Ultrafire G120 questions.

[ateallthepies]

Hi all,

I have already bought an Ultrafire G90 incan that uses a 12 volt bulb and runs O.K on 3 RCR123A batteries, though it does get very hot.

I have my eye on a Ultrafire G120 rechargeable version but am unsure on a few things. First, it runs on 4 RCR123A batteries but the G140 xenon bulb that is supplied is only rated at 14 volts?
Would the freshly charged RCR's at 16.8 volts insta-flash the bulb? Even if it doesn't, what sort of life would the bulb have running 2 volts over it's rating?

Also, are AW RCR123A batteries O.K to use in a 4 cell incan or should I get some IMR batteries?

Thanks,

Steve.

 

[ateallthepies]

45 views and no replies?


Steve.

 

[Phaserburn]

Steve: the rule of thumb is that you don't want to run a li-ion cell over 2C. That is, twice it's rated capacity. In the case of RCRs rated at 750ma, you wouldn't want to run a bulb with a greater current draw than 1.5A. As RCRs are a little overstated in their capacities IMHO, I would draw the max at 1.3A. But that's me.

Those voltage ratings sound a bit squirrely to me. A 3 li-ion cell lamp is generally rated at between 12-13V. 4 li-ion cells would be a higher rating, as you suspect. That whole setup sounds dubious to me.

I love good incans, and I'd recommend a different setup than the UF. Check out Wolf Eyes. You can use the larger 18mm cells, with much better capacities. Larger capacity cells keep incans brighter and whiter much longer. WE quality is leagues ahead of UF; I have both. You also get alot of different lamps to choose from, the WE ones and those from Lumens Factory. Both are high quality lamps. The UF lamps are only ok.

 

[lctorana]

I have run this combination, 4 x AW black protected 16340 cells driving a 14V LA in both a WF-501D and a WF-502B.

The result?

Short term: Very nearly as bright as a RoP, perfect light colour. The bulbs seem to take the punishment well, too.

Long term: The coating is stripped off the reflectors. Must have just evaporated away.

Conclusion: A worthwhile and fun experiment. Perfect for impressing your mates. I just wouldn't use it long-term in that configuration.

 

[FlashKat]

You are calculating the batteries at 4.2 volts. RCR batteries are usually calculated at 3.6- 3.7 volts. It will work without any problems.

 

[mdocod]

There was some discussion on the G140 bulb awhile back, but these days, it's not getting as much hype with better quality options available that run with better reliability, more run-time, similar or better output, using less larger cells that are less stressed in operation and easier to charge (half the charging bay requirement).

IIRC the bulb draws upwards of 1.3-1.5A, which is pushing it for RCR123 cells. IMR16340s would be preferred but they might insta-flash the lamp. See, that was the problem with the G140, it really depended on the fact that it was going to strain the heck out of the RCR123 cells in order for the bulb to survive. It's a recipe for

Measure the inside of the host and see if it will support a cell that is ~18.6mm diameter. If it will, then you should run a pair of 18650s in it instead. If not, it will probably still accept a pair of 17670s.

Use an IMR-9 or P91. If you can fit the 18650s, then you can even move up to a WA1111 in the FM G4 socket D26 module.

As an alternative that is a fair bit better built and has better compatibility and lego options in the tactical arena, check out the Seraph line from LumensFactory. Long term it will probably be more satisfying, especially if you delve into the mini-turbo heads (D36 etc).

-Eric

 

[ateallthepies]

Thanks very much all.

So are there options out there that can be as bright running off only two 18650 cells verses four RCR123A cells? I thought it was the voltage that determined the brightness of the lamp?


Steve.

 

[mdocod]

Hi Steve,

the brightness of a lamp is determined by a combination of factors. The primary concern is usually wattage when comparing lamps of similar expected life. But filament design and the temperature it runs at has a very large effect on efficiency.

Assuming all things are equal in efficiency in drive level, a 7.4V 2A bulb would be just as bright as a 14.8V 1A bulb. Both are 14.8 watts. Technically speaking, the 14.8V bulb in this comparison would probably be slightly brighter (maybe 10%) since filament designs can be better optimized up around 12V to maximize efficiency (more surface area). However, the primary concern when comparing tactical lamp assemblies is going to be a combination of total wattage and over-drive (or lack-thereof) effects.

A great example, the P91 from surefire, advertised at only 200 lumens, produces a true 400+ torch lumens when driven from a pair of large li-ion cells (this has been confirmed). This has a lot to do with the effects of the bulb being driven much harder by the li-ion cells than it would be from CR123s, but there is also the factor that SureFire rates bulbs very conservatively. On this configuration, the bulb runs ~7.5V@~2.7A, or around 20W. On a pair of large 18650 cells, run-time is upwards of 40+ minutes.

The G140 bulb on 4xRCR123s is probably also right around 20W, and likely producing a similar ~400 lumens fresh off the charger, however, the run-time is probably only around 20 minutes and the cells are heavily taxed, which will wear them out quickly and causes more rapid dimming through the discharge.

-Eric