Found out the hard way that rechargeable flashlights don't work if they aren't always charged.
Posted by zfuller@reddit | preppers | View on Reddit | 84 comments
Not a real emergency but the neighbor called to help find some goats at sundown, we haven't needed our headlamps or flashlights in months. We turned them all on before leaving. Once on site they all died, ok no big deal they weren't charged. But now we realized that lithium batteries die forever if you don't keep them charged. What do you guys keep in your go bags? I feel like rechargeable would be the way to go in an emergency bc there might be an option to charge them with generators but finding replacement batteries in an isolated situation would be hard. I doubt that we will be able to keep all of our flashlights charged on some kind of rotation in between emergencies. Any help appreciated.
Alarming_End_1731@reddit
Just get rechargeable batteries and wall charger for your aa flashlights, they should stay charged until you are ready to use them like standard batteries. Keep them stored in a battery organizer that comes with a battery tester.
ihatespam_yesIdo@reddit
I love these, different sizes and colors, and just insert dead rechargeable batteries upside down so you know to charge them. https://a.co/d/07cJbasm
Upstairs_Echo3114@reddit
How old are they. It takes years of neglect for li-ion batteries to fully die. Do they have removable batteries? If so there are chargers that can charge them specifically for storage, but they wont be at full capacity. And yes you can keep them charged on rotation: just use a calendar it chart and top them up every 3–6 months. And if you have household use lights, swap them out with the lights in the go bags every time you charge them so they all get similar use.
Paranormal_Lemon@reddit
It doesn't take long to kill them if they are left discharged, a few months is more than enough.
Upstairs_Echo3114@reddit
Okay. Do you think they were storing flashlights with dead batteries in their go bags? The effect you're talking about is when they're deeply discharged, which would happen when a light without protection circuitry is powered by a battery without protection circuitry is left on until the battery runs down completely.
I have some cheap-ass rechargeable lights and they shut off when the battery drops to and certain voltage to prevent full discharge.
Paranormal_Lemon@reddit
If you run it till the protection kicks in it doesn't take long to go past the permanent low voltage cutoff level. Going from 2.8 to 2.5V is a fraction of a percent of SOC. Even if it doesn't cutoff it degrades faster at low voltage, especially if they are cheap Chinese cells.
Longjumping_Day2513@reddit
yeah we all have been in that kinda situation
Jammer521@reddit
I have 2 small solar lanterns that have a solar panel on top, I leave them in a south facing window on there side, they get a lot of sun everyday and are always fully charged, they aren't my only backup lights but just thought I would toss that in that you can solar charge small lights by sitting them in a sunny window
EnergyLantern@reddit
Some chargers will restore lithium batteries if you don't keep them charged. I happened to buy a charger that made my lithium batteries work again.
You need a charger with a "wake up" feature.
Wing-527@reddit
Yeah this is a super common trap.
I ran into something similar with my bike lights — if I don’t charge them after every ride, next time I use them there’s a good chance they’re dead. Same idea with flashlights.Also, for backups it can actually make sense to have non-rechargeable options instead of relying 100% on lithium rechargeables. Way less maintenance.
Redundancy > perfection in prepping.
Seth0351USMC@reddit
Also bad batteries kill good flashlights...either keep lithium in them 24/7 or remove the batteries when not in use
Lost_Engineering_phd@reddit
The main issue with rechargeable lights is that the voltage converter and battery management circuits are always live, and act as a small but constant drain. I have a 10,000 lumen monster with a USB output that is powered by a set of massive 21700 cells. I keep a piece of paper between the contacts in storage so it does not self discharge. For a very long duration battery light I have a 6V LED lantern with a Zink-Air 45 Amp hour battery. It is not the brightest light, but it can run for an incredibly long time. The Zink-Air battery is low current but has an insane energy density.
Paranormal_Lemon@reddit
Depends on the light, I have some that will run 2-3 years with the power button light on.
Lost_Engineering_phd@reddit
I'm interested in how you doing this? Are you using a solar light of some kind, or is this a battery only light?
Paranormal_Lemon@reddit
Just a 21700 single cell light with a small LED in the button. One of them also has tiny color LEDs by the main LEDs, you can switch them on and off separately. I've also has lights where the main LEDs would run 2-3 months at the lowest level, like. 01 lumens.
Useful-Contribution4@reddit
I store all mine around 90%. I have 18650, 21700 and 26650 LiFePO4.
I've left the 18650s and 26650s stored for 3 years. They were at 49-56% and charged back to 100%. It was not even less than 1% loss from degradation.
I also left my battery in an anker bolder LC90 flashlight. I charged it to 100%. Forgot about it 2 years ago and it still worked. The 18650 was at 42%.
Mind you the 18650s are salvaged from modems. The 26650s are K2 cells and were new.
Then enloop NiMH AA and AAA I store at 80%. I dont do lithium for AA or AAA. They drain too fast and just overall dont perform.
Paranormal_Lemon@reddit
That's really bad, 5% per year is typical for high quality cells. I've left 18650s for 4 years and they were still over 4.0V.
Useful-Contribution4@reddit
I dont mind honestly. As long as the actual capacity degradation stays within spec.
Paranormal_Lemon@reddit
I've only seen that happen on really worn cells that were starting to get internal shorts/dentrites, it may be time to replace them
MaliciousDroid@reddit
Li-ion batteries shouldn't drain too fast unless you store them in a flashlight with parasitic drain. If the flashlight is a clicky mechanical switch, it will lose 1-2% charge per month in storage. If it's an e-switch, you need to twist the tailcap a bit to lock it out and disengage the circuit, otherwise it will discharge after a couple months.
zfuller@reddit (OP)
So the clicky ones should last 50 months if put away fully charged and not used?
Paranormal_Lemon@reddit
In my experience good cells (Panasonic, Sony, Samsung etc) loose about 5% a year, but I've seen it as low as 2-3%.
MaliciousDroid@reddit
It depends on the battery, and it's not good to keep li-ions at 100% charge long term, best to store it at around 3.7v or around 70% for battery health.
Nimh batteries are more stable at full charge in long term storage, but have worse capacity and output, so they're good for emergency headlamps you keep in the car.
ReactionAble7945@reddit
The rechargeable Chinese flashlights.. I killed the charger on 1 pretty quickly. I have a second one of that type so, I charge the battery in it, but kind of sucks. I have a 1k lumin tiny chinese flashlight. If you can get past them lying about the 1k lumin, it is a great probably 500 lumin flashlight that is tiny.
The days of buying name brand special flashlights are gone. Technology advanced and now you dont have to get that special flashlight from some engineer that is wow. The standard cheap one is pretty wow.
Paranormal_Lemon@reddit
Leaving them in a discharged state or draing too low absolutely damages them permanently.
SheistyPenguin@reddit
Many ways to skin this cat, but the way we do it:
For infrequently-used stuff with internal Lithium ion batteries: get a smart plug+power strip, and schedule it to turn on for a few hours every X days or months. You shouldn't need much; a few hours maybe 2-4x per year should suffice. Lithium ion has a shelf life of 10-12 years whether you use it or not.
Paranormal_Lemon@reddit
High quality 18650s last longer than that, I have many in that age range that still test well over 90%, and still have low internal resistance. It's the lipos that don't do so well, like the ones that come built in. Anyway they are so cheap now so what if they only last 10 years.
Paranormal_Lemon@reddit
What you want are flashlights with a mechanical switch, I like Convoy lights a lot. Charge it after heavy use, that's it. Been using lithium ion for 20 years now, I've never picked up a light and had a dead battery.
kcwildguy@reddit
This is why my emergency flashlights are battery models with no batteries installed and fresh batteries taped to them. I’ve been caught like that before.
Ryan_e3p@reddit
If I may make a recommendation, don't tape the batteries to the flashlight. Put a piece of paper in between the batteries and the cap! I've had to try to wrestle in the dark when camping one night and it helped a lot, and just opening the cap and removing the paper is likely a lot easier than trying to figure out the + and - orientation for the batteries.
overkill@reddit
I was going to suggest this, but you suggested it better and quicker.
Mountain_Answer_9096@reddit
No criticism but I'd like to add to this. If you live in a place which is very wet (biblical amounts of rain where I am this year) use something that won't absorb moisture to separate the batteries. Absorbent materials can get damp enough to connect the circuit
Ryan_e3p@reddit
If that was the case, you'd likely have other issues as well (corrosion of metal conduit, moisture getting inside the light housing, etc).
If you have a flashlight rated to be watertight, no moisture should be getting in to be absorbed or make contact with anything, be it paper or metal.
Mountain_Answer_9096@reddit
Very true. I've got a bunch of cheaper flashlights that were advertised as waterproof but I have my doubts, hence the recommendation. We've suffered battery corrosion with flashlights that are stored in the car before, so we usually seal those in shrink wrap for long term storage without moisture control
kcwildguy@reddit
Great idea! Thanks for sharing it.
antidumb@reddit
That's a great idea!
np0x@reddit
I love my flashlights that use 18650 batteries…from a dead ebike battery I have a box of good batteries that I store at 75-% and will never run out during any normal storm power outage window… :-).
My flashlight is a fancy Fenix that uses these batteries…
SwoodyBooty@reddit
18650s will probably be high value goods one day.
Cain-Man@reddit
You can buy the 18650 batteries all day on Temu. I keep several flash lights with fresh batteries and more flashlights that are solar powered .
np0x@reddit
Sadly….
RedSquirrelFtw@reddit
I bought two battery organizer boxes, one for charged batteries and one for "to charge" batteries. Once in a while I go through and charge them all. When buying any kind of light or radio or anything I try to make sure it takes AAA or AA batteries and avoid anything with built in battery.
RedOnlineOfficial@reddit
I have a few dual fuel lights with backup batteries packed with them. My EDC is dual fuel and I always have a few spares on me.
Content_Chemistry_44@reddit
I was designing special flashlight that you don't need to charge, but still you have a small crank and capacitor (not supercapacitor) where a small charge stores. Just few revs, about 2-5 seconds, you have light for maximum 10 minutes. The circuit has a lot of room to improvement. But I am not working on it anymore. The advantages of this system, is that you don't need to crank as a hambster, and you can leave it at any place for much much years, discharged to 0v (completelly). When you take that again, you will need only few revs or some 5 seconds for a 10min of light.
https://streamable.com/emc2zj
EnergyLantern@reddit
Lipo4 are better than regular lithium batteries. There are dual use flashlights that use alkaline batteries and some flashlights use solar.
We have a few candles but we don’t use them.
ResearcherHappy8438@reddit
“Better” is quite subjective. Lithium ion batteries have significantly better energy density than LiFePO4, which is one of the reasons they are typically used in devices where weight / size are important factors. That’s why flashlights nearly always use lithium ion batteries.
EnergyLantern@reddit
In an emergency, I need power and the Lithium powered batteries either give out, or they are not charged even though I charged them.
The LifePo batteries that I have stayed charged.
I'm not saying you can't use both but in reality, I have to use whatever works and the LifePo4 battery that I have has retained its energy.
ResearcherHappy8438@reddit
What flashlight are you using that has LiFePO4 cells? What type of cells are they?
EnergyLantern@reddit
JayPark that I saw on sale on Amazon. I am sure there are better flashlights.
It is a fat 5,000 mAh cel 21700 cell I believe.
ResearcherHappy8438@reddit
Those are all lithium ion cells, not LiFePO4.
legos_on_the_brain@reddit
Good batteries shouldn't be that bad. Sounds like a cheap light and cheap battery.
The protection circuit should keep the battery from getting low enough to be damaged. If not then don't use those lights.
FL_FireFit@reddit
Be careful keeping batteries flashlights as well. I went to use one of mine after letting it sit for a few months and one of the batteries broke open inside. Battery acid was all over the inside of the battery compartment. Like others said in this thread, I now keep batteries taped to the side of most of my flashlights.
616c@reddit
IME, when needed urgently (instead of planned activity), rechargeable are far more likely to fail than a headlamp with AAA batteries and a zip-loc bag of spares.
For working in the attic, rechargeable are great. Recharge the night before. Come out of the heat to recharge.
For finding roof leaks in the middle of the night, it really sucks to be cold and wet and in the dark, cycling through all the rechargeable flashlights.
For my hiking backpack, I carry replaceable battery-powered and spares from a different batch. On a Grand Canyon hike, leaving at 3:30am with headlamps, it was stupid easy to hand someone a zip-loc with spare batteries. Not as easy to loan a battery charger for an hour, hoping they'll keep it out of the rain. Nobody needed more than a few hours of lamp, so knowing that window really helps planning.
dittybopper_05H@reddit
Never have to worry about whether the batteries are dead.
dittybopper_05H@reddit
and for you people who are paranoid about fire:
You can use candle lanterns.
DannyWarlegs@reddit
So funny you ask, im in the middle of replacing some older batteries right now. I use a mix of AA/AAA, and 18650s. In my basement across from my never used back door I have a black 6 box bookshelf thing from Walmart next to an outlet, with all my radios, headsets, flashlights, etc stay on their chargers when not in use.
I also have a large EBL multi battery charger where I keep the aa and aaa batteries charged up, and another for the 18650s.
I have the extra ones stored in plastic battery boxes that I can grab and take with me or throw into a bag. Every now and then I'll remember and walk past and swap out all the ones on the charger for ones in the cases, or I'll have a dead remote and remember to cycle them.
Its been working pretty good so far but some of thrm are getting to 10 years old and went a lil long between charges. So now im making a maintenance schedule for my batteries to cycle them between in use, in charge, and in storage.
In the event of an emergency, I have a backpack I can fit all my chargers and batteries into with a 12ft 3 way extention cord and a power strip, along with some extras.
I keep some cheap power banks, 2 high end power banks, a solar one, and a solar charge pannel along with a few other little usb lights and gadgets in the shelves I can toss into the bag too.
All in, I have a plastic pencil box of each AA/AAA, another of odd sizes I need and coin cells, and about 20 18650s that are in rotation.
Every thunderstorm i also get everyone's personal flashlight and toss in a fresh charged 18650, and toss that old battery on charge again.
XRlagniappe@reddit
I have a mixture of battery types. I tend to buy products that take AA and usually have non-rechargeable Lithium batteries.
TheGanzor@reddit
Lithium batteries don't break when fully discharged, though?
LakeAdventurous7161@reddit
Instead of rechargeable flashlights, I prefer those that work with batteries - and then use rechargeable "batteries" in them. Same for other devices that are available with batteries: I but that version, and use rechargeable ones (AA, AAA). As I use them for a few different devices, I always have charged ones, and in addition, I could always use them with just batteries. Another plus: No issues with a degrading built-in rechargeable battery for which a replacement might be hard to find.
cslack30@reddit
I like having the ones that can either use a rechargeable battery or normal ones specifically for this reason. Then you’re not locked into having to remember they’re charged
Pando5280@reddit
Have some cheap but good single mode (on/off - - I despise multi-mode flashlights) lights for the house.These have a digital indicator showing % of power remaining and charge directly via USB C cables so no keeping track of chargers. My bug out bag lights are also single mode but better quality and have been upgraded with 18650 batteries that also charge directly off of USB C cables so no charger needed. Batteries are from a US diving company (OrcaLight) and are made for underwater cave exploration so they have been rock solid.
karebear66@reddit
I have both rechargeable and regular battery powered ones. I also recharge quarterly my jackery and other power banks.
zfuller@reddit (OP)
Whats jackery?
karebear66@reddit
It is a brand of a power bank. It can be charged by house current or solar panels. It has 1000 watt hours. It has A/C, 12v, and USB outlets. Great in emergencies and camping.
zfuller@reddit (OP)
I can't respond to everyone but thanks for all of the responses, I'm going to diversify my quiver of lighting capabilities. This culture on this sub is fucking cool, really appreciate not being called an idiot. 🤙❤️🤙
Fit_Acanthisitta_475@reddit
I don’t like rechargeable flashlights for this reason. I switched to 18650 batteries power flashlight and got plenty of 18650 batteries on hands.
scottawhit@reddit
You charge them when the clocks change and you charge your smoke alarm batteries. They’ll be just fine being charged 2x a year.
Quinnman1211@reddit
The acebeam tac AA 2.0 is a great option. It is budget friendly, rechargeable and can also take an AA battery. It has the best of both worlds, rechargeable when it is handy and replaceable battery when that works too. Highly recommend!
boraginaceae_bird@reddit
I have rechargeable headlamps and I just use them enough (walking the dog, painting, cleaning, etc) that they get charged every couple weeks.
celeigh87@reddit
The instructions on any rechargeable item I've bought is to charge at least every 6 months, even if not used. Not doing so voids the warranty due to the fact that this kind of thing happens. Rechargeable batteries lose their ability to hold a charge if they aren't cycled through their capacity on a somewhat regular basis.
Eeyor-90@reddit
I keep at least one non-rechargeable light. I store it with one battery reversed so it won’t drain if accidentally switched on in my bag. I also keep a spare set of batteries in the same bag. My rechargeable stuff is kept plugged in on a power strip that I have set up on a timer. The timer will turn the power strip on once a week for 3 hours to charge everything.
Karma111isabitch@reddit
This is the answer
Foreign_Attention_83@reddit
I keep a go bag in my vehicle at all times. Would it be a bad idea to keep spare batteries in there? With the different weather changes, would the batteries lose power or deteriorate? For example it’s in the 30degree F temps right now but when summer comes around and it gets to maybe 110 degrees in the summer sun? Would they corrode or be useless over time
Capt_Gremerica@reddit
This is brilliant!
LizDances@reddit
Ohhhh I have aspirations to a timer-ed power strip! This is the dream.
baardvark@reddit
The timer is a good idea!
UncleHayai@reddit
All of the flashlights that I have "stashed" have Eneloop NiMH batteries in them. Those are ultra-low self discharge batteries, so they will hold their charge for years. Plus they deal with hot and cold environments without degrading.
The other benefit to Eneloops is that if there is an issue with my rechargeable batteries, I can grab any alkaline batteries that happen to be available and get my light back into action.
Lithium primaries are another option, but are pretty expensive for disposable batteries.
CeeTheWorld2023@reddit
I recharge,all my chargables, every 15 days.
Hard learned lessons, from hurricanes and Tuesday outages.
P00rSuggestions@reddit
I just grab a different flashlight. I have them everywhere. And even if I don't, I have batteries. What kind of junk ass light isn't multifuel in 2026!? Or, maybe I just don't buy lights if they aren't. I think a hug part of prepping is being versatile. It's important for both you and the tools you implement.
Successful_Ride6920@reddit
I recharge everything the 1st of the month (or thereabouts).
Mala_Suerte1@reddit
I try to buy flashlights that are both rechargeable and take regular batteries. I do have a few that are just rechargeable and I'll throw them on a charger once a month. I also keep plenty of eneloops and a 70 watt foldable solar panel to charge the batteries off grid.
Which-Meat-3388@reddit
The flip side with rechargeable is that depending on the battery type, it may be worse to keep it 100% and charging all the time. You might notice even with brand name pocket battery banks how they never seem to last very long. Li-ion is great until ages. Phones, laptops, and EVs have largely mitigated that with limited or smart charging.
Like others I have a mix of replaceable and rechargeable. Any rechargeable I get these days can be charged from USB. Even if you found it flat you more than likely can charge it back up quick. I like the timer idea others are using though, going to use that for something else.
greeenappleee@reddit
Store lithium at 3.7v. I use my lights a lot so I always have a few charged. The ones at 3.7v would need to be charged before usage. If they get below 3.7v top them up. A lot of quality chargers even have a storage mode now. Yes leaving them dead for a very long time kills them permanently but just dont do that. I have batteries that have help 3.7v for years without needing to be topped up. I just check every few months.
The power density of 3.7v lion destroys the 1.5v rechargeables or disposables but they make lights that can take both chemistry aa or aaa ex sofrin sp10 pro which is great for if you cant recharge right now but the lower voltage battery comes at a performance hit.
ExtensionCritical732@reddit
My best lights are rechargeable. But I have plenty of AAA flashlights and eneloop batteries.
It’s hard to find something more practical unless you’ve got a dedicated charging station that can keep the lights charged without shortening the battery life.
Subject_Role1352@reddit
I have rechargeables, I use them often enough, and keep a station where they charge.
For the infrequent use lights, I use non rechargeable lithium primary cells. They have a very long shelf life, wide temperature range, and don't leak.
They are more expensive, but worth it for me.