Anyone have a recomended discharge rate for testing IMR cells?

[ENAUD]

I have some batteries that I wish to test for actual useful capacity. Some are new, and some are approximately 1 year old. I want to discharge them down to 3.2 volts on my Turnigy multi charger and track the useable mAh each different cell can deliver from a full charge. batteries to be tested are: EH IMR 18650 (2000mAh), AW IMR 18650 (2000mAh), and ORBOTRONIC SX 30 IMR 2100 (mAh).

These cells will be mainly used in a ProVari and typically will be driving a 1.4Ω-1.8Ω coil at anywhere from 3.6v to 4v depending on the type of atomizer. An actual use type load would be most accurate for my test, and I can adjust my charger to discharge in .1A increments. I just don't know what a good average discharge load the ProVari would be drawing from my batteries within the stated range of my typical usage is. Thanks in advance for any advice...

 

[Ryedan]

This is an interesting one . I agree the best rate of discharge to test at is what you'll be drawing from the battery in use. The average values of your vaping setup are 1.6 ohms and 3.8V which draws 2.38A in a mechanical mod. The current draw in a regulated mod to maintain 3.8V output will be less with a fresh battery at 4.2V and more with a battery at 3.3V, plus there is efficiency loss in the system, however the battery will spend most of its time around 3.7V, very close to your 3.8V average output.

You're going to be doing a continuous discharge which I think will drain the battery a bit faster than vaping's intermittent use does. 2.38A plus 20% equals 2.86A. I would test at 2.7 or 2.8A. IMO testing all the batteries at that rate will give you a very good idea of how they will perform compared to each other.

Keep in mind though that I am not a battery engineer and this is my opinion only

And please let us know how your testing turns out.

 

[ENAUD]

Thanks for the reply Ryedan. After reading your reply I see that all I can achieve is a 1A max discharge rate. This will be good enough for my purposes. I am trying to get a sort of baseline on my batteries. By having an actual mAh discharge value from a fully charged and rested battery, I will then have a value to help me analyze them in the future to determine when it is time to discard/replace them. It will also give me info to base decisions on which batteries to make future purchases of.
My EH cells are all old enough where all I can do is achieve relative comparisons between them. My AW and Orbotronic cells are relatively new, and as such I will have a better idea of what type of energy loss happens at, say, six months time in use. I am just looking for a way to verify and track, where my batteries are at in terms of useful lifespan.

 

[zoiDman]

I am by No Mean and Expert on Batteries or Testing them. But I have Gleaned a Lot of Information about batteries and the Way they can be Tested from Flashlight Forums like Candle Power.

CandlePowerForums - The Front Page

And in the Past, have done Many Google Site Searches of these Flashlight Forums for Reviews and Tech Info.

 

[ENAUD]

Thanks Zoi, I am aware of that forum, but haven't taken the time to really dig around there or register...It could be dangerous to my vape budget

 

[zoiDman]

Thanks Zoi, I am aware of that forum, but haven't taken the time to really dig around there or register...It could be dangerous to my vape budget

Just Like this Site has a Wealth on Great Info on all thing e-Cigarettes. Some of the Flashlight Forum have the Same. Only about Flashlight, Batteries and LED Drivers/Emitters.

I went thru a Phase of Buying el-Cheap-O or Knock-Off Flashlights on e-Bay. Then Tearing them down and rebuilding them with a Better Driver. I learned quite a bit by Lurking on those Flashlight Forms. And read Many Reviews and saw Many Test Graphs about Batteries.

Not Say'n that I fully Understood Everything I read. But if you have Technical Questions about How To Test a battery, I'm sure many of your Questions can be answered there.

zoiD

 

[Ryedan]

Thanks for the reply Ryedan. After reading your reply I see that all I can achieve is a 1A max discharge rate. This will be good enough for my purposes. I am trying to get a sort of baseline on my batteries. By having an actual mAh discharge value from a fully charged and rested battery, I will then have a value to help me analyze them in the future to determine when it is time to discard/replace them. It will also give me info to base decisions on which batteries to make future purchases of.
My EH cells are all old enough where all I can do is achieve relative comparisons between them. My AW and Orbotronic cells are relatively new, and as such I will have a better idea of what type of energy loss happens at, say, six months time in use. I am just looking for a way to verify and track, where my batteries are at in terms of useful lifespan.

I thought you were more interested in how much vape time you get from each rather than when it will be time to replace them. Of course your plan will help with that too

I vape primarily mechanical mods. I'm more interested in internal resistance increase so I monitor voltage drop at a given atty resistance over time. I'm currently rotating through four VTC cells so they should age at roughly the same rate. I retired a pair of MNKE 18650s when they got to an additional 0.6V drop at 0.5 ohms. I could tell the difference in vape from a new pair of cells I had bought and it was getting to the point where I would have had to build the atty for which battery I was going to use it on. I figure I got around 200 charge cycles out of them and that was good by me.

 

[ENAUD]

I thought you were more interested in how much vape time you get from each rather than when it will be time to replace them. Of course your plan will help with that too

How much vape time will be a guesstimate at best, but I think my results will give me some comparative data about which cell should
in theory, last longer on a charge. Without firing at actual power use levels, and being a constant discharge rate, all I hope to be able to achieve is a ballpark feel for the different cells. Useful to me, perhaps just useless information in the end...

 

[suspectK]

I've had a dranetz and IR camera setup to test some new 14500 cells.. I'm so lazy.

 

[ENAUD]

Well, I've managed to run all of my 18650 IMR cells through a discharge cycle and recorded some observations. I may have discovered a bad cell in the bunch by doing such a simple test. Cells were discharged with a constant load of 1A and charger cuts off when cells hit 3.00 volts at determined load. Resting times since charge were pretty much an unknown, but all cells had been charged within a day or two.

Cell................Cut off Voltage.....Time to cutoff........mAh discharged.........Ending Static Voltage( no load )

EH IMR #1------3.12v---------------96.08min.-----------1600mAh--------------3.71v
EH IMR #2------3.00v--------------117.49min.----------1962mAh--------------3.50v
EH IMR #3------3.00v--------------109.08min.----------1817mAh--------------3.54v

AW IMR#1------3.00v--------------110.11min.----------1835mAh--------------3.45v
AW IMR#2------3.00v--------------114.36min.---------1908mAh---------------3.45v
AW IMR#3------3.00v--------------112.54min.---------1880mAh---------------3.46v


ORB SX30 #1---3.00v--------------116.52min.---------1946mAh---------------3.44v
ORB SX30#2---3.00v---------------117.22min.---------1954mAh---------------3.45v

EH cell #1 dropped out early, and I can only wonder if that is due to age, or was it the cell that was over discharged at some point, and I revived with a jump start??? No way to tell at this point, but that cell is flagged, and probably will be recycled soon. All of my other cells show pretty similar profiles, and though I didn't graph them out, ( I could check where voltage is at at pre-determined intervals during discharge) I didn't see the need for such accuracy for my purposes. I did however note, that the ORB cells seemed to drop down to 3.5v-3.4v sooner than EH and AW cells time wise, so a little more of their energy was available at a lower voltage than the AW and EH cells, but this occurred sometime after 1000mAh discharged. Another surprise was that, across the board, aprox 400-600mAh of the available energy was only available at 3.2v-3.0v under a 1Amp continuous load. For entertainment purposes only, I am going to use these cells in rotation now, and when the ProVari starts blinking indicating low battery, will further discharge the cell to get an idea of non-useable mAh left over at that point.

 

[zoiDman]

Side Note:

Here is an Interesting Thread...

http://www.e-cigarette-forum.com/fo...587759-purle-efest-18650-battery-warning.html

 

[WattWick]

Thanks for the reply Ryedan. After reading your reply I see that all I can achieve is a 1A max discharge rate. This will be good enough for my purposes. I am trying to get a sort of baseline on my batteries. By having an actual mAh discharge value from a fully charged and rested battery, I will then have a value to help me analyze them in the future to determine when it is time to discard/replace them. It will also give me info to base decisions on which batteries to make future purchases of.
My EH cells are all old enough where all I can do is achieve relative comparisons between them. My AW and Orbotronic cells are relatively new, and as such I will have a better idea of what type of energy loss happens at, say, six months time in use. I am just looking for a way to verify and track, where my batteries are at in terms of useful lifespan.

Did you check to see if your charger supports regenerative discharge? It's when you dump power from one battery to another instead of relying on your chargers heat sink. Not sure about Turnigy chargers (or which one you got) but I know my PowerLab 6 does this.

Just a thought. Anyway... thanks for doing this! Been thinking about making a cradle to use with my "proper" charger as well... just haven't gotten around to it. Sort of doubt I ever will.