12 Volt Lithium Battery...Possible ?

Discussion in 'Gen 3 Prius Technical Discussion' started by TruSound, Feb 24, 2012.

  1. ducatiduke

    ducatiduke Junior Member

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    Gang- Porsche has had this upgrade on some of their models for some time. In fine German fashion, it is bloody expensive to gain a little more performance out of their cars. Its kind of cool if you think about it. Perhaps more car companies will do this - at least in the sun belt.
    Cheers!
     
  2. windstrings

    windstrings Certified Prius Breeder

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    I bought this for my 1507cc motorcycle.. It's a beast.
    Yes, it's a drop in replacement for my old lead acid.
    Yes, it obviously has all protection circuitry already in the battery.
    It warns not to charge more than 14.8 volts into it "all protection circuit can handle". Here are the specs. Search Results
    2A peak, / 30 watt max. / 36 Amp hour
    Charges at 14.4V 12V 36AH 540CCA LifePO4 LFX
    Even with a much larger 12V battery, you still don't want to take the chance of running it dead or you won't be able to boot the computer that in turn starts the car. Much safer if there is a question to leave car in ready mode... It will cycle on and aff as needed, and much less often if you turn off any fan blowers and the mfd screen.

    I don't see an issue, I haven't studied physical sizes for easy drop in yet. But I don't see a reason to consider it unless it's just for fun or you other one died. The 540 cca of the lithium would never be utilized since it's just to boot the computer and run light accessories. No real reason to need prolonged accessory support without car in ready mode Anyway.
     
  3. David Beale

    David Beale Senior Member

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    Another possibility is NiMH. You can get rather large capacity NiMH cells (30 A-Hr), but you will need 10 of them for a 12V replacement battery. Cost would be just over $300. It would be slightly lighter than the stock battery but about the same size. It would charge just fine from the Prius system, just not to full capacity (perhaps to about 80%).
    Advantage - no damage from fully draining the battery or leaving it for months sitting.
    Disadvantage - it's a lower capacity battery, though this probably wouldn't cause any problems as fully draining it causes no damage. You would have to worry about "reverse charging" a cell or two if you did drain it down with a load.

    So yes, there are alternatives. Most are just not very practical. More expensive and "experimental".
     
  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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  5. windstrings

    windstrings Certified Prius Breeder

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    As with any new technology when the public isn't savy, supplies are sketchy, prices are all over the map.

    I remember when HID bulbs first came out how it was rape and pillage to try and buy a replacement.

    I see Lithium batteries "such as I bought" I picked up for 300.00 while others with half the capacity sells for 600.00 elsewhere. Seems the "automotive" sites stick you the worst... prob because thats the most cutting edge application and therefore the public isn't savy to prices yet.

    The main advantage to lithium is if your gonna leave your car unmanned for extended periods of time... like 6 months to a year or more... Lithium has phenomenal shelf life and will be there waiting for you with minimal loss when you get back.
    The weight difference is not worth considering for the money but the amount of juice you can pack into the same small space could be for special applications where someone can't or doesn't want to leave the car in ready mode.

    I"ve seen recent post after the storm of using the prius as a generator.. the 12V battery simply does not have the juice to feed to an inverter without the cars inverter constantly having to fire up "via ICE starting and cars inverter engaging".... its a lame way to keep power running... using a 25+K car to act as a 200.00 generator....your asking for trouble when someone trips over cords and shorts out something.
     
  6. jnadke

    jnadke Junior Member

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    NiMH would be bad, since it would develop memory problems being recharged every time the engine starts up. When you repeatedly discharge NiMH to 80%, then charge it to 100%, an oxidation layer builds up where essentially the 20% you've been using becomes the ONLY useable part of the battery.


    The problem is, the AUX battery is used to power all your electronics when the engine isn't running (stereo, cigarette lighter, main car computer, etc). Lead-Acid batteries are relatively cheap to replace, and are meant to have long life cycles. You'd be replacing the AUX battery a lot if you replaced it with a NiMH.

    Generally speaking, the AUX battery doesn't have to have a long life, just long enough until the engine starts up again.


    But yeah, as others mentioned, you can't just pop in a 12V Lithium battery. You need a charge controller, as Lithium batteries have maximums in the amount of current they can take. Now these probably exist, I'm sure in maybe some hobby RC car or power tool markets you could find the electronics.

    It's probably do-able, but I'm not sure you're entirely solving any problems, unless you like leaving your car idle to listen to the stereo a lot.
     
  7. jnadke

    jnadke Junior Member

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    These could actually work.

    These are actually Lithium Iron Phosphate batteries. They have no issues with charge sensitivity like Lithium-Ion batteries.


    The problem is, Lithium Iron Phosphate only has about 2x the energy (per pound -- which may be different than size) as Lead-Acid the car currently uses. It's not the 5x improvement Lithium-Ion can be.

    The advantage is, Lithium Iron Phosphate is safer. When a battery is overcharged, the only thing it can do with the extra energy is turn it into heat. Lithium-Ion and NiMH both decompose when heated (leading to catastrophic results). Lithium Iron Phosphate does not decompose (this does not mean the battery can't burn out -- it's just unlikely to start your car on fire).

    In a Lead-Acid battery, there's a lot of water in there to absorb the extra heat, which is why they're valued since they tolerate overcharging very well...


    As I said above, you're not really solving anything unless you like to idle the car a lot for long periods of time (20 minutes+) with the stereo on.... and don't want the engine turning on.


    The show-stopper is cold weather. Lithium chemistry doesn't like cold, and keep in mind the AUX battery powers the COMPUTER too that runs the car. By cold we're talking about 0 to 20 F.
     
  8. windstrings

    windstrings Certified Prius Breeder

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    You "can" simply drop it in as a lead acid replacement... That's what they are intended for. Motorcycles always come stock with lead acid and these are for motorcycle or similar replacement.

    There is some confusion about lithium batteries. When bought in the simple "non protected" form, yes they need a sophisticated controller. Usually the only use for "non protected" cells are very high amperage needs like in RC planes... They charge them to a higher voltage to squeeze more juice into the battery at the risk of getting to critical levels.

    But These have controllers built in to protect. The normal properties of the lead acid charging system does just fine.
    My motorcycle "without modifications" bring my lithium to 14.0 volts and no higher.

    As far as getting cold, it has to get real cold... Around zero to seriously limit voltage. The resting voltage "as well as under load" are already higher than lead acid anyway.
    Remember you are not turning over a car engine so very little amperage is needed.

    Even on my motorcycle they say in very cold weather to simply leave the headlight on for 30 seconds before you attempt high amperage starts. That will warm the battery up enough to make it more robust for the start.
    But as mentioned, that's a non issue... All we need is to boot the computer then the inverter pulling off the main traction battery reimburses.

    SCH-I535 ? 2
     
  9. jnadke

    jnadke Junior Member

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    My point was these batteries are not the same lithium batteries the newer Prius/Volt uses.

    The Prius/Volt uses Lithium-Ion (aka Lithium Cobalt) batteries. Charge controllers are required because these batteries are massive safety risks when they overheat. A full battery is just a resistor, so if you overcharge you don't harm the battery necessarily, but you dump a ton of heat into it and it can start on fire.

    The Lithium-Iron-Phosphate is inherently safer, because its less prone to break down when overheated. The charge controller is unnecessary for safety, only longevity.

    In this fashion, the charge controller is more simplistic, since you only need a diode to control voltage. With the Lithium Cobalt batteries the charge controller must be sophisticated enough to control voltage, current, AND temperature.


    But yeah, replacing the 12V battery with this one would be a worth-while upgrade, since it's more stable under storage. You don't need a charge maintainer.
     
  10. windstrings

    windstrings Certified Prius Breeder

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    I have mixed feelings... The lead acid is still good in both of my 2006's and no need for a muscle battery like in my motorcycle do I'm prob gonna do nothing unless it goes out... But then spending the bucks for calling lithium doesn't seem needed or cost effective.
    The main reason I did it in my bike is the massive 540CCA and longevity and no acid vapors to corrode stuff.
    If you did go lithium, you should be able to get a much less expensive battery since very little "cca rating" is needed... That may make it cost effective.
    They are definitely light and clean to operate!... A cool upgrade for those who appreciate the cutting edge and innovative.... Which is a large percentage of prius owners!

    Oh and Btw, the "Shori" battery I bought comes with two types of battery connectors. You shouldn't need any special adapters or connectors... It also comes with lots of compressed material to custom snug the fit into your battery compartment.... They thought of everything!

    SCH-I535 ? 2
     
  11. fuzzy1

    fuzzy1 Senior Member

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    Is that really true? I thought both used non-Cobalt members of the Li-Ion family. Here is post from someone else with a similar belief: prius plug-in batter vs nissan
     
  12. SynEco@eVehicle.co.nz

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    Just Upgraded the PRIUS 2004 12 volt Aux Battery to four ThunderSky LiFePO4 cells 40A/Hr.
    Battery weigh 6kg vs the Toyota 12V battery at 13 kg.
     
  13. David Beale

    David Beale Senior Member

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    NIMH cells do not develop memory. NiCd cells do.

    The lithium 12V batteries for motorcycles are for loosing weight, not extending the life of the battery.

    Putting a lithium battery in the Prius would not extend the non-use life of the battery. The 12V battery in the Prius is depleted by "parasitic loads", not self discharge. If you did put in a lithium battery, such as the ones made for motorcycles, it would work just fine with the charging system as they have circuitry for that. The -problem- would be the lithium battery would likely have lower capacity, so would discharge faster from the "parasitic loads". This would then get you closer to destruction of the battery as a lithium one will be damaged (destroyed) by full discharge. They do have circuitry inside that opens the circuit when they get too low on charge, but they will continue to self discharge after that and if left too long will be destroyed eventually.
     
  14. TheForce

    TheForce Ron Paul 2012

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    Are you using a BMS to top balance the batteries ( I would not trust any BMS that does this ) or are you running them bare and bottom balance them?
     
  15. C2Hopp

    C2Hopp New Member

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  16. bisco

    bisco cookie crumbler

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    that's the ticket...
     
  17. SynEco@eVehicle.co.nz

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  18. windstrings

    windstrings Certified Prius Breeder

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  19. Easy Rider 2

    Easy Rider 2 Senior Member

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  20. neez

    neez Member

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    Lithium batterys will explode and catch fire if abused. You can't just charge them with a straight 14v from the prius inverter which can't control current or voltage to the battery. You'll overcharge and catch your prius on fire.

    The other issue is this will not help with your fuel economy unless you idle your car for very long periods of time. Most likely, if you're driving, an optima yellowtop has more than enough juice to fun your fans and electronics until your engine starts up again. Only on worn out batteries does the engine start up prematurely to charge it. But a good condition battery won't make any difference by adding more capacity.
     
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