Slashdot Mirror
Rechargeable Batteries - Yes or No?
TheFifthElephant asks: "I currently use quite a few devices that require various size batteries and I feel horrible just tossing them when they die. I saw a recharger at a retail store today and was thinking to myself how much waste it would reduce by using rechargeable ones. Which units have you used happily and/or which units have you heard of/read about satisfying someone else? Are the more expensive units better? What chemical rechargeable batteries last the longest/recharge the most?"
I use NiMH batteries for my wireless mouse, and my camera. Got a simple charger over at radioshack, and it works quite well. The batteries provide equivalent if not better power than alkalines and though they cost more up front, are definitely cheaper in the long run.
This sig has been temporarily disconnected or is no longer in service
Moreover, they do have a distinct advantage: they're cheap and of high capacity, though not good for many recharge cycles. While a pair of Ni-MHs cost about $8, a pack of 4 rechargable akalines costs about the same price. Like regular akaline batteries, they have pretty high capacity (about 2200(I think) mAh for a AA, compared with the low 1000's range for most Ni-MHs), and actually come charged, with a long shelf life without discharging itself.
I use these batteries for most of the things that don't work with Ni-MH (graphing calculator, small electronic devices), as these have the usual 1.5 volt, instead of the 1.2 volt on most rechargables. Their downside is the fact that they can only be charged 10-20 times before they leak (the package said 40).
There's not much in the way of real copper in pennies any more. See here So you'll need pre 1837 pennies to get pure copper!
Most of the brands of rechargeable batteries have about the same performance.
:-)
Bullshit. First, there are different kinds of rechargeables -- NiCd, NiMh, Lithium, to name a few most widespread. Their characteristics are quite different. Second, as usual you typically get what you pay for.
But not buying batteries from an electronics store is good advice. They are horribly overpriced there, any brand...
Rechargeable batteries, like toothpaste, is a commodity product.
Toothpaste? You mean you alway buy the cheapest toothpaste you can find??
When you buy a product, you indirectly support the value system in the country of origin.
I do? How interesting... Is it one of those "if you do drugs you support terrorism" rants?
"Made in USA", "Made in Japan", or similar Western-country label is usually a safe bet in terms of (1) the quality of the product and (2) the value system in the country of origin.
Thanks for a good laugh... To start with, Japan is not a Western country. To continue, US produces large amounts of very shoddy products. "Made in USA" is definitely not a guarantee of quality. And what was it about value system again?
Kaa
Kaa's Law: In any sufficiently large group of people most are idiots.
Also, when buying NiMH batteries, pay attention to the mAh rating, which is how much power they hold. AA NIMH batteries might range from 1200mAh or lower to 1950 mAh (the best capacity I've bought so far). This gives you a good indication of how long the batteries will last between charge; clearly there is a big difference out there. And the more expensive batteries do not always have the greatest capacity.
On chargers, there are a lot of different and bad chargers out there. The worst never shut off, just tell you to be sure you only charge batteries for x hours. If you forget and overcharge you can destroy the batteries! Also, if the batteries were not completely discharged then you can overcharge and destroy the battery even if you charge for only the time stated.
The next worst chargers have a simple timer in them and do shut off after x hours. But they still can overcharge a battery if it wasn't fully discharged, or if you try to charge a lower capacity battery. And if you get a higher capacity battery and try to charge it, it will not fully charge.
My rule of thumb is that I never use a charger that insists on charging batteries in pairs. Such chargers cannot sense individual cells, which would allow them to stop charging each cell when it is fully charged. There are a few chargers out there that do sense individual cells and shut off properly though. I think Best Buys sells one for about $30. However, the $9.99 Ray-O-Vac NiMH charger sold at WalMart does this fine. I'm not a Ray-O-Vac fan at all, but I do use and recommend this charger.
And take batteries out of any charger when charged, never trust chargers that promise to keep batteries ready by trickel charging them. I've had them cook batteries.
Again, I want to stress that one should never use chargers that do not sense individual cells and that have to charge in pairs. I have several (I just got one with the 1950 mAh batteries I bought recently) but never use them (I bought the batteries and recharger just to get the batteries, the price was right). Don't risk your expensive batteries to a cheap charger, it will seem to work fine for a while, then you will find that all of you batteries have started leaking and failing.
Remember to look for and pay attention to that mAh rateing when buying batteries.
In applications where the battery might last for years (TV remote control for example, or garage door opener) do not use rechargable batteries. Use Alkaline batteries in these applications; rechargeables will loose their charge too fast, and alkalines are the best choice (I have a garage door opener with the same alkaline battery in it for 19 yeras now).
And thanks for asking here rather than doing a simple Google search on the topic.
I'm an American. I love this country and the freedoms that we used to have.
NiMH recharcheables make Alkaline rechargeables look pretty week. They make normal alkaline batteries look weak as well.
I've had very good luck with Ray-O-Vac. Ray-O-Vac also makes higher capacity line of NiMH batteries than other manufacturers (check the labels for the mAh rating).
-------- -------- Support Wesley Clark for president!!!
Who modded that up? The memory effect only exhibits itself in situations of very regular charge/discharge cycling. Regular deep discharges damage the electrodes and shorten the cycle life of a battery. All rechargeable chemistries will last longer if they're not discharged too deeply. Lead-acid ("car") batteries are particularly sensitive to deep cycling, but it applies to NiCd and NMH too. Don't flatten them if you can help it!
It's important to differentiate between batteries and cells when talking about deep discharge, too. An individual cell can be taken down to 0v without major damage. Once in a while it can be beneficial, to reform the electrolyte. However, in a battery pack, which has several cells wired in parallel, discharging until "flat" can cause serious damage: The cells in the pack are not identical, some of them hold slightly more charge than others. As the pack voltage drops, some of the individual cells near zero, cross it, and actually get reverse charged by the other cells in the pack. Reverse polarity destroys cells very effectively. Packs should never, never, ever be discharged below 0.5v per cell.
As to the parent post: Lithium-ion chemsitry produces 3.6 volts per cell, which is fine if you're designing a new device, but it makes them unsuitable for retrofit or use in standard AA applications. Lithium secondary cells are also tremendously sensitive to current and voltage limits during charging. Exceeding their specifications can cause pressure buildup, violent cell rupture, damage to the device and possible injury to the user. Because of liability, manufacturers don't sell bare lithium secondary cells to Joe Hobbyist. You can buy packs, with the appropriate overcharge protection circuit already wired in series.
Lithium primary (non-rechargeable) cells, on the other hand, are very handy in certain consumer applications: They produce 3.0 volts per cell, exactly double that of the traditional carbon-zinc and alkaline chemistries. They're also very light. The CR-V3 battery is designed to drop into compartments that would normally hold a pair of AA's. Certain digital cameras are designed with the CR-V3 in mind, giving the user a lot of flexibility in battery selection: My Olympus C-2100 can take four AA's of any chemistry (although alkalines don't last very long), or a pair of CR-V3's if I want to travel light and don't mind the price premium.
Since 9 volts is an even multiple of the Lithium primary cell's 3-volt output, lithium-based 9-volt batteries are now available for applications like smoke detectors. They're also ideal in certain LED flashlights, where the low discharge current is well-suited to the lithium chemistry, and the light weight means that many such flashlights will float, which they wouldn't do if heavier alkaline batteries were used. However, none of this is relevant to rechargeable applications.
Wal-Mart Wages Don't Support Wal-Mart Workers, Stan Cox, AlterNet, June 10, 2003
... Workforce is the most expensive part of a business; no reason to expect they wouldn't try to trim the edges there.
Yup. They save money on their suppliers. But never would they think to do so on their employees, no
The iPod uses a lithium polymer gel pack, despite what people claim it can eventually degrade enough that it exhibits similar symptoms to memory (I think this is mostly due to exposure to excessive heat). There is a company that sells a replacement for the battery in the series 1 and 2 iPod's that are actually higher mAh rated then the Apple origionals.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
For the record, in 1982 the penny was changed from 95%Cu/5%Zn to 97.5%Zn/2.5%Cu (the copper being a thin cladding on the outside). The weight changed from 3.11g to 2.5g. If you scratch a modern penny, you can see the shiny silver zinc under the copper cladding.
Interesting bit of trivia: The old and new pennies sound very different when dropped onto a hard surface: the old ones have a bright ring; the new ones are considerably duller in tone. You can sort them by sound!
Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.