Swollen/Bulging LiFeYPO4 Batteries (TS-LFP60AHA)


New member
Oct 30, 2019
I stumbled into a supply of TS-LFP60AHA and TS-LFP90AHA batteries that a high school was getting rid of (abandoned EV project), and was able to pick them up before they went out to the dump/recycling center. The intent is to utilize these batteries for a home powerwall.

The datasheet can be found here: http://en.winston-battery.com/index.php/products/power-battery/item/wb-lyp60aha?category_id=176

I've been charging/discharging the cells individually using the iMAX B6AC v2 charger (settings below) to get a better idea as to what the capacity would be, to record the performance of the individual cells and sort out the bad from the good, and I've noticed that all of the cells that I've tested (only tested about 5so far out of the 50) are bulging after they've finished charging. This is somewhat concerning, and I was wondering if others have experienced something similar with your projects and have any recommendations as to how to proceed.

  • Charger settings: Battery Type: LiFe
  • Cells: 1
  • Charge Current: 6.0A (Datasheet recommends 0.5C, and 6A is only 0.1C of the batteries I've tested)
  • Charge Voltage: 3.7V (This is less than the 4.0V recommended by the datasheet and was chosen for safety and longevity)
  • Discharge Current: 2.0A
  • Discharge Voltage: 2.8V
Have people noticed this bulging occurring with thesebatteries?
Should these bulging batteries be discarded?
Any other thoughts on this?

If they are bulging, STOP CHARGING now! You're damaging them....
If they are LiFePo4 you should not be charging them to more than 3.45V/cell.
3.7 is way too high & they gas inside = bulge = damage.
If you read up carefully on the web, LiFePo4 reach full capacity with 3.45V or so.
You should set the charger to 3.45V & let the cells reach that & hold there until the current drops to a small amount.
There is no useful capacity above 3.45 & more is NOT better.
akaTylerDurden said:
[*]Charge Voltage: 3.7V (This is less than the 4.0V recommended by the datasheet and was chosen for safety and longevity)

Perhaps a link to the datasheet you are using? If it's a paper copy, take a picture or scan.
four volts...its WAY to high
Here you go, and read on what voltage the cell is damaged:

Original ThunderSky Winston part number: WB-LYP90AHA
Recommended initial and subsequent charging is to 3.65 V.
The minimum voltage is 2.5 V.
Maximum discharge current is 3C continously.
Operating temperature -45C up to 85C (discharging)
Energy density is 90 Wh/kg

if there is a bulge after charging, you are to late, you can,.... according to some youtubers....recover those cells.
I don't want to be rude..., but please throw them away, i would do it without hesitation.
First discharge to 0 volt btw

And please check your charger with a proper and good voltmeter, to ensure that it is giving the proper volt what the charger is telling you...just saying, you wont be the first

Interesting, shows 4.0V as the top voltage for these cells
Discharge to 2.8V.
Standard Charge/Discharge is 30A with a max 180A. That would be non-sustained max.


If they swelled up before they reached 4.0V, then they are probably toasted.

And from 100kwh-hunters' link:

LiFePo4 have cells that go above 4V as top charge. For instance WB-LYP60AHA is considered to be up to 4V and I have cells here that can take up to 4.2V but nominal max is 3.65.
Most of them are fully charged at around 3.6V but several can be charged to 4+V without a damage but with that said for longeivity you should stay below 3.6 for moste LiFePo4 cells.

The swelling can be due to overcharge but it can also just be because they are old and thrown out due to being depleeted and should be recycled.

Same as LiIon have cells that is considered to have max at 4.1V and some at 4.2 and some at 4.35....
I'll try charging/discharging with the limits of 3.5/2.8 volts accordingly based on the feedback. I'm only using the iMAX B6AC v2 charger, so I'm not terribly worried about rates.

Glad I didn't foolishly test all the batteries at these higher voltages! I was able to get all 50 cells (~17kWh's worth) for $100, so if I happen to ruin a couple, I'm not terribly heartbroken. They were meant for a EV car conversion as a class project. They were installed in the car and never actually used, so I'd hope that they'd still be in reasonable condition even if they were sitting for a while.

Thank you all!!!
Is there a date code anywhere? How long where they sitting? How long since they were last charged at the EV project site?
Korishan said:
Is there a date code anywhere? How long where they sitting? How long since they were last charged at the EV project site?

The only other writing appears to be a serial number? 08072309619

They purchased them a couple years ago, charged them on site, and doubt they discharged them at all since they couldn't get their motor controller working. I just acquired them a month or so ago.
Hrmm, they should be well within their life span. Interesting that one of them puffed up. Maybe it is a defective one and the others are ok (?) hope so. Charge slow and keep an eye on them.
Make sure the charger itself is charging to the correct voltage. The are a lot of Imax clones out there that are unreliable, and overcharge batteries.
Nice score :)
If not swollen, they should be good if the terminal voltage is above approx 2V I think.

re the 4V on the "specs", the bulging tells you what you need to know. In this case it sounds like a typical case of exaggerated numbers....

I know my LiFePo4 pack starts to become "unstable" if I let it charge beyond 3.45V, some cells start "running away" to high voltage & tripping limits.
Have a look for the voltage curves for LiFePo4 - you want to stay on the "flat" part of the curve at all times.
Korishan said:
Hrmm, they should be well within their life span. Interesting that one of them puffed up. Maybe it is a defective one and the others are ok (?) hope so. Charge slow and keep an eye on them.

Of the 5 that I cycled, all 5 puffed up. I've also checked the voltages on the iMax and they were what I set them to be. I'm wondering if it's what others have mentioned in that the voltages in the datasheet are just exaggerated for some reason? Everyone seems to be of the opinion that the 3.7v that I set was too high.

I'll probablytry running anothercell at 3.58v (lowest voltage the iMax will set for LiFe's),discharging to 2.8v, set up a GoPro on a time lapse with a view on the battery laying horizontal (shortest vertical height), put a deflection gauge in the middle of the battery (point of maximum bulgeability), put that in theGoPro field of view along with avoltmeter, and see what happens at what voltages.
Interesting plan, but don't waste cells, bulge = wrecked! These are probably very good cells worth $100 EACH!
Cells should never bulge, swell or vent gas with Lithium. If they do, something is seriously wrong.
A better plan would be to graph the voltage vs time & look for the point on the curve where it "kicks up" at the end.
That's when it's "full".
Also watch the current - when it drops that also indicates the cell is "full".
Absolute max voltage on LiFePo4 = 3.60V please!
You could probably keep experimenting with the bulged ones - discharge partly first
Strap them together firmly (you should have done this before you charged them, but never mind), wire them up in whatever series string size you want to use and charge them up. Run a discharge test with a BMSconnected and see if the cells will deliver what you need.
Never charge or discharge them horizontally.
I would never "cage" them or bind them together to prevent bulging.
I would rather see a bulge then a flying safety cap thru the room.:)
Or smoke that is not coming from a cigarette.:)

I don't know much about the imax 6.*.*
But the charging must be done to a max of 3.65v.
Like Daromer said one can handle 4v but the other can handle max 3v.

*.*What is also very important with lifepo4 is your charge curve.
When you reach 3.4v the charger must lower his charging current.
So when they are at the end of there charge it must be a charge current of 0.01a or less when it reaches3.65v
From what i understood, if they are so long unintended, you must tread them as new, ea initial charge.
They say max initial charge is0.5c, i would do max 0.1c and raise the voltige every timewith 0.1v after it reached the previous set voltige of course.
Start at 3.3v and from here work your way up.

To reach 4v it is only possible after the 3th charge or something, but slowly work up, with very low current, after the 3th or something cycle

The more full they get, the less current they can have.
Probably this is the cause of your bulging, charging full load at there (almost) full state

I hope i used the good words, if not i hope someone can chime in and tell you this with the proper words.


My two cents, hope this is helpful, best
+1 Having to compress cells is hiding a problem that shouldn't be there in the first place.
They should not be producing gas at all. Vents are only there for emergency release.

I'd have a careful read of pages like this one showing the voltage curves of LiFePo4:
notice how little useful SoC is available from a cell at 3.65V down to approx 3.2V.

Try CC charging your LiFePo4 cells to CV of 3.45V, let the tail current drop away once at 3.45V & then discharge measuring capacity.
You'll get 95%+ of the rated capacity & a cell that lasts, vs a short life if charged to 3.65V or higher regularly.

Charging a pack to >3.5V/cell will also cause you serious balancing issues where some cells will get pushed higher.
My own pack was unstable at 3.5V/cell & since I backed off to 3.45V/cell it has stayed nicely stable for ~18 months now.
I setup the test stand as shown in (external multimeter was simply to verify that the iMax was reading the proper voltages), zero'd the depth gauge, and started a discharge cycle with a max discharge of 6 amps (was only actually at 6 amps for a few minutes). Initial voltage of the cell was ~3.291 volts prior to discharging.

After discharging to 2.8 volts and waiting several hours (finished at night), I zero'd the depth gauge again, and started a charge cycle with a max current of 2 amps with charging voltage of 3.58 volts (lowest the iMax would set for LiFe's). After several hours, the charge finished and the cell had swollen to 0.249 inches (could assume ~0.125 on bottom and ~0.125 on the top).
After a few days of the cell being untouched, the swelling went down to ~0.125 inches total (~0.063 on each side).

This swelling does appear to be less than that I've seen in the past, however I haven't actually measured it in the past, so this is purely anecdotal based on just seeing/feeling the cells before/after charging them.

This still seems like quite a lot of swelling to me. I've heard of people compressing/caging cells, but that still seems iffy to me, and I can't seem to find any legitimate resources recommending that. I've also seen people charging in vertical and horizontal orientations, although I don't know if they're seeing this problem or not.

What are others thoughts on this?

Loving all the feedback and discussion everyone - thank you all for your input!!! =D
There is something not good.
Again never charge them horizontally, this is exactly why not.
The vent valve is designed for a certain amount of pressure to pop out.
If placed horizontally it can not get rid of his gasses.
Two things can happen:(bit extreme but duable).
It will explode because something is blocking the valve, or
You will find lithium everywhere.
Aldo the are extreme fire resistant and there overheating temperature is a lot higher than regular li ion technology.
Lithium will burn.
To speak frankly: I had something like WOW.
You know you are dealing with potential bad/dangerouscells, and despite some warning you charge them unintended (at night?)and horizontally, speaking frankly: i would not do it.

I have seen also those yt vids....I don't know, there is something wrong, it can be ?done?, but how they are charged after the vids and how they behave?
I also saw vids where they take out regulair 18650 cells out a 1000A lifepo4 cell, was fun to watch.

My best guess based upon your story:
They are very old, long not used and probably forgot what they must do, maybe they need some revitalization/bring back to life, remember to hold on some power in the right way.

What i would do, is buy or solder a different charger that you can set manually on your desired volt for charge.
Lab psu or just a buck converter(perfect those bucks in my opinion) with a zb or something, easy discharge, easy charge, 3 amp, give them time.
Maybe the chemistry will put itself back together, settle/balance ormaybe not.
Charge to 3.3v and discharge to 3.0 volts.
My first "test run" would be even at a smaller v span.
Charge to 3.2 discharge to 3.1.
With every cycle you can increase the voltage with 0.1.
Take on every cycle, with the same meters your measurements.
This is a painstaking time consuming thing, but what if you get them back?
If one is back with mine or someone else'smethod try to parallel 5 of them.

Try to cycle them 5 times.
3.2 to 3.1
3.3 to 3.0
3.4 to 2.9
3.5 to 2.8
3.55 to 2.80

The max range for your cells is: 3.80and 2.50
Long life range(if any left) 3.55 to 2.80

With ever 0.1v increasement,after a charge cycle, measure his dimensions, also on the end of the discharges cycle, just to be sure.
I really hope you can revive them and also others will have some hints, tips and/or tricks


Sorry forgot:
Stop charging when they get thicker, that would be your absolute border.