I am definitely not a flashlight-a-phobe like you guys. I only have two 'cheapies'. I have a 4D Maglight for lightpainting and use in scary parts of town, and a single LED 3AAA jober for most general purposes.

I just changed the batteries for the first time in the Maglight in say 3+ years. I can't count the number of explorations (20-40 est.) or estimated hours of usage any more. The last I estimated about a year ago was that I was past 24 hours of usage. Now I don't even know.

The LED I picked up last fall and I also just changed out the original batteries it came with. I also give this one maybe up to 24 hours of usage.

So anyway.... I've used these lights with low battery's waaaay to long. For the last 3-5 explores with either one I was wondering why I could no longer see well. With the LED I could barely see 5 ft' in front of me, and the Maglight was useless while trying to see what was up ahead in a drain.

I really ran these too long without knowing it at first. It was to the point where it was no longer safe going into place requiring flashlights since the lights we about as bright as my UER key chain light (actually that is was probably brighter).

SO, my question is, how do you guys know when to change out your batteries? How do you know what the 'line' is and when your batteries have crossed the line?

I changed out both of mine and tested them out in my basement and I can't believe how bright they actually are with new batteries.

Q: When are batteries worth replacing?

A: When you notice a significant drop in output or their utility diminishes. AKA when they aren't as bright. If you've noticed, I've replaced batteries mid-explore before, because I felt the light was simply not performing properly.

Q: How do you determine the threshold for lights not being bright enough?

A: For me, it's when my light doesn't perform at least 50-60% of what it did on fresh batteries. Sometimes I'll let it drain more, but I don't want to get stuck without light.

My Fenix LED lights, easy answer. They rapidly strobe/pulse when it's time to change them. They are 100% regulated, which means that they do not lose visual output at all, until they are ready to die. My Pelican M1 is regulated, but when it drops out of regulated output, it performs like an incandescent light, slowly diminishing in brightness for an additional 20 minutes or so.

As the last reply mentioned, unless a light has a specific 'low power' indicator like my Fenixes do, when to swap them out for a fresh pair is up to you.

My Fenix L2P happily uses discarded AA's from my camera or other electronics, and still shines bright even with almost dead batteries. I use that to get the last bit of juice from batteries I'd have otherwise thrown away.

I only use rechargeables, really, so I don't have that particular concern

I'm just glad that rechargeables these days can be charged back up whenever convenient, without worrying about memory effects and such.

Posted by trent I am definitely not a flashlight-a-phobe like you guys.

Flashlight-a-phile, maybe?

Posted by Glass Flashlight-a-phile, maybe?

Ahh, caught me there. Points to you.

Posted by trent SO, my question is, how do you guys know when to change out your batteries? How do you know what the 'line' is and when your batteries have crossed the line?

I switch mine out whenever I notice the output just isn't what it should be. I'm yet to use LED lights for any serious purpose (I bought a couple of 5-LED metal lights a while back, but never used them for UE) but I only noticed that it was running out of battery when it was becoming impossible to read a book with it.

For UE, however, for the time being I use Xenon/Incandescent lights. I always carry spare batteries (one fresh set) for each torch I have. I also always carry an easily-accessible secondary in my pocket, which is currently a 2AA Minimag. So if one of my lights does suddenly die, I can quickly switch to the secondary and figure out what's wrong with the main light from there. My whole "carry-a-spare" idea means that my pack weighs a lot more than it should, and it also limits my light choice to a certain extent. I'm switching to LED very soon, which should remedy the pack weight problem.

So, in summary, if you can afford (in backpack/storage terms) to carry spares for your lights, do so. Four D batteries aren't exactly light (believe me I know), so maybe carry spares for the other torch instead. That'll eliminate the guesswork in deciding whether or not to chuck the battery, and any concerns you may have about throwing away the remaining battery power.

Batteries are dead when they cannot support large enough current for the bulb to operate properly. To check for that, connect an multimeter in ammeter mode to tyhe battery for a second and see the reading. WARNING - doing that you are short circuiting the battery - dont hold it for too long. Also, you should approx. know what readings to expect in order not to burn the multimeter (which is typically rated for 10a max)

Posted by strangePlaces To check for that, connect an multimeter in ammeter mode to tyhe battery for a second and see the reading. WARNING - doing that you are short circuiting the battery - dont hold it for too long. Also, you should approx. know what readings to expect in order not to burn the multimeter (which is typically rated for 10a max)

That is NOT how you do it... Doing this, you could blow the fuse in your meter or ruin it completely. If you really want to meter the battery.. especially useful when you are underwater or being chased by security.. put the ammeter in SERIES with the bulb. You would have to measure at full battery and compare to the diminished battery tho... You really should be watching the Voltage drop across the cell (not current) when getting empty. Battery monitoring systems detect the voltage drop across cells to determine battery levels, not current levels.

MUCH easier just to replace batteries when you think they need it or when the light gets noticeably dimmer. You should always carry spare batts.

You really should be watching the Voltage drop across the cell (not current)

I would still insist that inability to support a certain current is the measure of battery's depletion, not voltage. You might have noticed that even tho voltage of a new and depleted batteries DO VARY a bit, that difference is not that significant. For example, that laser battery that spent days in cold water still (surprizingly) showed 7.4 volts as the potential drop, but even the smallest bulb wouldnt light up because almost no current would be going.
Direct measure with ammeter is safe to perform with small bats like aas, bs, cs and obviously not with car batteries which operate with energies that are orders of magnitude greater.

The voltage vs current thing is a lot of why 'battery meters' are iffy. Many batteries these days are designed to supply a nearly-constant voltage throughout the charge life, which then suddenly drops - leaving you in the dark. You need both voltage and amperage to get light, although regulation circuitry alleviates the voltage requirements somewhat.

It's my understanding that low-voltage batteries have to crank more milliamps into the regulator - so that my 1.2V NiCads are at a disadvantage to the plain-vanilla Energizers I recharge with a model train power supply. But that could be completely wrong, because I generally feed my lights when they're hungry. Today in a drain, I carried a 1-million-candle light, an LED headlamp, two good LED flashlights, and a keychain light (and cell phone, and if it comes down to it, a backlit watch), along with spare batteries for the LED lights. I guess I have darkophobia.

Posted by AnAppleSnail Today in a drain, I carried a 1-million-candle light, an LED headlamp, two good LED flashlights, and a keychain light (and cell phone, and if it comes down to it, a backlit watch), along with spare batteries for the LED lights. I guess I have darkophobia.

Testify!

Some people buy lights for the drains. Some go draining for the lights

Posted by AnAppleSnail Today in a drain, I carried a 1-million-candle light, an LED headlamp, two good LED flashlights, and a keychain light (and cell phone, and if it comes down to it, a backlit watch), along with spare batteries for the LED lights. I guess I have darkophobia.

The only thing missing would be a night light, for the extremely unlikely event you find a working 120v outlet.

Posted by trent SO, my question is, how do you guys know when to change out your batteries? How do you know what the 'line' is and when your batteries have crossed the line?

Petzl headlamps (at least the two models I've used) will start blinking on and off intermittently when their batteries are running low. It's a neat feature, but batteries are cheap enough so I usually just replace them whenever I start noticing a significant decrease in brightness.

Posted by TUGG The only thing missing would be a night light, for the extremely unlikely event you find a working 120v outlet.

"Emergency power" jumpstarter (8 amp-hour 12v battery) + inverter.

Man, that was an ooooold post. These days it's all Eneloops or megalights using sealed lead-acid batteries. Someday I'll use lithium-ions...someday.

Posted by AnAppleSnail "Emergency power" jumpstarter (8 amp-hour 12v battery) + inverter. Man, that was an ooooold post. These days it's all Eneloops or megalights using sealed lead-acid batteries. Someday I'll use lithium-ions...someday.

I'm surprised you've gone this long without venturing into LiIon territory!