Lishen 272AH thread?

[blutow]

Update to my 16 Lishens 272 that I received in february. At the moment I test every single cell, the capacity is between 290,8 and 294,0 Ah. I already testet 8 of 16.

What device are you using the capture the Ah's and how have you checked the calibration? I'm not saying 290+ isn't possible from those cells, but that's the highest I've ever seen reported on 272's by a good margin.

I've done capacity tests on a couple 4 cell packs of lishens I received last week. They tested at 278 and 276. I'm sure individual cells might have tested a little higher, but they were all reaching the end quickly based on voltage. My BMS was showing over 290ah on my pack tests, but the BMS calibration is off a bit based on a check with my amp meter and the victron shunt I used as my reference.

That's great if you are seeing 290+, but just wondering how you are confirming the numbers since they seem crazy high for a 272 cell. We're talking about 8% higher than the specified capacity.

 

[Pyke13]

Mine have all pretty much tested around 285ah but I’ve only drained them to 2.83v. One I tested to 2.5v gave me 290ah, I recon the rest would have been around 290ah or very close had I took them down to 2.5v as well.
that’s tested by using one of the capacity testers from AliExpress. This is the one I bought https://a.aliexpress.com/_mL6qxrv
as for calibration, the volts are a bit out so I guess the AH’s could also be a bit out

 

[Just John]

Mine have all pretty much tested around 285ah but I’ve only drained them to 2.83v. One I tested to 2.5v gave me 290ah, I recon the rest would have been around 290ah or very close had I took them down to 2.5v as well.
that’s tested by using one of the capacity testers from AliExpress. This is the one I bought https://a.aliexpress.com/_mL6qxrv
as for calibration, the volts are a bit out so I guess the AH’s could also be a bit out

That tester, and two other closely related versions measured within one or two percent of the two "professional" testers I have (ET5410 and KP184). It is very likely those are accurate results, just better quality cells than the Eve variety available. My Eve cells looks like they did the initial charge at the factory, and any that didn't measure over 280AH into the cell were sold on the grey market.

 

[Pyke13]

That tester, and two other closely related versions measured within one or two percent of the two "professional" testers I have (ET5410 and KP184). It is very likely those are accurate results, just better quality cells than the Eve variety available. My Eve cells looks like they did the initial charge at the factory, and any that didn't measure over 280AH into the cell were sold on the grey market.

That’s good news on the capacity tester.
for all we know the lishen cells are 300ah cells that haven’t made the grade. It’s easy enough to make up a spec sheet that says 272ah instead of 300ah. I’m not saying that’s how it works but it could be.
Im happy with mine testing mid 280’s, it’s still loads better than the agms I’m using just now

 

[squowse]

Mine have all pretty much tested around 285ah but I’ve only drained them to 2.83v. One I tested to 2.5v gave me 290ah, I recon the rest would have been around 290ah or very close had I took them down to 2.5v as well.
that’s tested by using one of the capacity testers from AliExpress. This is the one I bought https://a.aliexpress.com/_mL6qxrv
as for calibration, the volts are a bit out so I guess the AH’s could also be a bit out

Do you get more capacity on a slower current drain? Or does that not affect Lifepo4? The stated capacity is for 1C I believe.

 

[Pyke13]

Do you get more capacity on a slower current drain? Or does that not affect Lifepo4? The stated capacity is for 1C I believe.

I have no idea. I would assume so as there’s more likely a better recovery. I’ve no way of testing at 1c to compare

 

[Booboo]

I have some of these on order and am planning on putting them in a storage compartment on my travel trailer. I was under the impression these batteries would not catch on fire. After seeing the fire on this thread, I am worried. Should I change my plan and put them in a metal box outside the trailer? The only problem I see with the metal box is the extreme heat sitting in the AZ sun.

 

[blutow]

I have no idea. I would assume so as there’s more likely a better recovery. I’ve no way of testing at 1c to compare

I ran my pack test at a little over 100a. That's still a far cry from 1C discharge, but enough to generate a little heat in the pack by the end.

I have one of the cheap fan testers that can do single cells, so I'll eventually try one at low draw as a point of comparison.

 

[Pyke13]

I ran my pack test at a little over 100a. That's still a far cry from 1C discharge, but enough to generate a little heat in the pack by the end.

I have one of the cheap fan testers that can do single cells, so I'll eventually try one at low draw as a point of comparison.

You can also test a pack with the fan heater type tester. Just set the cutoff voltage to 12.0 or what ever you need it set at

 

[squowse]

View attachment 38349
Not too bad for a 272ah cell

Something that interests me on that. If you divide th total Wh by the Ah you get 3. Seems a bit low - the average voltage should be about 3.25? What was your cutoff voltage?

 

[blutow]

You can also test a pack with the fan heater type tester. Just set the cutoff voltage to 12.0 or what ever you need it set at

Thanks. I may try it, but I'm not sure I trust that thing enough to run it unsupervised and I don't have the patience to watch it for that long. I did a little test on it and the low cutoff seems to work fine, but I'm still a little apprehensive running 4 cells. I've got one cell that appears to be the low performer so far, I'll probably start with an individual test on that one.

 

[Just John]

I have no idea. I would assume so as there’s more likely a better recovery. I’ve no way of testing at 1c to compare

I've been testing 5 different types of cell testers, the fan heater types will work well below 15 amps for a cell, above that a diode gets over 90 degrees Celsius, almost 100 degrees (measured through the PCB no less). A 12v pack, the same diode will get up to 65 degrees Celsius at 8 amps. I will post some pictures later tonight (already have some posted of single cell test rates). I have only tested at up to 40 amps for a cell, and 27 amps for a 12v pack, but with actual professional grade testers, I didn't find any difference in capacity using that limited range. Just got a second tester, so will be able to test cells at 80 amps and will also post the results. So far, it looks like you have to get over .5C before discharge rates might affect capacity. BTW, you can run multiple loads at the same time and just add the results. That means if you had 14 of the heater style testers and started them all running at 10 amps each, just add the results of each for a .5C test.

 

[Pyke13]

Thanks for that info but I’m happy with the test results I got. I doubt very much I will ever be discharging at .5c or above. I’ve way over speced my system. I live in my truck full time and really lack power in winter, for the last 3 years I haven’t been able to run my fridge from November until March. This way I can now power everything even in winter and only have to run my petrol genny for a few hours once a week. I’m doing my final top balance just now and will be fitting the cells tomorrow. Any advice on a large capacity charger?

 

[blutow]

I have no idea. I would assume so as there’s more likely a better recovery. I’ve no way of testing at 1c to compare

I re-ran my 2nd battery pack today at a lower C-rate (both charging and discharging) and it looks like discharge rate makes a difference.

Results from same pack in 2 tests:

Yesterday - started with a fully top balanced pack (all cells at 3.65v), discharged at 100a until BMS shut down. Results = 276ah

Today - started with same pack charged to only 14.2v, discharged at 40a for most of the test and then 10a for the last bit. Result - 281ah

When I got to 272ah on today's test, I reduced the load to ~10a and that caused all cell voltages to recover a bit (you can see it in the right graph below when I reduced the amps. I was really surprised how much it jumped up when I thought the battery was about done. I stopped the test at 281ah with cells ranging from 2.6 - 2.8.

So, I got 5 more ahr's than yesterday's test on the same pack. Today's test started with a less charged pack and I stopped the test before BMS shutoff. So, maybe I left another 3-5ah on the table? Maybe I could find another 3-5Ah if I go with an even lower discharge rate? OK, I'm believer that 290+ Ah seems doable under ideal conditions.

 

[Just John]

Thanks for that info but I’m happy with the test results I got. I doubt very much I will ever be discharging at .5c or above. I’ve way over speced my system. I live in my truck full time and really lack power in winter, for the last 3 years I haven’t been able to run my fridge from November until March. This way I can now power everything even in winter and only have to run my petrol genny for a few hours once a week. I’m doing my final top balance just now and will be fitting the cells tomorrow. Any advice on a large capacity charger?

If it is a 12v pack, there is a 60 amp at 15v power supply on aliexpress I would use. That's a lot of amps for $200.

 

[Just John]

I have some of these on order and am planning on putting them in a storage compartment on my travel trailer. I was under the impression these batteries would not catch on fire. After seeing the fire on this thread, I am worried. Should I change my plan and put them in a metal box outside the trailer? The only problem I see with the metal box is the extreme heat sitting in the AZ sun.

I'm in Mesa, you should not have these in a box in the summer sun. 55 degrees Celsius is a common high, and I am pretty sure that 60 degrees is where you should not charge or discharge.

 

[Luthj]

The peukert coefficient for new LFP is not zero. Its closer to 1.005- 1.01 So there is some reduction in capacity as C rate increases. However its fairly minor compared to lead acid.

 

[Just John]

The peukert coefficient for new LFP is not zero. Its closer to 1.005- 1.01 So there is some reduction in capacity as C rate increases. However its fairly minor compared to lead acid.

I will also point out that temperature can affect it as well. I found 5 amp hour difference in capacity testing between 9 degrees Celsius and 25 degrees Celsius.

I am also aware of how voltage bounces back after a low voltage disconnect.

 

[Luthj]

I will also point out that temperature can affect it as well.

Indeed, I would say ~10% reduction between 25 and 0C

 

[Pyke13]

I will also point out that temperature can affect it as well. I found 5 amp hour difference in capacity testing between 9 degrees Celsius and 25 degrees Celsius.

I am also aware of how voltage bounces back after a low voltage disconnect.

Which gave the higher capacity, 9 or 25 degrees?