Li Ion Flashlight - with USB to charge phone

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wantsusa

Newly Enlightened
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Jun 5, 2010
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I am curious since I see some cool flashlights here and the fact that many of them use a 3.7 v battery if there are any flashlights out there that have a usb port on them that could charge a dead phone (say like an iphone that also uses a 3.7v li ion battery). If not would it even be possible to add something like an interchangeable usb tail cap for a flashlight that could act as a battery charger for a phone.

When I think of emergency situations and having a great flashlight, I just think it would be awesome if the flashlight could also be a lifesaver if you were out backpacking and needed extra charge for your phone in an emergency.

Sorry I wasn't sure which forum to put this in...though I love LEDs and I would just love to see an interchangeable tail-cap that could be used for this!
 
he sorta does the opposite of what I would want...take a flashlight, switch the tail-cap and boom charge the phone.
 
USB is specified to supply 5V; certain phones might charge with a dumb low-voltage supply on a USB line, but I'd bet most wouldn't (at least not properly). Supplying this from the kind of single Li-ion source used in most flashlights would require boost circuitry that isn't already present in the light. Also, given the way most flashlights are wired, you'd probably need to swap the head instead of the tailcap.

An interesting possibility, but it's so niche you'd probably have better luck finding a reversible charger that could do it. An example would be the Duracell CEF23 Mobile Charger, although that one is for NiMH and isn't equipped to handle ~3.7V 14500s in the bays.
 
I have one of these. Its ok, but not perfect. Flashlight is ok, but won't ever be your light of choice (plastic lens & collar)
Uses an 18650 2200mah unprotected, but charges slowly (maybe 300ma or less?)
Has a voltage indicator, but quite innacurate.
Will charge an iphone due to high ma, but about one full charge only.
Basically its inefficient, due to all the conversions from 3.7 to 5v and back but does job. Having said all that -the price is good, and I would buy again.
 
Yeah, i have one of those!

I love it! The flashlight part is very very easy to improve (better led, reflector and glass lens) but why bother? Its not like it is going to be your primary light, just toss a 18650 in there and put the flashlight somewhere in the bottom of your bag. When your phone is about to die half way an important call, just pop a USB cable between your phone and the 'flashlight' and you're good to go!

Yes the efficiency (3.7V --> 5V --> 3.7V) sucks and will be something like 50% at best, and yes the flashlight isn't all that good..... But than again, its a cheap multipurpose solution and if you happen to carry spare 18650cells for you primary light you can charge quite a couple of phones ;)
 
RepProdigious said:
Well... Very nice and everything.... But its one-time use only backup battery doesn't sound very appealing to me... Especially for $300!!!
Click to expand...


Normally you can run it on 2 cr123 primaries. The one time backup battery
are only for emergencies when you dont have accsess to primaries.

There must be a way to replace the used one time battery.
 
arcel1t said:
Normally you can run it on 2 cr123 primaries. The one time backup battery
are only for emergencies when you dont have accsess to primaries.

There must be a way to replace the used one time battery.
Click to expand...

Why cant they just make a side-by-side twin 18650 light (comp with quad r123) looking like that thing with USB output that can use either both cells for everything (light/USB) or one half for normal use (ie 18650 cell) and one for emercency (r123 primaries, also pretty good shelflife) behind some form of locked/extra tailcap........

I'd buy one of those!
 
LukeA said:
Like this?
Click to expand...

Got one and it is surprisingly decent. Got it so we could charge our phones/wife's iPod etc. while traveling. I always bring 18650s for my SF U2 or 17670s for my C2 so there is always some spare batteries for it.

Something using 2 cr123s would be better as an emergency backup, but most people are scared by the price.

Sverre
 
NoFair said:
Got one and it is surprisingly decent. Got it so we could charge our phones/wife's iPod etc. while traveling. I always bring 18650s for my SF U2 or 17670s for my C2 so there is always some spare batteries for it.
Click to expand...

You have one? Great! How's the efficiency on one of those? My el-cheapo 18650 USB emergency backup charger really really sucks from an efficiency standpoint so im really wondering if there's any single cell device thats actually good at creating USB worthy power!
 
RepProdigious said:
You have one? Great! How's the efficiency on one of those? My el-cheapo 18650 USB emergency backup charger really really sucks from an efficiency standpoint so im really wondering if there's any single cell device thats actually good at creating USB worthy power!
Click to expand...

Haven't tested it. Should try checking current draw, but haven't gotten around to it.

Sverre
 
It should do that nicely. It says it will deliver 5.2V at 1000mA.

It didn't like me trying to measure current (got a low battery warning and it stopped charging), but I got a 1 A reading a second when it was charging my cell phone.

It charged my my phone from 70% to 100% (950mAh battery) and the included 18650 was still at 4.0V so it can't be horrendously inefficient.

Sverre
 
Pics to come, I'm BRAND NEW to this whole forum thing, but with a simple step-up circuit that's got 5V available from USB works fine. No, I wouldn't go using this system primarily, but if you can jam the step-up circuit and appropriately sized wires anywhere on the lanyard of your torch, in the body, etc. - when push came to shove, you could get down and dirty and suck enough power from your torch to make that final Facebook update before the lack of oxygen under an avalanche, in a car sinking off a bridge, the in-laws dinner table, etc.

Obviously it's not ideal, but we're not going for ideal, so that's ok. Also, I'm assuming we all know enough about li-ions and such to be able to ballpark whether or not our cells are up to the task when we may need them for this purpose, based upon all the variables only we would know (last time topped-off, where the leads should go, what to watch for/listen for/feel for/etc.). I'm in the middle of building a rig now. Hopefully I can get it done this weekend and come back to post pics...

...of my torch phone charger and not how I burned my garage down. :oops:
 
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