Battery testing - choices for series circuits

[mke67]

I don't pretend to understand you guys tech speak, so I will wait for the layman's results, but I am glad this is being done. Thanks guys.

[JW50]

I don't pretend to understand you guys tech speak, so I will wait for the layman's results, but I am glad this is being done. Thanks guys.

I agree. But interesting tech (geek) speak. What is a PTC? Do I have one? Should I have one? Is it "protect thyself from cancer"? Or "Please Tell this thing to Cut off?

[mke67]

I agree. But interesting tech (geek) speak. What is a PTC? Do I have one? Should I have one? Is it "protect thyself from cancer"? Or "Please Tell this thing to Cut off?

Pray the Thermal Cut off works...

[firhill]

The LiFePO4's have no PTC at all, just like the IMR/Li-Mn.

I can pull current from a LiFe cell until the shrink wrap ignites, and there is no safeguard to stop it...thankfully they don't build internal pressure the same way as Li-CO. The worst byproduct I have seen is runaway discharge and venting/leaking.

That's the main reason the LifePo4's have been my (HV vaping) cell of choice for close to three years now.

[JW50]

That's the main reason the LifePo4's have been my (HV vaping) cell of choice for close to three years now.

Three years, and still here, sounds great. Any praying involved?

[forcedfuel50]

Ok, the new lab gear is here and set-up. I am going to build a test jig that houses the battery inside a tube mod. That way we can simulate the real world. I also have been thinking about the duty cycle test. It's not really accurate. A more accurate test would be a constant resistance test. That would simulate an atty load. The duty cycle test is inaccurate, because it is constant amps draw. This is not accurate because as the battery voltage goes down, the atty stays constant, so therefore the amp draw goes down with voltage. So instead of the duty cycle test, I will do these as constant resistance, with random duty cycles....

any ideas or thoughts on that?

I believe its unecessary. Yes, resistance fluctuates as the heating element heats up, but simulating atty loads does us little good anyway as most (14500 or larger) batteries have the amperage necessary to power our atomizers with minimal heat rise, so little useful data is gained other then to say, yes, it went X minutes at this load or achieved X mAh or X cycles.

Maxing out the batteries and testing their max C ratings will give us much more information about their capabilities, failure thresholds and max temperatures achieved.

[forcedfuel50]

GOOD STUFF!!!

I can't agree that 106deg F is "warm to the touch". IMO that is a bit too hot for longevity of the cell. Certainly the results at 4 amps are within safety/longevity limits.

I disagree, it is only warm to the touch at 106F. My body temp runs about 99F, which is warm. Yes, battery life is cut down, but, my concern in testing isn't overall battery life, it's safety. Thermal runaway doesn't happen until 200+F. For example, Panasonic list the thermal runaway temp of their batteries at 212F.

[forcedfuel50]

Not to badger you, but let me just pose the question one more time. For the public record..

Does Super-t manufacturing personally endorse a rating of 10c discharge for the AW IMR 18490?

I ask again because I am trying to get people to make legally binding statements about safety limitations..

LOL, easy there big shooter! I know it's exciting, but come in, relax, take a look around, drink a beer or two with us first

We don't manufacture the batteries, we just test them so all we can say is our testing of a particular batteries output will meet the demands of X device. If you want someone to make legally binding statments for a particular C rating, you'll have to bring the manufacturers in like Panasonic, Tenergy etc....

[forcedfuel50]

AW LiFePO4 3.0/3.2V 16340 Results

AW's Listed C rating: 5C

I subjected them to max load ratings, way beyond what our ecigs draw. I tried to get 4 of them to fail by subjecting them to a 10amp continuous load (20+watts) and draining them down to zero volts. They reached 180F, but none of them failed or leaked.

If you have trouble viewing the graphs, they can be found here: http://www.supertmanufacturing.com/id70.html

5 Amp Continuous Load, Stacked Cells:


5 Amp Continuous load, Single Cell:


10 Amp Continuous load Single Cell (over twice their rated amps):


5 Amp Duty Cycle. 5 secs on, 20 secs off, Single Cell:

[AriM]

LOL, easy there big shooter! I know it's exciting, but come in, relax, take a look around, drink a beer or two with us first

We don't manufacture the batteries, we just test them so all we can say is our testing of a particular batteries output will meet the demands of X device. If you want someone to make legally binding statments for a particular C rating, you'll have to bring the manufacturers in like Panasonic, Tenergy etc....

big shooter? lol...ok. It's not really all that exciting. I'll be happy to have the beer with you though (well maybe a scotch, I'm not a beer guy).

So here is the problem....earlier you said that the cells are good for "10c", but you won't back that up with a legally binding statement. You just differ to the manufacturer. There is the problem....you can't say it's good for 10c and then not be willing to take some accountability for that claim....

So in reality it's possible to get 10c (we all know that is true), but no one will back that up with a legally binding statement about "safe at 10c"

I was under the impression that the purpose of the thread here was to get legally binding endorsements about specific batteries. I can see we aren't ever going to get there. Pity....