| NICKEL-METAL HYDRIDE (NiMH)If you want to recharge your batteries, use Nickel-Metal Hydride (NiMH). These replace obsolete NiCad rechargeables. NiMH’s have much higher capacity than NiCd’s and don’t suffer from memory effect. Thomas Distributing and C. Crane have great prices on NiMH’s and carry the highest capacity D’s (9-11,000 mAh). Radio Shack sells them too but they cost a little more (and their D’s have less capacity). Also see our recommended chargers. NiMH’s are great all-around batteries but they have a high self-discharge rate (they go dead after a few months even if you don’t use them) so they’re not good for things like emergency flashlights or smoke detectors. | NICAD: NiMH is better RECHARGEABLE ALKALINE: few recharge cycles, small capacity HEAVY DUTY/GENERAL PURPOSE: puny; die quickly LITHIUM: Expensive, toxic, can’t recharge (exception: smoke detectors)NiCad’s are obsolete rechargeables. They’ve been replaced by NiMH’s which last longer, don’t suffer from the memory effect, and aren’t toxic. (more…)Rechargeable Alkaline (Pure Energy, AccuCell) can’t be recharged nearly as many times as real rechargeable batteries (like NiMH & NiCad). They also can’t be used in high-drain devices like digital cameras, and their capacity drops every time they’re charged. But they’re good if you need a rechargeable that puts out more voltage than an NiMH. (more…)Heavy Duty, General Purpose. These are Zinc Chloride and Carbon Zinc, respectively. “Heavy Duty” is a big misnomer; these are really “puny duty”. General Purpose are very susceptible to leaking. (more…)Lithium batteries are the most powerful batteries you can get, but they’re expensive, you can’t recharge them, and they’re toxic so you can’t just throw them in the trash. (You’re supposed to take them to your community’s hazardous waste facility.) They’re great for devices that use the 9V size, since they’ll last a long time (10 years in smoke detectors), but for other sizes NiMH is a better bet (see left). (Note: Lithium ion batteries are rechargeable but they’re not available in household sizes like AA, AAA, etc.) (more…) |
| ALKALINEIf you don’t use many batteries and don’t want to get a recharger, then just buy alkaline batteries. They’re inexpensive and give plenty of power. (If you’re using a high-drain device like a digital camera, then use the newer high-drain alkalines, such as the Duracell Ultra, Energizer Advanced Formula, or Kodak Photolife.) You can get regular alkalines or high-drain alkalines at most grocery stores, and generic is nearly as good as brand-name as long as it’s alkaline. If you buy batteries more often than once a month or two, you should probably consider rechargeables instead. |
Best Batteries | Batteries Compared | Battery Types | Battery Tips | Chargers | Charging Tips | Links
(NiCad) |
Zinc Chloride (Heavy Duty) |
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| Volts | ||||||
| Capacity | ||||||
| Capacity in mAh (AA) | depends on brand |
depends on brand |
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| Capacity in mAh (D) | depends on brand |
depends on brand |
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| Performance in hi-drain devices (e.g., digital cameras) | Special: Good |
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| Rechargeable? | ||||||
| Recharge cycles | of times |
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| Special Disposal Needs | ||||||
| Self-discharge rate | ||||||
| Memory effect | ||||||
| Price for 2 AA’s | $6.99 hi capacity |
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| Notes | ||||||
| Notes on the Table:Volts. The fact that NiMH & NiCD put out less voltage than alkalines is usually not a problem, unless your device uses six or more batteries. Capacity in mAh. Varies by brand. Alkaline figure is from ZBattery. Rechargeable alkaline figure is for Pure Energy Brand for AA, and Accucell brand for D. NiCd are for Golden Power and Radio Shack brands. NiMH figures are for batteries carried by Thomas Distributing and Radio Shack. Capacity for lithium, and carbon zinc/zinc chloride are not usually published by manufacturers and hard to track down; I got figures for these from a Battery FAQ website and from Accucell’s website, though both sites are now down. Recharge cycles. The number of times the battery can be recharged. Figures for Rechargeable Alkalines are from manufacturers’ claims. Getting the most cycles out of NiCads requires periodically draining the battery (or using a charger that does so). Getting the most cycles out of NiMH requires shallow discharging (charging before the battery loses too much power). Special Disposal Needs. See NiCads, below. Self-discharge rate. How quickly the batteries lose their charge just sitting in the drawer. Discharge is faster at higher temperatures. From Batteries in a Portable World. Prices. Pricing is from Radio Shack 2000 catalog for Alklanie, NiCd, and Lithium; from Thomas Distributing for NiMH; from Sundance Solar and CET Solar for Rechargeable Alkaline (Pure Energy & Accucell); from my local grocery store for Zinc Chloride. Note that CheapBatteries.com has cheaper pricing. |
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| Alkaline — your best bet if you’re not recharging |
Alkaline is the most common type of household battery. They became popular in the 1970’s, as an alternative to wimpy Carbon Zinc and Zinc Chloride batteries (e.g., “Heavy Duty” and “General Purpose” batteries). Alkalines have a lot of power and are inexpensive, but they usually can’t be recharged. (Exceptions listed below.)
Standard alkalines don’t work well in high-drain devices (like digital cameras), because they’re not good at pumping out lots of juice quickly. They’ll still work, but your battery life will be REALLY short. However, most manufacturers have introduced special alkalines which work well in high drain devices, such as Duracell Ultra, Energizer Advanced Formula, Kodak Photolife.
By the way, there’s not much difference in capacity from brand to brand, as long as you’re comparing standard to standard, and high drain to high drain — they’re all pretty much the same, despite the manufacturers’ commercials. Consumer Reports found that the spread between the best and worst alkalines was only 9-15%. Tests by ZBattery.com also showed little difference between name-brand alkalines.
Alkalines used to contain mercury, a toxic metal, but Congress banned mercury from household batteries in 1996. So alkalines don’t have any special disposal requirements — it’s safe to throw them away. The exception is button batteries, the kind that go in watches and calculators. Radio Shacks will accept button batteries for proper disposal.
Alkalines lose their voltage gradually — as opposed to rechargeables like NiMH or NiCad which maintain most of their voltage over the whole charge and then suddenly plummet.
| Rechargeable Alkalines — usually worse than NiMH |
Rechargeable Alkalines (RA’s) were designed to be the best of both worlds — the high capacity of an alkaline, combined with the rechargeability of a NiCad. They’re not.
RA’s get far fewer recharge cycles than a real rechargeable (NiMH), and their capacity drops every time you charge them. After as few as eight cycles, an RA could have HALF the capacity of a new RA, according to chart on Energizer’s and Accucell’s websites (which they’ve since removed). In fact, RA’s have lower starting capacity than the best NiMH’s right from the get-go.
RA’s also require a special recharger (not a standard recharger). And you can’t use RA’s in high-drain devices like digital cameras.
That said, there are exactly two cases in which RA’s could be your best choice:
- You need the extra voltage an alkaline puts out. Some devices that take multiple batteries won’t work with NiMH because the voltage is too low. (more on this problem) And with LED flashlights, even though NiMH will work, you’ll get a brighter light with RA’s.
- Your device is used infrequently (like a flashlight) and the high self-discharge rate of NiMH’s means that the batteries go dead on their own between periods of use.
The three RA brands I know of are:
- Pure Energy (available from Sundance Solar)
- Accucell
- Rayavoc Renewal (introduced in 1993 and discontinued in 2004)
How to Recharge. You need a special charger for RA’s. If you charge them in a standard charger they’ll explode. Get the charger from whatever retailer you get the batteries from. Keep your RA’s “topped off”. The sooner you recharge them, the more recharge cycles you’ll get out of the battery and the more total power you’ll get out of it.
Why there aren’t 9V rechargeable alkalines. From the Rayovac website: “There are two reasons: (1) 9V batteries actually have six small 1.5 V-cells inside them. Reusable alkalines need to be charged individually for reliable performance. Since you can’t access each cell inside the 9V battery individually, they could not be reliably recharged. (2) Most products designed to run from 9-Volt batteries last for many months. Recharging these batteries provides limited benefit in terms of cost savings (the cost of replacing batteries is not significant anyway).”
| NiMH (Nickel-Metal Hydride) – Your best bet if you’re going to recharge your batteries. |
NiMH’s are replacing NiCads as the rechargeable battery of choice, because they have a higher capacity than NiCads and don’t have the special disposal requirements that NiCads do. You can get AA’s from Thomas Distributing (800-821-2769) for $2.35 each. (Shipping is $4.50 for up to four batteries, and $5.75 for ten. I last checked their prices in early 2000, but check their website for current pricing.) If you need them today, you can get a pair of AA’s at Radio Shack for $9.99.
Unlike NiCads, NiMH’s contain no toxic metals and have no special disposal requirements, so when they won’t hold a charge any more you can throw them away. If you prefer, many manufacturers will recycle the batteries if you send them back. (e.g., Duracell, 1-800-551-2355 to get the address)
Note that NiMH’s come in different capacities; for example, one D-cell might be 2200mAh while another is 8000mAh. So always check the label to see the capacity. If the capacity isn’t stated, don’t buy it. Of course, you’ll pay more for higher-capacity batteries. Thomas Distributing has a good assortment of NiMH sizes, and they clearly state the different capacities. Note that some chargers may not completely fill up a high capacity NiMH D.
A possible downside shared by both NiMH’s and NiCads is that they put out less voltage than alkalines (1.2 V instead of 1.5 V). That means that devices which require four or more batteries might not even work at all with NiCads or NiMH’s. (They might work; it depends on the device. Doesn’t hurt to try. Appliances that take only one or two batteries usually work fine. Four batteries, maybe, and eight, probably not.)
Unlike alkalines which lose their voltage steadily, NiMH batteries maintain most of their voltage over the whole charge and then suddenly plummet, as shown in the graphs below. For this reason many electronic devices that tell you how much battery life is left have a hard time reporting an accurate level for NiMH’s. The voltage is very similar for both a fully-charged battery and a nearly-spent battery. Some devices (like my GPS wristwatch) let you specify in the setup menu whether you’re using NiMH or alkalines, so they can try to be more accurate with the battery-remaining indicator.
| NiCad (Nickel-Cadmium) — Old-school rechargeable. Use NiMH instead. |
NiCads are obsolete rechargeables. They’ve been replaced by Nickel-Metal Hydrides (NiMH’s). NiMH’s have much higher capacity and don’t have special disposal requirements, so in most cases you should use NiMH’s instead of NiCads. But if you still have some old NiCads lying around that you want to use, keep reading.
NiCads don’t last very long before needing a recharge. They typically have 50 to 67% less capacity than alkalines and NiMH’s. NiMH’s. Even “High Capacity” NiCads have way less capacity than NiMH’s (~900mAh vs. 2500mAh for an NiMH). If you’re using C- or D-cell NiCd’s, you’ll also have to deal with the fact that many chargers won’t completely fill up a high-capacity C or D.
A downside shared by both NiCads and NiMH’s is that they put out less voltage than alkalines (1.2V instead of 1.5 V). That means appliances that require four or more batteries might not even work at all with NiCads or NiMH’s. They might work; it depends on the device. Appliances that take only one or two batteries usually work fine. If your device needs more voltage then consider rechargeable alkalines, listed above.
Another downside of both NiMH’s and NiCads is that they self-discharge quickly (~20-25%/month). Self-discharge means they lose power even if they’re just sitting in a drawer — shelf life is about 2-3 months. So they’re not the best choice for, say, emergency flashlights. (Use alkaline or rechargeable alkaline instead.)
Also, when NiCads are dead, you can’t throw them away because they contain toxic metals. You can drop them off for recycling at ACE Hardware, Circuit City, Sears, Target or Wal-Mart. (Radio Shack won’t take them, according to the rep I spoke with on 10-27-99 at 1-800-THE-SHACK). For other stores in your area, check out the Rechargeable Battery Recycling Corporation’s website. And don’t be scared away by all that talk on the website about their recycling batteries with the special label; they’ll take any NiCad even if it doesn’t have the special label.
NiCads have only one advantage over NiMH’s, which is pretty minor: If you drain a NiCad down too far then a good charger can often resurrect it, but an NiMH drained too far will be more resistant to being brought back to life.
How to charge. Charge when you start getting poor performance in your device (the light dims, the tape player slows down, etc.) At that point they’ll be down to about 1.1 volts. If you drain them completely (e.g., if you wait until the light is completely dark), you’ll shorten the life of your batteries.
You may have read articles that tell you to drain your NiCads “completely” or “fully”. It’s crazy, but by saying “completely” they mean “NOT completely”. They mean to drain the battery down to about 10% of remaining capacity, or until the remaining charge is about 1.0 to 1.1 volts. (I know, it’s stupid for them to say the opposite of what they mean. Go figure.) The better battery chargers will perform this discharge for you automatically, and call it “conditioning”. If you drain to what you or I would consider “completely” (i.e., no capacity left), you’ll shorten the life of the battery, meaning you won’t get that many more recharge cycles out of it.
NiCads put out a fairly consistent 1.2V for the length of their charge, and when that charge is spent, the voltage drops rapidly. When a NiCad is spent is voltage will be around 1.0 to 1.1V. (Alkalines have a completely different power curve. Their power drops gradually over the life of the charge, pretty much a straight diagonal line going down.)
Don’t overcharge NiCads. Most chargers stop charging when a battery is done, but some don’t (especially older models). If your charger is dumb and overcharges a NiCad, its capacity may be decreased, and may even be completely ruined. In most cases, overcharging a battery for a day or sometimes even longer won’t hurt it, so don’t panic if you overcharge by a few extra hours. It usually takes at least an extra day to hurt it, but that really depends on your charger. Of course, all this is irrelevant if your charger shuts off when a battery is done. Check the manual to see if yours has this feature, or ask the manufacturer if the manual doesn’t say. (Or better yet, just get a good charger.) If your charger doesn’t prevent overcharging, ask the manufacturer how long the grace period is before it starts overcharging the batteries.
Let NiCads cool before recharging. Some rechargers figure that a NiCad is done recharging when it gets hot, so if you put a NiCad that’s already warm in your recharger, the charger may quit charging before the battery is fully juiced up. If your batteries are warm for some reason (like from sitting in your car), let them cool to room temperature before recharging.
Memory effect There’s a theory that NiCad batteries can suffer from a memory effect. The basic premise is that if you recharge a NiCad before it’s mostly spent, the battery will “remember” the capacity at which you recharged it, so you will have reduced the capacity of the battery.
Does this really happen in NiCads in household battery sizes? Heck if I know. Half the articles I’ve read argue passionately that it does happen while the other half insist it doesn’t. Consumer Reports didn’t notice any memory effect in their testing. Whether it exists or not, here are some things to pacify you: Most sources say that memory effect is only a problem if you REPEATEDLY recharge a NiCad before draining it most of the way. Doing it once in a while shouldn’t be a problem. Also, you can usually erase any memory effect by draining your battery most of the way and then recharging it. Finally, manufacturers tend to claim that their newer NiCads are less susceptible to memory effects, and that their newer chargers have special circuitry to prevent memory effects. Me, I’ve simply never worried about it. And of course, if you’re using NiMH’s (which you probably should be), you don’t have to worry about it either, since NiMH’s definitely don’t have memory problems.
For more, see our charging tips.
| Lithium — Lots of power, but are expensive and can’t be recharged. Use others instead. |
These are designed for very high-drain devices, like digital cameras, motorized toys, and portable CD players, and for smoke detectors (in which they last for up to 10 years). They’re more efficient than standard alkalines for high-drain devices because they can supply the juice much quicker. But they’re very expensive, and there’s absolutely no way to recharge them, so they’re a bad deal for high drain devices. Use NiMH’s instead.
Lithiums are useful in low-drain devices like smoke alarms — they last so long you can go for years without replacing the battery. When you go through only one battery every several years, you’re not as concerned that it can’t be recharged.
Don’t confuse AA Lithiums with Lithium-Ion battery packs (like the kind that come with some cell phones and camcorders). Those Lithium-Ion packs ARE rechargeable, but only when they’re installed in the device they’re powering, or in a special recharger. I don’t know of any Lithium-Ions in the AA size.
If you can’t bear to buy lithiums because they’re expensive and you can’t recharge them, but you get very little battery life in your digital camera (or other high drain device) with the alternative (NiMH’s), then consider making a battery pack out of NiMH D-cells. For example, my digital camera takes four AA batteries. I get very little battery life out of alkalines (they’re high capacity, but can’t pump out juice quickly enough) or NiMH’s/NiCads (low capacity), and I don’t like lithiums because they’re non-rechargeable. Solution? I built a simple battery pack with five D-cell NiMH’s, held in a fanny pack with a power cord running to the camera. Here’s a web page that explains how to make a battery pack for a certain digital camera. (The concept is applicable to other models of cameras and to other devices, though the voltage — and therefore the number of batteries used — might be different.)
| Heavy Duty, & General Purpose (when no type is specified, it’s one of these) |
These are Zinc Chloride and Carbon Zinc, respectively. If a battery isn’t specifically labeled something like Alkaline, Heavy Duty, or something else, then it’s General Purpose. “Heavy Duty” is a big misnomer; both Heavy Duty and General Purpose are really “puny duty”, and die quickly.
These two were the battery type of choice in the 70’s, before alkalines were available. Even recently they were still popular because they used to be a lot cheaper than alkaline, even though they were puny. But these days, alkalines are close to the same price, so Heavy Duty and General Purpose are slowly becoming extinct, thankfully. (Why pay the same price for a wimpy battery when you could get an alkaline instead?) Radio Shack doesn’t even sell them any more. Also, General Purpose aren’t suitable for continuous use (only for intermittent use), and they’re most susceptible to leaking.
The only redeeming value of Heavy Duty batteries is that they’re supposedly less likely to leak than alkalines. So if you have an expensive device that you use infrequently, where you expect to be able to keep the same set of batteries in them for a long time, then Heavy Duty might be a little safer, even though the overall battery life is terrible.
These batteries are crap. Don’t buy them.
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