Samsung 30Q INR18650-30Q 3000mah 15a cell

[hillzofvalp]

Could someone please do a comparison of the Panny BE to the 30Q?

 

[riba2233]

Could someone please do a comparison of the Panny BE to the 30Q?

They are not in the same category, one is middle C rate, other is high C rate cell.

But here is something:

http://www.dampfakkus.de/akkuvergleich.php?akku1=531&akku2=586&akku3=&akku4=&akku5=&akku6=&a=5

 

[bigbore]

Have you compared 18650 voltage sag to some decent RC Lipos ?
I suspect you will be losing some voltage on a like for like pack.

VTC5A has low DC Internal Resistance but lipo has less (approximately 10 mOhm/Ah).

Yes, It's the last thing I need to understand. The 5Ah LiPos I've been using are discharged at 10C and I don't remember the voltage I have while running full throttle. I do not have a telemetry to do the measurements but a couple of time a friend of mine mounted his Heagle Tree telemetry on my RC boat but I need to find the data.
With iCharger I measures my 5Ah LiPo cells at a temperature aroud 18-20 °C with a voltage of the cells at 4,15V and I have the minimum cell at 2mOhm and the maximum cell at 8mOhm. With the max I read it would be 1,6 mOhm/Ah.
Tomorrow I will try to charge a LG HE2 at 4,15V and then let's see what IR I have.
I don't know if iCharger is accurate in the IR readings but at least do not measures the cells IR while charging like other RC chargers.

 

[bellfador]

The charger measure only AC internal resistence and also the measurement is inaccurately. In your case the voltage sag is linked to DC internal resistence and DCIR > ACIR.

Your calculation is wrong . 8 mOhm for 5Ah is equal to 40 mOhm/Ah.

 

[Allex]

my comaprison with pf vs he2 vs 30q
Sorry, the graph is tricky to read!

 

[bellfador]

How is measured the internal resistance?

 

[Allex]

with this one:
http://www.hyperion-eu.com/products/product/hp-eos1420inet3/

 

[bellfador]

Here are my testings of 30Q.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=73701
I see some differences, but is close to DCIR.

 

[Allex]

Yup but you should not compare my iR results with yours, we have different rigs.

 

[bigbore]

The charger measure only AC internal resistence and also the measurement is inaccurately. In your case the voltage sag is linked to DC internal resistence and DCIR > ACIR.

Your calculation is wrong . 8 mOhm for 5Ah is equal to 40 mOhm/Ah.

I think you're wrong because 40 mOhm/Ah x 5 Ah = 200 mOhm

But anyway it seems I can not measure just one cell IR with iCharger right now. I think is designed to measure at least a 2S pack.

 

[bellfador]

Simple example:
One cell with 2Ah, 20 mOhm have 40 mOhm /Ah because when are connected two cell in parallel each with 1Ah, 40 mOhm summary capacitance will be 2Ah and internal resistance - 20 mOhm.

...Resistors in paralel: R12 = (R1*R2) / (R1+R2).

 

[bigbore]

AH!, OK, now I see what you mean and you're correct.

 

[okashira]

Easy calcs... 3S 1300 mAh turnigy nano 25-50C weight 139g, or 46.3g per cell. Dc internal resistence will be approximaly 7.7 mOhm or 166 mOhm /g and 37 mOhm/Wh. VTC5A have 377 mOhm /g and 152 mOhm/ Wh. Soon I will make a test on some lipo and I can tell with sure.

Prett sure you got the units messed up there.
You don't want to use mohm/gram, you want to use something like mohm*gram or 1/(mohm*gram)

Or better yet use some consistent critera to determine max acceptable power for a cell.

For example, you'd accept no less then 3.3V a cell under load from full charge to determine peak 5 sec burst current. For a 30Q, this might be about 35-40A. Call it 40.
That's 40*3.3=132W. at 46g: 132W/46g = 2869 W/kg

 

[bellfador]

Yes, mOhm*gram is correct.

 

[oneoone]

SO for someone with limited knowledge of cells, would this be a good cell to build a battery pack out of? I am looking at purchasing a small 14S6P triangle frame pack from em3ev made with 30q's. Is this a good choice for a bbshd?

 

[bigbore]

SO for someone with limited knowledge of cells, would this be a good cell to build a battery pack out of? I am looking at purchasing a small 14S6P triangle frame pack from em3ev made with 30q's. Is this a good choice for a bbshd?

I think if 3Kw continuous power is enough for you you can go that way

 

[okashira]

Updated 30Q data. Need to add Model S cell data.
Note that it's been cold in the house since I restarted, I think that accounts for all of the lost capacity. It was much warmer in July when I stopped. Cell was stored at 3.1V

 

[okashira]

Added all Model S Cell data to date.
I can offer no explanation for the strange behavior of the Model S cell. It seems to have actually picked up capacity after storage for six months at 3.2V. The data is real and I have verified it's good.

I am going to double check and make sure I didn't hook up the wrong cell tomorrow....

 

[Pajda]

Added all Model S Cell data to date.
I can offer no explanation for the strange behavior of the Model S cell. It seems to have actually picked up capacity after storage for six months at 3.2V. The data is real and I have verified it's good.

I am going to double check and make sure I didn't hook up the wrong cell tomorrow....

I have no scientific explanation too, but this seems to be a common behavior of Li-Ion cells. So I am only somewhat confused about Samsung cell, that it did not picked up some capacity as well.

I have noticed during cycle life tests of Li-Ion cells that the rest time between CHG and DCHG plays significant role in cycle life too. Even couple of hours rest time instead of standard 10-15min regain a few percent of usable capacity. It can be seen on my graph below. I am using 20 cycle tests, so the small peaks shows influence of another couple of minutes to hours of rest time between starting next 20 cycles. And after a 390 cycle you can see influence of ca 12 days rest time.

 

[okashira]

Added all Model S Cell data to date.
I can offer no explanation for the strange behavior of the Model S cell. It seems to have actually picked up capacity after storage for six months at 3.2V. The data is real and I have verified it's good.

I am going to double check and make sure I didn't hook up the wrong cell tomorrow....

I have no scientific explanation too, but this seems to be a common behavior of Li-Ion cells. So I am only somewhat confused about Samsung cell, that it did not picked up some capacity as well.

I have noticed during cycle life tests of Li-Ion cells that the rest time between CHG and DCHG plays significant role in cycle life too. Even couple of hours rest time instead of standard 10-15min regain a few percent of usable capacity. It can be seen on my graph below. I am using 20 cycle tests, so the small peaks shows influence of another couple of minutes to hours of rest time between starting next 20 cycles. And after a 390 cycle you can see influence of ca 12 days rest time.

Wow that is really terrible cycle life on your full DOD test.
Keep in mind, when I restarted, the temperature was much cooler. The 30Q may have picked up a tiny.

I did go through all the cells I had sitting on the tester. They all tested higher then the cell I had in there. I am pretty sure it's the right one so I'm back to cycling it. I did lose about 15 cycle of data though. :-/

Updated with 30Q data, over 500 now. You can see where I finally got my heater fixed and recently we had a heat wave. )

 

[ridethelightning]

gee. the 30q seems to have flattened off nicely.

 

[okashira]

gee. the 30q seems to have flattened off nicely.

Mostly due to warming. When I restarted testing, temperature was about 64 ambient. Recently I fixed the heater in the house and we had a heat wave. I suspect it will start falling again
Guess I should revise the "75°F" at the top of the chart.

 

[ridethelightning]

gee. the 30q seems to have flattened off nicely.

Mostly due to warming. When I restarted testing, temperature was about 64 ambient. Recently I fixed the heater in the house and we had a heat wave. I suspect it will start falling again
Guess I should revise the "75°F" at the top of the chart.

so, does that mean that running the cycles at low temp was actually accelerating permenent capacity loss?
cause now they seem to be sticking to a line that suggests that the capacity loss in the first tests has stopped altogether..but neither has the cell gained capacity much at the new higher temp.

 

[okashira]

gee. the 30q seems to have flattened off nicely.

Mostly due to warming. When I restarted testing, temperature was about 64 ambient. Recently I fixed the heater in the house and we had a heat wave. I suspect it will start falling again
Guess I should revise the "75°F" at the top of the chart.

so, does that mean that running the cycles at low temp was actually accelerating permenent capacity loss?
cause now they seem to be sticking to a line that suggests that the capacity loss in the first tests has stopped altogether..but neither has the cell gained capacity much at the new higher temp.

No... the temp rise was slow and the capacity loss countered it and so you got a flat-line. It was just a coincidence.
Capacity will fall again when it cools down in the house, or rise again when it warms.

 

[okashira]

Updated again, On the model S cell... went back to the original cell after trying 4 other cells. Strange beast.

Allex was kind enough to send me four NCR18650GA's... from two different sources to boot. I will start them soon. I will also add more Model S cells.