Rechargeable Batteries Test

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San Pedro

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The only one's tested that I can get here in Japan are the eneloop. I don't have any, but I do have some panasonics that are working very well for me. They are NiMH, and they seem to keep a charge. I can get a couple days of heavy use with the 2300 mAh batteries, and the 2000 mAh batteries also last quite a long time. I want to try the 2700 mAh Sanyo batteries with my next purchase (not sold under eneloop name).
 

timbrwlf56

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This review falls short of even being an attempt at a good article on batteries. You completely missed two of the best brands on the market, Tenergy and Powerex, the Powerex AA size cells are rated at 2700 mAh and blow away most of the ones you reviewed.

Similarly you failed to discuss *why* most of these chargers produce excessive heat in the batteries. Most of them are doing a quick charge, which is trying to stuff as many electrons back in to the battery as reasonably possible at high speed. This has two negative side effects, one it overheats the batteries making it dangerous to leave them charging unattended. Two, the excess heat degrades the internal chemistry of the battery over time causing it to lose the ability to hold a very good charge.

Powerex also sells a variety of quality chargers that offer two modes, a standard quick charge, and a slower trickle charge. The slower trickle charge charges the batteries much less aggressively over a longer time, and doesn't heat them up nearly as much and cause the degradation of performance over time. Get a set of good quality batteries and a charger that supports slow trickle charging and you'll be set for years.
 

michaelahess

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Rayovac 15 minute rechargeables. Can't get them anymore. They charge in 15 to 20 every time. Last nearly as long as alkaline's. Have a couple hundred, around 40 have been charged over 300 times and seem to hold just as much charge as the others.

I use 12 in each of my gas RC's. They are rock solid, never had one fail either.

Completely different than the Rayovac's "reviewed" here.
 

Codesmith

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Whats important for me is that I can reach into a drawer and grab a pair of recharged batteries and be confident they will work. The older NiHM batteries had a high self discharge rate.

If you search on the web you can find some tests that were done measuring the self discharge rates of various brands. Based on that article I chose to purchase some Eneloop batteries.

That article used a high end battery charger to run a variety of tests and then tested the batteries for self discharge at various time intervals.



 

chad1011

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Great artical, but I think it needs to cover different chargers as well. The "factory" chargers do a decent job but can't hold a candle some of the more advanced chargers available. Take for example the Maha PowerEx C808M. It can charge 1-8 AAA, AA, C, or D batteries at the same time in any combo nation of amount, size, and rating. The batteries can even be inserted at different times. Thanks to the 8 channel charging system, each battery get just enough power to charge, not too little or too much. The advanced chargers can also revive old rechargeable to near new condition.
 

JMS3096

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One thing that you forgot to mention about the Eneloops is that they hold their charge incredibly well. I've charged a set, let them lie around, come back to them nearly a year later, and still have them be usable.
 

N.Broekhuijsen

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I did some research to get batteries for my wireless mouse, and decided that since it would go so long on a single battery that the Eneloop batteries were best. (bought 1.5yrs ago). I always have the Eneloop batteries in the mouse, and it will last me a good 4-5 months on a single charge, whilst my energizers used to die after a week or 3. The mouse uses very very little power, so I decided that i needed the batteries with the longest shelf life.

Now im using the Eneloops with a non-eneloop charger, (some oooooold charger), and they have had no problems. best 20 Euro I ever spent on 2 cells. (yes they were expensive back then when they first came out in the Netherlands)
 

ossie

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[citation][nom]Tomsguiderachel[/nom]Why/how is our test flawed? We have to test the Eneloops with its own charger.[/citation]
Of course you wouldn't know how the test is flawed, when you have no clue about the subject at hand.
And no, you don't have to use the "Sanyo" charger... even if the manufacturer mentions it'll void warranty, if another charger is used. Would you tank your car only at the manufacturer's, or "recommended" gas station chain, just because he said so? I really doubt it...
Don't think the "Sanyo electrons" are somewhat different than the other ones.

Just to point out a few blatant flaws:
- a CDP, being a complex electromechanical system, is as an inconsistent load, as you can get
- a flashlight bulb is nowhere near a constant current load, it's resistance varies extremely due to temperature, and also due to age

The fatal flaw consists mainly in the "use the provided charger" policy - see below - and the unknown state of the cells, when "freshly" bought. A new cell must be slowly charged, to full capacity - a fast charger is incapable of that - and, even better, do a few cycles, to bring it at nominal capacity - the so called "break-in".
Most cell's capacity varies a lot within the first cycles of a cell's life.
[citation][nom]bri-guy[/nom]The quick charge feature doesn't affect how long the battery will run a device for, but it can significantly cut into the battery's long term life. I've heard that it can cut its life by half to 150 to 200 recharge cycles.[/citation]
If you would have researched a bit the subject, as it would've been expected for a serious review, you would've noticed that most "fast" chargers stop the charge cycle before the cell is near full. A few do a top-off charging to get at full capacity, but most don't. About trickle charge, you can mostly forget.
Hint: look up the Telefunken U2402B(-C) datasheet, for a controller IC that is doing it, almost as it should be done. From page 4 on, you can get most of the useful data.
If the used charge algorithm is done right, a good fast charger will not affect substantially a cell's life, surely not halving it.
OTOH, the "slow" chargers have no precisely defined stop criterion - most will do just a timed cycle, to get at full capacity, independently of the charge state at the beginning, because the dip, for the largely used -dV/dt stop criterion (cost "efficiency"), is too small to be reliably detectable. This is almost surely doing some overcharging, but as the charging currents are quite low, it wouldn't affect too badly the cells.
Usage of cell packs, with slightly different capacities, or charge state, will spread the dips out, making them practically undetectable - that's one of the reasons to use chargers with individual circuits, for every cell, especially for the "fast" flavor.
[citation][nom]bri-guy[/nom]In each of the reviews, there's a note as to how many recharge cycles the manufacturer rates them for. Unfortunately, it's no substitute for actually charging, draining and charging the cells, but 1,000 charge cycles would take at least a year[/citation]
If you're doing a 1C discharge / 0.5C charge (quite light handling), you could do easily 6 cycles/day - 1000 cycles would add up to under 6 months. Way faster, if you dare to push the cell to it's limits (5Cd / 2Cc). Don't believe too much in manufacturer provided life cycle data, rarely does a cell get anyway near those ideal conditions estimations. In real life a cell is almost surely to get some abuse, which will shorten it's life...
Cycle life depends a lot on (dis)charge rate, temperature, and especially over(dis)charge - that would kill them quite fast.
Badly selected fast charge stop criteria, is a guaranteed receipt for quick death - high end temperatures are telling.
 

anamaniac

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From what the internets has shown me, it appears the Eneloops will discharge about 15% per year. The NiZn batteries will discharge about 1% per day.
Both are nice batteries, but NiZn batteries certainly aren't for your keyboard/mouse.
 

bri-guy

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This is a great idea and we might cover it in the future. The question becomes which batteries do you use. The matrix of three or four chargers working with three or four different batteries makes for a staggering amount of testing.
 

bri-guy

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The key point is that each set of batteries was charged to the manufacturers' specifications and then drained under the same conditions. Sure we could have used different devices to drain them but the two used are representative of two different usage scenarios.
 

ossie

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[citation][nom]bri-guy[/nom]This is a great idea and we might cover it in the future. The question becomes which batteries do you use. The matrix of three or four chargers working with three or four different batteries makes for a staggering amount of testing.[/citation]
I have no idea of what you're considering a good idea. If you would've read the first comment, the used (secondary) cells (battery is a misnomer) were for the last years Maha's ones. Their products cover both hiCap/hiSfDis, and loCap/loSfDis scenarios, and provide a quite good charger, to my, and others, satisfaction. There is no universal panaceum.
For loSfDis use, Eneloops are better at higher discharge currents (lower internal resistance) than Imedions (hiIntR) but have somewhat lower capacity. It all depends on the appliance.
Testing mixes of unknown cells/chargers is another bad idea.
Just use one known good battery analyzer to determine the quality of the cells, and, eventually, compare it with the results offered by the bundled charger.
In many cases, the bundled chargers are mere crap - you would be disgusted/enraged by the lengths manufacturers go to pinch the last penny. I've seen the cheapest manufactured ones being limited to a wall adapter, and some receptacle, with contacts to hold the cell, which contains nothing more than a (somewhat) current limiting resistor. The price didn't reflect at all those cost cutting measures.
A more knowledgeable user gets a good charger, that satisfies his needs, and the best cells for his needs.
Bundled combos are for those who don't know a thing about this stuff, and mostly get badly "burned". In today's BS filled market, in which more money gets burned on marketing than RnD, a good, and honest, review is worth gold. Sadly, you're amateurish methodology doesn't help at all, it just confuses more ignorant readers.
[citation][nom]bri-guy[/nom]The key point is that each set of batteries was charged to the manufacturers' specifications and then drained under the same conditions. Sure we could have used different devices to drain them but the two used are representative of two different usage scenarios.[/citation]
The key point is you've charged the cells with the bundled charger, that's usually nowhere near "manufacturer specifications", and many times merely crap.
You also mostly didn't respect the cell "formation" rules - fast chargers can't. Try to cycle a few times those Energizers, and load them on some decent charger. You might be surprised by the result, if they weren't already ruined by the first fast charge attempt. 4C is stretching by far NiMH... even NiCd would be at it's limits.
About the "drained under the same conditions" part... In the previous comment the flaws where already outlined - you can't create identical conditions with a CDP, and a flashlight. While they might seem representative uses, they don't offer consistent, and repeatable conditions.
Creating (dis)charge curves at a few different rates is all you need to determine the quality, and proper use, of a cell. They are all telling. Go to the provided link, to see how it should be done - the site has even more useful information...
 

ilader

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However amateurish your test, it would have been more useful to me if you had tested in a digital camera, such as the Canon 480 mentioned above. I've been unable to find any rechargeable batteries that are useful in the many AA-powered digital cameras I've used.

On the other hand, the 3V CRV3 li-ion rechargeables (which sometimes can be used in place of a pair of AA) work quite well.
 

bri-guy

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Actually I had contemplated doing exactly this and I tried it out but the camera I was using was unrealiable in the number of shots it would take on a set of batteries. Sometimes I would get 650 shots, other times 350 shots.
 

hixbot

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umm you mentioned nothing of storage loss (self discharge).

The rayovac hybrids have been out for a couple of years now, you're dead wrong saying they were released in the past 6 months.

The point of these batteries is they have a low storage loss. Meaning they don't slowly drain when they are NOT USED. This makes them ideal for remotes and devices that are seldom used. They are not meant to compete on the grounds that they'll power a device non-stop for longer than the competition. Rather they'll sit in a device unused for months at a time, and still retain a charge. This is very unlike conventional NIMH batteries which will drain when they are not used.

I can't believe you didn't even mention self discharge in this article!

http://en.wikipedia.org/wiki/Low_self-discharge_NiMH_battery
 

bri-guy

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Self discharge is an important characteristic of rechargeable batteries, but a hard attribute to test. To have some quantitative data on this would require months if not a year of monitoring the cells.
 

caspian21

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The article did more positive than negative. It was important to get people to realize that the LSD rechargeables are much better than those most of us experienced in years past. Take the info the author provided and then move on. I half expected to see a request that Brian test the batteries by hoola hooping on a Wii Balance Board until they are fully discharged.

If people only rely on one article to choose their product it is at their own risk. Smart consumers can take the next step at a popular shopping site that starts with an "A" and read the reviews from electrical engineers if you want to see how the individual batteries perform in different products. At least Brian gave us something other than a new Nvidia box shot!
 

hixbot

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[citation][nom]bri-guy[/nom]Self discharge is an important characteristic of rechargeable batteries, but a hard attribute to test. To have some quantitative data on this would require months if not a year of monitoring the cells.[/citation]
Data, perhaps not, but self discharge should of atleast been MENTIONED.
 
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I have also been using the AA and AAA Eneloops in GMRS hand held radios + my digital Cannon camera + my CD player + various remotes + LED flashlights: To date thumbs are up. I use a smart charger and charge the batteries at 200 to 300mah rates for the AA and 150mah for the AAA. I have used many other NiMH batteries with reasonable permormance, but none the equal of the Eneloops. The ability to retain capacity over time "on the shelf" for a rechargable can not be overemphasized. Also my charger has the ability to determine the actual capacity of each battery in mah and Sanyo's advertised capacity for the Eneloop correlates very closely to their claims and has actually increased about 5% after five to ten charge cycles. Also the claimed 80 to 85% retention of capacity after one year of shelf life @ 70 degrees F has been confirmed by my tests also.
 
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