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Old 03-24-2012, 10:12 AM   #181
_cy_ OP
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Quote:
Originally Posted by write2dgray View Post
Excellent testing here - nice work! Also, one heck of a vetting process to get registered here :).

I hope you are enjoying the PL8 and beginning to flex it's capabilities. Lithium's the way forward for starter batteries in motorcycles (and cars). Next is replacement of the IC engine!

Hope the graphs are helpful and please let me know if there are ever any questions I can assist with.

Cheers,
David
ProgressiveRC
@write2dgray .. thanks so much for joining this set of tests. As a matter of fact there is something that we need your expertise on.

As you know using LiFePO4 for starting duties on a motorcycle is fairly new. multi-cell li-ion packs can and do get out of balance. hence need for intelligent chargers like Cellpro Powerlab 8 which balances multi-cell battery packs during charge.

all LiFePO4 motorcycle batteries contain at least 4 cells in series. since most don't contain balance/overcharge protection circuits. at some point all bare packs will get out of balance.

most motorcycle charging circuits with voltage regulators operate at 13.8-14.2. with some modern bikes charging up to 15v. Bike in question is BMW R800GS which charges at 13.95v at idle, then drops to 13.8v at higher rpm.

have duplicated R8 charging circuit with a HP regulated power by limiting charge to exactly 13.8v with CC/CV feature to terminate charge at exactly 13.8v, instead of preset charge points on Powerlab 8.

results was ... charged Shorai 18 AH (pb eq) to 13.78 (aprox 95% full).. when charge rate dropped to 50 milliamps. stopped charge... then allowed battery to rest overnight. voltage dropped very little to 13.73v indicating a full charge was reached.

then Shorai 18 AH was charged with Powerlab 8 in accurate mode with balance. very little milliamps was delivered to battery from 13.73v resting to fully charged at 14.4v. went to 0% out of balance within 2-3 minutes at 196 milliamp rate. Shoria 18 AH was not out of balance by much to begin with. but it's been operating with a charging system set to 14.5v.

question is ... by charging only to 13.8v like BMW R800GS ... does lower volt charging systems (13.8v) increase chances for out of balance cells?


13.73v after resting overnight. battery was charged to 13.78v by HP power supply
13.7v is normal resting volts after overnight with BMW R80G/S with 14.5v regulator

_cy_ screwed with this post 03-24-2012 at 05:10 PM
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Old 03-24-2012, 11:49 AM   #182
JoelWisman
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I second _cy_'s question, but will add another data point as I had a local rider bring by his Shorai LFX21 still in his 2011 BMW F800GS.

Measured his bike with calibrated 0.025% multimeter (fluke 289) 13.99 volts at idle and 13.88 at anything above 2000RPM which translates to probably 99% of the time with this rider.

24 hours after battery removed from bike and all loads 13.149 volts

Cell 1 3.2909
Cell 2 3.2911
Cell 3 3.2905
Cell 4 3.2759

The overall SOC is lowered because we did some six 5 second cranking tests and had the key on for about 10 minutes before removing the battery from the bike, but that does not explain to me the imbalance.

It's also interesting that cell 4 is for the second time the low cell on 2 different Shorai batteries from 2 different bikes. Two samples does not make scientific fact but it is at the least an unusual coincidence.
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Old 03-25-2012, 11:25 AM   #183
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How to determine accuracy of your meter

theoretical accuracy for a 3 1/2in 2,000 count meter is .05%. Fluke 87V spec's claim accuracy of .05% +1 Accuracy can be determined as ± (1.200)(0.5)/100 +0.001) = ± 0.007 V

Below Martel MC-1000 Multifunction Calibrator (Calibrated with standards referenced to NIST) putting out 1.200v ... Fluke 87V reads 1.200, Fluke 16 reads 1.201 ... Fluke 87V is dead on, Fluke 16 is amazingly close at reference std 1.2v, but drifts off at higher voltages. Fluke 87V reads .001v low at higher voltages. still well within .007v range guaranteed by Fluke.



Martel MC-1000 is now putting out 3.233v, Fluke 87V reads 3.232v and Fluke 16 reads 3.236v


here's a super coool reference standard watt meter traceable back to NIST
purchased this at a local electronics store last week. I'm a sucker for reference stds tools


trivia... set of weights certified by State of OK traceable back NIST


here's the best way to see if your meter is accurate. assuming you don't have access to a reference volt standard. find a brand new Fluke 87V say at HVAC supplier. easy to find, since Fluke 87 is the standard of the industry.

then take a lithium 3v battery, which puts out a stable reading. compared reading on new Fluke 87V compared to your meter. both reading same 3v lithium battery.


_cy_ screwed with this post 03-25-2012 at 05:19 PM
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Old 03-25-2012, 05:42 PM   #184
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Battery

Shorai,have them in two of my bikes. No complaints,or regrets
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Old 03-31-2012, 11:33 PM   #185
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Colebatch just successfully did a trip to Andes mountains with Shorai batteries under very cold conditions. proper starting procedures is a must under those conditions. for Adventure bikes a LFX 36 (currently in my R80G/S) with close to 500 cranking amps (12 amp hour actual) at minimum is needed.



one major benefit my LiFePO4 tests enjoy is starting out with a brand new battery. that part I insisted on. using someone's used battery that no telling what's been done to it could result in results that are valid or bogus. same for using the proper charger. a dedicated LiFePO4 charger is necessary to bring battery to full charge and balance the battery.

currently there is NO way to balance battery except to take out battery and charge on dedicated charger with balancing capacities. I've got a circuit design in mind that I'd like to get fabricated that hopefully will solve balancing issues while on the bike.

charging LiFePO4 battery packs is old hat for RC folks and electric vehicles folks. but catch is they all are using chargers with balancing circuitry. running LiFePO4 batteries bare with NO battery management systems is brand new. BMS large enough to support 200+ amps would be cost prohibitive and too large to carry on a motorcycle.

LiFePO4 mfg have not advertised it... but currently the only way to balance your LiFePO4 battery is with a dedicated charger with balance features. which can be sourced for under $40 if one knows what to look for. most folks don't need a Powerlab 8 with capacity to charge/discharge at 1350 watts. for most LiFePO4 batteries ... 2-3 amp charger is ample.

my results so far indicated ... LiFePO4 batteries put out more than ample current to start my R80G/S which admittedly only draws about 125 amps during warm weather. during cold conditions that goes up to 200+ amps.

actual vs PBEQ ratings. what counts is actual amp hours delivered! period!
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Old 04-04-2012, 07:36 PM   #186
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Saft was one of the earliest li-ion batteries that I fooled with on Candlepower forums. this Saft paper contains some very important information concerning why LiFePO4 batteries get out of balance.

back to that later... but first lithium cobalt is inherently dangerous when overcharged. unlike Lithium iron phosphate which is dramatically safer. all batteries when overcharged will do bad things. lithium cobalt is probably the worst... lithium cobalt is fully charged at 4.2v, but will accept a charge until thermal runaway (explosion) occurs about about 4.4v.

here's a article I wrote on this topic in 2007.
greatest danger using li-ion cells occurs during re-charging

for all practical purposes LiFePO4 cannot be overcharged without some real effort. LiFePO4 when fully charged volts spikes upwards preventing further charge without substantially raising voltage.

Let's say we have a shunt failure in an alternator charging system and volts spikes to say 19v. in case of Lithium cobalt... results would probably be thermal run-away with companion cells igniting ... making for some most excellent fireworks. vs same shunt failure with LiFePO4 battery... results would be severe overheating with lots of smoke. still not a nice result... if the same thing happened to wet lead acid with much nastier results ...

"For a significant improvement in safety in a positive electrode material it is necessary to move away from oxide materials to ones based on phosphates. Lithiated iron phosphate (LiFePO4) was developed by a team led by Dr. John Goodenough while working at the University of Texas 4 (Goodenough was also one of the principal researchers at Sony in the original development of lithium-ion technology). Phosphate bonds are much stronger than those in oxides, with the result that when abusively overcharged, LiFePO4 cells release very little energy. Cells using LiFePO4 have reasonable calendar life and excellent cycling characteristics as long as they are operated at moderate temperatures. Unfortunately, however, the added safety comes at the cost of significantly lower energy density (which in itself contributes to enhanced safety), so it is no coincidence that commercial success for this material has been achieved in products designed for short-duration, high-power discharges, such as those now used in commercial power tools."

@Joel...like I said earlier, sure wish we could merge these two threads that cannot help but cover much of the same materials. now I've got to post this same information in my thread.

finally found what I'd been looking for about cause for out of balance condition. charging at higher volt say 14.4v will not help balance LiFePO4 cells.

"LiMn2O4 and LiFePO4 materials cannot be overcharged and at the end of charge there is a steep voltage rise. This clear advantage regarding safety actually becomes a disadvantage for battery management because the charge can be limited by the first charged cell. Overcoming this issue can necessitate the use of more aggressive balancing circuits. The issue of ‘slope’ and balancing is discussed further below. ~


As already discussed, lithium-ion batteries must use electronics for cell balancing, so systems with sloping curves of this type are easy to balance; if the cells are at the same voltage they are necessarily also at the same SOC.

Other systems have much flatter SOC vs. voltage profiles and therefore face greater difficulties in cell balancing. Cells with LiFePO4 positives, for example, have very flat voltages over virtually the whole SOC range, steeply ramping up only at the very end of charge. This means that they must be charged into the sloping part of the curve in order to balance them. This requirement is fine for systems such as power tools that require full charging and are designed around the battery, but presents challenges for operation at partial SOC levels, such as in hybrid electric vehicles. In stationary applications LiFePO4-based batteries could not be charged over a range of voltages, if doing so would mean that their cells would not be
charging in the area with slope.

The biggest disadvantage of slope is that non-ideal charging can impact SOC in service. With lithium-ion cell voltages typically above 3 V there is little possibility to fine-tune the number of cells to meet specific application requirements."

http://www.battcon.com/PapersFinal20...008PROOF_9.pdf
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Old 04-04-2012, 08:38 PM   #187
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above translated:

charging can only occur on slope of volt ramp up to fully charged condition. due to extreme flat discharge volt of LiFePO4. range is very narrow indeed.

for our motorcycles four LiFePO4 cells in series are always used. different Amp Hour are achieved by prismatic cells batteries by using smaller or larger prismatic cells. cylindrical LiFePO4 cells use the same four cells in series to achieve voltage needed for motorcycle. but different amp hours are achieved by stacking additional cells in parallel, then hooked together in series.

prismatic batteries have the advantage of maximum of four cells. less cells go out of balance. cylindrical batteries with higher amp hours contain larger number of cells. more cells means higher possibility of cells going out of balance.

A123 cells in particular enjoy the advantage of staying state of the art. it's a fact most of $$ for R&D will be spent on cells that is being produced in the highest volumes. along with the highest amount of feedback as development progresses.

... back to motorcycle battery LiFePO4 out of balance condition ... BMS or battery management systems than can support 200+ amps are both prohibitively expensive and physically too large for a motorcycle.

so most LiFePO4 motorcycle batteries contain no BMS of any type. carefully matching up batteries can only go so far. at some point all multi-cell li-ion batteries will go out of balance. currently on batteries without BMS, the only way insure balanced cell is to charge battery up with a LiFePO4 specific charger with balance features.

let's say we've got a motorcycle system that charges at 14.2v max. so when battery volts reaches 14.2v, system stops charging battery by either shunting off excess current or shuts down current that exites rotor. either way at 14.2v ... battery stops charging.

let's say we've got 3 cells that go fully charged at 3.65v each ... with one cell lagging behind at 3.1v.
what happens is the 3 cells that reach full charge at 3.65v will all spike volts upwards to say 3.7v each. preventing the 3.1v cell from charging further.

3.7v x 3 = 11.10v + 3.1v = 14.2v .... preventing further charge of lagging 3.1v cell in above example
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Old 04-05-2012, 07:16 AM   #188
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Quote:
Originally Posted by _cy_ View Post
... back to motorcycle battery LiFePO4 out of balance condition ... BMS or battery management systems than can support 200+ amps are both prohibitively expensive and physically too large for a motorcycle.

so most LiFePO4 motorcycle batteries contain no BMS of any type. carefully matching up batteries can only go so far. at some point all multi-cell li-ion batteries will go out of balance. currently on batteries without BMS, the only way insure balanced cell is to charge battery up with a LiFePO4 specific charger with balance features.
Aside from the Lightning Nano, which other brands contain BMS circuitry? Why do the batteries need a BMS that can support 200 amps? Is this to ensure balance during discharge? To prevent over charging? Lead acid batteries aren't protected during those conditions. I would expect that as long as the batteries are balanced during charging, that will work fine and much better than no balancing at all.
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Old 04-05-2012, 09:16 AM   #189
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Aside from the Lightning Nano, which other brands contain BMS circuitry? Why do the batteries need a BMS that can support 200 amps? Is this to ensure balance during discharge? To prevent over charging? Lead acid batteries aren't protected during those conditions. I would expect that as long as the batteries are balanced during charging, that will work fine and much better than no balancing at all.
a true battery management system also includes protection from under-discharge. to achieve under discharge protection. entire load must be isolated by protection circuit. overcharge/balance protection can be achieved by either bleeding/shunting off excess current over XX volts for each individual cell.

there's an on going discussion if LiFePO4 batteries will self balance, if LiFePO4 cells in series even need a BMS?

yes due to highly tolerant to overcharge nature of LiFePO4 cells in series. the cells that achieve full charge will spike upwards, resisting further charge. the small amount of current that makes by full cells will continue to charge low cell(s). so to an extend cells in series are self balancing. but only under certain conditions. ie very slowly. higher the charging volts, higher milliamps that will get by fully charged cells.

LiFePO4 cell will accept current to 3.65v fully charged. with battery accepting less current as it approaches fully charged state. observing powerlab 8 in action LFX 21 @ 14v (94%) is still accepting 800+ milliamps tapering downwards with LFX 21 accepting aprox 180 milliamps to 14.6v.

for most folks that are not taking bike rides that are say 4+ hours long, combined with high loads. when bike is started then ridden, LiFePO4 battery likely is swallowing large amps headed for last leg of charge where battery does slowly self balance.

all the LiFePO4 batteries that I've tested so far needed to be charged with a balance charger to bring back into balance again after many severe crank cycles. admittedly most folks will not be putting their batteries under such severe loads.

so recommendations are ... if your rides are short, especially under load like heated gear in the winter. purchase a charger with balance capabilities to top off your battery and balance as a routine maintenance cycle.

starting charge cycle Powerlab 8 at 13.99v (94%) full ...


Powerlab 8 internally checking cells for balance


charge from 13.99v .. LFX 21 still accepts 838 milliamps




charge tapers downwards and stabilizes at about 180 milliamps @ 14.6v


Powerlab 8 beeps several times indicating charge is complete


all cells fully balanced


starting charge info from 94% full


total charge accepted by LFX 21 from 13.99v (94%) full is 108 mah at rates 800 milliamp to 180 milliamps. note most chargers will not deliver this much current to battery with accuracy of Powerlab 8

_cy_ screwed with this post 04-05-2012 at 10:11 AM
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Old 04-05-2012, 11:39 AM   #190
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Originally Posted by _cy_ View Post
@write2dgray .. thanks so much for joining this set of tests. As a matter of fact there is something that we need your expertise on.
No problem - happy to help and my apologies for the delay. A hectic product release schedule has had me away from emails and forums lately.
Quote:
Originally Posted by _cy_ View Post
question is ... by charging only to 13.8v like BMW R800GS ... does lower volt charging systems (13.8v) increase chances for out of balance cells?
The concept of balancing should never enter the equation at lower than a full charge state. In other words, being out of balance at voltages less than full is of little to no concern.

To expand: in the past some chargers actively balanced all cells regardless of state of charge (okay, some still do and many have the option). Most now agree to only mess with "balancing" cells to each other at a full state of charge, with the purpose being to bring all cells to an equal full charge state without one or more running away to a higher voltage. The problem with balancing at lower states of charges has to do with how cells are capacity matched prior to pack construction. Think of a series of glasses of water with slightly different volumes all filled to the brim. Now if you drank an equal amount from each glass you would find it takes an equal amount to refill them. However, if you drank an equal amount from each glass and then adjusted the water levels to be the same, then it would require unequal amounts to refill them. This is in effect what cell balancing at lower voltages achieves, unbalanced packs that require the exact opposite balancing action as they near full charge.

Finally, charging to around around 95-98%, which you are at the voltages the alternator provides, will result in a substantial increase in life cycles than trying to perfectly charge to full voltage. This is done any many applications and by many users to extend life where absolute maximum capacity is not critical, by for example setting LiPo max. termination to 4.17V per cell instead of the more typical 4.20V.

Cheers,
David
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Old 04-05-2012, 11:43 AM   #191
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In regard to battery management. Why doesn't lead acid use it? It can be damaged by excessive discharge and overcharging. Why should it be an all or nothing prospect? If you can't have the complete BMS, then nothing else is adequate?

I'm doing my own crude test of a LiFePo battery. I'm trying to kill it in my car. I've left the lights on until it is at about 2.3 volts and then connected a jumper pack for 30 seconds, removed the pack and it starts. Repeated the process three times in a row. The starter draws 330 amps. This is my daily drive. With all the lights and defroster on it charges at about 13.8 volts.
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Old 04-05-2012, 07:47 PM   #192
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Originally Posted by colebatch View Post
We took Husaberg FE570s, batteries used were Shorai LFX14L2-BS12 ... 14 AH.

More info here: Andes Moto Extreme
NICE .. a world record for motorcycle!!




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Old 04-07-2012, 04:59 PM   #193
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Just installed an American made battery Speedcell and it's lifetime is 5-7yrs, not cheap. Will see in how long it really last.
Light, has a push in plug for easy disconect and the only thing to watch out for is not to let the lights on without the engine on; engine on or off deal.
Anyone has any comment on this battery?
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Old 04-07-2012, 10:14 PM   #194
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Just installed an American made battery Speedcell and it's lifetime is 5-7yrs, not cheap. Will see in how long it really last.
Light, has a push in plug for easy disconect and the only thing to watch out for is not to let the lights on without the engine on; engine on or off deal.
Anyone has any comment on this battery?
Isn't that a shrink wrap battery? If so, it's probably fine as long as you don't ride in the rain, do water crossings, or play in the mud. deal breaker for me.
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Old 04-07-2012, 10:20 PM   #195
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Quote:
Originally Posted by Anorak View Post
In regard to battery management. Why doesn't lead acid use it? It can be damaged by excessive discharge and overcharging. Why should it be an all or nothing prospect? If you can't have the complete BMS, then nothing else is adequate?

I'm doing my own crude test of a LiFePo battery. I'm trying to kill it in my car. I've left the lights on until it is at about 2.3 volts and then connected a jumper pack for 30 seconds, removed the pack and it starts. Repeated the process three times in a row. The starter draws 330 amps. This is my daily drive. With all the lights and defroster on it charges at about 13.8 volts.
I don't think you do need a BMS for LiFePO4 batteries for over voltage or balance as long as you don't beet them up. You may or may not need one for under voltage, but it would be nice.

Short circuit protection, not really. It is just like with a lead acid battery. bad things happen when you short them, but not THAT bad.

Interestingly what I am finding is that the pouch cell batteries, or at least the Shorai seem to be more finicky as far as getting out of balance, venting when loaded heavy, and dying instantly when run too low or reversed.

I have now killed 3 Shorai batteries and don't think anyone is going to be sending me any more lol.

Doing the exact same thing the battery with A123 cells is still charging along merrily.
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