U2 Battery Comparison

[SilverFox]

The SureFire U2 has several battery options. I decided to check a few out.

At level 6 the U2 draws around 1.3 amps, so testing at 1.5 amps is a bit high, but close.

Please note the difference in the Pila 168A and the 168S. It makes a lot of sense to go with the 168A, if it will fit in your application. The larger size adds a lot of capacity.

The SureFire 123’s ended up at 93 degrees F, the 3 volt R123’s were at 90, and the Pila batteries were at 82 degrees at the end of the test.

The 3V R123’s are the first generation from Jon Burly. I believe he has some improved versions at this time. Please understand that these are a work in progress. It would appear that they are better suited to lower current applications at this time.

Ah = Amp Hours
Wh = Watt Hours
M = Minutes

Pila 168A = Fat Pila’s
Pila 168S = Pila’s that fit the SureFire L4 and other SureFire lights
SureFire 123 = Standard SureFire 123’s
1st Gen 3V R123 = First Generation of the 3 V (not the 4.2 volt) rechargeable 123’s from JS Burly’s.

Edit: I have added the results from a bare cell LG 18650 rated at 2.4 Ah. If your are considering using bare Li-Ion cells, make sure you have the proper charger and take care not to over discharge during use.

Two SF123’s and two 3V R123’s were connected in series for their respective tests.

Here is the data:

Tom

 

[elgarak]

How does the U2 react to the lower voltage of the pilas? Will all levels work?

 

[JanCPF]

elgerak,

Actually level 6 would not work very well on Pilas. Check out this thread.

Jan

 

[cy]

Silver, I'm not a runtime guy, but seems I got way more than 6 minutes from my 2x JSB 3V cells on U2.

I did carefully charge up both cells before testing. which charging two cells with a single slot cradle is a pita.

 

[SilverFox]

Hello Cy,

I believe 1.5 amps is about the limit of current draw for the 3 volt R123's. When I went to charge them back up, one cell took quite a bit less charge than the other. This makes me think that I tripped something internal, rather than ran out of capacity.

I may try to do the test again at 1.3 amps to see how well they perform at that rate.

At any rate, I still think the 3 volt R123's are better suited for lower current draws. The U2 on level 4, for example.

Tom

 

[KevinL]

Awesome graphs, as always.

I think the U2's level 6 falls outta regulation after the voltage falls to 3.7V-3.6V. After 60 minutes I lose level 5 as well. That explains a lot. Rechargeables are just on the fringe of the U2's regulation circuit's capabilities.. it does need the higher voltage to operate.

If I let the battery snooze for a while, I can get level 5 and 6 back, 6 briefly, but quite a lot of 5.

It also explains why CR123s can hold level 6 for nearly 40 minutes as well, which I've observed.

 

[PeLu]

[ QUOTE ]
SilverFox said:At level 6 the U2 draws around 1.3 amps, so testing at 1.5 amps is a bit high, but close.

[/ QUOTE ]

Isn't the U2 a more or less constant power device?
(more or less should mean that efficiency will be different for different input levels).
That means that the 2 CR123 cells will have to deliver more than 1.5A after a short time.


One more reason to pester West Mountain Radio to include this feature in the software....

 

[SilverFox]

Hello Peter,

The request is in and has been discussed at length.

Now, if they would only act on it...

Tom

 

[SilverFox]

I did another run of the 3 volt 123's at a lower AmpRate of 1.3 amps. The run time nearly doubled and there was less of an initial dip.

At 1.3 AmpRate
2- 1st Gen 3V R123 0.248 Ah, 1.110 Wh, 11.4 M

The cells heated up during the test to about 90 degrees F.

Tom

 

[wptski]

Tom:

Just wondering what your test setup looks like! /ubbthreads/images/graemlins/thinking.gif In order to read battery voltage, you must have some sort-of test rig using the U2 head alone, correct? Got a picture of your test fixture or whatever?

 

[cy]

silver, I ran another test of 2x JSB 3v in my U2. after aprox. 6 minutes continous runtime. circuit breaker kicked in.

imediately took 3V cells out, they were aproaching hot. I concurr these first gen 3V will not sustain large loads.

 

[SilverFox]

Hello Bill,

You give me too much credit.

I simply read what others reported the current draw of the U2 to be (at level 6), added a bit of a fudge factor, and dialed that into my CBA. My initial testing was done at 1.5 amps (I believe the U2 draws a little over 1.4 amps), but the 3V R123's quickly cut out. To further explore their limits, I ran another test at 1.3 amps.

As Cy has pointed out (and by the way, thanks for confirming my 6 minute run time) the difficulty with the first generation 3V R123's is that you can only re-charge one cell at a time and the charge time is long. After the test, I spend the better part of the day re-charging the cells before I can use them again. This, coupled with the short run time, makes these cells not the best for this application, in my humble opinion.

Tom

 

[wptski]

[ QUOTE ]
SilverFox said:
Hello Bill,

You give me too much credit.

I simply read what others reported the current draw of the U2 to be (at level 6), added a bit of a fudge factor, and dialed that into my CBA. My initial testing was done at 1.5 amps (I believe the U2 draws a little over 1.4 amps), but the 3V R123's quickly cut out. To further explore their limits, I ran another test at 1.3 amps.

As Cy has pointed out (and by the way, thanks for confirming my 6 minute run time) the difficulty with the first generation 3V R123's is that you can only re-charge one cell at a time and the charge time is long. After the test, I spend the better part of the day re-charging the cells before I can use them again. This, coupled with the short run time, makes these cells not the best for this application, in my humble opinion.

Tom

[/ QUOTE ]
Tom:

Thanks! I sort-of collect battery chargers. /ubbthreads/images/graemlins/grin.gif I don't know what charger you are using. I have charged two Pila 168S's hooked in parallel but they were about the same state of discharge. My theory is if they are over/under protected, one will shut off while the other continues charging. Two cells will still take twice as long to charge no matter what but you don't have to remove one and connect another.

I'm just not sure what would happen if two cells aren't in the same state of discharge. The Triton is one of my chargers that I use on my Pila 168S/JSB123 cells, it uses the cc/cv method, so when it's in the final cv stage and one Pila stops charging, will the Triton revert back to the first cc stage?? I suppose since the Pila is protected, trying this shouldn't damage the cell.

 

[wptski]

Tom:

I just tried charging two 4.2v JSB123 in parallel on my Triton. It was a set that came out of one of my lights, one read 3.31V and the other read 0V.

Normally one cell charges to around 500mAh. It stopped at 1000mAh, one cell read 4.12V and the other 4.17V which is par for the Triton. So, charging in parallel with protected cells that aren't at similiar states of discharge appears to work perfectly! /ubbthreads/images/graemlins/grin.gif

 

[SilverFox]

Hello Bill,

It is nice to know the theory actually works out in real life.

Tom

 

[SilverFox]

I took the plunge and got some LG 18650 2.4 Ah bare Li-Ion cells and a Universal Li-Ion charger from www.BatterySpace.com .

I have spent some time checking out the charger and am pleased with the way it works. Please note, this is not a rapid charger. It takes about 12 hours to re-charge a discharged cell. The green light on the charger comes on at 4.1 volts, and the charger tops out at 4.2 volts.

I added the test results from these cells to the graph on the first post.

Please note that these are bare cells with no protection. My charger offers over charge protection, and the U2 offers over discharge protection. Use of these cells in other lights may yield different results.

Tom

 

[wptski]

[ QUOTE ]
SilverFox said:
I took the plunge and got some LG 18650 2.4 Ah bare Li-Ion cells and a Universal Li-Ion charger from www.BatterySpace.com .

I have spent some time checking out the charger and am pleased with the way it works. Please note, this is not a rapid charger. It takes about 12 hours to re-charge a discharged cell. The green light on the charger comes on at 4.1 volts, and the charger tops out at 4.2 volts.

I added the test results from these cells to the graph on the first post.

Please note that these are bare cells with no protection. My charger offers over charge protection, and the U2 offers over discharge protection. Use of these cells in other lights may yield different results.

Tom

[/ QUOTE ]
Tom:

You've sure got lots of 18650 cells! You haven't received the cells from 4sevens yet either! Trying to burn up that SF U2? /ubbthreads/images/graemlins/grin.gif

 

[SilverFox]

I have had a phone battery that never worked very well sitting around on the shelf. I took it apart and found two Sony 18650 cells in it. I have no idea of the rated capacity. They are marked US18650S GR and then Sony EnergyTec.

I put them on the tester at 1.5 amps and what a pair of duds. I have added their graph to the others on the first post.

I got the phone battery free as a promotion and there was a problem with a connection on the board. It never would work steady, unless you held your thumb on it. I remember it being advertised as "high capacity" but do not know any values.

These cells may work at lower levels, but level 6 is just slightly brighter than level 5. After about 20 minutes, any part of level 6 is just not there. I'll save these cells for a less demanding light.

Tom

 

[wasBlinded]

Those are great graphs for U2 batteries, Tom. The only thing is that the 1.5 amp test is unnecessarily harsh on the CR123 cells. On level 6, the U2 won't need to draw a full 1.5 amps from these cells (more like 1.1 to 1.2 amps), since they start off at a higher voltage. I've had the opportunity to test 4 different U2 heads, and they all draw about 6 watts from the batteries - until hitting about 4 volts, where current draw is 1.5 amps. From that point downward, the U2 will continue drawing about 1.5 amps on level 6 as the voltage falls, and power to the LED will fall commensurately. So it looks like the U2 boost circuit has current limiting at 1.5 amps.

Just so no one tries it, it doesn't have current limiting above about 6.4 (I think, it might have been 6.8 or 7.2 volts, I don't remember) volts, so don't put two 3.7 volt R123 cells in the U2, you may fry it.

 

[cognitivefun]

does the Pila 168A fit into the U2?