5.11 Light for life

**pc830cop** · 05-16-09, 11:10 PM

I've been anticipating the 5.11 light for life to come out. What happened? I heard they took it off the shelf due to possible explosions!

**pgg** · 05-16-09, 11:38 PM

I know we were all waiting with baited breath but they never showed up

**ex401mp** · 05-17-09, 05:32 AM

Short life...

**drunkhunter** · 05-17-09, 08:49 PM

If this is the name for their new light that recharges in 90 seconds and has the different light options such as solid or flashing, I have played with the prototype. It seems like a nice light.

**TXCharlie** · 05-17-09, 10:00 PM

Those Ultra-capacitors can release a large current spike when shorted, so I'm not too surprised at that, although I would have guessed that they put a resistor in there to limit the current to a safe level for external shorts. Unfortunately that doesn't protect against internal shorts.

I've had several large electrolytic capacitors explode with me when I was working as test engineer at TI, but it's usually due to short circuits after they were fully charged, or (more commonly) because the capacitors were installed backwards.

Lithium batteries have a history of exploding too, especially when shorted out, overcharged, or a run-down battery is put in series with a charged battery, which causes a current flow past the point of being discharged, which is an effect similar to charging them backwards.

**MacLean** · 05-18-09, 12:16 AM

Charlie, a light bulb is a short.

**TXCharlie** · 05-18-09, 02:05 PM

Originally Posted by maclean

Charlie, a light bulb is a short.

A light bulb draws a specific amount of current depending on the voltage, tempature & type of bulb or LED, because it has a lot of resistance compared to a direct short. It's usually limited to less than an amp for a flashlight. When powering a bulb or LED, the current doesn't reach the point where things start vaporizing, but a direct short is another story.

A direct short across a battery is only limited by the internal resistance of the battery, because a short is usually almost no resistance - A small lithium cell can dump out over 10 amps into a short, or even more, which heats it up faster than an alkaline cell which has higer internal resistance, so it can only dump a few amps.

By contrast, an electrolytic capacitor can dump 20, 50 or 100 amps (for a very short time) across a short, depending on the value of the capacitor, the current rating of the conductive foil, and its internal resistance. The only reason the electrolytic capacitors normally don't explode when you short them is because they exhaust their stored energy in a matter of milliseconds, but sometimes they do.

The super capacitors I've worked with have a more limited explosion potential because even though they store much more energy, their conductive foil is so thin that it vaporizes quicker and offers more internal resistance, so a short normally just causes them to die instead of exploding - but if it weren't for that it'd be dumping hundreds of amps and exploding too.

I've never worked with the ultracapacitors like the 5.11 flashlight uses, but my assumption is that it would be the same for them, that they would normally die than explode, but they certainly store enough energy to explode.

**TXCharlie** · 06-14-09, 07:31 PM

quiz corner: capacitor quiz

Howstuffworks "Capacitor Quiz"

Quiz: capacitor quiz
Correct Answers: 10 out of 10
Wrong Answers: 0 out of 10
Your Average Correct:100%
See all quizzes!

quiz corner: batteries quiz

Howstuffworks "Batteries Quiz"

Quiz: batteries quiz
Correct Answers: 8 out of 10
Wrong Answers: 2 out of 10
Your Average Correct: 80%

**ManImBored** · 09-04-09, 04:34 PM

My partner finally got his light in today. It was dead when we got it and it really did charge in 90 seconds. Very bright on the bright setting and perfect lighting on the dim setting for looking through cars and at paperwork. Strobe setting works good too. We will see if it holds up.

**BigDawg** · 09-05-09, 12:45 PM

Is it the size of a Mag light type??

**ManImBored** · 09-05-09, 06:10 PM

Yeah its pretty big. In my opinion, too big for a duty belt. Its quite a bit bigger than a Stinger and just under the size of a Mag light. I will try and grab his tonight and snap some pictures.

**KaiGywer** · 09-05-09, 06:42 PM

Originally Posted by TXCharlie

I've had several large electrolytic capacitors explode with me when I was working as test engineer at TI, but it's usually due to short circuits after they were fully charged, or (more commonly) because the capacitors were installed backwards..

They're also fun to put in an outlet that has a switch. Step back, flip the switch

Ahh, the days of electronics class back in college

Originally Posted by ManImBored

I will try and grab his tonight and snap some pictures.

Would that make this thread NSFW?