 miles range when travelling at 60mph. That's more than eighteen times larger than Prius battery. In order for Rav4 EV to have the same range of hybrids(700miles), Rav4 EV will need to have 225 KWH battery! To be fair, acknowledge that Rav4 is a heavier SUV and Prius is a mid-size sedan.

    Dennis
  • midnightcowboymidnightcowboy Posts: 1,978
    Somehwere , it was stated I think by John that the Prius battery was 100 times the size of normaly batteries. Bascially kilowatt is 1000 ampere-volt hours assuming the impedence is purely resistive and does not contain inductive or capactive components. So the typically Prius battery is 1.5 KWH or 1500 WH or 1500 AmpVolt Hours. A typical starting battery is in the range of 600-800 AmpVolt Hours. Becuase the Prius 12 volt battery is only used in emegency situations then let's say it is only 300 SAmpVolt Hours. Thatt menas the Prius battery is only about 5 times as large as a normal battery in terms of true power: Killowatt or Ampvolt hours.

    The main reason that the voltage is inverted and increaste to 500 volts is because smaller wires can be used becuase the current is less.

    Powrer= current times volt times the angle between voltage and current (o for resistive, +/_ for inductive or capcitive) assume resistive.

    For example if the mote is a 2.5 Kilowatthour motor thatt menas the instantaeous power is 2500 watts or 2500 amp hours. If that is deliver by 12 volts then a current of 208.3 amperes while the same motor running 500 volts would only require a current of 5 amperes. The smaller the amperes or current the smaller the wire is need and the less loss due to impedence.

    P.S. - Were you awre the Prius can only go in reverse via the eletric motors. The ICE can not supply reverse power. Does that mean the Prius is a mild or soft hybrid in reverse?
  • "Were you awre the Prius can only go in reverse via the eletric motors. The ICE can not supply reverse power. Does that mean the Prius is a mild or soft hybrid in reverse?"

    Yes, I am aware. Prius ICE can not supply power to the wheel directly but it can power indirectly by generating electricity which then powers the main 50kw motor. Therefore, in reverse, Prius acts as a serial hybrid. Remember, the electricity generated from MG1 does not have to go through the battery, HSD can route power directly to the 50kw MG2.

    Dennis
  • nw1997nw1997 Posts: 227
    Can someone confirm this information. The cost to replace the Battery in the Prius is around $2,958.00. This is the battery that is in the trunk, in which is being constantly charged. The life expect. is 8/100K miles.
  • midnightcowboymidnightcowboy Posts: 1,978
    The battery is modular and you won't have to replace all modules; the cost should be much less than $2958. The warranty is for 8 years 100,000 miles or 10 years 150,000 miles if you live in California. No one has any idea how long the battery will last; they just haven't been out that long and there is not enough statistical data gathered. Toyota has given people an ample warranty to alleviate their fears on this new technology. Anyone who says different doesn't know either and to play up to FUD (Fear Uncertainty Doubt) is not good forum or business practice.

    If Hybrid battery life is your only concern, then I wouldn't worry about it and would go ahead buy and enjoy the new hybrid technology.

    YMMV,

    MidCow
  • The Rochester Hills-based firm said it and Cobasys LLC, its manufacturing joint venture, had entered into a settlement agreement with Matsushita Electric Industrial Co., Panasonic EV Energy Co. and Toyota Motor Corp.

    The settlement was reached through arbitration. As part of the agreement, Cobasys and Panasonic will cross-license each other on current and future patents to avoid litigation.

    http://www.freep.com/news/statewire/sw100650_20040707.htm

    Let the number increase and the price fall !!!!

    Dennis
  • gagricegagrice Pahrump, NevadaPosts: 31,450
    Let the number increase and the price fall !!!!

    I seriously doubt the price of NiMH batteries will get significantly cheaper. Batteries of all kinds have gone up in price no matter what the rest of the Electronics market is doing. The only competition is generic batteries that have proven themselves inferior to name brand. At least in all the ones I have bought. If you are counting on the price going down by the time you need to replace the batteries, I would be real surprised if they are. Hopefully the generous warranty will take care of all your battery replacements.
  • " Batteries of all kinds have gone up in price no matter what the rest of the Electronics market is doing."

    Consumer electronic AA Nimh rechargable battery prices has been going down since it was introduced. Not only the price, the capacity had gone up as well. When they came out they had 1500 mah rating(higher is better). Now, they have 2400 mah batteries for less than what 1500 mah used to cost!

    Dennis
  • Yesterday during the chat, someone mentioned that NiMH batteries do not have memory effect. That issue needs to be cleared up in detail.

    Short answer: NiMH do have memory effect but at a very slow rate.

    Long answer: Compared to AA NiCD batteries, AA NiMH batteries suffers much less of the memory effect. AA NiMH retains/remembers 80% of it's capacity after 500 cycles. Hybrid Electric Vehicle NiMH batteries' memory is 20 times better. They have 10,000 cycles until it is reduced to 80% of the original capacity. That is to show the rate of the memory effect. The battery is still completely functional after that point. Replacing the pack is up to the owner if he/she wants to regain efficiency of a new hybrid car.

    Dennis
  • gagricegagrice Pahrump, NevadaPosts: 31,450
    All I know is the NiMH batteries for my Canon S10 camera are about 25% higher now than they were when I bought the camera 3 1/2 years ago. I bought a cheaper generic battery and it lasted less than 6 months. All batteries are not created equal.
  • The life of HEV battery should not be measured with the miles it is driven but under what condition.

    For example, during highway cruising, the battery is rarely used. Another extreme case is, short and hilly blocks in San Francisco with stop signs at every corner. The battery would use up plenty of recharge cycles in this situation, only if you accelerate hard enough so that the battery supply power to the main electric motor.

    Dennis
  • "All batteries are not created equal."

    Very true. More importantly, not all chargers are created equal either! It is the cheap charger that damages the battery by charging too fast and over heating the battery. Overcharging the battery when it is full also damages the battery.

    The charger in the Prius is very intelligent and powered by 32-bit CPU. There are temperature sensors to protect the battery pack with active cooling system. It is also packed with the latest charging technology to prolong the battery life.

    Dennis
  • djasonwdjasonw Posts: 624
    According to what I've read, the computers manage the battery drain and so forth. What really kills these types of batteries is draining them down completely. The Prius computer does NOT allow this to happen. I have practiced this technique with cell phone and laptop batteries and it seems to work. Gagrice is correct regarding generics, they stink!
  • rfruthrfruth Posts: 630
    - snip -

    The 30-kW Sanyo battery pack sits under the rear carpet and forms the cargo area’s load floor. Inside the thin metallic cassette sit 250 nickel-metal hydride D-cells wired in series and producing 330 volt. You read that right. D-cells,the same size as, but not interchangeable with, the ones found in flashlights. Unlike said flashlight, an external cooling vent in the driver’s side rear window is part of the forced-air thermal management system. In hot weather it draws excess heat away from the pack, while an electric heater warms the batteries when the temperature drops. Ford says the system can handle temperature extremes from -40°º F to +122°º F.
    http://www.autofieldguide.com/articles/070402.html
  • Each NiMH cell is 1.2 volts. If there are 250 cells, then the total is 300 Volts. The pack will need to have 275 cells to get 330 Volts.

    Dennis
  • rfruthrfruth Posts: 630
    An example of new math or... I wonder if the Escape will use AC motor(s) or DC ?
  • robertsmxrobertsmx Posts: 5,525
    Why must NiMH batteries have 1.2V?
  • "Why must NiMH batteries have 1.2V?"

    Because of the chemstry of the battery. The voltage varies with the state of charge of the battery but nominal voltage is commly accepted as 1.2 volts.

    Dennis
  • gagricegagrice Pahrump, NevadaPosts: 31,450
    1.2 volts is the inherent characteristic of a NiMH Cell.
  • robertsmxrobertsmx Posts: 5,525
    Thanks both. Didn't know that, although I always wondered. I also know that the discharge characteristic is different from a typical alkaline battery (sustains voltage instead of losing it during the discharge). What limits the voltage though? In other words, a 9V NiMH battery isn't really a 9V battery (7-odd volts?), but what is the limiting factor?
  • "What limits the voltage though? In other words, a 9V NiMH battery isn't really a 9V battery (7-odd volts?), but what is the limiting factor? "

    Most 9V NiMH provide 8.4V. There are 7 1.2V cells connected in parallel. Some 9V NiMH use 8 cells to provide 9.6 volts. The trade off is in the capacity or the mAH.

    The battery that will be in Highlander hybrid or RX400h is said to have twice the power of Prius. It is not clear if it will have 403.2 volts with 6.5 AH or 201.6 volts with 13 AH.

    If you think electricity flow as a water pipe. The volt is how wide the pipe is and Amp per hour is how fast the water flows.

    Dennis
  • SylviaSylvia Posts: 1,636
    TODAY/Tuesday

    3-4pm EST
    noon-1pm PST
    Hybrid Chat Room
  • daysailerdaysailer Posts: 720
    First, I believe that you meant to say that seven 1.2V cells are connected in SERIES to provide 8.4V.

    Second, in your analogy, voltage would be the pressure accross the pipe while the diameter of the pipe is analogous to the impedance of the circuit. Current (amperes) is analogous to the rate of flow. In your reference to "amps per hour" I assume that you mean Ampere Hours which is the integral of current over time and is a measure of the energy delivered (at a particular voltage). Note that 1 amp for 10 hours is 10 AH, but only 1A per hour. You may be confusing battery capacity (AH) with discharge rate which is also important to a battery's rating since capacity will usually decline at high dicharge rates.
  • PF_FlyerPF_Flyer Pennsylvania Furnace, PAPosts: 9,403
    Be sure to check out our Town Hall chat lineup for Tuesdays... First up, talk the latest in new automotive technology during the Hybrid Vehicles Chat from 12-1pmPT/3-4pm ET
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    Mazda Mania Chat Room

    The Town Hall chats are a great place to take these message board topics LIVE. Hope to see you there this week!

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  • redly_oneredly_one Posts: 122
    NO NO NO

    If you stick a new module in with a bunch of dated modules, the results are bad. The old modules lose capacity over time, so their charge/discharge cycle is going to be far different from a new module. Not to mention how the algorithms in the BCM (Battery control module) will be farked up by adding a new module to an old pack....

    Just to clarify...when one module goes bad in a Prius HV battery pack, you will need to replace the entire pack.

    FWIW, I have tested modules from Prius battery packs (2001 and 2002)
  • redly_oneredly_one Posts: 122
    In a 2001 Prius, if the state of charge of the batteries was sufficient, the car would run full electric mode in reverse.

    We tested this quite extensively one night in a parking lot and monitored current/voltage/SOC/temp.

    The thing that I found interesting is that I could mush on the accelerator (in reverse mind you) and get going as fast as I could, and the highest current draw from the batteries we would see was around 30A. Which isn't so amazing when you convert it to HP (~24 HP). But at he time I was green and thought WOW.

    There were 3 guys in the car, each weighing ~200LBS, plus our test equipment.

    Oh, those were the days!!
  • john1701ajohn1701a Posts: 1,897
    > Just to clarify...when one module goes bad in a Prius HV battery pack, you will need to replace the entire pack.

    That is a direct contradiction to everything ever published about those modules and their controlers, both technical and real-world occurences.

    Please back your wild claim with a detailed explanation.

    JOHN
  • SylviaSylvia Posts: 1,636
    If someone has data they are sharing, let's not attack them. You may not agree with it or believe it, but it doesn't give anyone the right to be rude about it.
  • stevedebistevedebi LAPosts: 4,098
    Every battery powered device I've ever seen carries the warning not to mix battery types, and to replace all the batteries at the same time. So the Prius is different? Maybe, but unlikely.

    This is not to say one CANNOT replace only the bad batteries, but I doubt that the vehicle computers are programmed for this eventuality, since the variables are enormous (one variable in the total output for each battery that is new in an old stack). Most likely there would be some unusual warning messages from the computer, the severity would be based on how many old vs new, how bad the old ones are, etc.

    And I seriously doubt that you will ever get a Toyota engineer to say replacing some batteries in an old pack is acceptable. They will tell you to replace the whole pack...
  • rfruthrfruth Posts: 630
    Hey thats great you've tested the Prius traction battery tell us more can you ?


    And I also doubt that you will ever get anyone at Toyota to say replacing some batteries in an old pack is good enough. They want all the money they can get.
  • john1701ajohn1701a Posts: 1,897
    Then look at it from this perspective:

    It has *ALREADY* been proven that bad modules can completely (and automatically) be ignored without any negative affect on the pack itself. Then rather than multi-state support, you would have new-only support... which is another method of module replacement without the need for the entire pack.

    Now you have two examples to disprove.

    JOHN
  • stevedebistevedebi LAPosts: 4,098
    John,
    I don't doubt that the battery software controls account for gradual depeletion of the battery pack capabilities. If they didn't account for this, they would be idiots, because the packs are going to deplete over time.

    However, that doesn't mean the algorythm accounts for mixed old and new batteries. Maybe it does, maybe it doesn't. But (as was pointed out above), Toyota also would have no reason to want users to be able to replace a single battery, since they would get the return business of a new battery pack.

    The Prius depends on those battery packs. I have no doubt that there is capability to run with some battery modules out, but it is intended as a short term use, until the pack can be fixed. In general, the concept of messing around (in any fashion) with the batteries is unsound in a car that requires electricity to run.
  • gagricegagrice Pahrump, NevadaPosts: 31,450
    Very good point. I remember when radio control cars were the rage. You could change out one cell in the 6 cell battery pack, but it was never able to reach the voltage and current carrying capacity as a full new fresh set that were matched for peak voltage. No two cells are identical so to get a great battery you take the cells that will peak the highest voltage to build a super battery. Those were Nicad not NiMH. They try to tell you that NiMH does not have memory but I can prove otherwise with your laptop computer if it has not gone to the superior Lithium Ion batteries.
  • stevedebistevedebi LAPosts: 4,098
    The laptops and other small applications are different. The NiMh will gradually deplete it's capabilities if it is compeletely discharged. Toyota insists that since the Prius batteries don't fully carge or discharge, they will last for 10's of thousands of cycles.

    Considering the 8 year, 150K warranty, I bet they are correct.
  • gagricegagrice Pahrump, NevadaPosts: 31,450
    I wonder if they willingly put out that warranty, or were they coerced by CA regulators? I know with lead acid car batteries you can almost bet they will die the week after the warranty expires.
  • gagricegagrice Pahrump, NevadaPosts: 31,450
    On battery life expectancy: NOTHING with batteries that consumers own has an 8-year battery life.
    This was part of the debate that forced Toyota to warranty the Hybrid batteries for 8 years 150k miles. You may find it interesting as I did. This has been my skepticism from the start. Although with 8 years and 150k miles I would not fret over buying a hybrid.

    http://solstice.crest.org/discussion/ev/current/msg00392.html
  • rfruthrfruth Posts: 630
    Of corse nothing manages the batteries like a hybrid or costs like one either. Maybe if a cordless phone was $ 500.00 the battery would be managed better heck some $ 200.00 bicycle lightning systems that use Ni-MH batteries come with dumb chargers (they don't check the temp of the battery or for any existing charge, plug it in and the charger goes full tilt boogie even if it means cooking the battery) - but as you know auto manufacturers would offer zero warranty if they could, why risk warranty claims, for return business ?
  • gagricegagrice Pahrump, NevadaPosts: 31,450
    If I put 150k on a vehicle in under 8 years I would have no problem buying a Hybrid. Just get rid of it before the warranty is up. If batteries don't get hot in the charging stage and are not let go all the way down, they should last a good long time. I have a Dell Inspiron 7000 that is 5 years old and the battery is still good. I have a one year old Inspiron 4100 that won't run 15 minutes on the battery.
  • gagricegagrice Pahrump, NevadaPosts: 31,450
    On dumb chargers. I just changed the battery in a year old Panasonic cordless. It was Nicad and one cell would not hold a charge for more than a few minutes.
  • john1701ajohn1701a Posts: 1,897
    Poor charge management is why most rechargable batteries suffer shortened life.

    If your cell-phone shutdown at 40% and refused to power back up until you plugged it in, the battery would last dramatically longer. But instead, users drain the thing to totally dead on a regular basis. That's a huge difference from the way a system like HSD in Prius works.

    JOHN
  • john1701ajohn1701a Posts: 1,897
    NiCd rechargable batteries were inherently problematic. They suffered from memory-effect, were environmentally dangerous, and they could hold not as much power as NiMH. That's why NiCd is considered long outdated technology.

    JOHN
  • john1701ajohn1701a Posts: 1,897
    Another common hybrid battery misconception is that all the electricity feeding the motor comes from the battery-pack.

    While that is true for a "mild" hybrid, it is not for a "full" hybrid like Prius. In fact, 100% of the time the engine is providing thrust to the wheels it is also powering the generator-motor. The resulting electricity is immediately used by the thrust-motor.

    Preventing the battery-pack from being used as much obviously helps to extend the life of it.

    JOHN
  • gagricegagrice Pahrump, NevadaPosts: 31,450
    Question, I read an article that says the hybrid batteries are only charged by the regenerative action of slowing and braking. The writer said this caused problems on long uphill grades on a cross country test run. Is that true?
  • Becareful when someone use a general word "hybrid" since not all design were created equal. HSD can split power from ICE to generate electricity while climbing hills, assuming the hill is not steep enough to have spare power from the ICE.

    04 Prius battery ECU will not let the battery discharge below 40% SOC. The rest of 60% of the 1.31 kWH battery can provide 28 hp for 135 seconds. If you climb the hill at 60mph and the hill is so steep that the battery provides all 28hp for 135 seconds, Prius can trouble 2.25 miles before the battery SOC get to 40%. It is when the turtle icon appears.

    If the hill is not as steep and Prius main ECU request only 14hp from the battery, Prius can go up 4.5 mile long hill. That's a very long hill!

    I know you had bad experience with batteries. Let me give you another graph which shows the Cylinder D-shape batteries(Used in Japanese Prius) and Prismatic batteries(Used in US Classic Prius). They tested over 180,000 miles for Cylinder and 150,000 miles for Prismatic. Note that 04 Prius batteries has less Internal Resistence than last generation Prismatic modules. Basically, these batteries can keep going and going and going .....

    image

    Dennis
  • gagricegagrice Pahrump, NevadaPosts: 31,450
    That makes sense and goes along with what the writer was saying about the Prius. They were in the Rockies and he was trying to pass on a long uphill stretch. He could not feel the electric motor kicking in. He probably already discharged to the 40% level. So it was just the ICE which was not enough power to go around. I am not sure how fast he was going. I can't find the article now. I doubt it is that important. I am sure that the hybrid has forced vast improvements in battery technology. The last of the electric cars were also instrumental in improving NiMH batteries. I hope they are as long lived as Toyota is predicting. Thanks Dennis
  • stevedebistevedebi LAPosts: 4,098
    No, the Prius doesn't push the envelope in battery technology; it just makes sure the batteries don't get over charged or fully depleted. Nothing new there.

    It uses the plain old batteries, several years old technology...
  • john1701ajohn1701a Posts: 1,897
    Actually, it depends what you mean by "technology".

    The NiMH itself within the Prius battery-pack is record-breaking "technology". The energy-density is significantly higher than just "plain old batteries". Other NiMH simply cannot compare.

    JOHN
This discussion has been closed.