ON RECHARGEABLE BATTERIES!
How many of you have been wondering about the numerous rechargeable battery options which are available from sources such as Ebay and Amazon? Anyone whom has searched discovers a bewildering plethora of choices facing them. From Nickle-Cadmium (Ni-Cad), Nickle Metal Hydride (NiMh), Nickle-Zinc (NiZn), to SOME rechageable Lithium ion (not all), and these various batteries may even be rated in mAh or mWh for capacity as the seller or manufacturer deems fit.... Just what IS the actual meaning and difference, and are rechargeable batteries even worth their generally prodigious cost?
The Case For Rechargeable Batteries:
ALL batteries, rechargeable or not, are toxic to the environment. The chemicals inside of them are hazardous to the environment and ultimately to you. Whether you refer to the average Alkaline, Zinc-Carbon, Lithium, or even the Nickle based rechargeables makes no difference. Batteries grow old, corrode, and will leak their contents eventually. The fewer batteries we throw away the less of these chemicals we introduce into the garbage dumps, and from there into the soil and our drinking water supplies.
However, in this day and age, we have little seeming choice but buy batteries. Every portable and even some non-portable electric or electronic devices you own use them. It makes ecological sense to buy batteries which will decrease the sheer volume of eventual toxic sludge we are ultimately putting into the ground.
Ultimately, they are cheap, though you definitely will not think so upon first inspection. Even the cheapest of the mid-range of the rechargeable lot (NiMh) may cost you around $25 for 12 AA batteries... OUCH! That is over two bucks a battery, when alkalines run generally around a buck each for the cheap mid-range batteries.
Compared to $12 for a 12 pack of cheap AA alkaline, this seems quite economically unsound. Until you understand that they can be recharged up to 1000 times, that is. Put in perspective; assuming you get just half of the expected recharges according to the manufacturer, you are spending $25 initially for 12 batteries which are the equivalent of 500 packs of the cheap AA alkaline batteries you would have had to buy otherwise. 12 rechargeable batteries instead of 6000 disposable batteries. You have saved ultimately $5975, so the answer is YES they are economical. You also put 5988 LESS batteries in the dump. Remember that these figures are assuming only HALF of the manufacturers expected lifespan.... You might well save much much more than stated.
The Case Against Rechargeable Batteries:
Both Ni-Cad and NiMh batteries share the same problem..... Voltage. The standard battery voltage is 1.5 volts, yet the chemical process limits these two batteries to 1.2 maximum volts. This can be a problem in any voltage sensitive device, such as many camcorders, cameras, high powered (3 Watt or more) LED flashlights, etc... These devices will assume that the batteries are only three quarter charged, and will tell you to change batteries or even shut down when the battery is still mostly charged. This is not a problem with low draw devices, such as Walk-mans, radios, clocks, remote controls, or even bulb type flashlights.
NiZn (at 1.6 volt) works for the high voltage need devices, but has relatively low storage capacity (approx half) compared to NiMh.
Expensive does not guarantee better. For example, the no-name Chinese NiMh batteries ordered from Ebay may have better battery life and output than many supposedly superior well-known brand names. Storage capacity can also vary wildly from one manufacturer to the next.
Also, they are no more "green" (ecologically safe) than regular batteries when thrown away.
Rechargeable Battery Personal Opinions:
NiCd ( Ni-Cad, Ni-Cd or Nickle-Cadmium)
In my book, Ni-Cad are junk. They have a intrinsically low battery voltage, 1.2 volts instead of the standard 1.5 volts. Worse, they tend to develop a 'memory' which makes both battery life and usability very limited, and they have a very low current storage capacity compared to every other battery available. Ni-Cad's only claim to fame is that it is rechargeable and it was first in development That is it. Though I own and use numerous of them, I do not advocate them and will not personally buy any more of them.
NiMh (Ni-Mh or Nickle-Metal Hydride)
Very reliable battery with VERY high capacity. However as previously stated, they may not work very well in all devices due to being 1.2 volt, which in my book is their only shortcoming. They are very economical batteries, and work excellently in bulb type or low to medium wattage flashlights, and all low draw devices. I own several and am a big fan. It holds more juice than even non-rechargeable alkaline batteries.
One thing quickly noticed is that, compared to standard alkaline batteries, they are extremely lightweight. My four cell "D" battery mag-light is a featherweight with NiMh batteries, and the "D" cell NiMh batteries I use have an astounding 10,000 mAh capacity per battery! (That is a nominal rating of 10 amps per hour... Compare that to a regular alkaline... I dare you!)
NiMh are available in all standard battery sizes, from AAA to "D" and even 9V, as well as many oddball sizes.
NiZn (Ni-Zn or Nickle-Zinc)
Reliability is unknown to me, as I do not own any. I advise searching for buyer feedback on Amazon. I intend to get some for my digital camera etc., to test them out, but have not done so as yet. Their specs look good at first, but you will notice they are rated in mWh (milli-Watt per hour) instead of the standard mAh (milli-Ampere per hour) rating system.
I will simplify and demonstrate the difference:
A common rating for a NiZn AA battery is 2800 mWh. A common AA battery in NiMh is 3000 mAh. Sounds similar doesn't it? NOPE! Lets do some math.
1 Watt = 1 Volt * 1 Ampere.
The NiZn is rated at 2800 mWh which is the same as 1750 mAh.
2800 mWh/1.6 volts or Amperes=Watts/Voltage.
This means the NiZn battery can sustain a load of 1750 milli-Amperes for 1 hour. The mWh is a rating of overall power not capacity. The NiZn battery can sustain a smaller amount of electricity at a higher voltage than the NiMh battery. On a high Amperage load it will go dead much faster.
The NiMh battery is rated at 3000 mAh, and can sustain a much greater amperage load for the same time period of time. However, the voltage is 1.2 volts so the power in Watts per milli-Ampere is less. Overall conversion shows that TOTAL power in Watts is still higher at 3600 mWh than the NiZn at 2800 mWh, due to the much greater amount of electricity stored in the NiMh battery.
3000mAh*1.2 Volts or Watts = Amperes*Voltage.
Over all, in both available power and amount of a load it can sustain, the AA NiMh battery has whipped the NiZn battery hands down in all respects.... except one. The NiZn should run the high voltage dependent devices such as camcorders etc.. far longer than the NiMh.
I suspect the change from mAh to mWh is actually to make the NiZn battery seem more comparable to the NiMh. Cost of the NiZn is still cheap however. One BAD feature the NiZn suffers from is that it requires a special charger. Most chargers are for Ni-Cad and/or NiMh, and they will not work with the NiZn batteries.
The NiZn battery is not to be knocked as the mAh output and voltage from the specs are both comparable if not superior to a standard alkaline battery, it is much lighter than both the NiMh battery or the Alkaline, and chargers for them are relatively inexpensive on Ebay.
One major drawback is that I can only find three battery sizes available for the NiZn; AAA, AA, and Sub C (not to be confused with a "C" cell).
However, one can offset this problem and buy an AA or AAA to "C" cell or "D" cell converter cheaply on Ebay if you wish. These converters are a plastic case which are exactly the size of a "C" or "D" cell and hold inside two or three AA or AAA batteries. If you have a device using a specialty CR123 battery, you can also buy a AAA converter which works well.
Li-ion (Lithium Ion)
The Lithium Ion battery is expensive. I do not like them, as I find the cost outrageous, and the specs not that particularly amazing for the cost. They also can be confusing in that you can accidentally buy a specialty AA lithium rechargeable battery that has a voltage of 3.7 volts, which is more than TWICE that of a standard AA of 1.5 volts. Buyer beware, as accidentally putting these in your regular AA camcorder or camera will zap it deader than disco. (4*1.5 Volts=6 Volts - verses- 4*3.7 Volts = 14.8 Volts... can you say smoke?)
To be fair though, the Li-Ion is supposed to maintain peak voltage throughout its cycle. I will personally believe the claim when I see it. Some devices require a specialty lithium battery though, and in this case I do advise buying a rechargeable version if available. The chargers are also expensive and exclusive, adding to the detriment.
First place "most bang for the buck" goes to the NiMh rechargeable battery wherever it is feasible to use it. Second place goes to NiZn for wherever the first place winner doesn't work.