DC to DC inverter questions and why don't other manu use this?

[BuddTX]

DC to DC inverter questions and why don\'t other manu use this?

The Arc Light has what is called a "DC to DC inverter" that allows the ARC AAA to drive a 1.5 AAA battery power a 4 volt LED bulb.

Exactly what is a DC to DC inverter, and why don't other manufactures use this? How does it "trick" the laws of physics?

Imagine if other manufactures used this? Using the same math, let's say Princeton Tec put one of these inverters in it's 8 AA cell Surge. If one, 1.5v battery can drive a 4 volt bulb, would this inverter allow the surge to power a 32 volt bulb, and keep it at the same brightness for many hours?

I would gladly pay 10-30 bucks more for a light with this feature! This could make the Surge 5 time brighter than it currently is?

There has to be a catch?

Any thoughts?

 

[Empath]

Re: DC to DC inverter questions and why don\'t other manu use this?

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by BuddTX:
How does it "trick" the laws of physics?
.................. There has to be a catch?
<HR></BLOCKQUOTE>

The catch is the loss of current. The power is the product of volts X amps. You can't get more power by changing the voltage. The voltage increases, but the available amperage decreases proportionally. And there is also the loss due to inefficiencies in the system. We manipulate the values to suit our purpose, but magic isn't permitted. The power available remains the same.

 

[BuddTX]

Re: DC to DC inverter questions and why don\'t other manu use this?

Thanks for the reply.

But still, wouldn't the same principle apply to a larger flashlight?

 

[machspass]

Re: DC to DC inverter questions and why don\'t other manu use this?

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by BuddTX:


But still, wouldn't the same principle apply to a larger flashlight?<HR></BLOCKQUOTE>


Yes, it could somewhat. I have been doing some experimenting with DC-DC converters lately. As previously stated, power is the product of voltage and current. You can manipulate these parameters somewhat, but you can never get out more power than you put in, or even the same amount for that matter, due to inefficiencies.

Think of it functionally like a transformer. If you step up the voltage, the current goes down, and vice versa. In other words, if you were to have an output voltage of 10V and current draw of 100mA, and the input voltage was 5V, then the input current would be at least 200mA. This is ideal. In reality, with losses, the current would be higher.

You would have to check the ratings of the DC-DC converters, but the small package size ICs won't output more than about 10V and 200mA. If you were to drive a higher voltage light with the same current, you would have a bright light, but would drain the batteries quickly. It's a trade-off.

Have you seen these 12VDC to 120VAC inverters that you can use a 12V car battery to power equipment that uses household power, like when you're camping? Yes they're wonderful inventions, but you must watch what you're doing. It isn't unusual to find one rated for 360W continuous. Well, if you have a 360W load at 120V, that's only 3A, but you're drawing this power from a 12V battery, so to supply 360W, the current draw on the battery would be 30A ideally. It would actually be more like 40A to 50A with losses. Your battery wouldn't last long with this kind of load and you would be spending the night stranded in the woods.

Sorry it's a bit long winded, but I hope it helps.

 

[Marked]

Re: DC to DC inverter questions and why don\'t other manu use this?

Its converter not inverter.
Inverter changes the polairty of the voltage + to - or - to +.

 

[BuddTX]

Re: DC to DC inverter questions and why don\'t other manu use this?

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Marked:
Its converter not inverter.
Inverter changes the polairty of the voltage + to - or - to +.<HR></BLOCKQUOTE>

The ARC Website calls it an inverter: http://store.yahoo.com/flashlight/technology.html

The Lite Site calls it an inverter: http://thelightsite.tripod.com/reviews/arcaaale.htm

But the PUNISHMENT ZONE calls it a CONVERTER http://ledmuseum.home.att.net/arcle.htm

Your explanation makes sense, it INVERTS it, like inverting fractions. I just was quoting what the manufacturer calls it.

Thanks.

 

[Chris M.]

Re: DC to DC inverter questions and why don\'t other manu use this?

I was under the impression that Inverters changed DC current to AC current- like those 12VDC-to-AC-mains thingys you can buy at camping stores to run your TV off the car battery.

And doesn`t the Arc-AAA "invert" the DC from the battery into AC in order for it`s inductor-based booster circuit to work? I don`t really understand these things though so I`m probably wrong.

 

[Gransee]

Re: DC to DC inverter questions and why don\'t other manu use this?

I did a little reading and Marked is right,the term "converter" and not an "inverter" is correct for this type of circuit. Inverters are used to "invert" positive voltage to negative voltage as required by some circuits in cell phones, computers, etc. They work similiarly (using an inductor and PWM switch) and you can use an inverter to boost the battery voltage to drive an LED (just reverse the connections to the LED).

I think some manufacturers also refer to the 12v to 120vac supplies as inverters as well.

The DC to DC inductor based converters used in our flashlights have been referred to as "inverters" incorrectly by me in the past. My apologies. I will change the website to be more correct.

Btw, to answer your question BuddTX... Empass, Mach and Chris are correct. By giving up some battery life you gain increased brightness. We find that our average customer wants the most light possible from a small package so a DC to DC converter is the way to go.

Peter Gransee

 

[Darell]

Re: DC to DC inverter questions and why don\'t other manu use this?

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Gransee:
so a DC to DC converter is the way to go.
<HR></BLOCKQUOTE>

I know that *I've* certainly been converted. Assimilated too.

But when I'm inverted I get a nasty head-rush, so I don't do that anymore.

 

[BuddTX]

Re: DC to DC inverter questions and why don\'t other manu use this?

Thanks, Peter!

 

[Empath]

Re: DC to DC inverter questions and why don\'t other manu use this?

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Gransee:
Empass, Mach and Chris are correct. By giving .............<HR></BLOCKQUOTE>


Empass? Empass?
I hope this isn't a hint that the engraving on my CPF Member Edition has a typo. Oh, well, that would be unique; sort of like a double die strike on a stamp or currency - more valuable as a collector's item

 

[Jonathan]

Re: DC to DC inverter questions and why don\'t other manu use this?

If you are interested in high power, high efficiency switching regulators for incandescent lamps, take a look atLight Bulb Voltage Regulator

This is not a boost converter such as is used to run a white LED from a couple of AA cells, but is rather a PWM regulator which cuts the battery voltage to exactly what the bulb needs. As the battery discharges and loses output voltage, the bulb sees a constant voltage, and maintains full brightness. When the battery is nearly depleted, the regulator drops the output to a dim but still running level so that you can find your replacement batteries.

I use this sort of circuit (built from the schematics on the site) on my bike headlight. I've not used the LVR itself, but have heard nothing but good reports.

-Jon

 

[Brock]

Re: DC to DC inverter questions and why don\'t other manu use this?

moving this thread over to the new and improved "Electronics Forum. Batteries Included" at http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=forum&f=6