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Old 04-24-2013, 02:46 AM   #451
Cortez
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Old 04-24-2013, 11:51 AM   #452
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Video below about Optimate Lithium LiFePO4 chargers recovering Ballistic LiFePO4 batteries. still in the middle of testing Optimate LiFePO4 charger .. but one of the tests entailed recovering a LiFePO4 battery discharged down to .5v or pretty much dead.

after analyzing Optimate Lithium hunkered down in trickle mode for several hours before ramping up to normal charge mode, then optimize mode. before finally reaching float. that recovered LiFePO4 battery has been resting at 13.7v for several weeks.

more to come later when I dive into technical details on how exactly is Optimate Lithium LiFePO4 charger is managing to do this without balance ports/leads.

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Old 04-25-2013, 12:21 AM   #453
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Quote:
Originally Posted by Hicks View Post
battery compartment on the LC:





will have to check it.
so which LiFePO4 battery did you decide to go with?
your R12GS LC sure is one sweeeet ride!
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Old 04-25-2013, 04:25 PM   #454
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Hey Cy, I am also beginning to look at the Antigravity Lith., but I am unable to find if they have internal balance circuits.
Would you know if they do ?
Thanks again for all your help!!!!
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Old 04-25-2013, 05:18 PM   #455
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Originally Posted by frogy View Post
Hey Cy, I am also beginning to look at the Antigravity Lith., but I am unable to find if they have internal balance circuits.
Would you know if they do ?
Thanks again for all your help!!!!
Antigravity uses no internal BMS .. Antigravity has one of the best track records of all the LiFePO4 mfg out there. evidently Antigravity does an outstanding job in matching LiFePO4 cells in their batteries.

one should use Optimate Lithium LiFePO4 charger that balances internal cells on batteries without internal BMS or balance ports for maintenance.

more importantly Antigravity uses beefy internal straps to connect cells. how cells are connected internally makes a HUGE difference in amps delivered. batteries that uses cylindrical LiFePO4 cells has advantage of stronger enclosures to support larger amps.

smaller LiFePO4 batteries that use cylindrical cells has an advantage due to higher capacity to deliver big amps. prismatic pouch cells lack structure so are more difficult to connect together to deliver big amps.

larger Amp hour LiFePO4 batteries has the advantage of more compact form factor using 4s prismatic pouch cells. instead of larger number of 4s cylindrical cells in parallel.

example EarthX ETX36 with internal BMS (3lb 11oz) uses 4x larger prismatic pouch cells to achieve about 14AH actual capacity. Antigravity 24 cell (5lb, no BMS) = about 14AH actual, both deliver excellent performance differently. one with 4x larger pouch cells vs 24x cylindrical cells.

it's important to note that LiFePO4 mfg are constantly improving their products. for example Shorai has constantly made improvements to their batteries. what's valid today may be completely different 6 months from now.
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Old 04-26-2013, 05:22 AM   #456
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Wow, Thanks Cy.
Pretty fast service for the little $ that I pay for this site...wait a minute, this sites free. Really great help here from Cy and others.
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Old 04-26-2013, 07:50 PM   #457
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thanks frogy ... Adv community at 287k+ members worldwide is nothing short of amazing!!!
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Old 04-27-2013, 05:51 PM   #458
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I'm not exactly sure why you would *need* a special charger for LiFePo4 batts, although it would allow you a bit more precision, it isn't needed. I see the Optima being recommended has enough bells and whistles to make anybody with a pocket protector ejaculate, but LiFePo4 (I bought CARB's) has nearly the same charging specs as lead acid, in fact, they have slightly more range than lead acid - can be discharged lower safely (2.75v/cell, 11v)and have slightly higher charge limits (3.65v/cell, 14.6v) conservatively. This is good for the batts, they never really use all their capacity. To wit, I run a house on LiFePo4 batts and was able to use all the same charge controller I've been using for 25 years of lead acids and still leave a cushion against abuse. Caveat to that, check your specs, there are some roue voltage levels around, but they wouldn't be appropriate for 12v anyway.

I would suggest that there is plenty of experienced people who have found that saving an over-discharged LiFePO4 is really a minor event, they take abuse very well. if you want real knowledge of liFePo4s, I recommend going to www.evtv.me and you will see all the gore and the glory of these wonderful batts on the test bench. I will never go back to lead acid. Not only that, my batts only cost 1/3 more than a comparable lead acid pack, have >3x the cyles and a much nicer discharge voltage level.

BMS is really the boogey man of these batts, they account for a large percentage of failures. High balancing the cells is counterproductive, it doesn't matter if one charges .05 volts higher, it is far more important to bottom balance, this is where the damage occurs. Cell manufacturers are just now coming around to that. Bottom balance each cell to 2.75v static (~2.65v under discharge), then charge to 3.65v (under charge) and use as normal.
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Old 04-27-2013, 11:32 PM   #459
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Quote:
Originally Posted by Tweaker View Post
I'm not exactly sure why you would *need* a special charger for LiFePo4 batts, although it would allow you a bit more precision, it isn't needed. I see the Optima being recommended has enough bells and whistles to make anybody with a pocket protector ejaculate, but LiFePo4 (I bought CARB's) has nearly the same charging specs as lead acid, in fact, they have slightly more range than lead acid - can be discharged lower safely (2.75v/cell, 11v)and have slightly higher charge limits (3.65v/cell, 14.6v) conservatively. This is good for the batts, they never really use all their capacity. To wit, I run a house on LiFePo4 batts and was able to use all the same charge controller I've been using for 25 years of lead acids and still leave a cushion against abuse. Caveat to that, check your specs, there are some roue voltage levels around, but they wouldn't be appropriate for 12v anyway.

I would suggest that there is plenty of experienced people who have found that saving an over-discharged LiFePO4 is really a minor event, they take abuse very well. if you want real knowledge of liFePo4s, I recommend going to www.evtv.me and you will see all the gore and the glory of these wonderful batts on the test bench. I will never go back to lead acid. Not only that, my batts only cost 1/3 more than a comparable lead acid pack, have >3x the cyles and a much nicer discharge voltage level.

BMS is really the boogey man of these batts, they account for a large percentage of failures. High balancing the cells is counterproductive, it doesn't matter if one charges .05 volts higher, it is far more important to bottom balance, this is where the damage occurs. Cell manufacturers are just now coming around to that. Bottom balance each cell to 2.75v static (~2.65v under discharge), then charge to 3.65v (under charge) and use as normal.
Tweaker .. thanks for dropping in .. have been involved with li-ion cells almost from the beginning. back when A123 was just getting started.

was part of the group on Candlepower forums that was on the bleeding edge for li-ion use. was in on the group buy that helped finance world's first protected R123 cell. or in other terms world's first li-ion cell with internal BMS.

there's been HUGE advancements in li-ion technologies .. no one can know it all .. always welcome learning new ways of doing things. visited site you suggested, but flat don't have the patience to sit through 90+ minutes of rambling just to see if what they have to offer is of interest....

some enlightening is in order if you think all PB chargers will work for LiFePO4 cells. your particular charger may work fine, but there's considerable differences in lead acid chargers.

LiFePO4 4s for motorcycles max charge is 14.6v ... it's common for PB chargers to put out 14.9v with some PB chargers going up to 15.9v range in sulfate mode. then not all PB chargers are intelligent with a true float mode. some PB battery tenders will put out say 14.8v at low milliamps so long as it's plugged in .. those will kill low self discharge type cells. but do just fine on wet pb with high self discharge rates.

since data is fresh on my mind, let's use example of Yuasa Smartshot 1.5amp and Yuasa Smartshot 900 that I'm currently testing for Yuasa.

Yuasa 1.5amp output range is completely different from Yuasa 900. Yuasa 1.5amp is a multi stage intelligent charger that puts out 14.8v during absorption stage, then switches to float mode at 13.2v .. ideal profile for AGM, including long term maintenance. but not recommended for LiFePO4 ...

Yuasa 900milliamp is also an intelligent charger with a true float mode. but Yuasa 900 during absorption stage puts out 14.2 to 14.6v ... when current goes to almost zero, Yuasa 900 switches to float mode at 13.2v to 13.6v ... this charger was designed for AGM .. but is almost a perfect match for LiFePO4 too.

Now let's compare to Optimate Lithium LiFePO4 charger .. which is another animal all together. there's LOTS going on but unless someone has monitored charger with electronic instruments and has deep understanding of LiFePO4 cells. most folks will not have a clue how Optimate balances cells without separate balance ports.

lets revisit BMS or battery management systems for a bit ... note requirement for BMS on a motorcycle is completely different than a BMS for an electric vehicle.

voltages are much higher with electric vehicles = more cells vs motorcycles always uses 4s config, some with additional series in parallel. current discharge profiles again are completely different. BMS for electric vehicles typically has a high overhead that drains milliamps from battery pack. that will drain pack to dead of not maintained.

vs BMS on 4s config motorcycle LiFePO4 typically configured to shunt current when set voltage is reached. this allows cells that have not reached set voltage a chance to catch up. these shunt type BMS are very efficient with almost no overhead. I've measured these shunts hooked up LiFePO4 cells for months, almost no voltage drop measured.

currently not aware of any motorcycle LiFePO4 batteries with BMS capable of controlling current loads generated. it's possible to control with MOFET in parallel, but no one has put it into production yet.

getting tired of typing... will address LiFePO4 cell balancing another time

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Old 04-28-2013, 10:04 AM   #460
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1. In this chart you have showed over and over, if each cell is 3.3v and the battery is therefore 4 * 3.3v or 13.2v, I understand it could be charged more than 13.2v and the chart shows 13.3v is 90%, but how do you explain that 100% jumps up by over 1 volt to 14.34v ? If this is accurate, is it more of a theoretical than practical limit? I'm looking for voltage data to indicate a charge level for diagnostic purposes (to troubleshoot my accidentally discharged battery), and to watch the voltage on my dash when I first turn on the key (no alternator on).

2. And if this is a Shorai chart, how would it apply to vendors using A123 cylindrical cells?

=============
3. Problem:
I have an 8 cell A123 pack (SyclBatt.com, called 4.6Ah, no longer sold) simple construction that is 1.5 years old and I accidentally drained it overnight (with my GPS) to around 9.x volts. I'm headed out on a 3 day remote trip and trying to decide if I can trust it. It will get down to 40f at night. Did I drain it too far and damage it? The headlight came on dimly and all I remember is it was 9.something volts (not cranking)?

So I charged it (CTEK charger, 3 years old) back up to 13.85v which dropped to 13.35v after I started the bike once... and drops about .2v each time I start the bike (and is ~ 9v, 8v, 7v DURING cranking on those 3 successive tries). I then rode it and it charged up to 13.35v or so, so I can conclude the bike charging circuit works.

I left it sit overnight at 13.1v and it stayed the same, then was able to start the bike in the morning.

The good news is this battery has high current (radio?) quick disconnect connectors and I also have a 4 cell (called 2.3Ah) battery pack I will take with me and can swap connections in an instant (put it in your sleeping bag at night if cold!). I tried it and the 2.3A started fine. It is a BMW 650 motor (G650 XCountry).

A tiny 4 cell is a great backup which I'd like to have again in the future when I buy either an EarthX or Antigravity probably.
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Old 04-28-2013, 11:10 AM   #461
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Quote:
Originally Posted by snooker View Post

1. In this chart you have showed over and over, if each cell is 3.3v and the battery is therefore 4 * 3.3v or 13.2v, I understand it could be charged more than 13.2v and the chart shows 13.3v is 90%, but how do you explain that 100% jumps up by over 1 volt to 14.34v ? If this is accurate, is it more of a theoretical than practical limit? I'm looking for voltage data to indicate a charge level for diagnostic purposes (to troubleshoot my accidentally discharged battery), and to watch the voltage on my dash when I first turn on the key (no alternator on).

2. And if this is a Shorai chart, how would it apply to vendors using A123 cylindrical cells?

=============
3. Problem:
I have an 8 cell A123 pack (SyclBatt.com, called 4.6Ah, no longer sold) simple construction that is 1.5 years old and I accidentally drained it overnight (with my GPS) to around 9.x volts. I'm headed out on a 3 day remote trip and trying to decide if I can trust it. It will get down to 40f at night. Did I drain it too far and damage it? The headlight came on dimly and all I remember is it was 9.something volts (not cranking)?

So I charged it (CTEK charger, 3 years old) back up to 13.85v which dropped to 13.35v after I started the bike once... and drops about .2v each time I start the bike (and is ~ 9v, 8v, 7v DURING cranking on those 3 successive tries). I then rode it and it charged up to 13.35v or so, so I can conclude the bike charging circuit works.

I left it sit overnight at 13.1v and it stayed the same, then was able to start the bike in the morning.

The good news is this battery has high current (radio?) quick disconnect connectors and I also have a 4 cell (called 2.3Ah) battery pack I will take with me and can swap connections in an instant (put it in your sleeping bag at night if cold!). I tried it and the 2.3A started fine. It is a BMW 650 motor (G650 XCountry).

A tiny 4 cell is a great backup which I'd like to have again in the future when I buy either an EarthX or Antigravity probably.
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.



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 ..


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Old 04-30-2013, 07:20 AM   #462
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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.
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Old 04-30-2013, 07:29 AM   #463
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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.
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Old 04-30-2013, 09:28 AM   #464
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Quote:
Originally Posted by Honkey Cat View Post
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.
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?
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Old 04-30-2013, 09:30 AM   #465
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Quote:
Originally Posted by achtung3 View Post
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.
thanks much for asking .. need more info to be able to answer..

what bike and what battery?
what temps bike operated at?
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