Urgh...batteries suck

[KennyR]

Flashlights (torches, in UK): they're the thing you don't need 99% of the time, but when you do, you need them badly. It's storing the things that's the hard part. Or rather, storing them with batteries installed.

After being caught short needing a flashlight for the last time, I bought one or two, put in brand new batteries, and hung them up in a place I'd always know where they were. A month later, I needed one, so I went for it...and the batteries were practically flat. I know batteries discharge naturally, especially in warm places, but not that quickly.

How can I store these things without the batteries discharging? Sure, I could store them seperately, but that's hardly very convenient if I'm in suddenly the dark or need the flashlight for something quick like looking behind furniture. Is there a clever trick someone knows to store them but keep them ready?

[KennyR]

X-ray wrote:
Kinetic torch, my mate

http://shops.bizarsoftware.com.au/ATAShop/catalogue/category16/category78/product174

The mode of operation may remind many users here of their first sexual experience, but the benefit is definite light at the end of the tunnel and no need to buy batteries. Gets you out of a fix at least... :-D

:-D I already have one, hanging up beside my other flashlight. ;-) It's just not very bright. Good enough for finding other flashlights in the dark or not breaking my neck, but not very useful generally, especially outdoors. And it's one of the brightest of the kinetics.

Squatting at the window in the dark frenetically pumping some small rod-shaped object is liable to attract attention too, I suppose. (Luckily, my flashlight uses a pump handle, not shaking, yay. Much less onanist.)

[KennyR]

Blob, one biggish problem with candles:



Apart from the fact that the wind blows 'em out when you go outside. And the fact that I can never find matches to light them.

[KennyR]

Ah, the Sherpa. I know it. I wish I'd have seen it before I got my own kinetic, it looks pretty good. Although, I'd like to know just what 'superbright' actually is. The one I have was advertised as this too. :-P On the other hand, mine is LED, which, while far more efficient, isn't as bright as a xenon bulb like that on the Sherpa.

[KennyR]

Nice hat, but I bet its batteries still go as flat as three-week old Irn Bru if left inside.

[KennyR]

T_Bone wrote:
Flashlights suck, I use a propane lantern.

I had one, but threw it away. The mantles were too difficult to maintain. Besides, they can't throw a beam, and looking for the remote control down the couch is liable to be quite an experience with one.

[KennyR]

Seriously though, I'm thinking of just dumping alkaline and going for NiMH rechargables instead. Problem is, they have a lower voltage per battery (1.2 compared to 1.5). Well, thats not the big problem. The big problem is that packaging for every flashlight I ever bought screams: "Only use alkaline batteries in this product!" They don't recommend it, they demand it. Anyone know why?

[KennyR]

Karlos wrote:
Alkaline batteries have higher current densities and are less likely to leak than other disposable batteries. They probably don't suggest rechargables because they don't output the power and hence results in a lower brightness. Also, rechargable batteries (lead acid excluded of course!) generally don't cope with higher current demands well (OK, these things are relative, but a normal bulb drains a lot more juice than most battery driven components), so you get a dull beam that doesn't last too long - not exactly what they are trying to sell.

You're right apart from the current demands; NiMH is better under high drain than alkaline. But not the kind that flashlights will give.

NiMH also has a nice flat output, and can punt out just as much current until its drained. It doesn't tail off, so no yellowing of bulb light (not that I get any anyway, my flashlights are all LEDs). That in itself presents a problem: the current drain from LEDs is so low that its really not much more than just leaving the batteries inside and not turning it on! I'm not sure NiMH likes that kind of job. In fact I'm pretty sure it doesn't.

I could recharge NiMH every 30 days so I'd never have problems. At this rate, I'll be replacing alkaline every 40 without ever using the damn things!

[KennyR]

Ok, done some research into NiMH batteries, and I'll think I'll do the switch. They may only be 1.2V compared to alkaline 1.5V, but apparently alkaline lose EMF quite quickly and they average at 1.2. NiMH give a much more even discharge, which is useful since the flashlights don't have current regulators and go dimmer as alkaline drain.

And most of all I don't need to keep replacing them. If I charge them every two weeks I won't have to worry about leakage or hydrogen gas buildup. No arguing with the energy density though - alkaline still kick NiMH ass, so I wont get my 900 hours of light. Pity but not the end of the world, unless it really does come to the end of the world. In which case I'll loot a shop and get alkalines.

Ladies and gentlemen, you may keep your primitive combustion products and homemade voltaic piles. I'm going rechargeable.

[KennyR]

gizz72 wrote:
Why not change the flashlight bulb to something efficient to say, small but powerful LED

None of my flashlights actually have bulbs. They're all LEDs. But actually providing light isn't the reason I keep running out of batteries, it's the drain the flashlights have when not on that's freaking me out.

[KennyR]

@Karlos

They are white (although they look slightly bluish), and they are brighter than most ordinary flashlight bulbs. A Lightwave 4000 (with 10 white LEDs) which is advertised to run with 900+ hours on 3 D batteries, and a Lightwave 2000 (4 white LEDs), advertised for 340 hours on 3 AA. Actually they'll probably still be bright enough to read by long after that. So they ain't high current! ;-) (The LW4000 is probably the world's most efficient flashlight, and I had to ebay for it and get it stateside.) Oh, and my kinetic, with its purple LED that seems to be lit no matter how long the thing is left on. But isn't very bright.

LEDs rule, but they have one important failing: they don't throw a beam. Further than 10m, they're useless. Thats why some manufacturers are making hybrids with both xenon/halogen bulbs and LEDs. LEDs for ultimate battery economy, bulbs for long distance.

It seems even the world's most efficient flashlight still suffers from parasitic drain.

[KennyR]

Karlos wrote:
However a superbright red LED (harder to see though) would probably give twice the battery length. A green version would look far brighter to the human eye and still last maybe 60% longer than white LEDs.

There are green torches out there. You're quite right in that green LEDs are both more efficient and mostly useless, but wrong that they would look brighter. The human eye sees about 1/3 of reflected green light, while it sees 2/3 of white. Have a look at this Q&A on the flashlight review site.

[KennyR]

Blobrana wrote:
Ever considered keeping your batteries in a fridge? (In sealed bags of course)

I don't really have to go to those extremes: alkalines lose about 2% charge per year somewhere like a drawer. But fridge or drawer, they're not in the flashlight where I want and need them. I could go with X-ray's suggestion and fumble about with my kinetic to find them, but then I wouldn't be properly ready for armageddon. ;-)

[KennyR]

bloodline wrote:
The Band gap required to produce Blue light is HUGE.

It's no big deal. You just plug the band gap with a suitable dopant.

[KennyR]

Hmm, I got a battery tester and the batteries aren't as flat as I thought. They're sitting at something like 85% capacity.

Still, thats not 100%, so out they go and in go the NiMH. The old ones can go in a drawer to await the end of civilisation, where I can barter them for virgin brides.