Regulated VS. Direct Drive

[Supernam]

Generally, it seems that regulated lights are more desirable due to their high-tech nature and the fact that every time you click it on, it's at full brightness for the duration of it's runtime. However, I'd like to comment in favor of direct drive for the following reasons:

1) Direct drive is more efficient. Clearly a battery connected to a bulb is much more efficient than running to circuitry which wastes energy in the form of heat.

2) With today's high tech batteries, such as Li-Ion and NiMH, discharge curves are quite flat.

3) And finally, the reason why I like direct drive is for situations in which you do not want to be left in the dark without warning.

Personal example: My cousin, his friend, and I did a hike up Yosemite's Half Dome last summer. My cousin was extremely out of shape so we had to take ridiculous amounts of breaks. When we reached the top, we the sun had already set an it would be a 6 hour hike back down to base camp in the dark. Being the only flashaholic in the group, I had my non-regulated Black Diamond "Spot" headlamp, and my non-regulated Inova X5 as my primary navigation lights. Both lights, while noticeably dimmer at the end of the hike, still had usable output that dimmed GRADUALLY throughout the hike. No surprises, no sudden drop. While you may be thinking, "Well a regulated light acts the same way once it drops out of regulation." However, the tail end of a regulated light's runtime graph is much steeper than a non-regulated one, due to all the energy being used up to keep it in regulation.

I have my share of both regulated and non-regulated lights. This is not an advocation of one type over the other, just wanted to give some recognition to a design that, while being more primitive, has its place.

Can anyone else think of situations in which non-regulated lights are more favorable?

 

[yellow]

with Incans a regulated light wont go at switching on
with Led there will be (more or less) same brightness during runtime.
with Led the direct drive needs a resistor and thus also looses efficiency

when it comes to "end of regulation", some lights go into direct drive moon mode when voltage gets low, others just quit. Its the user who has to care for this.
I dont like my lights to dimish in output.

PS: on a hike I use low or med mulitlevel very much and have at least a spare batt with me (for every light that might run long enough on high to deplete the batt mounted)

 

[Andrew Nik]

Regulated forever!
I love my M6-R and U2.

 

[TORCH_BOY]

I prefer regulated for everyday use, If I were in the bush with only one set of batteries I would then go for Direct drive

 

[Long John]

Answering this question is more extensive than it looks at the first view.

The point about the efficiency is two edged.
A non regulated light needs no power which is wasted in the circuit BUT a regulated light with different brightness levels allows much longer runtimes at lower levels, so for the user it's more efficient.
Also there can be a need for a regulation. In all the cases where the batt.-voltage is lower than the vf of the Led.

Using resistors in DD-Led lights are not obligatory. It depends on the vf of the Led at the rate of the supplied voltage of the batts.

In therms of reliability, the DD-light is in advantage opposite to a regulated light, due to the fewer connection points at first and secondary due to the circuit risk for itself.

Conclusion:

Both systems have their rights to exist and both have their advantages and disadvantages.

I own both and love both

Best regards

____
Tom

 

[mdocod]

1) Direct drive is more efficient. Clearly a battery connected to a bulb is much more efficient than running to circuitry which wastes energy in the form of heat.

this statement, is unfortunately, very false when dealing with incandecent bulbs.

Incandescent lamps drop in efficiency BIG TIME as the voltage sags. for example..
lets look at a 12V 100W 3600 lumen lamp.
at 12V, it's 36 lumens per watt efficient.
now if your voltage sags to just 11V, the output drops to 2650 lumens at ~88W, now it's only 30 lumens per watt
now lets say it drops down to 9V, the output drops to 1300 lumens at ~63W, now it's only making 20 lumens/w.

depending on the type of cell you are dealing with, it is not uncommon at all to have a large operating range of voltage, from fresh to ~dead on many cells can be as much as 30% or more in voltage variation.

 

[LowBat]

Personal example: My cousin, his friend, and I did a hike up Yosemite's Half Dome last summer. My cousin was extremely out of shape so we had to take ridiculous amounts of breaks. When we reached the top, we the sun had already set an it would be a 6 hour hike back down to base camp in the dark. Being the only flashaholic in the group, I had my non-regulated Black Diamond "Spot" headlamp, and my non-regulated Inova X5 as my primary navigation lights. Both lights, while noticeably dimmer at the end of the hike, still had usable output that dimmed GRADUALLY throughout the hike. No surprises, no sudden drop. While you may be thinking, "Well a regulated light acts the same way once it drops out of regulation." However, the tail end of a regulated light's runtime graph is much steeper than a non-regulated one, due to all the energy being used up to keep it in regulation.

At least you were prepared. When I hiked down in the dark from Half Dome in 2003 all I had was this little $6 novelty item:

Actually the 3mm blue LED worked well and I could see where to step. I just wish I didn't have to hold the momentary button down for 6 hours. The three AG3 batteries lasted just long enough to get me down. I suppose I shouldn't have been playing with the red laser so much. This hike and a few others where I didn't take any lights (didn't plan on the sun going down) taught me to always take a "real" flashlight on every trip.

Back on topic: my preference is for regulation, unless it's a simple low drain LED that has a relatively flat curve on direct drive.

 

[Paladin]

From the standpoint of not wanting to carry spare cells in addition to the two or three lights I'm carrying, I've had some "battery fade" instances with regulated lights at most inconvenient times.

The problem is because I often use them momentarily and at reduced output. Then when called upon to deliver "full power" the weakened cells won't deliver. My Streamlight 2L Tasklight drops out fairly fast, as does the Gladius. When either loses regulation they act pretty much like when the Gladius "dimming feature" is manually implemented. It's not something I like to have happen when I'm in the middle of lighting up a subject.

Paladin

 

[CM]

To me there is great appeal in having a light with a consistent output, regardless of the state of the power source (within limits of course) I see no disadvantage in terms of complexity with a properly designed circuit, over that which is direct drive or resistively current limited. The argument that DD is much simpler and less likely to fail does not really hold water for me as since a properly designed circuit will yield MTBF's that probably exceed the life of the LED itself. If one does fail, I always have a spare on hand somewhere within easy reach.

 

[soffiler]

I've had an LED driver circuit fail. Fortunately it wasn't in some dire situation, but it did happen. I won't name any names but it was a Chinese-manufactured light. It taught me that added complexity extracts a cost in decreased reliability.

As a result, when I really rely on my lights the most (mountain biking at night) I use a direct-drive Coast Focusing Led Lenser as the supplement to my HID, and I've got two regulated LED's (Pelican M1 and Fenix P1D-CE) to back up the Coast.

 

[FlashCrazy]

Answering this question is more extensive than it looks at the first view.

The point about the efficiency is two edged.
A non regulated light needs no power which is wasted in the circuit BUT a regulated light with different brightness levels allows much longer runtimes at lower levels, so for the user it's more efficient.
Also there can be a need for a regulation. In all the cases where the batt.-voltage is lower than the vf of the Led.

Using resistors in DD-Led lights are not obligatory. It depends on the vf of the Led at the rate of the supplied voltage of the batts.

In therms of reliability, the DD-light is in advantage opposite to a regulated light, due to the fewer connection points at first and secondary due to the circuit risk for itself.

Conclusion:

Both systems have their rights to exist and both have their advantages and disadvantages.

I own both and love both

Best regards

____
Tom

Tom, very well said. Both styles have their merits. For lights running the emitter at high current, direct drive isn't so bad...in fact, I'd be willing to say better in some cases. Take for instance a light that I've modified. It uses a SSC P4 emitter and runs on 3 D cells (NiMH)...direct drive with a .5 Ohm resistor. It measures about 1050 mA at the start. Three hours into the runtime, it measures 750 mA. Five hours later it still measures about 600 mA. There's not a whole lot of perceptible difference in brightness with an SSC emitter running at 700 mA vs 1000 mA. At seven hours into the run, it's at 550 mA...still darn bright. I ended the run at 10 hours, and was showing 390 mA...more than enough brightness for most tasks....super bright for night hiking. If this light was regulated and set for 1000 mA, it would last about 4 to 5 hours. My light at 5 hours still seems just about as bright to the naked eye, and then you get another 5 hours of very bright operation....plus many more of further diminishing output. You want an emergency light?, direct drive in my opinion is the way to go.
I have regulated and non-regulated lights and like them both. But don't knock a direct-drive light using NiMH cells...like Supernam said, the discharge curve is pretty flat, and in some cases better than a "regulated" light...especially if this "regulated" light drops out of regulation quickly and then is nothing more than direct drive, with not much "oomph" left.

 

[soffiler]

FlashCrazy raises an excellent point: in actual use, the gradual dimming you get from DD running on NiMH (flat discharge curve is key here) is really quite hard to notice, simply because it IS gradual, and because the human eye has an ability to adjust itself to different lighting conditions.

 

[Long John]

Thanks FlashCrazy and also for the good real world example:twothumbs.

At the moment I'm also modding a real nice DD-light: Barbolight U-15 newest generation.
It's 4 Led's are wired 2sx2p, so in the improbably case of a breakdown of one circuit, the other 2 Led's would still work (I've tested it).
It's the most sturdy and reliable light due to this circumstance and amongst others, I've ever seen.

Best regards

____
Tom

 

[ace0001a]

I think it also depends on the driver design...that very same light that Flashcrazy is talking about can run for more than 5 hrs and have "useable" light...perhaps not as long total runtime, but obviously there's going to be a trade off between overall runtime and brightness level curve. For example, Malkoff Devices states "The runtime is 6+ hours at the rated output it will continue to operate at reduced output for several more hours" for his 3D SSCP4 Modded Mag running @ 1A with a driver designed by him. For modding, I think the debate would come down to the quality of driver you use. I think that if you buy a light that has regulation circuitry in it, if it's made by a good company (or custom flashlight maker) than it should have good design that affords good brightness along with good runtime. Personally I prefer regulated flashlights over direct drive for the constant brightness level and I always think that if you're going to use a flashlight for serious usage, that you should have a spare set of batteries with you...

 

[soffiler]

ace0001a: depending on HOW serious, add a whole spare flashlight along with the spare cells...

 

[FlashCrazy]

I've had an LED driver circuit fail. Fortunately it wasn't in some dire situation, but it did happen. I won't name any names but it was a Chinese-manufactured light. It taught me that added complexity extracts a cost in decreased reliability.

As a result, when I really rely on my lights the most (mountain biking at night) I use a direct-drive Coast Focusing Led Lenser as the supplement to my HID, and I've got two regulated LED's (Pelican M1 and Fenix P1D-CE) to back up the Coast.

Now there's someone who packs some "heat"! An HID backed up by a Focusing Lenser...it doesn't get much better! I wouldn't want to be in your path! Are you using a stock Lenser, or a SSC modded one?

 

[FlashCrazy]

Thanks FlashCrazy and also for the good real world example:twothumbs.

At the moment I'm also modding a real nice DD-light: Barbolight U-15 newest generation.
It's 4 Led's are wired 2sx2p, so in the improbably case of a breakdown of one circuit, the other 2 Led's would still work (I've tested it).
It's the most sturdy and reliable light due to this circumstance and amongst others, I've ever seen.

Best regards

____
Tom

Sounds like a great light, Tom! I'll have to check that one out...

 

[FlashCrazy]

For modding, I think the debate would come down to the quality of driver you use. I think that if you buy a light that has regulation circuitry in it, if it's made by a good company (or custom flashlight maker) than it should have good design that affords good brightness along with good runtime.

Good point here...it does depend on the driver. Along the same lines, when evaluating a direct drive light a lot depends on the batteries used. Forget alkalines...period. Their discharge curve looks like a ski slope. Use NiMH batteries or Lithium, and you'll think you're using a regulated light. I think many bad opinions of non-regulated lights come from people who used alkalines in them. Look at this thread: http://www.candlepowerforums.com/vb/showthread.php?t=166956. It shows the difference in ouput curves. Look at the link that shows the Coast Focusing Lenser (Hocus Focus) using alkalines (post #5), then look at the link I posted (post #7) that shows the same light on NiMH batteries.

 

[Hans]

At least you were prepared. When I hiked down in the dark from Half Dome in 2003 all I had was this little $6 novelty item: hgeez <snip> Actually the 3mm blue LED worked well and I could see where to step. <snip>
Back on topic: my preference is for regulation, unless it's a simple low drain LED that has a relatively flat curve on direct drive.

Imagine you had had a Jil DD on that trip - also direct drive, but a far more usable beam for something like 20 hours. Just drop a spare CR2 in your bag and you're set for *several* night hikes.

I must admit, I like regulated lights with different levels a lot, but on trips where I depend on a working light I still like carrying my Jil DD. Sure, usually only as a backup nowadays, but still. There simply aren't quite so many things that can go wrong with a good direct drive light.

Hans

 

[soffiler]

Now there's someone who packs some "heat"! An HID backed up by a Focusing Lenser...it doesn't get much better! I wouldn't want to be in your path! Are you using a stock Lenser, or a SSC modded one?

Hi FlashCrazy:

It's got an SSC P4 U-bin. I basically used the instructions posted by EngrPaul, but I omitted the copper spacer. As a result, I had to make a shim to move my lens closer to the emitter.

I do a lot of night-riding, especially in the wintertime when night-riding is the ONLY choice on a weeknight after work. In the warmer months, we start in daylight and finish up at various times, sometimes needing light, sometimes not. My helmet-mount HID has a fairly tight throwy beam good for 450 lumens, and I learned the hard way that I need a supplemental "low beam" as well. The Coast adjusted full-wide does a fantastic job mounted on the handlebars. In the warmer months I actually leave the HID at home, since the lights usually come on just to get us out of the woods.