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

[_cy_]

Originally Posted by JoelWisman

The F800GS has a 13.8 volt charging voltage. I don't know why, it almost as if they were planning on putting a GEL VRLA battery in the F8's and changed their minds and dumped AGM's in them at the last moment without changing the regulation voltage. It is not as if BMW is stupid, the R1200GS/GSA, S1000RR, K1300S/GT, K1600GT/GTL all have charge voltages around 14.4 ~

As shown in tests, the Shorai will balance in series slowly when seeing the charging voltage my Capo puts out which varies greatly by load and engine speed but gets into the 14.55 volt range for brief periods and averages about 14.34 on the freeway.

question... at what rpm is the 13.8v charging voltage measured?

if F8 is putting out to 14.55v even for brief periods (what rpm?).. then voltage regulator is showing it's limits. F8 is so darn computer controlled, it's flat amazing... how is the charging volts controlled? via conventional voltage regulator? or via CPU?

it's OK to use any conventional lead acid battery charger with Gel/AGM settings. if you keep track of volts LiFePO4 battery is getting charged to. setting any AGM/Gel charger at 2amp setting is the safest. for termination voltage is limited to about 14.4v.

"The peak charging voltage for Gel batteries is 14.1 or 14.4 volts, which is lower than a wet or AGM type battery needs for a full charge. Exceeding this voltage in a Gel battery can cause bubbles in the electrolyte gel, and permanent damage."

LiFePO4 batteries like getting charged at .5C rates. Shorai spec's 3C max charge rate, but can easily take 5C rates. note battery will only swallow large amps until it reaches about 80% full, then battery will slow down accepting current. unless volts is stepped up to push higher current towards battery.

normally I'll charge at 1-2C rates ... for Shorai LFX21 AH (pb eq) that's 7AH actual rating... so 2C = 12amp charge rate. when charged at 2C to 3C rates it's amazing how fast these LiFePO4 batteries charge up to 80% of full charge. then rates slow down for final phase.

[JoelWisman]

Originally Posted by _cy_

question... at what rpm is the 13.8v charging voltage measured?

if F8 is putting out to 14.55v even for brief periods (what rpm?).. then voltage regulator is showing it's limits. F8 is so darn computer controlled, it's flat amazing... how is the charging volts controlled? via conventional voltage regulator? or via CPU?

Two different bikes...

The F800GS, the bike this battery was used in for so long, puts out 13.8 volts from just above idle all the way to red line.
At idle, the F800GS will put out as much as 13.95 volts, but only if you aren't running any accessories. I know this is backwards of the norm, it's due to something called refraction that was not intended for the model, but trust me, the F8 spends 100% of it's time at 13.8 volts except for when idling.

The F800 also typically has a 120mV AC ripple at a frequency of 3x engine RPM.

The F800 is the bike the terrible imbalance in the Shorai occurred in.


The Aprilia Caponord is the bike I have been using to see if higher voltage will balance Shoria LiFePo4 cells that are in series, which surprisingly, it will though slowly and likely with significant stress to the fullest cell.

At a continues RPM anywhere between 2000 and 10,000, the Caponord hunts and pecks between 14.1 and 14.55 volts. 95% of the time it is between 14.2 and 14.4 volts. This behavior does not change at any RPM once the RPM is high enough to meet demand.

Recorded in averaging mode, it comes out to 14.34 volts with no idling.

[JoelWisman]

Both the F8 and Caponord have SCR shunt regulators on PM alternators.

[_cy_]

give me a bit... will yank same Shorai LFX21 AH off G/S.... charge to 100% full, perform a measured discharge test. then charge back up to exactly 13.8v using HP regulated power supply at 1C.

then will measure resting voltage after several hours, to find out how much charge was achieved by a charging system limited to 13.8v.

by the way it doesn't hurt Shorai to fully discharge (9.2v) a few times. but for for all practical purposes battery is dead below 12.7v. ... consistently draining LiFePO4 down to 9.2 will kill the battery and only squeeze out a tiny bit more energy.

how far one drains down any Lithium ion battery effect number of cycles battery will achieve to 80% DOD. battery life can be dramatically different. battery could deliver low as 500 cycles vs 2,000 cycles to 80% DOD.

my guess is this the reason Shorai tell folks to never discharge below 80% DOD.

[Rajin Cajun]

Originally Posted by _cy_

here's what en-route ... this state of the art charger will allow me to charge at 40amps. more importantly will allow precision high amp discharge tests.

FMA PowerLab 8 v2
High-power 1344 watt, 40 amp charger for 1S-8S Lipo packs. with JST-XH & ThunderPower balance board! USB cable to transfer data to my laptop.
http://www.progressiverc.com/fma-powerlab-8.html

Cy, have you had a chance to try out the Powerlab balance charger?

[_cy_]

Originally Posted by Rajin Cajun

Cy, have you had a chance to try out the Powerlab balance charger?

unfortunately no ... still trying to get the correct 4S adapter needed for Shorai. the assortment of balance boards and cables are designed for RC battery packs. which all have a male lead that plugs into balance board.

Shorai uses a female 4S cable. so been having fun coming up with a proper cable to fit to Shorai's balance port.

minor issues with getting correct cabling to access the power of Cellpro Powerlab 8 is well worth it. No other charger allows me to discharge at 1350 watts. or charge at 40 amps. Powerlab 8 is the most powerful RC LiFePO4 charger available.

[JoelWisman]

Little more info on the sickly Shorai LFX18 Lost Rider sent me.

I got it fairly balanced, after 12 hours of standing with no charge or load, all cells are within 0.5 mV.

Interesting thing, If I look at each cell out to the micro volt, you can watch each of the first 3 cells hold steady and the last cell slowly count down. I can't measure that many digits accurately on a 4 volt range, but i can measure repeatably.

Cell number 4 has a self discharge rate much higher then the previous 3, and cell 4 was the one that arrived way discharged compared to the others.

After charging the now balanced Shorai, there is still an 11% disparity in cell capacity measured by running each cell down to 3.2165 volts at a 1 amp rate.

I'd love to see performance on a newish LFX18 to get an idea if this battery was damaged in service, defective, or if Shorai just has shit QC in cell matching.

[_cy_]

starting charge/discharge/charge cycle

Shorai LFX21 AH (pb eq) is charged to 100% full


starting regenerative discharge at 99% full


1,700 mAH discharged at aprox 7.5amp


4,071 mAH discharged


discharged to 5,386 mAH final volt 12.64v indicating discharge stopped at 90%


battery is quickly charged to above 12.86v then stopped to transfer to HP regulated power supply


battery is charged at 1C at exactly 13.8v ... HP regulated power supply will terminate charge at 13.8v


Shorai LFX21 AH at 1C is quickly coming back up


13.76v .. charge rate is down to 500 milliamps

[click to show pic]
[click to show pic]

[JoelWisman]

never mind, thought u were balancing, checking balance is next step i'm assuming

[_cy_]

what I'm doing is duplicating F8 charge rate of 13.8v with HP power supply set to terminate current at 13.8v. after battery reaches 13.8v ... will allow battery to rest to determine charge level achieved.

yes I can check balance, but that's not the purpose of this particular test.

Shorai LFX21 AH (pb eq) is now 13.78v charge rate is down to under 50 milliamps. at this rate will take another few hours to reach 13.8v. for all practical purposes we are there.

[JoelWisman]

Thats interesting, the down to 50mA part. That means there is high resistance to any more current going through the battery at that voltage, yet those cells are no doubt still charging, very slowly.

If current continues to fall off, it's clear why they can get out of balance at that voltage!

With a lead/acid battery of motorcycle battery size, around 100mA+ will continue to flow at 13.8 forever. Full cells will continue to pass appreciable current and expend it by gassing electrolyte which in a VRLA will recombine without venting.

It doesn't harm the full cells but continues flowing current so any lower cells will all come up to full, hence, the battery is self balancing.


If the current acceptance of the Shorai continues to fall off at 13.8...... Of course it would get out of balance!

Minute differences in capacity, internal resistance, self discharge...... one cell ends up lower. BUT the fullest cell stops flowing current and over time the imbalance compounds till you have a light paper weight.

Can you continue for some time and see how low the current gets?

[_cy_]

current acceptance of Shorai battery at 13.78v is higher than the 50 milliamp rate measured. meaning reduction in current as battery approaches set 13.8v set point is caused by HP regulated power supply not battery. closer to set voltage of 13.8v charge rate will decrease until it terminates entirely at 13.8v. note I set the 13.8v limits on HP power supply before applying load.

if one delivers say 18amps or 3C to Shorai battery would swallow amps until battery reaches aprox. 90% full, then slowly taper downwards as battery approaches fully charged state. this is providing voltage delivered to battery remains constant.

at 13.8v LiFePO4 chemistry is also approaching fully charged state and is slowly tapering downwards in terms of further current acceptance. to find out difference one would increase charge rate to 14.4v after 13.8v is reached. then measure current battery accepts at higher volt.

higher the volts, higher the current rate pushed into battery. it's acceptable charge at 3.65v per cell rate to reach fully charged state of 3.6v per cell.
_______________

Shorai battery has been resting for 4 hours since it was charged to 13.78v.
resting voltage is 13.74v ... this means F8's charging system terminating at 13.8v, still results in a fully charge LiFePO4 battery. provided long enough runtime is allowed to for battery to reach 13.8v state. end of charge would be reached faster at 14.4v vs 13.8v. but the differences would be small.

if Shorai battery had been charged to fully charged state of 14.4v. after resting overnight. voltage would still be about 13.7v.

-------------

10 hours later... 13.73v resting ... proves charging LiFePO4 battery to 13.78v still achieves a fully charged battery. difference is how long it takes to top off the final 10% or so of charge cycle. noticed after R80G/S voltage regulator was changed from 14.2v to 14.5v. how long it took to fully charge LiFePO4 battery went down. at 3,000 rpm, amps delivered to battery went from 19.5amp to 22.5am with same load of lights and heated grips.

when dealing with heated gear in winter conditions. at slower discharge rates actual AH ratings comes into play. then if riding in slow traffic conditions before putting bike away for the night. 15-20 minutes riding in those conditions with heated gear on could easily deplete a 6 Amp hour battery to under 70% condition.

so yes contrary to what some folks say about amp hour ratings doesn't really matter. yes it does under cold conditions with heated gear on. then factor extra amps needed to wake up LiFePO4 battery the next morning before starting bike in cold conditions.



10 hours later resting 13.73v

[Speedo66]

Anybody have any experience with the BikeMaster TruGel AGM batteries?

[_cy_]

finally got correct lead with double male 4S to make final connection from balance board to Shorai battery.

Shorai battery was charged to 13.78v by HP regulated power supply. then allowed to rest for a few days. question was raised if an F8 charging system regulated to 13.8v would fully charge a LiFePO4 battery?

answer was documented above ... yes a charging system limited to 13.8v will charge to full. but where difference is how fast the last 10% or so of charge is stuffed in.

Powerlab 8 has an A123 extra accurate charge mode with balancing. that's what I used on Shorai LFX21 AH after sitting a few days. last charge was to 13.78v .... Powerlab 8 registered Shorai has being 92% full starting point. all cells all balanced to zero within a few milliamp charged.

very low total milliamps delivered to Shorai before terminating at 3.65v per cell. in accurate charge mode with balance. with a resting 14.30v four hours later. Powerlab 8 really stuffed Shorai to completely full.

Shorai accepted 190 milliamp @ 3.65v per cell during last phase of charge.


all cells show 3.65v delivered


volt drop to 3.62v after full charge reached


resting after 4 hours .. an amazing 14.3v after getting stuffed full by Powerlab 8 in accuate charge mode.


resting voltage 14.24v after sitting overnight

[write2dgray]

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