Trustfire 14500 900mAh protected - Measurements

[txg]

hi there,

I've been reading cpf for some weeks now, and i recently measured the output of my 14500 li-ions from dx i'm using in my akoray k-106. hopefully, some people around here are interested in what i got out of these cells.

my measurements are done with a diy computer controlled battery charger, you can read more about it here:
http://www.stefanv.com/electronics/battman2.html
(thats not my website, but i built my device according to these instructions)

at first, i measured the output at ~1.1Amps, which is 598mAh/2148mWh:

in my opinion, capacity is too low...i didn't expect to get 900mAh out of it, but 700-800 would be nice.

i did another test with very low current (120mA), but results didn't get better:

I'm a little bit disappointed of these results, as these li-ions dont have more mWhours than my gp recykos...which are not as dangerous to use as li-ions (even if they are protected). the only advantage of these batteries is higher brightness of my k-106 on high. but if the light is used on med or low, runtimes are the same on li-ion or ni-mh.

for comparison, here are my results with recyko cells, note that i've tested 4 of them in series here, so you'll have to divide mWh by four.

so hopefully i was able to provide some interesting information.
keep up the good work! :twothumbs

 

[txg]

have these cells been measured before? (i could'nt find anything comparable) or why is nobody interested in this subject?

 

[niner]

have these cells been measured before? (i could'nt find anything comparable) or why is nobody interested in this subject?

I have a few of these cells. They worked okay, but I never bother to check the mAh. I will check them out tonight with CBA II.

 

[wapkil]

I don't have the CBA or similar equipement but some time ago I made a simple discharge test to compare AW 750mAh and TrustFire 900mAh batteries. I simply discharged them using a 10 ohm resistor:



This is (obviously) not the constant current or the constant power test. The continuous lines represent the voltage and the dashed lines the power. The current was much lower that in your test and this probably explains the higher mAh and mWh results.

EDIT to add: I missed your 120mA test. In my test the current was ~400-350mA so I don't know why your results are lower. OTOH the difference between my "~400mA" and your 120mA test results is less than 6% so they are rather similar.

 

[txg]

thats interesting, you'll get a little bit higher capacity although your discharge current is higher than mine on the second attempt with ~120mA.

it's also interesting that the AW cells aren't much better, although it seems like these are very good cells...

these 14500s are my first li-ion cells, and i thought their energy density is much better than even good NiMhs, but actually it seems like even the AW cells are outperformed by good sanyo 2700s, and the LSD Cells are at least close.

 

[wapkil]

thats interesting, you'll get a little bit higher capacity although your discharge current is higher than mine on the second attempt with ~120mA.

it's also interesting that the AW cells aren't much better, although it seems like these are very good cells...

these 14500s are my first li-ion cells, and i thought their energy density is much better than even good NiMhs, but actually it seems like even the AW cells are outperformed by good sanyo 2700s, and the LSD Cells are at least close.

You still get better results in terms of the power to weight ratio - the TrustFires weight ~20g while Eneloops with similar capacity are ~26g. Unfortunately it's not that good with power/volume.

EDIT: Well, what I actually meant was the energy/weight and energy/volume ratios, not the power. It seems that I need to get some sleep.

 

[txg]

that's right, I'm actually measuring 18.8g vs. 26.0g. but in a single AA light this difference is not so significant 😉

 

[wapkil]

that's right, I'm actually measuring 18.8g vs. 26.0g. but in a single AA light this difference is not so significant 😉

Hmm, that's interesting. My scale is not calibrated but it measures between 25.9g and 26.2g for my Eneloops (eight of them). The TrustFires weight was 19.9g and 20.3g. I think that this difference in weight between your batteries and mine may suggest that they are from different batches.

BTW, the LED driver when used in step-down mode for LiIons will usually be more efficient that in step-up mode for NiMHs. This can result in slightly better runtime with LiIons, even when there is no difference in capacity.

 

[phantom23]

AW and Trustfire 14500 have very similar capacity. Olight I15 worked for 53 minutes on AW, I did my test with Trustfire 14500with the same flashlight.

Runtime was 1 minute shorter! My cell was charged twice (Li-Ion reaches full capacity after at least 3 cycles), last time 24 hrs ago.

 

[txg]

That's nice to know, so it actually seems like li-ions in AA size are at least at the moment comparable to Ni-Mh when it comes to energy/size ratio, their only advantage is their better energy/weight ratio, which isn't really interesting in AA size flashlights.

Seems like 18650's are the way to go, as they are able to store as much energy as three good AA's in a smaller volume. Also, single cells are easier to charge than multiple cell designs.

 

[baterija]

That's nice to know, so it actually seems like li-ions in AA size are at least at the moment comparable to Ni-Mh when it comes to energy/size ratio, their only advantage is their better energy/weight ratio, which isn't really interesting in AA size flashlights.

BTW, the LED driver when used in step-down mode for LiIons will usually be more efficient that in step-up mode for NiMHs. This can result in slightly better runtime with LiIons, even when there is no difference in capacity.

Like Wapkil said the voltage difference can buy you driver efficiencies. Your numbers show your cell about 5% higher capacitythan Silverfox's battery shootout shows the Eneloop at 3A draw. Throw in a 5-10% more efficient driver and there starts to be a noticeable if not huge difference.

Higher current levels for NiMh (to make up for the lower voltage) also introduce more power loss from resistances in the current path like a switch. Given the loss in a resistor being I squared times R we're looking at about 9 times higher loss in the NiMh lights - since current will be about 3 times as high at the tailcap. That 20 milliohm switch resistance that consumes .02W on Lion drawing 1A suddenly is consuming .18W at 3A with the NiMh.

Even without significantly more energy capacity the 14500 can supply more energy to the LED. The devil is in the details of the specific implementation.

 

[txg]

here's some new data for you:

trustfire 14500 black (dx sku26124).

#1:

#2:

so it seems like they are very little better than the blue trustfires, in mWh its about 6%. please notice that these batteries are longer than normal, they fit in my akoray very tightly, but i can't transport them in my battery cases.

 

[m99]

dx sku.26124 is 51 mm long so they're a half mm shorter than dx sku.03435, but still one mm longer than a standard AA.

 

[RedForest UK]

I am only getting about 300mah from my blue trustfire 14500's, they last 18-20minutes in my akoray k-106 with a current draw of 1.1A. I would think i may have faulty cells but i ordered some more and got very similar results.. :shrug:

The second set were also about 1.5mm longer than the first set and a little wider, they were a very tight fit, even thought i ordered exactly the same sku. I'm guessing its just the lottery of which sku. is closest when packaging now to be honest..