C and D cells in alkaline batteries are 1.5 volts just like AA and AAA. Perhaps you're thinking of the various smaller sizes of lithium batteries.
No, I'm thinking of C and D cells as compared to AA and AAA cells.
All of the above cells are 1.5v. The more batteries, the higher the voltage. Presumably, the LED matches the voltage, although in many lights the LED is rated for LESS voltage. By driving more voltage through an LED than it's rated for, the LED burns very brightly... At a cost of heat and LED life. These lights that are "overdriven" should be avoided, because while they put out an impressive amount of light, they tend to fail at the most inopportune times. If you're doing a night dive or a cave dive or a wreck dive for example, the situation can get pretty serious pretty quickly, especially if your backup light is the same "overdriven" kind of light and was purchased at the same time.
...But as far as the batteries go - all of the above have the same voltage. However, because of the physical size of the battery, D's last longer than C's, which last longer than AA's, which last longer than AAA's.
My point in my above post was that my opinion is that LED lights equipped with C cells will last longer (or have it's batteries changed less often) than LED lights equipped with AA or AAA cells.
...And regardless of which batteries your light uses, your light head, bulb, LED or whatever should always match in terms of voltage.
Delrin bodies are nice but with today's higher power led's heat dissipation is helped along with aluminum bodies where the entire body in effect becomes a heat sink.
Agreed... Which is why the Heser Backup is my favorite light. An aluminum sleeve inside of the delrin body acts as a heat sink quite nicely, and the diver experiences the advantages of both a delrin body and an aluminum body.
Since water takes care of most of the problem it's not a necessity but an aluminum body shouldn't corrode any more than an aluminum head. Anyway, all dive gear should be washed
Of course... And I'm not implying that it shouldn't.
Like the argument previously in this thread, I suppose it's a matter of how much diving you're doing. If you're diving once or twice a month, an aluminum body or head will take years to corrode, assuming that you rinse it thoroughly after every use. If you dive twice a day like I do, it's a matter of months before the sheen is gone and pits begin to show. Ultimately, if the pits happen at the O-rings, you'll flood the light. When this happens is a matter of how well you rinse your gear, but it's still going to happen.
With a delrin-bodied light with an acrylic head, it's not an issue. Ever.
The advantage of a magnetic switch or button is that it can't leak and with multi-mode lights (multiple power settings) it makes selecting them easier than rapidly twisting the head on and off. With the Intova many prefer the button to the switch since when mounted on a chest D-ring it's easier for the sliding side switch to accidentally come on than the rear mounted button magnetic switch.
You mention that it's an advantage, but never said what the advantage was... That it didn't leak? Neither does a twist-on switch. That it's easier to select multi-mode settings? A good light shouldn't have multi-mode settings like strobe, half power, or multiple bulbs. There should be one bulb and one set of batteries that will cast a focused beam at 100% power for as long as it can - between 30 and 50 hours should be a minimum, and 60+ hours would be an advantage. The less it'll run, the less dependable it is. The more "features" the light has, the less dependable it is. The quicker it uses it's batteries, the more often it won't work when you need it to, and the more often you'll have to change batteries and the more chances you'll have of pinching an O-ring or improperly assembling it and flooding the light.
...Which is why a Heser Backup rocks so much.
Lights should be very simple - when you go for them, they turn on and work and cast a powerful beam as far as it can. Anything that gets in the way of that should be avoided and is "surface logic" aimed at impressing in the dive shop... And has nothing to do with actual use underwater.
For what it's worth, any light with a button on the back rather than a hitch for tying a bolt snap (or for some people, lanyard) is missing an ability to mount the light in a very convenient way. Once you see the proper way to mount a light to your rig, you won't want a light that doesn't have a hitch in the back for mounting.
The water pressure gradually builds and doesn't increase fast enough to trigger the button. If it were not magnetic I'd agree that buttons are not for dive lights.
It's not a matter of "increasing fast enough" - it's not like there's a chamber inside the light that "balances" the button, and it's just a matter of it "catching up." The button is sealed, and therefore water pressure activates the button. Period.
What the manufacturers do to avoid this is minimize the surface area of the button and put more powerful springs inside the button. The problem still exists - they've just figured out a way to avoid it.
...Which is great until you realize that the problem will reappear at a given depth. The button might work great at 50 feet or 100 feet, but will it work at 250 feet when the pressure differential inside the light is that much greater? After all, there is a limit as to what the spring will hold... And that's all there is to it.
If you're never going to those depths, then fine... But why go through all of these semantics when twist-on switches never have the problem in the first place?
There are advantages as well as potential disadvantages for both magnetic switches and Delrin vs aluminum.
My scooters have magnetic switches - most scooters do. They're called reed switches. Do a search for "reed switches" and find out how problematic they are.
A simple solution would be to avoid them altogether with a tried-and-true twist-on light...
What was best in the days before heat generating power led's and choices in power levels may not automatically be the clear winner today.
Yeah, thank you for pointing that out, Mr. Helpy Helperton.
I'll be sure to let the me diving today let the me that dove yesteryear that information... 'Cause I probably am not completely "up" on modern technology.
I got a kick out of a video I saw the other day. In it, Ronald Reagan (then president) was addressing a crowd gathered at a prestigious university. A question was posed to him; something along the lines of, "How do you see your generation dealing with the modern nuances of the Information Age? What do you plan to do about older peoples' misunderstanding or inability to use the Internet?" His response was, "Uh, 'my generation' INVENTED the internet."
It's a farce to believe that someone who has seen decades of diving lights - and the technology that supports them - is somehow out of touch with the latest technology. In fact, it's quite the opposite.
...So you'll have to excuse my surliness about your comment.
The type of light you recommend is still a pretty good choice among several for a backup light. There is a very robust version produced in China today that sells for $38 that is virtually the same as those being talked about above (Torpedo, etc) except it's powered by 3 AA's. It's a very tight beam, 170 lumens, and will run for hours.
You might want to look again at your Chinese version and the lights that I'm recommending.
The Chinese version runs on 3 AA's. The LED is overdriven. There is one O-ring in a PVC plastic body. It produces a tight beam that's "170 lumens" and will run for 10-12 hours.
A Heser Backup, by comparison, runs on 3 C cells and does not overdrive it's LED, making it more reliable. There are two much more substantial O-rings mounted on a delrin body (that doesn't get brittle with age or change it's structural properties with depth) with an internal heat sink. The light produces a tight beam that's both whiter and brighter than any Chinese knockoff and will run for more than 60 hours.
You might as well have said that a Corvette and a Honda Civic are the same car because they both have two doors and a hatchback.
...And while yes, the Corvette may be steeped in tradition, it'd be a farce to believe that today's offering is not technologically advanced.
