LifeP04 Pouch battery pack

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Voltist

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Hi all, here is my battery pack for my mid drive build, I sourced the cells and bms from China. I want the safety, long life of phosphate chemistry, these cells are rated 50 amps continues discharge. Pack is 48 volt 16s 10 a/hr. Also, not having parallel packs should result in better balancing for additional cell life. I am curious why more are not using these cells .
The box is built from mostly 1/8 abs sheet chemically welded and fits snug in a Kona fire mountain frame, using existing bottle mounts. I'm gathering the parts for the build, including bbs02 750 kit, I will post piks of finished bike asap
 

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Since you don't state or link which specific cells they are, it's actually not possible for us to tell if other people are using them or not. ;)

As for ratings, well, lots of vendors rate things however they like, so they might or might not actually do what they say. To be sure they will, you'd probably want to test them to see what their internal resistance is (and if they are all identical resistance), and what their voltage sag is under that kind of load, at various states of charge.

As one example, Headways are often rated kind of high for what they'll actually handle realistically without too much sag, and are not always consistent for internal resistance (so different cells react to loads differently).

BTW, one thing to beware of is that many pouch cells, even LiFePO4, will swell up during charge or discharge, without even compression across the cell surfaces, so keep that in mind with the construction/housing of the pack. The problem is worse as they age, and at higher currents and/or deeper discharges.


5C is not really that high a rate, though--there are a number of cells that can handle that pretty well (the EIG NMC "C020" cells I'm using, as one example).


If by "not having parallel packs" you mean not having a bunch of smaller cells in parallel groups, well, realistically it's functionally identical to having a larger cell of the same capacity, as long as it's built correctly to share the loads.

But it's certainly easier to build large-capacity-cell packs than it is a bunch of smaller cells, and it could be more reliable not having to worry about the parallel connections. :)
 
last I looked, a lot of BMS battery packs were built like this, with pouch packs.

Actually, I have a pack like that that is pretty old. 36v 1P12s or something like that.

The reason I don't use it is that this LiFePo pack weighs 3 TIMES more than my newer 18650 cell based pack. I've been using the e-bike a lot more since I quit using LiFePo4 cells...

Just my 2 cents...
 
That's a good looking battery, and it should serve you well.

The reason more people don't use LiFePO4 is because the LIFePO4 tech is outdated now, and the industry has moved on to better things, with even better things on the horizon. NMC and NCA batteries (often found in 18650 round cell format, example: the Samsung 25R) are 1/3 the weight, ~1/3 the size, and often lower cost, with similar life expectancy, and have been around for a while, with many Ebike manufacturers and vendors using them.

Mr Ping still makes LiFePO4 batteries. ( http://www.pingbattery.com/ ) he's the last quality Ebike supplier I know of who does.
 
chas58 said:
last I looked, a lot of BMS battery packs were built like this, with pouch packs.

Actually, I have a pack like that that is pretty old. 36v 1P12s or something like that.

The reason I don't use it is that this LiFePo pack weighs 3 TIMES more than my newer 18650 cell based pack. I've been using the e-bike a lot more since I quit using LiFePo4 cells...

Just my 2 cents...
Click to expand...
I weighed the pack and including housing it weighs 4490gms, or about 9.88 lbs, thats for a 480 w/h pack. It does have a lower energy density than lithium ion, but is really 3 times heavier?
I guess when the rubber meets the road i will be able to judge the decision i made to go life. I actually chose an air fork to compensate :D
 
amberwolf said:
Since you don't state or link which specific cells they are, it's actually not possible for us to tell if other people are using them or not. ;)

As for ratings, well, lots of vendors rate things however they like, so they might or might not actually do what they say. To be sure they will, you'd probably want to test them to see what their internal resistance is (and if they are all identical resistance), and what their voltage sag is under that kind of load, at various states of charge.

As one example, Headways are often rated kind of high for what they'll actually handle realistically without too much sag, and are not always consistent for internal resistance (so different cells react to loads differently).

BTW, one thing to beware of is that many pouch cells, even LiFePO4, will swell up during charge or discharge, without even compression across the cell surfaces, so keep that in mind with the construction/housing of the pack. The problem is worse as they age, and at higher currents and/or deeper discharges.


5C is not really that high a rate, though--there are a number of cells that can handle that pretty well (the EIG NMC "C020" cells I'm using, as one example).




If by "not having parallel packs" you mean not having a bunch of smaller cells in parallel groups, well, realistically it's functionally identical to having a larger cell of the same capacity, as long as it's built correctly to share the loads.

But it's certainly easier to build large-capacity-cell packs than it is a bunch of smaller cells, and it could be more reliable not having to worry about the parallel connections. :)
Click to expand...

Here are the cells i am using : https://www.aliexpress.com/item/New-Lifepo4-battery-cell-10ah-3-2V-3C-discharge-electric-scooter-battery-packs-for-bicycle-electric/32330083547.html?spm=2114.13010608.0.0.eiQlbY
I did not measure individual resistance of cells before assembly, won't take many charge cycles to measure capacity. Don't need higher discharge rating for this system.
 
Drunkskunk said:
That's a good looking battery, and it should serve you well.

The reason more people don't use LiFePO4 is because the LIFePO4 tech is outdated now, and the industry has moved on to better things, with even better things on the horizon. NMC and NCA batteries (often found in 18650 round cell format, example: the Samsung 25R) are 1/3 the weight, ~1/3 the size, and often lower cost, with similar life expectancy, and have been around for a while, with many Ebike manufacturers and vendors using them.

Mr Ping still makes LiFePO4 batteries. ( http://www.pingbattery.com/ ) he's the last quality Ebike supplier I know of who does.
Click to expand...

Yes technology moves on but I still havent found a safer lithium battery to date. I fly e r/c planes and racing drones and have cobalt batteries with 60c discharge rating. Very volatile batteries, capable of thermal runaway and fire if conditions met.
However i will probably use round cells next as i have purchased a spot welder just for that.
 
Thanks for linking the cell. The specs there don't seem to match what you've got listed above, though; it says they are only 30A cells. (3c) Seems pretty average for the chemistry, as far as vendor-stated claims go (there are a number of LiFePO4 cells that cant' even do 1-2C without a fair bit of sag, so if these don't sag much at 30A, then that's pretty good).


Brand Name: GTK
Model Number: 10ah lifepo4
Internal Resistance: Less than 5 mohms
Charging method: CC/CV
Weight: About 215g
Charging current: 0.5C 5A
The discharge current: 3C 30A
Discharge Temperature: -20 ° C ~ + 60 ° C
Life cycle: More than 2000 times
Nominal Capacity: 10000mah
Click to expand...
 
Regarding safety of cells--the chemistry is only a part of that. Actual manufacturing and QC processes probably have more to do with how safe any particular cell is, because contaminants in the process anywhere along the line change teh chemistry of the cell in various ways; mechanical damage to cells in factory or warehouse handling, or improper sealing allowing moisture or humidity to get in, all can compromise any particular cell.

There's been enough troubleshooting of packs built both by members of cells they bought new from varous vendors, and of packs built by various vendors of cells of unknown origin, that it's become fairly obvious that many, maybe most, of the cell manufacturers either have little or no QC, or else they are only selling the rejects from that QC on the "open market", with the rest of the cells going to big manufacturers whose battery-powered products we may or may not ever see ourselves.


Worse, there have been definite instances of recycled garbage cells obviously removed from other battery packs being resold either as "new" cells or built into packs. The most notorious are the Ultrafire/Surefire/Efest etc type 18650s, and the various places that sell cut-tab A123 cells (genuine or not). These cells *might* be good, but have a much higher chance of being damaged in some way, and because their origins are unknown, so are their properties, life expectancy, and firebomb chances.


BTW, this all applies to all formats and chemistries of cells.
 
My mistake Amberwolf, 3c rating, I intend to insert my watt meter to measure peak draw on the pack, that's why I like mid drive I have 8 spd gearbox for the hills. The supplier has pretty good ratings so hoping the pack works out. I agree it's difficult to have full confidence in the quality of cells buying directly from overseas. The really big vendors don't bother with small orders from enthusiasts building one off projects. Its buyer beware for sure
 
Voltist said:
chas58 said:
last I looked, a lot of BMS battery packs were built like this, with pouch packs.

Actually, I have a pack like that that is pretty old. 36v 1P12s or something like that.

The reason I don't use it is that this LiFePo pack weighs 3 TIMES more than my newer 18650 cell based pack. I've been using the e-bike a lot more since I quit using LiFePo4 cells...

Just my 2 cents...
Click to expand...
I weighed the pack and including housing it weighs 4490gms, or about 9.88 lbs, thats for a 480 w/h pack. It does have a lower energy density than lithium ion, but is really 3 times heavier?
I guess when the rubber meets the road i will be able to judge the decision i made to go life. I actually chose an air fork to compensate :D
Click to expand...

My 2013 LiFePo4 360Watt/hr battery weighs 10lbs.
My 2016 18650 high density 360Watt/hr pack weighs 3.5lbs.
(Samsung SDI INR18650-32E).

The LiFePo4 pack does have an aluminum/plastic case, so that adds a little weight.
 
Thanks chas58, that sounds right, my battery is lighter because of the 3c rating of the cells, which hopefully is up to the task. You probably have higher rated cells, such as A123. A friend has the 38120 headway cells and they never get warm with a 500 watt bbs02. Yes, Lifep04 is heavy. Thanks for sharing which 18650 cells you use. I'll likely use similar for next build, as i now have a spot welder.
 
This cells should be fine for your build. But close to it's limit so don't flog them up a long Steep Hill. A lot of people here on E.S. need a battery that can deliver 40 50 or 90 amps which would Place those cells out of limit. I run lifepo4 for 4plus years with 984 cycles at 85amps now. They are just starting to show age and may break down my 24s pack for a commuter bike as 12s and 40amp use as they are big and heavy. Still working. Just don't over discharge.
 
That's my intention use the gearing. Probably good the bms has thermal sensor. Thanks
 
I have A123 20ah pouches. I have had Ping lifepo4 and it didn't like a 40amp controller. I think the 48v 20ah Ping limit is 28amp on the C.A.
I don't use a bms on the A123 first rc balance charged for two years then just bulk charge and monitor. It almost nevr has a balance problem. Good luck.
 
Well, my LiFePo4 pack is a 4 year old generic chineese thing, so I doubt it does much more than 2c.

the great thing about LiFePo4 is the constant power. even at 90% discharge, the speed did not drop off. Of course the battery meter would say it was still at 80% charge when it was at 90% discharge. But having consistant speed is a good thing.
 
Its simply due to weight. LifeP04 is much safer than the other chemistries no matter how bad the QC in manufacturing is. You can cross wire, puncture LifeP04 packs etc with out starting a fire how safer they are is understated. The fact the fire hazards that are lipo batteries is used a lot shows what matters most in the ebike community so far is power to size. Lithium ion is better but bad manufacturing process and you got a fire hazard. LifePo04 technology can't improve due to the lack of users I can't get why such a safe chemistry is not used more in high powered settings.

Again no other battery can take this abuse.

https://www.youtube.com/watch?v=nMf6scF13lI

Again no fire just smoke.

https://www.youtube.com/watch?v=EMARDvMz62A

Also as someone else said with LifeP04 there is no speed drop off. I can kill the throttle threw 90% of the battery and get max speed.
 
boytitan, safety was the primary reason for my choosing LifeP04 for this project. I can adjust the programming of Bafang controller to limit current draw if needed.
Cycle life was the next reason for this chemistry.
I play with racing drones and high performance r/c foamies and some of my batteries are Cobalt 60C discharge. I am aware of the consequences of a damaged or compromised pack and store and use them accordingly. My commuter bike needs to deliver 20 amps and be safe enough to charge overnight in the garage.
Not sure if the average buyer of commercial ebikes, especially the cheap ones, are aware how dangerous some lithium cells can be.
Case in point the Samsung S7 early on was apparently the result of too much capacity in too little space with the result of thermal runaway. As you stated, other than fire from short circuit, LIfeP04 cells themselves will not burst into flames
Energy density is for sure the only downside for now, can't wait to see what the future holds for batteries
 
chas58 said:
Well, my LiFePo4 pack is a 4 year old generic chineese thing, so I doubt it does much more than 2c.

the great thing about LiFePo4 is the constant power. even at 90% discharge, the speed did not drop off. Of course the battery meter would say it was still at 80% charge when it was at 90% discharge. But having consistant speed is a good thing.
Click to expand...

Interested to know what that pack powered and how many cycles you estimate its had
 
It isn't true that a LiFePO4 pack will not burn from a short or other conditions; if you put it in the right circumstances, it definitely will, depending on pack characteristics.

Here's a few threads, just here on ES
https://endless-sphere.com/forums/search.php?keywords=life*+fire*&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=headway*+fire*&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

Even A123 isn't immune, but I can't find the thread about it right now. I think it was an EVTV video, so that should be on Youtube on their channel.

There is also a collection of fires in a few threads by Bigmoose, by year; they should be in the Battery Technology subforum; will have info/links to various types of packs, if you're interested.
 
Noted, however in the first link, it appears the batteries were burned by a short causing a wood fire.
quote ' I reckon it was more likely a wiring issue, some short creating heat and catching fire to to his WOODEN panel insulation!!
I see that all lithium based cells can be volatile, and no, i have no idea what the precise composition of the cells i built a pack from.
Bottom line, safety , good maintenance and pack assembly is important , these things can bite!
 
amberwolf said:
It isn't true that a LiFePO4 pack will not burn from a short or other conditions; if you put it in the right circumstances, it definitely will, depending on pack characteristics.

Here's a few threads, just here on ES
https://endless-sphere.com/forums/search.php?keywords=life*+fire*&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=headway*+fire*&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

Even A123 isn't immune, but I can't find the thread about it right now. I think it was an EVTV video, so that should be on Youtube on their channel.

There is also a collection of fires in a few threads by Bigmoose, by year; they should be in the Battery Technology subforum; will have info/links to various types of packs, if you're interested.
Click to expand...

The point is the chances are lower. A miswiring in my gaming pc has a higher chance of causing a fire then a LifeP04 battery.
 
Voltist said:
chas58 said:
Well, my LiFePo4 pack is a 4 year old generic chineese thing, so I doubt it does much more than 2c.

the great thing about LiFePo4 is the constant power. even at 90% discharge, the speed did not drop off. Of course the battery meter would say it was still at 80% charge when it was at 90% discharge. But having consistant speed is a good thing.
Click to expand...

Interested to know what that pack powered and how many cycles you estimate its had
Click to expand...

used it with a 14a controller on a Q100 motor (36v).

It died after about a dozen charges.
The controller sucked the battery down, so I always disconnected the battery. I'm wondering if this habit didn't cause some problems with the BMS or something else.

After a couple of years the range seemed down by about 30%, and then it got to the point where it wouldn't power for much more than 30 minutes. I did periodically charge it over the winter to keep it from going completely flat.
 
Drunkskunk said:
NMC and NCA batteries (often found in 18650 round cell format, example: the Samsung 25R) are 1/3 the weight, ~1/3 the size
Click to expand...
of what?

Setting aside power density,

pretty sure not **that** big a difference wrt energy density, Ah capacity per pound or cubic foot.

And no way on longevity, at least for low C-rate usage,

plenty of LFP packs cycled 300+ times per year coming up on ten years now with **zero** capacity loss.
 
There is **no** question that LFP is **much** safer than the other LI chemistries usually included in "LiPo" and "Lithium-Ion" catagories.

Fire bullets through them, drive steel rods through them, wildly overcharge, short-circuit, even the big 1000+Ah prismatics, no danger of thermal runaway, fire explosion etc.
 
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