Rechargeable blues

Most of my portable electronic gear runs on AA batteries so instead of buying alkalines all the time I tend to rely on rechargeable NiMH cells.

NiMH batteries supposedly last a long time, don't suffer from the memory effect and can be recharged like a couple thousand times at least, or that's what it says on the box. But looking back, the actual performance seems to be a lot worse.

I have a few NiMH batteries 4 to 5 years old, they may have about a hundred cycles behind them at most but their capacity is now much less than what it used to be. I have a decent charger optimized for NiMH so I'm a bit disappointed. It's so bad that sometimes a freshly recharged pair of NiMH's will last just about 10 minutes in my camera or barely suffice to power up a flashlight.

All in all, I've become wary of relying on rechargeables. Very often a spare pack of alkalines has saved the day in the field when several pairs of freshly recharged NiMH cells just died within minutes.

Now I'm a bit at a loss. Maybe I should look for a better charger or maybe there are better brands out there and my NiMH batteries are just crap. But I would sure love to hear about your experience.

Have you EVER fully discharged them?

A good battery conditioner will probably fix the majority of them but they still have a limit on the # of cycles they can handle.

Also there is a HUGE difference in battery quality between cheap expensive rechargeable.


I used to be into high end Electric RC Cars and would go through batteries, and wow there are TONS of different things to check when buying batteries... capacity, cell manufacture, rated # of cycles (normally related to manufacture and then the level battery you buy.)

Also charging, and making sure they are discharged prior to a recharge even though they don't need this it helps.

ETc Etc

Try moving up to the newer low self-discharge NiMH like the Sanyo Eneloop. Some of your problems may be related to the NiMH battery staying in a discharged state for an extended period of time and the low self-discharge rate of these new batteries helps combat that. However, I'm with you, I always keep a set of alkalines, or better yet, lithiums, handy just in case.

Craig.

You really only need to fully discharge once every 20 or so cycles is the rule of thumb I'm seeing now.
Couple issues, are you using highr capacity NiMH ir the newer low self discharge? The higher capacity (>2100mAh) obtain that higher capacity at a tradeoff. They tend to have a thinner insulator which causes faster self discharge and is more fragile. Some of the worst batteries are the 2500mAh but then there are some like the sanyo 2700mAh's that were released after the low self discharge and have some of that chemistry in them and they seem to be decent. Sanyo Eneloop (200mAh low self discharge), RayOVac Hybrid (2100mAh Low Self Discharge), Maha Imedion, uniross hybrios, etc are some of the newer technology which not only hold their charge better but are tested out to 1000 cycles.

Charger can make a big difference and just because a charger is called a smart charger doesn't mean its all that smart. I had bought a $30 RayoVac PS4 charger a few years back which was a smart charger but started having short life from my batteries to the point I'd have to carry that charger around and top them off before using them. I got tired of that fast and stoped using NiMH for a while. Couple years later I started reading about these new low self discharge batteries and wondered if my charger would work with them so I started researching it. Turns out it was a known bad model (PS4) which never really put more than 75% of charge on the batteries. I had two or three other chargers before that, some simple trickle chargers, others so called smart chargers. I got rid of them all and bought a $40 Maha c401fs and ran my batteries through a slow charge on it, discharged them in a fashlight and slow charged them again. I put a few in our digital camera and it jumped from 50 pictures to 250 pictures from some old 1600mAh batteries. I bought a set of sanyo eneloops and started reaching 500 pictures on a charge.
A year later I bought a maha c9000 for $60 and started testing my batteries. I dug all the old ones out of my drawer and found the Sanyo's from 1999-2001 that were 1500-1600mAh rated were testing around 80% of that rating. Some 2000mAh rayovacs from 2004 or 2005 tested around 80%. Radio shack and energizers were all under 50%. This was early in 2008 when I bougth the charger so I had batteries from 7-9 years old that were just at the end of their useable life (80% is a general rule of thumb) even though they had not been well taken care of. I went and bought several packs of eneloops and replaced all my old batteries with them. I now run the refresh/test cycle ono the c9000 once a year and record the capacity so I can see how well they are doing.

Hopefully my post wasn't too long and your still reading but to sum it up if you buy cheap batteries and chargers then you can't exect great performance. Just like any other tool, you can buy a $5 china mart knife but can you expect to be great? I probably spent way more than $100 over the years on cheap chargers to not have them work well, its far less expensive in the long run to buy the better ones up front.

I agrea. I have a Voltcraft IPL-7 charger. It charges mine batteries much beter than the cheap chargers ever did. I'm currently swithced to eneloops and recycko's for all mine AA's and AAA's.

Thanks for all the feedback (no Eugene, that wasn't too long, in fact I did read all of your post )! Part of the problem could be most of my rechargeables are high capacity. Currently the ones I trust the most are Sanyo 2700mAh, but that's because I only bought them pretty recently. Haven't tried the Eneloops yet but they look promising.

Being used to NiCd I do tend to discharge batteries fully before recharging. Part of the problem could be the "smart" charger, though. I've got about 4 different chargers right now and I'm not really happy with any of them. Have been thinking about getting a better one and probably will very soon. But another issue is that I use much of my portable electronics on a fairly sporadic basis so self-discharge is definitely a problem.

I've been very happy with my Lacrosse BC-900 charger when used with Eneloop 2,000 mAh AAs. The charger will go down to 200 mA (default) for a gentle charge rate that is easy on the batteries.

Weird. I wrote a reply to this thread and get:



When I try to submit it. Anyone see this before?

-john


Edit: Since I can post *this*, must be something in the content of my post?! Weird.

+1 on the Lacrosse charger and Eneloop strategy, that or the Maha model cited should go a long way to restoring your rechargables.

I do confess that I will not rely entirely on rechargeables in an emergency, although I have several means (solar, auto, local power inverter) to recharge cells without a power source. I also buy a 32 pack of alkaline AAs every year, and use these for incidental uses along the way. If I lost power tomorrow, I have about 28 AAs to rely on without dedicating any thought to a recharging strategy. For $8 its a reasonable insurance of sorts. It may not be entirely environmentally sound, but I do use the NiMHs on an every day basis.

I think the problem is something to do with the links. Here is the post w/o the links:

You need a good, independent cell charger:

candlepowerforums.com > Flashlight Electronics - Batteries Included > Flashlight Electronics - Batteries Included - Threads of Interest > Charger Comparison

And good batteries:

candlepowerforums.com > Flashlight Electronics - Batteries Included > Flashlight Electronics - Batteries Included - Threads of Interest > NiMh Battery Shoot Out

candlepowerforums.com > Flashlight Electronics - Batteries Included > Flashlight Electronics - Batteries Included - Threads of Interest > NiMh Battery Shoot Out Part II

AND YET, keep in mind these batteries *will* self discharge.

What I do is I have two bins, a "charged" and a "discharged". Once the discharged bucket is empty, I just switch buckets and start over.

You also need to "right size" your battery collection. Don't have too many batteries, otherwise you'll run afoul of self-discharge. And of course, you want enough to get the job done.

You are better off with a smaller collection of good high capacity batteries than a larger collection IMO.

I'd say the Sanyo 2700 batteries with the Maha C9000 or AccuManager 20 would probably be good. I have a MH-C401FS, and while it isn't the latest, greatest, it does OK.

Oh, buy your stuff on-line. Buying rechargeable in a store both limits your choices and you end up paying more. I've had good luck with:

thomasdistributing.com

For both batteries and chargers.

FWIW, I've switched to lithium ion wherever possible. It has almost no self-discharge or memory effect. The only gotcha is you need devices that are designed for it.

Good luck,

-john

WRT Lithuim Ion, bad advice. Comsumer lithium Ion has average of ~300 cycle, costs more, takes even more complex chargers, limits the devices due to less standardization, etc. Look at my bob and gear pack now, I'd need to carry about 10 different chargers if I switched everything from AA to lithium Ion. CPF loves Lithuim Ion because they tend to use their gear every day, puts run time as the top priority, and had a flashlight centric view of batteries. If you include radios, GPS, etc then lithium ion becomes a poor choice.

Now with NiMH you don't want to treat them like NiCad so don't fully discharge them every use, every 20 is the recommended number now (according to CPF and other sources).

Remember also that even though a charger may be multi channel, smart, etc that it still may not be a good charger. There are various methods used to determine a full charge and better chargers will combine two or more. Also charge within the recommended .5 to 1C, charging too fast generates heat which shortens the life, charging too slow makes the end of charge harder to detect and tends to result in overcharging. So stay away from "fast" or the "slow gentle" chargers.

Thanks.



I think you are misunderstanding. I didn't say lithium ion was perfect for every situation. In fact, *rechargeables* are not optimal for every situation.

But I also think you are professing a somewhat slanted view of the technology as well. Lithium ion is light, good power density, fairly easy to charge, holds its charge and works well in the cold.

When it comes to lithium ion I exclusively use 18650s and the neither charger nor the batteries were overly expensive.

I haven't burned a 123A in my flashlight for years now with this method, but I also have a 2x123A battery pack as a backup.

And it isn't flashlight specific. My Yaesu VX-5 uses a lithium ion pack by default, and it would probably be pretty darn heavy if it had enough rechargeable AA cells to do the job.



These sound like good things. Of course, lithium ion is also good for devices you don't use often because of the almost nil self-discharge.

Yes, I understand there are cases where the duty cycle of NiMH is an advantage.

I mentioned I use NiMH too. I also use primary lithium AA and AAA and 123A cells.

Everything has trade offs. Pick the right tool for the job.



Yep, not all chargers are designed equally. This is why I pointed to an actual empirical test of chargers.

-john

> I have a few NiMH batteries 4 to 5 years old, they may have about a hundred
> cycles behind them at most but their capacity is now much less than what it
> used to be.
>SNIP<
> It's so bad that sometimes a freshly recharged pair of NiMH's will last just
> about 10 minutes in my camera or barely suffice to power up a flashlight.

A hundred cycles over 48 months is at the lower end of battery life, but we all know better than to expect the thousands promised on the box. I'd also expect NiMHs to expire on their own after the passage of 4 or 5 years.

Another issue is that NiMHs are 1.2V; alkalines are 1.5V. I've got some devices that expect 1.5V from each cell and they won't operate with rechargeables at 1.2V. I would expect a flashlight to run on 1.2V cells unless it's a high output lamp instead of regular filament. I don't know what LEDs require.

Additionally, high recharge voltages damage cells. If you're using a quick recharger (minutes instead of hours), you're cooking the chemistry, destroying the cells' ability to take and hold a charge.

If all your stuff is four or five years old, I'd considering buying all new high-capacity batteries and a new, modern charger that does not promise 60-minute charging. I think you've gotten all the life out of your old ones.

The self discharge of NiMH is about the same as low self discharge NiMH so no advantage there. They do weigh less but in anything that uses them in a pack such as GPS or radio you still need a special charger so the weight savings is lost there. Then figure in the cost of replacing the battery pack or cells about twice as often as NiMH even if they are not used since they deteriorate with age.

I don't understand what you are saying here. The self discharge rate of NiMH is much higher than lithium ion.



Again, I don't understand. If you use any type of rechargeable battery, you need to make provisions for charging in the field, or providing spares. This would be the same for NiMH or lithium ion.

Lithium ion doesn't work for many devices due to the difference in voltage (witness GPS) and I'm not suggesting you go crazy trying to make it work.

Although, I will point out that *if* you try to take a generic external battery pack, lithium ion is going to be a big win if you are carrying it due to the lighter weight.

example



I suppose. It hasn't been my experience, FWIW. Even with a decent, independent cell charger and effort doing charge management, NiMH has always been a bit of work, and I've always had cells go bad in what seems like a short period of time. Contrast that with the handful of 18650s I swap out in my EDC light which I use all the time which have never been problematic and I have yet to have one go bad.

It has been charge, use, repeat.

The original poster talked about use in a flashlight, so as a random comparison here are two total flashlight solutions (light + two sets of batteries + charger):

Example AA Solution


Example Lithium Ion solution


(source for both lights - fenix-store.com)

Pretty close price-wise IMO.

I'm not saying lithium ion is the answer for everything, but I think it has compelling cases. And actually, it pretty well excels in flashlights (use specifically mentioned by the original poster).

-john

Comparing lithuim ion and traditional NiMH then yes NiMH self discharges faster but the newer low self discharge NiMh are about even with lithium ion.

The problem with your example solution is your listing one top of the line charger for one device. You can use that same Maha c9000 for a dozen different gadgets so the price gets divided between all of them as well as the pack weight. With lithium ion devices you need a charger per unless in the race case of a flashlight you can charge individual cells.

So look for example:

AA Solution
$50 Maha C9000
$50 AA Powered flashlight
$200 handleld GPS
$200 two way radio
$200 digital camera
$50 couple dozen Sanyo eneloops for each and spares for each

Lithium Ion solution
$15 lithium ion cell charger
$50 lithium ion powered light
$20 LG 18650 3.7V 2600MAH
$200 handheld GPS
$20 Power supply/charger for GPS
$30 Spare battery pack for GPS
$200 two way radio
$20 power supply/charger for radio
$30 Spare battery pack for radio
$200 digital camera
$20 power supply/charger for camera
$30 Spare battery pack for camera

remember the maha comes with a wall and car charger so to get the equivalent with the lithium ion solution each device usually comes with a wall charger but then you need the vehicle charger or an inverter. The bateries are all different, the one from the gps won't fit the camera, the one from the camera won't fit the gps, the one from the gps won't fit the radio, etc.
Even if you eliminate the second chargers you still have 4 instead of 1. Ok sure its nice you can charge everything at once but you can buy 8 bay nimh chargers or buy a pair of c401fs, etc.
You still can't share the lithium ion batteries between devices.
Again, your solution does look best if you only look at flashlights, as I said before, but looking at a bigger real world picture, newer technology (low self discharge nimh), ability to share the spares, and the ability to supplement with a $10 bulk pack of 30 AA's if needed the advantages of lithium ion are quickly outweighed by standard AA's

Actually, you *need* a top of the line charger to effectively manage NiMH batteries, IMO.



I won't bother responding to the rest since we are obviously not communicating. I've never said using AA technology wasn't flexible, etc.

-john

Perhaps a universal charger that charges Lithium Ion and NiMh and NiCd AA and AAA might be useful such as the Ansmann Digicharger Plus

http://www.adorama.com/ANDGP.html

A lot of gadgets with dedicated Lithium Ion cells usually have the recharging circuit built into the device and many of those gadgets just need a DC-DC universal regulator i.e. 12V cigar connector to whatever the DC Voltage requirement of the gadget is designed for. Many of these gadgets are also more compact and lighter than their AA or AAA NiMh equivalents.

Is there such a thing as an AA powered mobile phone?

That's where this type of device comes in handy.

-john

OK, so I just bought a pretty darn smart charger as far as the specs go. Will see how it works in practice but I've already determined most of my older NiMH batteries are basically shot. Maybe I'll be able to revive a few with the refresh function but I got another pack of Sanyo 2700mAh plus I see some Eneloops on the way.

BTW, what has been said above re: Lithium being ideal for flashlights. It may well be true but I'm more than willing to sacrifice what marginal improvement Lithium can offer for the versatility of AA batteries. There are some very high-performance LED lights that run on AA's. Having all your portable gear run on standard AA's, flashlight included, is a huge benefit IMO. Especially for a relatively sporadic, preparedness-minded user.

One nice thing about the Eneloops is the mostly plain white cover. I can write my yearly test results on it with a sharpie.

[quote=Tom_L]OK, so I just bought a pretty darn smart charger as far as the specs go. Will see how it works in practice but I've already determined most of my older NiMH batteries are basically shot. Maybe I'll be able to revive a few with the refresh function but I got another pack of Sanyo 2700mAh plus I see some Eneloops on the way.

So you must have gotten the Maha Powerex MH-C9000 Wizard One.
If so, read those instructions carefully and figure out what the recommended charge rate is and let the charger do it's thing. You'll find it's often far less amperage for a far longer time than the typical drug store "quick" charger.

And that's a good thing.

As someone has already mentioned, charging at too high a charge rate will simply cook the batteries. Sure, "quick" charging is convenient just don't expect the lifetime to live up to the packaging hype.
The battery companies are not in the business of making batteries that last. They're hoping that mister average customer will use the cheap "quick" charger that came with that four pack and wear out those four after perhaps a hundered times.

Also, you just can't ever forget that NiMH batteries self-discharge at about 1% a day