Flashlight recharges in two minutes!

[Uncle Bob]

...but is it regulated?

This new development sounds interesting, a flashlight (not a shake light) that stores it's rechargeable energy in an ultracapacitor. It doesn't say how bright they are though.

http://www.spokesmanreview.com/tools/story_pf.asp?ID=198170

 

[Kilovolt]

On top of the video included in the manufacturer's website it says:

QUOTE

Ivus Product Demonstration
[SIZE=-1]This video demonstrates Ivus Industries' flashlight charging in 1 minute.[/SIZE]
[SIZE=-1]In the 1st brightness mode (60 Lumens) it will stay on for 90 minutes + 25 min of economy mode.[/SIZE]
[SIZE=-1]In the 2nd brightness mode (200 Lumens) it will stay on for 20 minutes + 25 min of economy mode.[/SIZE]

UNQUOTE


It is probably the rated output of the LED's but still......:naughty:

This is the place:

http://www.ivusinc.com/ivusdemo.htm

 

[lctorana]

Maths lesson time.

Let's assume that:

• you can achieve 60 lm with 3W power input, or 1A @3V.
• the charger and storage device are 100% efficient - no losses.

After 90 minutes, 1.5Ah has been eaten.

To recharge 1.5Ah in 1 minute, the generator would have to put out 90A at 3V, or 270W. That's getting up toward half a horsepower!

I really, really want to see this. The device must be as big as a car altenator!

And does anyone think it would be humanly possible to turn the generator handle, let alone sustain this effort for 1 minute???!!!:laughing:

As my grandmother used to say, if it sounds too good to be true, it probably is.

 

[knot]

And does anyone think it would be humanly possible to turn the generator handle, let alone sustain this effort for 1 minute???!!!:laughing:

Alternatively, you could just plug it into the wall.

 

[elgarak]

Maths lesson time.

Let's assume that:

• you can achieve 60 lm with 3W power input, or 1A @3V.
• the charger and storage device are 100% efficient - no losses.

After 90 minutes, 1.5Ah has been eaten.

To recharge 1.5Ah in 1 minute, the generator would have to put out 90A at 3V, or 270W. That's getting up toward half a horsepower!

I really, really want to see this. The device must be as big as a car altenator!

And does anyone think it would be humanly possible to turn the generator handle, let alone sustain this effort for 1 minute???!!!:laughing:

As my grandmother used to say, if it sounds too good to be true, it probably is.

The power calculation is correct; the current is not. There's no indication that the charging happens at the same voltage as the discharge.

It's still an awful lot of power, but might just work.

 

[knot]

The power calculation is correct; the current is not. There's no indication that the charging happens at the same voltage as the discharge.

It's still an awful lot of power, but might just work.

And, like all Maxwell ultracapacitors, the BCAP0120 are capable of accepting charges at the identical rate of discharge.

http://www.maxwell.com/ultracapacitors/products/medium-cell/bcap0120.asp

 

[TorchBoy]

This is the place:

http://www.ivusinc.com/ivusdemo.htm

Did I just watch a torch charging for a whole minute? Ah well, more interesting that watching paint dry.

60 lumens would take less than a watt. If you assume 80-90% efficiency for the charger/driver system then maybe about 1 watt. (It's a top price so I'm assuming top LEDs and driver.) That's about 300mA, or 13.5 amps (roughly) to charge in a couple of minutes.

However, it would have to be regulated, considering the voltage decay curve that discharging capacitors follow. So I agree that the capacitor would be at a higher voltage than the LED requires. How much more? That's anyone's guess, but the current required doesn't look so bad.

 

[TorchBoy]

What does the charge on supercapacitors do if they are charged and abandoned? Does it leak away? I suppose this torch would love a float charge - no chemical battery to boil off.

 

[65535]

In theory you can't overcharge a capacitor or even a battery if you never create a voltage potential higher than the designed capacity of the cell across the leads.
Pretty cool idea, with he new carbon nano tube caps coming out we should get some pretty interesting mods.

 

[276]

looks interesting

 

[leukos]

This technology could eventually allow us to harvest lightning, then we could really have guilt-free lumens!

 

[Robban]

This technology could eventually allow us to harvest lightning, then we could really have guilt-free lumens!

I can see it now. Nut jobs all over the world hammering down lightning rods in their lawns and hooking up old car batteries to them

 

[lctorana]

Don't knock it.

If it wasn't for Benjamin Franklin and his kite, we wouldn't have electricity and our entire hobby...

 

[LA OZ]

No doubt that the day will come when these supercapacitors are small enough to replace common batteries. I believe this is likely to happened in a decade or so.

 

[lctorana]

Sorry, but I disagree.

Capacitors and batteries both store charge, but the discharge curve of a capacitor under finite load is one of exponential decay. The bigger the capacitor, the longer the time constant, but the voltage *will* drop to 37% of the rated charge in RC seconds, where R=load.

They can and do supplement batteries in certain applications (think car audio) but can never ever do more than that.

They are the exact electrical equivalent of a flywheel.

 

[Crashking]

i wish they would have shown how "bright" the flashlight was before the charge... or if it would even light up at all... all that video could really be telling us is that it takes the charger 1 minute to figure out the flashlight is already charged fully

 

[LukeA]

Don't knock it.

If it wasn't for Benjamin Franklin and his kite, we wouldn't have electricity and our entire hobby...

nor practically everything else in our lives.

 

[eyeeatingfish]

This seems like a very intriging product. Ill have to watch this one.

 

[paulr]

Let's say 60 lumens @ 1 watt, so 90 min = 1.5 WH = 5400 watt-seconds

Let's say the capacitor is at 2.5V. We know E = 5400 W-S = 1/2 CV**2
so C = 2 * 5400 / (2.5**2) = 1700 farads!!!

http://www.maxwell.com/ultracapacitors/products/medium-cell/bcap0120.asp shows a 2.5v capacitor the size of a C cell with 120 farads, so assuming the light uses three of them we're still a long way short of 1 constant watt through the whole 90 minutes. I can believe 60 lumens for a couple minutes or a much-reduced output for 90 minutes.

 

[OhMyGosh]

I have a capacitor light I built several years ago. It is 33 farad 5.5v.
It charges in about 5 minutes (I could charge it faster but I don't want to abuse the caps). It runs a single 5mm LED for 2 hours. The Maxim inverting regulator fades at about 1.8v.

(Deleted comment about no lumen specs - read before you post OhMyGosh)