Jim does not have this cell listed on his ebay page, so will not profit from this review, be it good or bad. So, I'm just going to set out the facts with no favouritism, and no massaging of the figures. Whatever values I measure, I'll post here.
This will be a test of the cell’s overall capacity, as measured with a 0.2C discharge, and then seeing how capacity alters as discharge rates increase – is capacity maintained well, or does the voltage sag and lead to the cell not delivering it’s stored energy before the minimum discharge voltage is reached.
With my review of the Ultrafire 3000mAh cell, I expressed that I had an interest in testing the cell, as I had previously owned two of them, and wanted to see how a new one compared to two older, used cells. As it is, it compared badly. With this 3600mAh cell, any curiosity I had was entirely of the morbid variety.....
Fact is that we all know that there is no currently commercially available cell with a 3600mAh capacity. The stated capacity of this cell is quite simply an out and out lie. The real question here is, is this actually a decent enough cell, but with an exaggerated capacity - like the Trustfire 3000mAh; or is the fake capacity an excuse to put any old cell under that bright wrapper. If we know for a fact that the cell isn't what it claims to be, who knows what it might actually be.
I'm going to cut right to the chase here, and say that it's the latter. Capacity is very low. Voltage sag was surprisingly low up to a 2C discharge rate, but that's about as positive as it gets.
Testing Equipment
As I have stated in all my reviews, I try to carry out all my charging on one charger, an iCharger 106B+, and carry out the discharges and internal resistance tests on a second charger – an iCharger 208B. The idea is to be charging one battery while discharging another, in order to speed up the workflow, but to always use the same charger for the same steps, to ensure that results are directly comparable.
Voltage is measured with a Precision Gold WG 020 multi-meter, dimensions with a Precision Gold digital calliper, and weight with a Neva digital scale stated to be accurate to 1/100th of a gram.
The base of the cell is attached to the charger via a 12” 16AWG cable with a large, strong magnet soldered to it. The positive button is attached via a magnet (if it adheres well) or via a crocodile clip. In this case, the magnets adhered well at both ends. Where it has been hard to get a good contact, and so internal resistance has been high, I have sometimes resorted to feeding a split ring or paperclip through the cell's vent holes to give the croc-clip something that it can grips securely. I had to resort to this technique with the UF 3600mAh to minimise IR.
Results at a glance
Ultrafire 18650 3600mAh protected
Provided for testing by Ebay UK member ‘big_f_d_d’
Big_f_d_d does not currently have this cell listed on his ebay page, so I cannot comment on pricing, but it is freely available from other ebay dealers, or the common China/HK electronics retailers – for instance, KD, DX, DD, BIO, BOB, Manafont, et al are likely to stock these.
|
|
Cell 1 (1) |
|
Initial voltage on receipt |
3.33V |
|
Measured length |
68.70mm |
|
Measured width (max) |
18.40mm |
|
Weight |
43.73grams |
|
Internal resistance at initial voltage |
172mOhm |
|
Capacity from initial voltage down to 3.00V @ 0.7A |
5mAh |
|
Internal resistance after storage charge |
178mOhm |
|
Capacity from 4.2V down to 3V @ 0.7A |
775mAh |
|
Capacity from 4.2V down to 3V @ 1.0A |
779mAh |
|
Capacity from 4.2V down to 3V @ 1.5A |
751mAh |
|
Capacity from 4.2V down to 3V @ 3.0A |
N/A |
|
Capacity from 4.2V down to 3V @ 5.0A |
N/A |
(1) This is a single cell provided to me for testing, rather than a purchase that I have made – these cells are normally supplied in pairs.
Although the cell started at quite a low voltage of 3.33V, the fact that only 5mAh was discharged before the cell dropped to 3.00V, didn't bode well. Internal resistance was quite high. though a good deal lower than the 3000mAh Ultrafire I tested. While the capacity was higher from a full charge, it was still low. The only upside was that from 0.7A through to 1.5A, capacity didn't actually drop that much. I didn't risk going beyond an approximately 2C discharge rate. The fact remains though that while voltage sag didn't appear to be much of an issue, you are starting with such a low capacity to begin with, that this cell just isn't worth considering.
Construction
The wrap is fairly thin, but not excessively brittle.
You have a foil style base, which is more likely to experience wear and tear than a solid metal base. As with many newer Ultrafire cells, the foil has the brand name printed on it. This inscription can act as an insulator – for instance, if you had the needle point of a multi-meter in direct contact with the text. However, with the width of a coil spring or sprung plunger in the tail of a light, you should be able to make good contact.
Light compatibility
|
Light |
Characteristics |
Fits |
Functions |
|
Olight M20 |
Wide tube, spring at head, sprung plunger at tail cap |
Yes |
Yes |
|
SWM T20CS |
Short tube, dual springs |
Yes |
Yes |
|
Jet IIIM |
Wide tube, tail spring only |
Yes |
Yes |
|
Fenix TK15 |
Two-piece tube – narrow at head Short tube, short spring at head |
Yes |
Yes |
|
Fenix TK11 |
Narrow tube, tail spring only |
Yes |
Yes |
|
Eagletac G25C2 |
Wide tube, sprung plunger at head and tail (minimal travel at the head end), physical reverse polarity protection |
Yes |
Yes |
|
Nitecore IFE2 |
Narrow tube, physical reverse Polarity protection |
Yes |
Yes |
Charger compatibility
|
Charger |
Fits |
Functions |
|
4Sevens single bay |
Yes |
Yes |
|
Trustfire TR-001 |
Yes - just |
Yes |
|
Ultrafire WF-139 |
No (2) |
Yes (2) |
|
Ultrafire WF-188 |
Yes |
Yes |
|
HXY-042V2000A |
Yes |
Yes |
|
XTAR WP2 II |
Yes - snug |
Yes |
|
Pila IBC |
Yes |
Yes |
|
Jetbeam/Sysmax Intellicharge i4 |
Yes - Just |
Yes |
(2) While the cell is too long to sit all the way down in the cradle of the WF-139 charger, with the cell sat in the bay at an angle, the positive button on the cell makes contact with the charger’s positive terminal, and charging will commence.
|
Cell |
Voltage |
Internal resistance |
|
Ultrafire 3600mAh |
3.33V (as received) |
172mOhm |
|
Ultrafire 3600mAh |
3.72V (storage charge) |
178mOhm |
|
Ultrafire 3000mAh |
3.93V (as received) |
248mOhm |
|
Ultrafire 3000mAh |
3.74V (storage charge) |
288mOhm |
|
Trustfire 3000mAh |
4.00V (as received) |
123mOhm |
|
Trustfire 3000mAh |
3.74V (storage charge) |
135mOhm |
|
Ridbatt 2600mAh #1 |
3.74V (storage charge) |
129mOhm |
|
Ridbatt 2600mAh #1 |
3.74V after initial capacity test (storage charge) |
135mOhm |
|
Ridbatt 2600mAh #1 |
3.74V after all testing complete (storage charge) |
117mOhm |
|
Xtar 2600mAh #1 |
3.85V (as received) |
139mOhm |
|
Xtar 2600mAh #2 |
3.79V (as received) |
136mOhm |
|
Keeppower 2600mAh #1 |
3.78V (as received) |
123mOhm |
|
Keeppower 2600mAh #2 |
3.78V (as received) |
119mOhm |
|
Hi-Max 2600mAh #1 |
3.79V (as received) |
153mOhm |
|
Hi-Max 2600mAh #2 |
3.80V (as received) |
163mOhm |
I have compared the Ultrafire 3600mAh with the similarly exaggerated 3000mAh cells from Ultrafire themselves, and from Trustfire. As the Trustfire 3000mAh cell was found to actually be in the same capacity range as 2600/2500mAh cells, I have bulked out the rest of the internal resistance table with cells listed as having a capacity of 2600mAh, which seems more in line with the true capacity of the Trustfire. We’ll see how the Ultrafire compares.