How healthy are your batteries? (How to measure internal resistance)

[qumefox]

The value of the resistor really isn't critical so long as it's low enough to give a measurable drop in the battery voltage. Theoretically the IR measurement should be about the same regardless of the amount of load.

 

[BShanahan14rulz]

Cool, thanks Qume!

 

[LarryDFW]

I am using a 5.1 Ohm resistor, but I'm thinking this load isn't big enough to give meaningful results. Should I use a resistor that would net the max current that the cells can handle, or is shooting for ~1-2 amps high enough? Or perhaps, is my 5.1 Ohm just as good?

Your 5.1 ohm resistor will only draw about 0.8 amp.

I use a 3.1 ohm resistor to draw about 1.3 amps (closer to typical 445 load)

The I.R. resistance should be similar.

LarryDFW

 

[Jackagain]

Here's a good tutorial on Li-Ion battery charging:

Charging Lithium-Ion Batteries

 

[sinner]

Sinner;

One caution for old laptop cells.

Normal life for #18650 cells is 4 to 5 years depending on mfg.

Laptop batteries are 2-3 years old usually when discarded.

LarryDFW

Oh well!! i didnt really came back to the battery section again, my bad..
Okay Larry Gotcha!! I discarded almost all of them a while ago because i was reading at the batteryuniveristy website about charging it and the hazards these old batteries can impose, its not worth it..
Some guy was stupid enough to suggest me that its ok but i had a doubt..
And if u have a tiny bit of doubt in something , just leave it (life experience)

I've got some new sanyo 2600mAh's and CR2's that i got from cnqualitygoods which ive been using instead..

 

[Sigurthr]

Does anyone know what the ranges of internal resistance are for 16430's?

I measured my two "cheap" trustfires from Lazerer today; 280mOhms and 400mOhms. I really notice a difference between them, the 400mOhm one craps out way earlier than the other cell under the same load. I didn't measure my good AW cells since... they're good!

 

[lasersbee]

If your AW cells are "good"... I would measure them and use
that as a yardstick...

Jerry

 

[Sigurthr]

My AW's are protected cells, I'm not sure if the circuit will allow a 1.5C load full current, so I haven't tried them, and as I said; I know they're "good". If the circuit activates it would spoil the readings at the very least.

I'd select another load but I don't have any other power resistors to try this with.

 

[Hiemal]

Wow, I just measured my "new" Ultrafire CR123's, and their internal resistance varied anywhere from 400 milliohms to almost 1 ohm.... very very disappointing! Already contacted the seller, that's a little ridiculous...

 

[Hiemal]

It was for 4 different batteries Cyparagon.

 

[LarryDFW]

Wow, I just measured my "new" Ultrafire CR123's, and their internal resistance varied anywhere from 400 milliohms to almost 1 ohm.... very very disappointing! Already contacted the seller, that's a little ridiculous...

That is the major problem with Ultrafire, and other 2nd tier manufacturers.

Look for "brand names" like Panasonic, LG, Sanyo, and Samsung for much lower internal resistance.

LarryDFW

P.S. Just saw some testing on protection circuits.
The ones tested were 60 milliohms.
That means about a 0.12 volt drop at 2 amps current.

 

[LarryDFW]

I just received a shipment, and tested some new cells:

Panasonic 3100mah #18650 cell

The Panasonic had nice low internal resistances:

Tested with R = 3.1 ohms
Internal resistance : ~60 mOhms @ 1.34 amps load (~ 1/2 C load rating)

Very good IR, with 500 mah more capacity (+19.2% , 3100 vs 2600)
More capacity should improve laser run time capability.

According to 18650 Battery Testing Experts @ Cadex :

75-150 mOhm - Excellent
150-250 mOhm - Good
250-350 mOhm - Marginal
350-Up mOhm - Bad

LarryDFW

P.S. Just saw some new testing on protection circuits.
The ones tested were 60 mOhms (same resistance as these cells).
That means a 0.12 volt drop at 2 amps current.

 

[lasersgopewpew]

i have some 18650 batteries i pulled from a useless(to me anyways) laptop battery that was pretty fresh and new, that i no-longer needed and got 76mw for the cell i tested, i figure thats pretty darn good and finally have some cells i trust in my 11 watt flashlight(kaidomain c8 xml-t6) can anybody test a new 10440 cell and post the readings from a good cell?

 

[LittleGeenLaser]

How healthy are your batteries? My Tenergy 750Ah RCR123A are still doing very well recharged them over 2300 times and 3 out of the 4 of them I got in 2009 are still going strong out of my Electronic cigarette at 2.2-2.4 ohms resistance run time is about 3 to 4 hours and the samsung 4.34 VDC lithium cells I got from Larry run about 18 hours before needing recharging at around 3.75 VDC WOW

 

[LarryDFW]

I just received a shipment, and tested some new cells:

Panasonic 3400mah #18650 cell

The Panasonic had nice very low internal resistances:

Tested with R = 3.1 ohms
Internal resistance : ~55-60 mOhms @ 1.3 amps load
Very good IR, with 800 mah more capacity (+19.2% , 3400 vs 2600)
More capacity should improve laser run time capability.

According to 18650 Battery Testing Experts @ Cadex :

75-150 mOhm - Excellent (55mOhm even better)
150-250 mOhm - Good
250-350 mOhm - Marginal
350-Up mOhm - Bad

LarryDFW

P.S. Just saw some new testing on protection circuits.
The ones tested were 60 mOhms (~= to this cell).
That means an additional 0.12 volt drop at 2 amps current.

 

[LarryDFW]

How healthy are your batteries? . . . and the samsung 4.34 VDC lithium cells I got from Larry run about 18 hours before needing recharging at around 3.75 VDC WOW

Glad to hear the Samsung 3000mah cells are performing that well.

The 3400mah Panasonic cells have tested with even lower Internal Resistance . . .

and should have even longer run times.

LarryDFW