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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    a clarification about importance of cells remaining in balance within a series/parallel cell battery.

    it takes 4x LiFePO4 cells in series (4s) to make up correct voltage that mates to 12v system. prismatic cell batteries uses cells of different sizes to make up different AH batteries. number of prismatic cells always remain 4s for a 12v system.

    cylindrical cell LiFePO4 batteries also use 4s configuration to achieve proper voltage to match 12v system. there are several sizes for cylindrical li-ion cells. for instance 18650 denotes 18mm x 650mm ... the most common size used for motorcycle batteries are 26650 or 26mm diameter x 650mm long.

    A123 makes the highest quality cylindrical LiFePO4 cells... one 26650 = 2.3AH at 3.3v nominal ... so 4x 26650 in 4s = 13.2v @ 2.3AH ... an 8 cell 26650 uses two stacks of 4s cells in parallel to make a 4.6AH battery.

    12 cell 26650 uses three stacks of 4s cells in parallel = 6.9AH battery... add 2.3AH for each additional 4s stack in parallel, so a 24 cell battery has 6x stacks of 4s cells in parallel.

    if/when a single cell goes out of balance, that stack has a lower voltage than rest of stacks in parallel. which immediately will reverse flow to weaker stack. if out of balance cell is severe, due to lithium batteries low internal resistance, discharge to weaker stack will destroy battery.

    if I understand correctly, Joel has purposely unbalanced LiFePO4 cells in 4s to approx 8% differences and watched cells achieve balance again towards end of charge.

    will be recreating this scenario and many others during balance tests in progress ... more to come on this topic
  2. _cy_

    _cy_ Long timer

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    true enough Earth-X still has to prove it self in long terms tests. overcharge protection is limited to 3 amp on Earth-X balance circuits.

    as each cell reaches a set voltage, excess voltage is shunted off until a set point is reached. this allows cells that have not reached cut-off voltage to reach full charge.

    balance circuits will not work until full charge is reached. so balance circuit also acts as an overcharge protection circuit within limits. which are 3 amp on Earth-X boards.

    provided one doesn't jack up volts to push current into a 4s stack. LiFePO4 cells naturally reduces amount of current it will accept closer it gets to full charge. so a 3 amp limit should be plenty to prevent overcharge within normal charge voltages of a 12v charger.

    Antigravity is an excellent battery as proven by your dealership's zero failure rate for Antigravity. but don't underestimate advantage of your recommendation of correct size Antigravity battery for each bike. will the bike be used for Starbuck duties or Adventure bike duties to parts unknown?

    IMHO a major reason for failures for LiFePO4 motorcycle batteries is mfg under sizing recommended batteries. the dreaded combo of Cold short motorcycle rides with heated gear will result in a motorcycle that will not start the next morning.
  3. JoelWisman

    JoelWisman Long timer

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    I see what your saying. The balance circuit that earthX is using will prevent the kind of over voltage damage that occurs when a series of cells is badly out of balance through shunting from one cell to the next provided that the charging voltage does not exceed normal charging voltage. Yes I agree 100%

    But this isn't actual BMS over-voltage protection and will do nothing to stop the whole battery from being destroyed from over-voltage if the charging voltage becomes excessive.

    Something not that uncommon on a modern shunt regulated bike with a PM charging system is for the shunt to fail or the shunt ground to go bad. In this case system voltage climbs above 20 volts and even at idle, the F800GS for example has 11 amps of excess current available with all accessories switched off.

    In this case the earthX battery is likely to dramatically fail just as any other LiFePO4, or lead/acid battery for that matter because it does not have actual BMS over-voltage protection, nor for that matter does any other LiFePO4 or lead/acid battery for power sports i'm familiar with.

    Agreed?
  4. _cy_

    _cy_ Long timer

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    yes .. totally agree there is no overcharge protection in cases of regulator failure where voltage goes way over normal. Earth-X battery's 3amp limits would be swamped probably resulting in a melted battery.

    a BMS that could handle 200+amp loads would probably be bigger than the LiFePO4 battery itself. which is not to be confused with MOSFET that could be made to switch on/off 200amp under set trigger conditions. but as you pointed out earlier, more complexity = additional points of failure.
  5. JoelWisman

    JoelWisman Long timer

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    Transistors have come a long ways in the past few years

    '<a href="http://www.flickr.com/photos/joel_wisman/8526677893/" title="152218-2 by joel.wisman, on Flickr"><img src="http://farm9.staticflickr.com/8109/8526677893_191d75b1b0_z.jpg" width="640" height="426" alt="152218-2"></a>

    200 amp continues at 90c amb
    600 amp for 5ms 90c amb
    2ma drain, thats problematic
  6. _cy_

    _cy_ Long timer

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    amazing how far modern electronics has come. should be easy enough to key trigger point for said MOSFET to open/close at say when an over voltage condition exists.

    LiFePO4 reaches full charge at 3.65v per cell, 4s = 14.6 .. 4s x however many stacks in parallel = 13.2v nominal with a max charge voltage of 14.6v needed to achieve full charge.

    as you've found out during over voltage abuse tests ...cylindrical LiFePO4 cells will absorb an amazing amount of abuse and still keep working. li-ion cylindrical cells typically contain safety valves designed to open at set temps to release internal pressures. vs prismatic cells will balloon to vent pressures.

    normal 12v charging system operate 13.8v to 14.2v ... so if said MOSFET triggers at say 14.8v or what ever voltage slightly over 14.6v full charge condition.

    above would prevent battery from being destroyed by severe overcharge conditions like say when F800's voltage regulator fails. then when volts drops below say 14.8v, MOSFET goes back to it's Normally closed condition.
  7. Bli55

    Bli55 -

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    How so?
    Shunt regulators, clocks, memory etc. themselves eat a little current all the time. I also know many people using alarms with anywhere between 5-20 mA drain....


    As for cy's suggestion of employing such MOSFET, it sounds really good "on paper". :clap
    Could there be a drawback apart from extra conplexity? If such system fails, will the normal state be battery-connected (i.e. no problem) or battery disconnected (problem :D)?
    Could you make additionally this same mOSFET to disconnect the battery at LOWER than set voltage? :deal

    Than we'd have a battery that cannot be destroyed by failure of charging system, nor by cell reversal by severe discharge/imbalance!! :deal
    And yet still be able to start your bike in the morning!

    Now, I've seen enough to know things are never this good and simple, so what am I missing? :evil

    Only thing I can guess at is need for cooling since a MOSFET will be passing all battery current...
  8. JoelWisman

    JoelWisman Long timer

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    The current drain would be any time the battery output was on, and you would also need a control and sensing circuit that would draw current.

    You wouldn't likely need much cooling because it isn't normal for the battery to be passing large amounts of current for very long.

    Components like this are used in full BMS systems which do have over-voltage, under-voltage, and balance management already, just not in any power sports batteries I am aware of.

    The disadvantages are cost, some reduction of full output, complexity increasing odds of battery failure, fires, and that 2ma drain.

    If the circuit were very high quality then any increase of failures would be extremely small as well as chances of fire being hugely reduced. But we're talking more money.

    But 2 ma constant drain is a problem. By itself it would cause an earthX ETX18 to go stone cold dead in 4 months. Ad in some current for the sensing. circuit and the typical 1-3 ma most bikes draw all the time and your down to needing to charge the bike every 3-4 weeks of which avoiding is one of the primary sellers of LiFePO4 batteries over lead/acid.

    Also factor in that although the internal BMS could be well designed, what the industry usually opts for kills more batteries then it saves. On a smaller scale these circuits are already on nearly every li-ma and li-co battery pack on the market and when you find a failed one, more often then not if you tear out the protection circuit the cells are still just fine.

    It's a great idea and as technology gets better and cheaper it may hit the market and be an improvement, but so far has not.
  9. meijer's trails

    meijer's trails Been here awhile

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    Hi Cy, can you recommend a 6v 4ah LiFe replacement for a vintage Japanese motorcycle.bno electric start, only lights and horn. No turn signals.

    It was using the 6n4a-4d-1
  10. _cy_

    _cy_ Long timer

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    sorry not aware of anyone offering a LiFePO4 6v motorcycle battery. you'd have to build one yourself in 2S config.

    but why go to all that trouble? put the stock 6v battery back...
  11. _cy_

    _cy_ Long timer

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    ah .. but at what temperatures?
    and minor details but for how long?

    when temps drops ... that's when actual amp hour capacities, not PB/EQ comes into play.

    LiFePO4 at 14f AH capacity drops in half. don't forget your LFX18 actual AH is about 4.6AH, not 18AH. it's 18AH PB/EQ (lead acid equivalent) .. LiFePO4 warm up procedures requires amps flow to heat battery ... which lowers internal resistance, bringing back up LiFePO4's ability to deliver huge amps. above cold weather start procedure specific to LiFePO4 uses up amps ... assuming you've got a full charge, at a tiny 4.6AH ... your margin of error is slim indeed.

    LiFePO4 is no different than any other battery in that when current draw goes up, actual amp hour capacities goes down.

    this means if you only crank for say 1-2 second intervals .. your LFX18 will deliver a high number of crank cycles. but when you try to do extended 200amp cranks .. LFX18 will fall flat on it's face .. not because it's a bad battery. but because it's too small for the job!!!

    for Starbuck duties .. IMHO LFX18 is still too small for 990 ... certainly not for real Adv duties to parts unknown. go with AGM or if you've got the $$$ ... use largest LiFePO4 you can stuff into available space.

    don't forget Starbuck duties could include the dreaded .. Cold start, short ride with heated gear... don't be surprised if your 990 will not start the next morning at say 25f ...

    Joel Wiseman, one of the most knowledgeable techs on Adv, did an excellent video on this very topic... more detailed info within this thread ..

    <iframe src="http://www.youtube.com/embed/7SflmGhblRY?feature=player_detailpage" allowfullscreen="" width="640" frameborder="0" height="360"></iframe>

    <iframe src="http://www.youtube.com/embed/ySNbSZTgplA?feature=player_embedded" allowfullscreen="" width="640" frameborder="0" height="360"></iframe>
  12. _cy_

    _cy_ Long timer

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    look at what just come in the door ... Optimate Lithium 12v LiFePO4 battery charger.

    Optimate claims to be able to charge our motorcycle LiFePO4 batteries while balancing internal cells without balance ports.

    If true .. this would be the ideal LiFePO4 charger, especially for batteries without balance ports and/or internal BMS. Which includes almost all LiFePO4 battery mfg except Earth-X. Shorai are equipped with balance ports but not BMS. (my Shorai LFX36 contains internal BMS and balance ports) Antigravity comes without internal BMS or external balance ports.

    Getting ready to put Optimate to work charging up LiFePO4 batteries with cells purposely shunted into an unbalanced state.

    More to come ....

    note: All Earth-X batteries are built with an internal BMS (battery management system) which balances internal cells while providing overcharge protection to about 3amp.

    [​IMG]
  13. Bli55

    Bli55 -

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    _cy, :clap
    More battery goodness!

    REALLY Really interested in what you make of this "no need to think" charger as I'm considering getting one like it or something chunky with knobs to twist... :D

    I know you are a big fan of Earth-X, however....one thing stopped me ordering one (let's skip over the fact that none would fit in the standart compartment) - yes, they are waterproof, but only to IP66.

    Of cource, Antigravity don't provide exact info on their website (I assume IP66 or 67??), but at least they had one in a YTZ10-S case (BMW G650X) - decided on the larger 12 cell and will let you know how it gets on with battery duties...
  14. _cy_

    _cy_ Long timer

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    yup .. just finished unpacking Optimate Lithium LiFePO4 Charger ... and heaven forbid, reading the instructions :D

    more to come on Optimate ... you are not the only one wanting feedback on Optimate, which is a 12v LiFePO4 specific charger. designed to balance charge LiFePO4 batteries without balance ports.

    yup a big fan of Earth-X and Antigravity .. both are watertight.. but most importantly, smaller sized LiFePo4 models are able to deliver impressive 200amp cranking performance!

    really don't understand all this concern about how water tight a LiFePO4 battery is rated. for instance Shorai is not rated waterproof .. but as you can see in picture below... no bubbles are showing. I only dunked Shorai for about a minute and didn't do a dunk test with charging port open. No I didn't dunk Shorai for 20 minutes for the simple reason... even if I dropped my bike during a deep water crossing. there is no way I'm letting my bike remain underwater for very long. then if I really was worried about it... a dab of silicon grease would seal nicely.

    [​IMG]
  15. _cy_

    _cy_ Long timer

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    here's a picture of Earth-X ETX36 next to Shoria LFX36 .. both survived 200amp extended cranks with flying colors. Shorai LFX36 has survived a one year long term test with lots of 200+amp cold extended cranks. the jury is still out for Earth-X but it's looking pretty strong!

    Earth-X ETX 36 is considerably smaller than LFX36 and water tight.

    [​IMG]

    pretty darn $$$ expensive! that's why my recommendation is go with a quality AGM... unless saving weight is more important than $$$. then if one is actually riding to parts unknown with little to no support .. go with largest AH LiFePO4 battery one can stuff into space available.

    HUGE $$ differences in what one can get away with using for LiFePO4. for instance someone that only rides from a heated garage with a lithium charger handy... that person can get by with a much smaller LiFePO4 battery. but there's a base size a 1,000cc class high compression motorcycle will need.

    someone only riding during warm weather, again from a fully equipped garage. their needs are going to be different than someone riding a looong ways from support.

    all those extended 200amp crank tests look extreme, until one factors in what usually gets downed bikes going again. lots of times hooking 12v directly to fuel injection pump, then banging on pump, while cranking and cranking... and cranking will get your bike running again. with a good chance once bike gets running again, problems will clear itself. vs a looonngg $$$ expensive trip to the dealership :cry
  16. _cy_

    _cy_ Long timer

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    I'm in the middle of doing tests for Optimate Lithium LiFePO4 charger. which claims to balance LiFePO4 batteries without balance ports.

    have not gotten to point of testing un-balanced batteries yet. still testing LiFePO4 batteries that are in balance from 2.3AH to 20AH actual. with and without internal BMS

    so far Optimate Lithium has done an impressive job!!! brought a LiFePO4 battery that barely registered .5v or completely dead back to life. that same battery is now reading 13.7v or fully charged. it probably will never have the same capacity again... but recovering a LiFePO4 battery from dead takes special algorithms.

    more to come ....

    [​IMG]
  17. _cy_

    _cy_ Long timer

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    you are still lumping several different brands of battery tenders (chargers) as one. not all battery chargers are the same.

    but at least we now know you are talking about AGM. which has a relatively low self discharge rate of 1%-3% per month. AGM does not need a battery tender (charger) for a few months storage. unless bike has a large parasitic drain.

    AGM batteries if kept on a charger (tender) that does not terminate current after full charge condition is reached. that charger will eventually kill that AGM battery.

    3 Stage Chargers
    <table border="1" width="60%"><tbody><tr><td valign="top">Bulk</td><td>14.2-14.4 volts</td></tr> <tr><td valign="top">Acceptance</td><td>14.2-14.4 volts</td></tr> <tr><td valign="top">Float</td><td>13.2-13.3 volts</td></tr></tbody></table>
    Float Charging a Battery - Once an AGM battery is charged to 14.2-14.4v (full charge), it should be removed from the charger to avoid over charging. unless using a charger that reduces it's voltage down to 13.2-13.3v after full charge is reached and goes into float mode.

    a battery begins to decay as soon as it is removed from the charger with a phenomenon call self discharge. Due to self discharge of batteries, they are always losing a certain percentage of power as they decay, just sitting there. A float charge won't overcharge the battery, but keeps it from decaying as it sits there too. Think of float charging as being similar to equalized water pressure in two pipes. Both pipes are at the same PSI, pushing water against one another. Should one leak, the other pushes water in it's place.

    note above voltages are specific to AGM, not gel which should not be charged over 14.2v. Gel batteries need a specific charger or risk getting overcharged.
  18. veetwo _tls

    veetwo _tls RENOVATIO:

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  19. AKohler883

    AKohler883 Been here awhile

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  20. _cy_

    _cy_ Long timer

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    claims of an AGM sulfate at 13v during extended float is completely new to me. So I called Deltran, mfg of Battery Tender Jr.

    they also have never heard of an AGM battery sulfate during extended float mode at 13v. They said if a Battery Tender brand charger kills an AGM battery from extended float. Please do call them. it'd be news to them that an AGM battery will sulfate during float.

    [​IMG]

    just got off the line with Yuasa technical ... they are now aware of the wrong information you pointed out and should removing it soon. thanks much for pointing it out...

    purpose of the 28 day renewal cycle is not to prevent sulfation. but to test battery by making it go through a full charge cycle, to determine health of battery. a fully charged AGM battery will not sulfate during a 13v float.

    if battery is getting ready to fail anyways .. a std battery maintainer will not detect said condition. vs Yuasa's 1.5amp charger by making it go through a full charge cycle will flush that out.

    [​IMG]