Battery Internal Resistance Measurements

[684Alpha]

Hey guys, thanks for the great thread bap
please forgive my noobness. just wonder if anybody has tried these samsungs, says they are 30A and protected (maybe?)
3000mAh Samsung ICR-18650-30A-B 4.35V High Capacity Li-ion Rechargeable 18650 Battery Cell

:cheers:

 

[mikepetro]

Hey guys, thanks for the great thread bap
please forgive my noobness. just wonder if anybody has tried these samsungs, says they are 30A and protected (maybe?)
3000mAh Samsung ICR-18650-30A-B 4.35V High Capacity Li-ion Rechargeable 18650 Battery Cell

:cheers:

They are 4.35V cells. This means you need a special charger if you want to use the full 3Ah capacity. If you charge them with a standard 4.2v charger, it will work but you will only get about 2500mAh out of them, give or take.

The protective layer they speak of is not the same thing as a "protected" battery. "Protected batteries" have a high current cut-off limit. The protective layer they speak of here is a technique for minimizing the possibility of thermal runaway, but will not limit current.

 

[Phone Guy]

How important are the internal resistance levels? And at what point to they just become numbers on a spec sheet before actually changing the way a battery performs in the real world?


I've measured a few of mine and here's a couple examples.

Sony vtc4 measured at about 0.035 mohms
Panasonic cgr at about 0.053
Pink Samsung icr 0.097
Green Sony 18650 GR (8A) 2600 mAh, measured out at 0.107

In my related devices (Futura DNA20 and semovar nivel chip I'm not seeing any performance differences) they all claim to be drained around the same times, unable to sustain a high wattage setting with a partly drained battery. Sometimes you can fool the device by removing and replacing the same battery back in and continue vaping for a little while longer...then when the device says (think) the battery it's drained and I pop it in my nitecore charger I immediately get a solid first light and the 2nd light starts to blink which tells me the battery wasn't out just low...Again I've had this happen with multiple batteries on both the svoemesto semovar and the Futura DNA20.

Contrary my old mod was an eVic and when it drained a battery - it was drained. Popping that battery into the charger started is charging on the first led (which immediately goes solid when taken from the other two mods)

So I was under the impression battery internal resistance helped control or regulate voltage drop? I'm not sure that's true....The vtc4 with the lowest numbers do the same as my higher capacity Samsung's with triple the internal resistance.

 

[mamu]

Internal resistance does effect the unloaded voltage cutoff. The higher the internal resistance the higher the unloaded voltage cutoff.

With the Sony 18650 30A batts (has the lowest internal resistance of all 18650 30A batts) running on the Raptor (series batts) @ 15W, the unloaded voltage cutoff is 6.2v, vs the MNKE 18650 30A batts (has much higher internal resistance) that have an unloaded cutoff voltage of 6.7v - 6.8v when running at the same 15W.

That's real world data/testing there that can't be ignored. With all things being equal (30A batts, same batt connectors, same power setting, etc) how else would you explain those results but for the internal resistance differences between the batts?

 

[bapgood]

Phone Guy - do you still have the evic?

One thing that shouldn't be over looked is the battery contacts, wiring, etc. These things can effect vdrop substantially.

Also what is the voltage cutoff on the evic? It could be lower, and thus the difference your seeing on the charger. Most of these type of batteries are designed to be able to be discharged to down around 2v and still charge fine.

 

[Phone Guy]

Yes I still have the eVic. But I don't know what the cutoff voltage is for that device.

Honestly I'm not sure what the voltage cutoff is for the DNA20 or the nivel chip either...LOL

I guess I should look that up huh?

 

[bapgood]

Yes I still have the eVic. But I don't know what the cutoff voltage is for that device.

Honestly I'm not sure what the voltage cutoff is for the DNA20 or the nivel chip either...LOL

I guess I should look that up huh?

Just thinking you could run the VTC4 in the evic and see what your charger looks like after you have discharged the battery in the evic.

 

[Phone Guy]

In the spirit of testing, I'm using my eVic right now with a freshly charged vtc4, running a 1.7 ohm coil at 11 watts which is the eVic maximum. When it's depleted I'll check the voltage with my DMM and stick it in my nitecore i4.

I don't know what the cutoff voltage is for any of my devices (eVic, Futura DNA20, Semovar Nivel chip) but I'll say unscientific experience tells me the semovar (nivel chip) has the highest voltage cutoff and the eVic has the lowest.

Why? My vaping habit hasn't changed with the new mods, however they do go to higher wattage...and I catch myself replacing batteries sooner and/or more frequently with the semovar, Futura and eVic (in that order).

But I will test all three over the next couple days and report back my findings...I'm guessing you'd like them all to be with the Sony vtc4?

 

[Phone Guy]

Ok, that was power vaping! Whew!

2100 mAh 30A Sony vtc4 dead in eVic. Metered out at 3.4V drained. Stuck it back in nitecore i4, started charging as expected from the first (bottom) light.

I'll test the semovar and/or Futura DNA20 tomorrow.

 

[dutch onsea]

Why don`t you start w the semovar? when it shuts down , have a go inthe futura and afterwards you could still try the eVic

 

[Phone Guy]

Why don`t you start w the semovar? when it shuts down , have a go inthe futura and afterwards you could still try the eVic

Are you suggesting moving the same partially drained battery from the semovar to the Futura then finally to the eVic?

What would that accomplish? (Just curious)

FWIW: I'm vaping the semovar right now at 11 watts using a vtc4 battery. I figured I'd do 11 watts (like on the eVic) to keep the play field as level as possible.

 

[Phone Guy]

Well I'm wrong and a little surprised.

Drained a Sony vtc4 in the semovar at 11 watts, since the eVic only goes up to 11 watts I was trying to compare Apple's to Apple's...

Anyway drained it down and I got 3.414 volts on my DMM.

I guess the trick is 11 watts?

I'll test the dna20 next, but now I'm not confident in my previous statement.

 

[bapgood]

The higher the vaped at wattage the more load the battery will see and vdrop under load will be higher.

 

[Phone Guy]

Finished with the Futura DNA20.... the vtc4 reads 3.396 volts on the DMM... and the dna20 says check battery but keeps trying to fire (at 11 watts)

And putting the Sony vtc4 in the nitecore i4 it starts charging on the first (bottom) light. Same as the last two tests.

So to my surprise, at 11 watts they all three cutoff at 3.4volts. And to be honest I think I vaped the most liquid using the DNA20.

I tested with the same Taifun GT tank and coil, changing cotton wicks each time, I had to refill on the DNA20. The other two were so close I'd say no difference.

Well, that's my study

 

[Phone Guy]

Ok so now the question is was it the vtc4 low internal resistance that allowed me to drain them dry? (Dry being 3.4v in this case)

Or was it the 11 watts setting?

How would other higher resistance batteries fair? Like my pink Samsung ICR? With 97mohms? Better? The same?

 

[684Alpha]

They are 4.35V cells. This means you need a special charger if you want to use the full 3Ah capacity. If you charge them with a standard 4.2v charger, it will work but you will only get about 2500mAh out of them, give or take.

The protective layer they speak of is not the same thing as a "protected" battery. "Protected Batteries" have a high current cut-off limit. The protective layer they speak of here is a technique for minimizing the possibility of thermal runaway, but will not limit current.

Thanks Mike. Very helpful

 

[bilboda]

Finished with the Futura DNA20.... the vtc4 reads 3.396 volts on the DMM... and the dna20 says check battery but keeps trying to fire (at 11 watts)

And putting the Sony vtc4 in the nitecore i4 it starts charging on the first (bottom) light. Same as the last two tests.

So to my surprise, at 11 watts they all three cutoff at 3.4volts. And to be honest I think I vaped the most liquid using the DNA20.

I tested with the same Taifun GT tank and coil, changing cotton wicks each time, I had to refill on the DNA20. The other two were so close I'd say no difference.

Well, that's my study

Seems I forgot the wattage setting affecting the battery cutoff. I was disappointed in the dna in the Futura but it seems now that I can, I vape everything at around 18 watts, lol, not that I need that much. Imho, your pink samsung will be at a higher voltage when it quits on all those mods.