westsam

Got my new charger and charged the AA's for the first time. Tried them out this morning and got less than an hour on blinking mode with my Fenix L2D Flashlight. Is this the norm for rechargeables? This is about half the time of alkaline batteries. Used the Energizer rechargeables. Has anyone tried the new Duracell rechargeables?
thanks for your help

KLW2

I think that it usually take 2 - 3 charges to get them to full strength...

matthew_deaner

The L2D should last almost twice as long using rechargeable NIMH batteries. See:
https://www.cpfreviews.com/Fenix-L2DCE-Premium-Q5.php

However, the L2D switches to its lowest mode of operation when using low alkaline batteries, so it will run for a while even with very low alkalines, albeit with a lower light output than with rechargeable batteries.

With rechargable NIMH batteries, you often get what you pay for. The Wal Mart no-name ones are junk. Duracell outsources NIMH battery production and quality can be hit or miss. I've had the best luck with Sanyo Eneloops. You can order them from amazon.com. Rayovac Hybrids are also pretty good.

mike

The smaller the batteries, the less re-chargeable they seem to be.

I did the recharge gig for awhile. Invested in a bunch of rechargeable batteries.

Guess what - after about a year of that nonsense, I am back to good old use-and-toss alkali batteries. The cost of rechargeable batteries and the recharger, and the half-life of rechargeable batteries convinced me that it just wasn't worth it.

The secret, I believe, is to use modern LED lights which use a lot less juice and have a longer run-time.

When you are getting 30+ hours of run time on a pair of batteries, the rechargeablity issue is not so significant.

BCRider

A lot of it depends on your charger. The cheaper ones actually overcharge the cells heavily and that is why they come off the charger hot. This reduces their lifespan a lot.

One of my other hobbies is model airplanes where we pay a LOT of attention to our battery packs since the welfare of our models relies on this. The fast chargers we use in that case are far fancier and more expensive but they don't harm the cells like the cheap chargers do. Or switch to the good old overnight trickle charge where you charge the cells at the 1/10C rating.

I've got a bike headlight that I use each winter that I built up about 7 years ago now. It uses a 5 watt bulb and some 2000 mah NiMh cells. I'm still on the same pack and it's always been charged using the overnight trickle option. My packs used in my models typically last around that long as well and are all trickle charged rather than fast charged.

If you insist on using fast chargers at least spend a bit more and get one that specifies it uses a delta peak or peak detect system for shutting off the charge. Keep in mind though that fast charging, even with the ideal peak detection systems, is harder on cells than the trickle charge option and the cell life will be reduced. Shifting to trickle charging is one way to avoid that issue.

JTGraphics

Whats the mAh on the batteries you bought?
You want to get the highest you can I only use 2000mAh or 2400mAh for all my stuff cameras and flashes also.
In general the higher the mAh the longer it will stay charged.

Technojunkie

Ditto the advice for trickle vs. fast charges if you go the cheap route. The Energizer NiMH AA batteries I bought work great with Energizer's trickle charger but the Energizer 15-minute charger gives terrible battery life. In retrospect the fast charger's built-in cooling fan was a hint.

chephy

I find that the biggest issue with rechargeable batteries is not that they don't hold too much charge, but that they lose charge while they just sit around, even when they aren't used.

ItsJustMe

You're wasting your money buying name brand rechargables. Go up to batteryspace.com.

You need a good charger, namely a smart charger. If it takes 12 hours to charge, it's a trickle charger and they're garbage. Also, I wouldn't put my batteries into a 15 minute charger; that's simply too fast and I'm certain it damages the batteries. I use a MAHA charger that will charge a battery in about 2 hours, and even at that rate the batteries get pretty warm.

I also recommend getting a charger that meters each cell individually. If you have one that will only charge batteries in pairs, and your batteries aren't precisely matched, the battery that's deader will be the last to get charged, and may never get fully charged properly. Also it helps if you have devices that use an odd number of cells.

Also, it depends on the device. In fact modern rechargables hold equal or more energy than alkalines, but they run at a lower voltage. If you have a device that's designed assuming alkalines, it may not be able to run on less than about 1.3 volts per cell, which means it'll only run for a small amount of time on NiMH rechargables, and will stop working even though the rechargable has a TON of energy still inside, just at too low a voltage for the device to work right. If you get a device with a more modern design which takes NiMH chemistry into account, it's normal for rechargables to last LONGER than alkalines.

Also, as has been mentioned, NiMH typically lose about 10% of their charge per week. This doesn't bother me because I use so many batteries that they're always in rotation. If it's a problem though go check out the new cell types that are low self discharge. Sanyo Eneloop batteries are one such make, and they're designed to hold charge for months.

Captain Slow

ItsJustMe nailed the problem... rechargeable batteries will measure 1.2VDC fully charged, whereas fresh alkaline cells measure 1.6 to 1.65VDC. Older lights generally had 3V or 6V incandescent bulbs in them, so running rechargeables meant putting up with dim lights. LED blinkie taillights are the same way... you can run rechargeable AAAs in them, but they'll be much dimmer than with fresh alkalines.

Now, though, we have all these "smart" AA & AAA LED headlamps & flashlights. They have battery discharge monitors in them to prevent circuit damage. See, up to a point, the lower the available voltage, the more current the circuit will attempt to draw. This will damage LED drivers. So, the monitor circuit is preset to a "bottom" voltage, below which the device will shut off.

Your light is designed to run at an optimum 1.5 - 1.6VDC, and probably has a low voltage cutoff set right at 1.2VDC. Well, 1.2VDC is the fully charged voltage of your rechargeables... So even though they're charged up and ready to deliver hours of voltage... your light thinks they're nearly dead alkalines.

As you might suspect, unless there's a conspicuous switch on or in the light, there's no way to tell the thing you want to use lower voltage batteries. The manufacturer never suspected that you would want to.

The solution is to buy a headlamp or flashlight that was designed to run on rechargeables. I run a pair of Performance Vista-5 lights, each with five bright white LEDs. Each light takes four AA NiMH, and by using Eveready 2300 mAH rechargeables in them, I get runtimes of eight hours or so on low output before the indicators start to blink red.

I do have a budget minded solution for you, if you don't want to plump for new lights. Get a charger that's designed for alkaline batteries... Radio Shack has several. You can recharge plain old alkalines 2 or 3 times before they're completely spent. Each recharge will net you less runtime, figure on half what a fresh AA will deliver... But hey, it's a little something extra, kinda like an extra 2MPG in the family hauler.

BCRider

Um.... no they are not. But it does mean you need to be more patient. Trickle charging actually does the least long term harm of any of the methods. If getting a good long life from the cells is important (we're talking number of cycles here, not duration of one discharge cycle) then trickle is actually the way to go.

matthew_deaner

The Fenix L2D is designed to run off of rechargeable NIMH cells. It will not cut out at 1.2 volts like some older lights.

Cave

I use a Fenix L2DCE with 2500mAH NiMH rechargeables (I think Energizer, might be duracell though). Lasts somewhere around 2 hours (in 2 lots, not all at once). This is on Turbo mode.

I suspect there is something wrong with the batteries or the charger if you're only getting 15 min of flashing.

Cave

Re some of the other comments:

The Fenix light works well with rechargeables. It is regulated, the output is very steady until the batteries are almost out and then fades very quickly to low mode.

The runtime is good considering the light output. I also have a Cateye EL 500 which runs for ages on 4 AAs, but the light output is not as good. You won't get 30+ hours from a pair of AAs with any sort of decent light output. Blinkies are another story, just replace the alkalines once a year.

Have a look at the charge rating on the batteries. 2500 mAH NiMH is good. I think you can get up to 2800mAH now. The cheap nicad ones are maybe 700mAH. Rechargeable alkalines or low-capacity rechargeables aren't much good for the sort of lighting you want; the discharge rate is too high and they won't give much runtime at all.

Have a look in the Electronics forum, some people have tested batteries and you should find details there.

cyccommute 

You got it right. It takes a few cycles for NiMH batteries to reach full potential.

charles vail

Generator hub

ItsJustMe

Well, it's true that trickle chargers can work, but a really good, modern smart charger can actually be better for batteries than a trickle charger. The best ones actually can reverse some of the oxidation of the electrolyte by pulse charging. I've had batteries that were in pretty bad shape that a friend gave me. I don't know what kind of charger he had but he was 'giving up on rechargables'. They didn't work very well the first charge, but after about 10 cycles through a smart charger they had recovered and were working pretty well.
You're right that trickle charging won't really ever harm a battery, so if that's all you use, it'll probably be as good as anything else, but OTOH a trickle charger won't recondition a damaged battery either.

cyccommute 

Sure, if squinting into the darkness is your thing.

Me, I prefer smoking pavement...even if I'm not moving

charles vail

That's some awesome torch illumination what are you using?

Andy_K 

Only when the battery is in use. All rechargeables lose their charge when not in use, and in general really high mAh batteries (2500 mAh, seemed to be the problem spot when I last looked into this) lose their charge faster than low mAh batteries when not in use.

cyccommute 

Not all NiMH lose their charge when not in use. Sanyo Eneloops lead the way with new electrodes that don't self discharge at as high a rate as the older versions. Their claimed storage life is a year with less than 10% self discharge. There are several other newer rechargeables from Duracell and other companies that are nearly as good.

Even these, however, need a few cycles to reach full potential.

tarwheel 

I have used a Fenix L2D flashlight for the past year, and I get long life from my rechargeable batteries. My daily RT commute is about 90 minutes, and I typically can go all week on a pair of batteries. I don't use my Fenix in the turbo mode, however, which burns batteries must faster. I run it on the highest non-turbo mode in the mornings, when it's darker, and run it on the medium non-turbo mode in afternoons. In other words, total run time is about 5-6 hours on a pair of rechargeables.

Although I've got several different kinds of rechargeable batteries (Sanyo, Duracell, Energizer and Rayovac), the Sanyo 2700s last the longest. These are great batteries and I wish I had bought more when I ordered them.

JTGraphics

May be so but I have several and rotate on a regular bases so I never have a problem with having charged batteries in my devices I don't let them go dead and I don't use regular batteries at all around here, I have about 30 AA and 20 AAA that are used for everything, I have a box for ones that need charging and ones that are freasly charged.
My important and good set for stuff like my camera flash are kept in sets and are marked such and always get charged together, an important part of keeping things running longer with them, other stuff just garb use and rotate stock.
My cycling lights get rotated every 3 weeks when in use a lot, which in more than enough to keep them going all the time.
Get more and rotate its that simple!!!!!

ItsJustMe

As cyccommute says, Sanyo Eneloops have very low self-discharge. I have a couple of sets of them and they're performing well.
Also, as I said before, self-discharge over time isn't that big of a deal if you're using the batteries constantly; IE in the winter when I use my lights daily I swap in freshly charged batteries every weekend. Over the course of a week the self-discharge isn't that big of a deal.

The only time self-discharge is a big deal is when you plan to just leave batteries in something for months then expect the thing to work (like emergency flashlights).

crhilton

I have several hours on my AA energizer rechargeables. I put them in a cateye 1200 candlepower light. I think they might have run longer now than those alkaline batteries I was using.

The AAA's in my blinker (the original alkalines) have many many many many hours now. I think they're mutants.