Motorcycle Batteries .. AGM, GEL, Wet, Lithium Iron Phosphate (LiFePO4)

Discussion in 'The Garage' started by _cy_, Jan 20, 2012.

  1. _cy_

    _cy_ Long timer

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    what an excellent question! ... glazed eyeball alert...

    to answer requires an understanding of how a LiFePO4 battery functions. how it charges back up and what happens as battery approaches fully charged state.

    first lets address how LiFePO4 cell discharges it's power. meaning it's discharge curve is not completely flat like a lipo or lithium cobalt cells. LiFePO4 drops 1 volt for the first 10% of discharge, then only drops about 1/2 volt for remaining 90% of power.

    Shorai's chart apply to all LiFePO4, cylindrical or prismatic pouch .. notice 14.6v or fully charged to 13.3v covers 10% of total available power.

    discharge curve is almost flat for remaining useable power. 13.3v to 12.86v is where useable power range occurs, less than 1/2 volt range. more power is available down to 12.73v for another 10%. but it's best not to drop below 12.85v for max battery life.

    [​IMG]

    now let's cover what happens during last part of charge cycle. which happens to be identical to discharge cycle but in reverse.

    when recharging a LiFePO4 battery first goes into bulk mode. when battery will basically accept all the amps you can throw at it. most chargers get no where near limits.

    as battery gets closer to full, LiFePO4 naturally slows down rate of current absorption. when current absorption slows down to milliamps or almost zero current flow at 14.6v. an intelligent battery charger will reduce voltage down to 13.6 range or float mode.

    if one removes battery charger before LiFePO4 is allowed time to fully absorb charge and current is still flowing at 14.6v. then battery's voltage will drop back down to voltage matching actual stage of charge shown on Shorai chart above. for instance if your 8cell LiFePO4 measures 13.1v with a known to be correct meter. it's at 40% state of charge.

    this is the principal that Optimate Lithium LiFePO4 chargers uses to balance cells without separate balance ports. Optimate lithium stops charge before LiFePO4 cells has reached full charge. then allows voltage to drop back down, then starts charge cycle back up again. each cell has different internal resistance that control rate of charge. by stopping charge cycle, then restarting ... this allows cells with less charge state a chance to catch up to cells with higher charge state. Optimate Lithium measure internal resistance to tell when LiFePO4 battery has reached optimal charge. which will different for different type LiFePO4 batteries.

    whew... got to stop typing .... too much info all at once puts most folks (including me) to sleep....zzzzz
    will cover your 8 cells LiFePO4 a bit later ..

    [​IMG]
  2. Honkey Cat

    Honkey Cat Tailights Fade!

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    I can only comment on my ballistic lithium battery which i found to be crappy in build quality. It worked until it caught a small fire and burned terminals. I currently have a braille lithium battery lite series and i am really happy with its quality and performance. IMO best ive seen and used.
  3. achtung3

    achtung3 Long timer

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    Hello CV,

    It seems to me that you have quite an extensive knowledge about this, mean while I have none and have a question.

    I bought a lithium battery for my bike and it is a Speedcell, I only ride the bike once a week or two weeks about couple of hours with stops, I take my battery off the bike everytime when I garage the bike, the battery sits in the corner of my kitchen because it is warmer than the garage so when I am ready to ride it starts the bike at first or second crank.

    The question is: Am I charging enough of the battery on my rides or am I depleting and wearing out the battery sooner than its programed to do?
    If the later what should I do to make it last longer?

    Thanks.
  4. _cy_

    _cy_ Long timer

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    thanks much for your valuable feedback ... real world experience is what counts.

    would you kindly tells us what model Ballistic, Braille and what bike it was installed in?

    just as important how bike was used .. super cold conditions far from support or always short rides from garage?
  5. _cy_

    _cy_ Long timer

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    thanks much for asking .. need more info to be able to answer..

    what bike and what battery?
    what temps bike operated at?
  6. achtung3

    achtung3 Long timer

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    It is an MV F4 05
    The bike itself runs hot, 160-190+.
    The normal temp around here is between 50-60, now somedays maybe in the upper 60's.
  7. _cy_

    _cy_ Long timer

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    OK got most of info needed, MV is a 1,000cc class modern bike being operated in mostly warm temps ... what size Speedcell?

    not familiar with Speedcell. with the rapidly adoption of LiFePO4 batteries by the motorcycle industry. unlike conventional lead acid mfg who's got LOADS of osha, epa, etc. etc. etc. to deal with.

    literally anyone can start a LiFePO4 battery business in their garage with little to no regulation.

    Speedcell appears to use A123 cells (26650) in 4s, then stacked in parallel to add more AH. 4cell = 2.3AH 8cell = 4.6AH and so on...

    recommendation is to add a hard protective layer around battery. LiFePO4 batteries with only a shrink wrap protecting metal straps that connect cells are especially vulnerable to dead shorts.

    if said LiFePO4 battery gets discharged HARD ... straps will get hot .. possibly melting shrink wrap. once shrink wrap is melted, metal straps are exposed. which could result in a fire from a dead short.

    shrink wrap is designed to be heated with an airgun. which then shrinks wrap around cells. heat from straps connecting cells will shrink wrap further. with a good chance of exposing strap, which could result in a dead short. IHMO shrink wrap alone is not a good choice for an outside layer on LiFePO4 motorcycle batteries. your mileage of course may veri...

    it's not unusual for a motorcycle to draw 200+ amps... 4.6AH battery discharge at 43C or 200amps. those tiny straps carry a LOT of current and can heat up.

    A123 (26650) cells are rated:
    • Maximum Continuous Discharging :70A, 28.0C rate
    • Maximum Impulse Discharging (< 10 sec): 120A, 48.0C rate

    [​IMG]
  8. Global Rider

    Global Rider Alps Adventurer

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  9. Global Rider

    Global Rider Alps Adventurer

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    That would apply to a GEL as well; part of the VRLA family.

    And that is exactly why a low self discharge in these batteries is a totally unimportant aspect to the user unless you are a dealer storing them on a shelf or disconnecting the battery.

    The parasitic drain far out does any self discharge drain.

    Its sort of like worrying about a 15 pound weight savings on a 500 pound motorcycle.
  10. Global Rider

    Global Rider Alps Adventurer

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    So tell me, why would a crude charging system on your average vehicle be OK to charge a LiFePO4 battery?

    Can you point me to a post in this thread that discusses the charging of these batteries.

    I mean, if the cells are in series, you definitely want to charge each cell individually for long life because charging them in a string does not guarantee balanced charging. What circuitry in detail is housed in any of these batteries to do so?
  11. _cy_

    _cy_ Long timer

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    "glazed eyeball alert"

    which batteries? there's been several posts on charging for several different chemistries ..

    it's been stated many times already ... but here goes again.. reason why LiFePO4 matches a 12v charging system when a lithium cobalt (LiCoO2) doesn't match a 12v charging system is ....

    voltage for a 4s (4 in series) LiFePO4 ranges from 12.85v to 14.6v ... almost all 12v charging systems charges at 13.8v to 14.2v. then factor LiFePO4 discharge curve ... 14.6v to 13.3v constitutes about 10% of power available. 13.3v to 12.85v represent the majority of power available. at 12.85v 20% remains... at 12.75V 10% remains... don't go below 12.85v for max life.

    hope I've not lost everyone yet ... this means a standard 12v charging system mates to LiFePO4 in 4s config almost perfectly without mods. then factor LiFePO4 are extremely stable and hard to catch on fire.

    main drawback to LiFePO4 batteries for motorcycles is cost ... due to raw cell costs .. LiFePO4 mfg have only so much room to work with. unfortunately due to marketing pressures ... some mfg have been forced to inflate Amp hour ratings into PB/EQ. IMHO this has resulted in folks buying LiFePO4 batteries too small for the job. which results in unhappy customers.

    and yes to some folks .. saving 22lb (925 odyssey 24lb vs EarthX ETX36 3lb 11oz) on a 368lb bike (R80G/S dry) is worth the extra trouble and $$$. to others... NO way, much cheaper to loose 15lb of blubber :D ... AGM still works excellent.

    now let's take a brief look at lithium cobalt (LiCoO2). which are the cells used in Boeing 787... Lithium cobalt (LiCoO2) batteries are inherently unstable and need all sorts of safeties to keep li-ion batteries from going to thermal runaway (explosion)

    before we cover lithium cobalt (LiCoO2) voltages ... let's cover why LiCoO2 need overcharge protection. a single LiCoO2 cell operates between 3.65v to 4.2v fully charged with a very linear discharge curve. LiCoO2 is fully charged at 4.2v, but will accept current so long as current is delivered until thermal runaway (explosion) occurs. what makes LiCoO2 inherently unstable is the tiny window this happens in... overcharging a LiCoO2 cells by little as 1/2v could cause that cells to go into thermal runaway (explosion) which then overheats neighbor cells, which then also goes into thermal runaway .. and so on...

    this is why Boeing installed insulation walls between cells. so if any one cell goes into thermal runaway, hopefully neighbor cells will be insulated and not be drawn into a chain reaction.

    unfortunately Boeing doesn't have the option of changing to more stable LiFePO4 chemistries. as that would entail years of paperwork to approve new systems.

    now let's switch gears to why LiCoO2 doesn't match 12v charging systems. putting aside dangers of LiCoO2 going into thermal runaway.

    LiCoO2 operates between 3.65v to 4.2v ... in 3s config = 10.95v to 12.6v fully charged... not a match..

    in 4s config = 14.6v to 16.8v or not a match for a 12v system charging between 13.8v to 14.2v.

    please read earlier posts detailing how Optimate Lithium LiFePO4 chargers balance cells without separate balance ports.

    ... clear as mud .. no ...
  12. Global Rider

    Global Rider Alps Adventurer

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    The one pointed out in my post.

    Lets not go off topic.

    You stated
    So again and based on your statement, why would a crude charging system on your average vehicle be OK to charge a LiFePO4 battery?
  13. _cy_

    _cy_ Long timer

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    1. sorry I'm not understanding what you are asking?

    2. already answered in detail in last post (#472) why a standard 12v charging system is an almost perfect match for LiFePO4 batteries in 4s config.
  14. Bli55

    Bli55 -

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    Installed 12-cell Antigravity YTX10 in place of Yuasa lead-acid.
    Weight 1.2 vs 3.2 kg!!!! :clap

    Shall try and remember to write about its performance in a year or so... :D
  15. _cy_

    _cy_ Long timer

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    thanks for dropping in ... all feedback are welcome!

    12cell antigravity = 6.9AH actual .. an excellent battery
    what model motorcycle and what's the coldest temps bike will need to start at?
  16. Global Rider

    Global Rider Alps Adventurer

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    Well you told one poster...
    I am assuming by PB you are referring to lead acid battery chargers. If that is the case, how is charging of Li-Ion batteries handled by a charging system that cannot be much cruder than the alternator in a car or motorcycle?


    So they are charged as a string...in other words in a series of 4 Li-Ion cells. Thats not good. What controls the charging of each individual cell then?

    Is there a charging controller within these Li-Ion batteries. A simple yes or no will suffice.

    And since most if not all voltage regulators regulate to 14.2 to 14.4V on your average vehicle, how is a string of 4 cells fully charged? Its not!

    BTW, what company do you work for at the moment?


    Also...."Which is more reliable ... Points or Electronic Ignition for Airheads?"

    One is more maintenance-free...problem is, it cannot be repaired roadside. When electronic ignition fails, you are walking. I can get my points system running again.
  17. _cy_

    _cy_ Long timer

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    have already posted an elegant answer in post #472 on why LiFePo4 in 4s configuration is an almost perfect fit for 12v charging systems.

    have you actually read it? sorry for having to dive into technical mumbo jumbo, but to answer some type questions. it just cannot be avoided.

    #472 was written in the simplest possible manner and still be technically accurate. unfortunately it's not possible to answer certain questions with a simple yes/no. for instance not all LiFePO4 batteries are constructed the same. some have internal BMS (battery management system) some don't ... some have charging balance ports, some don't ... and so on.

    yes PB = lead ... which as you know includes several different types of batteries. each has a slightly different charging profile. for instance gel cell batteries should not be charged much over 14.2v. so if you leave a gel cell on a battery maintainer/charger that puts out say 14.9v without a float mode. given enough time, that charger will end up killing your gel.

    12v charging systems in automobiles and motorcycles almost universally will charge between 13.8v to 14.2v range.

    unlike battery chargers which run the gamut ... with output all over the place. one important factor is time .. killing a battery with incorrect voltage from a charger requires time. this is why using the wrong battery tender/charger can be fatal for batteries. it's hooked up to battery for months at a time.

    if you take the time to actually read a few post back. several posts have already been put up explaining in technical detail how certain chargers work with AGM, Gel, wet PB and LiFePO4.

    getting tired of typing ... besides for most folks including me ... reading too much of this type material all at once will put you to sleep zzzzzzzz...
  18. Global Rider

    Global Rider Alps Adventurer

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    Which post number?

    You never did answer who you worked for at the moment.
  19. Global Rider

    Global Rider Alps Adventurer

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    A piddly year?

    Lets try in at least ten years. Then we'll know if it is any good. :wink:
  20. Global Rider

    Global Rider Alps Adventurer

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    That why we use the Xantrex TrueCharge 2 charger. You select the charge algorithm. And it has temperature compensation where it counts...at the battery, no on the circuit board.

    Others like the Battery Tender, Optimate, CTEK...well....no further comment.