One Battery for the whole PCT?

[JimSproul]

I bunpoed into this and was curious what you think.

"The tiny little Pak-Lite LED flashlight lit the way on a 2,600 mile Pacific Crest Trail trek on one bulb and battery! Its compact, lightweight and rugged construction makes it a favorite of hikers. The dual-mode, high intensity, 2-LED unit can light up a tent for 600 hours on low or 75 hours on high. Perfect for backpack or car."

http://www.cyberguys.com/templates/searchdetail.asp?productID=6853&return=9822&core_cross=SEARCH_DETAIL_CUSTOMER

:-?

[Footslogger]

Neat ...and timely since I'm in the planning stages for my PCT hike. Wonder how it would compare on an overall basis with the Petzel 2 LED headlamp (?? model name - - too many similar ones any more - Tikka, Pikka, Zikka etc.)

Guess you could just add an elastic headband ??

'Slogger

[iamscottym]

I've used lights like that before. They're alright, but headlamps are more convenient. Plus, for the weight, 9V batterys offer very little power. Just think, a 9V battery is basically 6 smaller batteries, and since power is proportional to volume of chemicals, which is pi*r^2*L for a cylinder, the smaller you make the cell the more the jacketing weighs in comparison to the volume of the chemicals. Therefore, the bigger the cell, the more power to weight. That means D cells are the most efficient, but they are far more power than you'll need.

I have a tikka plus and a tikka xp, and they are both amazing. The tikka plus has a lower power setting so it'll give you more battery life, but I prefer the XP.

I know very little about the PCT, so I can't really advise you as to what you'll need. However, if you don't plan on resupplying and don't mind a bit of fuss, I would get a headlamp like the tikka, or even just a couple 100mA LED's, and wire it to 3 AA lithium. You get the benefits of a larger cell (compared to AAA) and the flat discharge and cold weather performance of lithium. A word of warning about lithium cells in non regulated output headlamps- you can burn them out because li cells sustain a higher voltage during discharge than alkaline, but you'll be okay if you stick with low/medium settings.

[Johnny Swank]

With the battery life of led headlamps these days, I wouldn't worry too much about which one to buy. A tikka will buy you something like 40 hours on the high setting, which in trail terms translates to several months on the trail. Batteries in the LED headlamps take forever to completely discharge, so you have some time to play with. Every gas station from Maine to Georgia carries AAA batteries, so why worry?

[Footslogger]

If all you are using it for is reading in the tent or navigating to answer nature's call at night you might even be able to get away with this model ...rated at 140 hours operation on 3 AAA cells

http://en.petzl.com/petzl/LampesProduits?Produit=497


'Slogger

[Johnny Swank]

The TikkaPlus gives you virtually the same number of hours at one of the lower settings, with the option to kick up the light output with the maximum setting for the same weight (ok - 5 grams more). That, to me, seems to be the sweet spot between lower light output/low weight and high output/high weight.

LED headlamps seem to be gaining weight each year as they add more bells and whistles. I hope some of the more basic models stay on the market.

[rafe]

LED headlamps seem to be gaining weight each year as they add more bells and whistles. I hope some of the more basic models stay on the market.


It's the way of the world... but seriously, the bulk of the weight of a LED headlamp really ought to be in the batteries, or else it's a poor design for thru-hiking. One of the weight-saving measures seems to be the use of flat button-cells for power (eg., CR-2032.) This saves weight but uses a more expensive and harder-to-find battery (with lower battery life also.)

On a Petzl Tikka, probably 75-80% of the weight is in the three AAA cells.

[highway]

I have started taking this little light:

http://www.basegear.com/gerberinfinity.html

Single extrapowerful LED and with a clip that I can slip on the bill of my visor for night walking/work/reading/writing. It takes a single AA and I have not changed it in more than a year. I like the older style, the one that rattled, better.

Lights are a personal thing. They all work-give light, right:D

[doodah man]

On a Petzl Tikka, probably 75-80% of the weight is in the three AAA cells.

The Pak-Lite web gives the snap on LED/switch part at 4 grams. A 9V lithium battery weighs about 35 grams... so the battery is 89.7% of the weight for this flashlight.

Also, I think that in addition to volume, the voltage has to be factored in when doing the energy storage comparison. Watts = Volts x Amps. Both AA and AAA are only 1.5 V versus the 9V battery used in the Pak-Lite. At the Pak-Lite web page, they indicate that at the low setting one of the flashlights with a lithium battery ran continuously for over a year and still produced enough light to read by. Assuming that is true, that is amazing. doodah-man

[rafe]

The Pak-Lite web gives the snap on LED/switch part at 4 grams. A 9V lithium battery weighs about 35 grams... so the battery is 89.7% of the weight for this flashlight.
Yep, that makes it very appealing!


Also, I think that in addition to volume, the voltage has to be factored in when doing the energy storage comparison. Watts = Volts x Amps. Both AA and AAA are only 1.5 V versus the 9V battery used in the Pak-Lite. Energy would be in joules, watt-hours, or milliwatt-hours, etc. For a given voltage (eg an AA or AAA cell, 1.5V) you can rate a battery in milliamp-hours. Safe assumption is that the volume of a battery (not its voltage) correlates best to its overall energy capacity. Higher voltage is achieved by stacking cells in series. Take apart that 9 volt battery and you'll see that it's a stack of six 1.5-volt cells.

[The Solemates]

Neat ...and timely since I'm in the planning stages for my PCT hike. 'Slogger


i noticed this over on the PCT-L. when ya shootin for? 2007 or 08?

[Footslogger]

i noticed this over on the PCT-L. when ya shootin for? 2007 or 08?

============================

Probably gonna be 2009 actually. Trying to push away from full time work going into the end of 2008 and then start focussing on the important stuff ...like backpacking !!

Wife and I are going to re-hike the AT in 2010 ...but this time TOGETHER !!

Sorry for the thread swerve.

We now return you to your regularly scheduled thread ....

'Slogger

[doodah man]

Energy would be in joules, watt-hours, or milliwatt-hours, etc. For a given voltage (eg an AA or AAA cell, 1.5V) you can rate a battery in milliamp-hours. Safe assumption is that the volume of a battery (not its voltage) correlates best to its overall energy capacity. Higher voltage is achieved by stacking cells in series. Take apart that 9 volt battery and you'll see that it's a stack of six 1.5-volt cells.
You got me there... the energy stored would be proportional to internal battery volume. I am not at all electrically inclined, but my feeble attempt was to regurgitate something I had heard many years ago when I asked an electrician why my dryer was on 220V instead of usual 110V. His explanation was essentially that at a given Power (Watts), electrical systems tend to have better efficiencies at high volts and low amps because the losses are often related to amps squared. This may or may not have anything to do with the phenomenal operation time claimed in the Pak-Lite sales pitch. Whatever the case, the web page is certianly worth a visit just on the basis that it would be a vialble option for some folks and just plain interesting for the rest. Thanks for setting me straight... today was a success... I learned a little more... doodah-man

[iamscottym]

Damn, I really should pay my $20 to get the edit function. As an addendum to my previous post in regards to the volume of chemicals and it's respective weight compared to the weight of the jacketing. Chemical Volume is= pi*r^2*L where measurements of r and L neglect the jacketing, whereas the weight of the jacketing is proportional to 2*pi*r*L (sides) + 2* pi*r^2 (endcaps). This means that chemical volume(~weight~energy) is proportional to r^2, but jacketing weight is proportinal r, so the smaller cells are less energy/unit mass.

It's basically what I said above, but more technically correct.

9V's, because they basically have 2 layers of jacketing (1 on each of the 6 cells, and another to wrap the 6 cells in a 9V package) are terribly inefficient in terms of energy/mass.

Not to bore you all, but the disadvantage of lots of small cells is why the new li-ion rechargeable cells are so great- they are 3.6V/cell (nominally), and have the similar lightness found in their non rechargeable lithium conterparts (which, however are nominally 1.5V/cell).

doodah- R=i^2, while in most applications results in better efficiency for higher voltages and low currents is sort of irrelavent in lights. That is because there is very little resistance in a headlamp except for the bulb. Since power dissipated by the bulb comes out as light (and heat), raising the voltage would just mean you'd need a filament with a higher resistance to get the same light output as a lower voltage and lower resistance bulb (P=iV).

[Two Speed]

Man, have I got the worst itch to break the ol' HP-48 out for a good ol' fashioned nerd fest! iamscottym, lots of good, double-clutching math there, but you're neglecting something: the Pak-lite uses the battery as the body of the flashlight. As an example, the singe AAA that highway mentioned is a good light, but some of the relative weight reduction offered by a more efficient battery design is offset by that battery requiring a full length body to contain the battery and conduct the current up to the LED.

The Pak-lite uses a commonly available and cheap battery. The Gerber looks like it'd be a handy little light. Probably both good lights, depending on what you want your light to do. Personally I don't feel the need for a powerful light and I find that the Photon Micro-Light 3 (http://www.photonlight.com/Photon-Micro-Light-3-Keychain-LED-Flashlights-p/p3-keychain-led-flashlight.htm) is plenty good enough for me. I epoxied a velco patch on the light and on the underside of my favorite ball cap, and voila! I have a 7 gram headlight! Epoxy another velcro patch on a handy spot in your pack, and never have to look for your headlight!

Of course, the attributes I find so appealing about the Photon 3 might not suit someone else. Personally I'd recommend finding what suits your hiking style best and not worrying about pulling double derivatives to figure out which light is a fractional percent more efficient.

'Slogger, do you think we can hijack these poor guys as SSWB crew members? :D

[Footslogger]

'Slogger, do you think we can hijack these poor guys as SSWB crew members? :D

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ABSOFRIGGINLUTELY !!

[iamscottym]

Two speed- I know the 9V light is all battery weight, but in my first post I believe I mentioned that if that kind of light floats your boat, you're better off making your own with a couple of 100mA leds and 3 lithium AA cells. It may not be as pretty, but it will certainly be much more efficient weight wise.

Case in point: (I'm using Nimh chemistry for my example because I knew the numbers off hand. They'd be similarly proportional for alkaline or lithium) Your average 9V is 250mAh, 1.6oz. Your average nimh AA is 2500mAh, 1oz. You'd need 3 in series for sufficient voltage to power leds (leds wired in parallel).

in mWh's, it comes out like this: 9V 250mAh= 2250mWh/1.6oz= 1406.25 mWh/oz ; 3AA 3.6V 2500mAh= 9000mWh/3oz = 3000mWh/oz. Thats 213% better than the 9V!!

Granted, overall the 9V is lighter, but if you're not doing a resupply and you need the light, larger cells are the way to go.

Two speed- if you're up for a nerd-off involving discharge curves, internal; resistance, etc I've got plenty more! I just figured I wouldn't bore the nice folks here for the sake of listening to myself talk. Haha.

[Two Speed]

I'm gonna get a ringer. If you want see a real nerd in action, go here (http://ledmuseum.home.att.net/ledleft.htm). If you want to argue silly math I'll meet you here (http://www.whiteblaze.net/forum/showthread.php?t=18685). :D

('Slogger, I'll keep 'em distracted while you slip 'em a Mickey Finn!)

[Footslogger]

('Slogger, I'll keep 'em distracted while you slip 'em a Mickey Finn!)

=============================

Mickey Finn nothing ...I'm just about to break into some math and physics of my own. Was just trying to keep it light but once upon a time I was smart and knew all about electricity and engineering stuff.

'Slogger

[Panzer1]

The law of diminishing returns applies to flashlights, When you have a head light that weights 3 ounces or less, it really dosen't matter if you can get a new light that only weights 2 ounces because the savings is only 1 ounce and that isn't much. After a while you are spending a lot of time talking about saving a little bit of weight.

We're lucky to be living in a time when you can go hiking with a LED light. They are light weight enough and very reliable.

Panzer

[rafe]

You just have to go to the battery data sheets (http://data.energizer.com/PDFs/E92.pdf) and read off the milliamp-hours (mAh). Multiply that by the battery voltage and you've got milliwatt-hours (mWh).

Now, a bright LED wants, say, 25 mA at 3 volts or so (they're diodes, but with a big forward drop.) That's 75 milliwatts (power consumption.)

AAA batteries are, say, 1200 milliamp-hours at 1.5 v. Two in series is 1200 mAh @ 3v = 3600 mWh.

Finally: 3600 mWh (2 x AAA) / 75 mW (LED consumption) = 48 hours on time (1 LED, two batteries.)

[iamscottym]

panzer- 1oz may not be a substantial amount of weight, but some of us have fun just figuring out all the electrical stuff behind it!

[Panzer1]

panzer- 1oz may not be a substantial amount of weight, but some of us have fun just figuring out all the electrical stuff behind it!

Yea, I know, I just thought it would be fun to point that out.
I do believe that the same people who obsess over the 1 oz will probably also have the lightest packs on the trail.

Panzer

[rafe]

It's worth pointing out that hikers of yore carried some pretty heavy flashlights and headgear. I used to carry this rig with four AAs in a plastic box, with a wire to a lamp unit on a headband. Probably weighed half a pound all told. It had an incandescent bulb, nowhere near as efficient as a LED.

[Two Speed]

Reviving an old thread here. How many of you folks have used a Pak-Lite, and if so, how does it's field performance stack up against the claims on their website (http://www.9voltlight.com/home)? Perspiring minds (like mine) want to know.

(BTW, I just noticed that I have just exceeded 1,200 posts. I love me!)

[Sly]

On the PCT I mostly hiked to just before dark and only used a headlamp 10-15 minutes a day which translates into 25 hours. Even the least efficient headlamp should only use 1 change of batteries for the entire trail.

With that in mind I got the new Petzl E+Lite. Sweet!

http://www.rei.com/online/store/ProductDisplay?storeId=8000&catalogId=40000008000&productId=48124596&parent_category_rn=4500596

[Two Speed]

First, that don't have nothin' to do with my question.

Next, I'm busy insulting you here (http://www.whiteblaze.net/forum/showthread.php?t=22511), so what are you doing engaging in thread swerve? Besides, you should leave that to professionals, like . . . , well any WhiteBlaze member, which would include you. Oh damnit, I just got caught in my own logic, or lack thereof.*

*No, none of my snarkiness is inspired by being envious of Sly's impending departure for a LD hike, and I don't like it when people tease me about it. :p

[Footslogger]

[quote=Two Speed;336996]First, that don't have nothin' to do with my question.

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...and that's something new ?? HELP WITH MATH PLEASE !!

Oh yeah ...and I'm guilty as hell too.

'Slogger

[Two Speed]

[quote=Two Speed;336996]First, that don't have nothin' to do with my question.

====================================

...and that's something new ?? HELP WITH MATH PLEASE !!

Oh yeah ...and I'm guilty as hell too.

'Slogger

And I note that you were looking at the same light, yet offer no relevant input.




:banana:banana
Well done! The crew of SS WB salutes you!
:banana :banana

[The Old Fhart]

Terrapin_too-"Now, a bright LED wants, say, 25 mA at 3 volts or so (they're diodes, but with a big forward drop.) That's 75 milliwatts (power consumption.)"That doesn't hold true for some of the really bright LEDs like the Luxeon 1 watt LEDs (they make 3, 5, and 8 watt LEDs) that may require 3.9 volt to operate at perhaps 1200 ma. Walmart sells a Coast LED Lenser model for $20 with three 0.5 watt LEDs that operates from one AA battery and uses electronics to convert the 1.5 volts from the single AA battery to the higher voltage needed to run the LEDs. This hand flashlight is quite bright but the battery life is a few hours.

Bottom line is battery life depends on light output, what you need the particular LED flashlight for, and how much you will be using it. Yes, you could get a light to last the entire hike but the light output would, to put it bluntly, suck. I have an extremely bright LED flashlight I use at home that weighs 1.4 pounds, uses 6 AA batteries, has 128 LEDs and is basically a spotlight. While not too useful for the trail, I needed a light at home that has extremely high light output with reasonably long battery life.