Fortune 100AH Battery

[Allgood-Energy]

I have an unusual problem with a fortune 100 Ah Cell from ElectricCarParts.com in SLC. I live in Utah and picked them up directly.
The End Cell on the Positive end Swelled UP and bulged Like it has been out gassing and the port is clogged or sealed. Lucky it has not exploded.
I bought the 8S cell set a year ago and balanced them then and topped them off 2 months a go and have not connected them up since, except to monitor the cell voltages and only to the voltage monitor. They have not been used at all except to top them off, once in a while. They have not been connected to a real load or charged above 29 Volts and 5 Amps.
I had the end cell swell up and bulge the other day. Very Strange to have a cell just expand like that. Here are the pictures of the Problem.
I have been wanting to connect them up to a 200 Amp BMS and inverter and MPPT solar control with 400 watts of solar. I have been busy with other things so these cells have been just sitting on my Desk with nothing connected except the monitor wires not even the voltage monitor display. I have been connecting the monitor display once in a while to see how much the voltage has dropped just sitting. The voltage has Not dropped much Just sitting.
Do You have any explanation?
Very Very Strange and troublesome.
Is It Safe to Keep this battery or is it a disaster waiting to happen?
Not Sure how many days this has been this way.

I just heard form Carl at ElectricCarParts.com and they are going to replace it, but they are currently out of stock for a couple of weeks.

 

[curiouscarbon]

Hi @Allgood-Energy, thanks for your post.

Sorry the cell expanded! I would probably try to keep it separated from living spaces. If it expands more, the vent on the top could let out gas or liquid material which would be unsafe to touch or inhale. Glad a replacement will be on the way when restock happens.

As for why, I cannot immediately say.

May I ask what voltage were cells stored at? (~3.2 like in the pic?) LiFePO4 seem to not enjoy sitting above 3.45 Volts per cell for long time. So one thought was that they sat at 3.5-3.6 for long time and that maybe contributed to eventual swelling. Conjecture

If it becomes stinky, get the cell outside ASAP! And vent the room with fresh air ASAP.

If this happened to me I’d be troubled, so I empathize. What the heck, cell!

 

[Allgood-Energy]

You would think that the cell could not have expanded this way without a lot of current either going in or out of the battery.
Also the Vent must have failed closed to build enough pressure to bulge the case in this way.
But I know that this just happened on it's own, No Charge or load current caused this problem because nothing has been connected.
Also the monitor wires are open connections when NO display monitor is connected.
The only explanation is internal resistance problem. Maybe a thin spot in the plate insulator where a dendrite formed and caused a small short that burned it self out, causing the out gassing in the cell. This is only explanation i can come up with. I Just don't know what caused this.
If the dendrite theory is correct the cell voltage of this cell #8 is the lowest and is .02 volts lower than the rest.
Please tell me if you have a theory.
I am having a problem trusting these cells NOW, Sure don't want a Fire. Hopefully this is just a anomaly and won't be a problem.
Tell me what you think.

 

[Allgood-Energy]

Entropy at work. Any High Energy state system will tend toward a lower energy state or organization.

 

[curiouscarbon]

except to top them off, once in a while.

topping off to 29V?

 

[Allgood-Energy]

What's wrong with 29 Volts it's 0.2 Volts lower than its operating Voltage. These batteries are made to be charged at 3.65 Volts per cell and 29 Divided by 8 is 3.625 Volts the Normal Cell Voltage is some what lower. But here are the Specs. If you think its a bad Idea to charge this High, tell me why? Most LIPO4 batteries are rated up to 4.2 Volts per cell but no one charges that High. I would Think this should be a safe top off Voltage.
Tell me if I am wrong and why?
Here is the web Site I got the info from.

Fortune Battery 100Ah

3.2V 100Ah Fortune LiFePO4 battery cells with more than 2500 cycles, 2C high continuous discharge rate, high energy density for Pure electric vehicles powe

www.evlithium.com

Features of Fortune LiFePO4 Battery cells:

1. 2C 200A Continuous Discharge Current
2. 6C 600A Pulse Peak Current（10s)
3. Bolt Terminal Structure, easy to assembly
4. With Endcaps Protection

Parameter​
Capacity（Ah）	100
Product category	Prismatic aluminum case
Thickness（mm）	36
Width(mm)	130
Height(mm)	290
Nominal voltage(V)	3.2
Weight（Kg）	2.7
Standard current discharge（A）	0.5C
Operating voltage range(V)	2.2～3.65
Operating temperature range(℃)	-20～55
Maximum charge rate (Continued)	1C
Maximum discharge rate (Continued)	2C
Cycle life（times）	80%DOD≥2500 times

Precautions and Safety Instructions

1 Standard cell Precautions

a. Do not expose the cell to extreme heat or flame.
b. Do not short circuit, over-charge or over-discharge the cell.
c. Do not subject the cell to strong mechanical shocks.
d. Do not immerse the cell in water or sea water, or get it wet..
f. Do not disassemble or modify the cell.
g. Do not handle or store with metallic like necklaces, coins or hairpins, etc.
h. Do not use the cell with conspicuous damage or deformation.
i. Do not connect cell to the plug socket or car-cigarette-plug.
j. Do not make the direct soldering onto a cell.
k. Do not touch a leaked cell directly.
l. Do not use for other equipment.
m. Do not use Lithium-ion cell in mixture.
n. Do not use or leave the cell under the blazing sun (or in heated car by sunshine).
o. Keep cell away from children.
p. Do not drive a nail into the cell, strike it by hammer or tread it.
q. Do not give cell impact or fling it.

2.Cell Operation Instructions

2.1 Charging

a. Charge the cell in a temperature range of 0°C to + 50°C.
b. Charge the cell at a constant current of 0.3Cuntil 3.65V, and then at a constant voltage of 3.65V until
0.05C. Charge rates greater than 1C are NOT recommended. (C : Rated Capacity of cell)
c. Use a constant current, constant voltage (CC/CV) lithium-ion (Li+) cell charge controller.
d. Do not continue to charge cell over specified time. 。

2.2 Discharging

a. Recommended cut-off voltage to 2.2V. Recommended max continuous discharge current is 3C。
b. For maximum performance, discharge the cell in a temperature range of -20°C to +50°C.

2.3 Storage Recommendations

In case of long period storage (more than 3 months), storage the
cell at temperature range of –10 ~ +45°C, low humidity, no corrosive gas atmosphere，No press
on the cell；And more than 3 months need to put a charge according to the standard charge and
discharge process

 

[Substrate]

No need to "top off" your LFP - that's lead-acid think. Keeping cells that are not being used absolutely fully charged like you are is not necessary - and unhealthy since it appears that you may be going a long amount of time without putting them into service.

How hot is the environment your batteries are in?

My sense is that you are unnecessarily topping these off and keeping them at full charge longer than they need to be. Put *some* sort of load on the bank to discharge them a bit while you are waiting for things to happen with your project.

Oh, and disconnect the bms in case you are topping off to compensate for an inactive bms possibly discharging the bank for some reason over a long period of inactivity.

 

[curiouscarbon]

not criticizing 29V

just asking to clarify. for understand

did not understand if top off was higher than 29V

 

[JoeHam]

You should store LiFePO4 cells at approximately 50% SOC for longer lifespan.

Not saying that was the issue but there is little or no need to top them off when they are not in use.

And Carl is a solid guy so good on him for a no questions asked replacement.

 

[BigGun]

Was the BMS ever hooked up ---If not --did you charge in series --How closely were the cells monitored while charging

 

[Allgood-Energy]

The 8S battery was only topped off 3 or 4 times since it was purchased a year or so ago. The power supply used to charge it is only capable of 10 Amps and was set precisely at 29 Volts. When connected it was not using a BMS because they were well balanced from the start.
Well its looks like its not a good practice to Top off LIFPO4 batteries. Is it not what a solar charging system would do that has a BMS.
This may be a lesson to set your Charge Limit to 3.4 Volts per cell or 27.2Volts on the BMS. Just remember if you don't charge to maximum Rated voltage this will reduce you watt hour capability. But if your batteries are damaged you have nothing. Lesson Learned
So what % of full charge is recommended. Will Prowse jump in and tell us what the proper top off voltage is for battery Life.

 

[BigGun]

Without the BMS hooked up and not monitoring the cells closely --there's a chance that cell got over charged

 

[curiouscarbon]

please note, the X axis is not uniformly scaled..


i recommend ensure using bms and charge to 3.5 volt per cell.

3.525 volt per cell if you want slightly faster charging.



with 8S that would be nearly 100% charge but much safer than 3.625 volt per cell (as you learned, the change in voltage per energy added is very big around 3.6+ and ouch. sorry.)

if you want to know what will says for long life LFP setting, i believe they had 14.1V for a 4S pack long life setting. that’s 14.1/4=3.525 volt per cell. 8S would be 28.2 thanks hope this helps in some way

good luck with all future operations

 

[Allgood-Energy]

Hey Thanks for the info. Lessons Learned some times can be hard.
Sounds Like the voltage I was charging at was a full 1 Volt too high.
Doesn't sound like much but has real bad results.
Thanks Guys

 

[Allgood-Energy]

So Guys: I have a new battery to replace the swollen one. How close does the cell voltages have to be to be considered Balanced?
Is 20mv close enough to be considered balanced.
What mv difference is considered unbalanced?

 

[curiouscarbon]

So Guys: I have a new battery to replace the swollen one. How close does the cell voltages have to be to be considered Balanced?
Is 20mv close enough to be considered balanced.
What mv difference is considered unbalanced?

Dear @Allgood-Energy,

The ultimate answer might be that it scales according to the Ampere hours capacity of the battery cells.

So a higher Ampere hour cell mean higher normal voltage difference acceptable. To what degree I cannot say.

A number of users here seem to consider 20 milliVolts = 0.02 Volts difference to be sufficiently balanced for safe operation.

I strive to have <10mV = 0.01 V balance as kind of a game, but when I can't easily achieve it, 20mV is enough for me personally.

30mV = 0.03 V would bother me.

One more thing... depending on the difference in aging of the cells, a different voltage may actually represent a state of charge equilibrium, but this is challenging to quantitatively evaluate without logging the temperature and charging/discharing lifetime history of a cell.

Basically, as long as one cell is not hitting high voltage disconnect voltage (3.65 V max) or low voltage disconnect (2.0-3.0V depending on your setting/cells) you should be good. If the number is low enough that you feel good about it and HVDC and LVDC work then maybe it's safe to call it "balanced".

Hope this helps, good luck!

 

[time2roll]

So Guys: I have a new battery to replace the swollen one. How close does the cell voltages have to be to be considered Balanced?
Is 20mv close enough to be considered balanced.
What mv difference is considered unbalanced?

20mv is OK if that is what shows at 3.50 to 3.65 volts. Need to run them up and see what goes.

 

[Substrate]

Other than gross differences in balance, cell voltages measured at rest are not that meaningful and you can be led into a false state of trust.

Voltage / balance differences are meaningful while *under charge*. THAT is where it matters most.

 

[curiouscarbon]

The best system would monitor each cell voltage in realtime, and while amps are flowing, automatically calculate cell internal resistance every time there is a load.

No BMS available does that as far as I'm aware.

 

[Allgood-Energy]

So I have been Charging and Discharging Individual Cells using a 5.7 OHM 50 watt Resister and my Power Supply Limiting the Charge Voltage to 3.5 Volts and I am finding after the battery sits without Charge or Load the voltage on each cell changes after an hour or so. Right Now I have a ran a 5 amp load for about an hour and the Balance remains around 8 to 12 MV. I think this battery is ready to be connected to a 200 AMP BMS and Capacity tested using my 24 volt Inverter. Then next step is to connect the MPPT solar Charge Controller.
I think this is good enough. Then I could capacity test.
Do you have any other suggestions.