Last updated:  

Recommended Batteries
for Particular Uses
16 May 2014

Original article by Ian Mander, 22 July 2002

Low current drain. Small battery size. Good shelf life. Alkaline and silver oxide cells are often interchangeable (for the same size cells) – silver oxide will last longer but are more expensive and harder to find.

Silver oxide cells with W or SW on the end are intended for use in watches, with the W cells lasting a little longer than the SW cells.

Alkaline or perhaps
lithium iron-disulfide

NiCd or NiMH
rechargeable if you use it a lot

High current drain situation. It really depends on how much current your flash uses (which may not be very easy to measure) and perhaps how often you want to change your batteries.

Another consideration is how fast you want your flash to cycle (how fast it will get ready for the next shot). Lithium iron disulfide and rechargeables (Sanyo Eneloop in particular) hold their voltage much better under load, so a flash will cycle faster.

LSD NiMH rechargeable

Lithium iron-disulfide as a backup if not using LSD NiMH

NiMH cells can give high current, have high storage density, and capacity is not much reduced under heavy load. Reusability makes them very cost effective. LSD cells, especially high quality ones like Eneloop, tend to have a slightly higher voltage under load, which is good for voltage-fussy cameras.

For cameras that are used often, go for the largest LSD capacity available, preferrably Eneloop XX. (Note: Apparently Energizer ACCU Rechargeable NiMH AA cells are wider than standard and may get wedged in your digital camera.)

For cameras that may be used irregularly or infrequently go for Sanyo Eneloop or other LSD NiMH battery. Their low self discharge will mean the batteries still have plenty of life in them when the camera is next used, thereby eliminating a major frustration for many users!

For single use batteries nickel zinc/nickel oxyhydroxide batteries rate a mention since they perform quite well. NiOOH cells from various companies outperform modified alkalines, but don't bother with expensive NiOOH cells - they won't perform any better than less costly ones (sadly the inexpensive GP Digi1 is no longer available).

Although modified alkalines (such as Duracell Ultra or Energizer e²) have been designed for this sort of high current use I don't actually recommend them for ongoing digital camera use because they won't last as long as a single charge of NiMH cells or NiOOH single-use cells, so using them on a regular basis will be very expensive. However, if your NiMH cells go flat while away from your charger, modified alkalines will do a reasonable job as a temporary stand-in.

If modified alkalines are not available and you're desperate, use one of the top brands of normal alkaline battery (eg, Duracell, Energizer). The cheaper brands have been known to struggle to give enough juice for more than a handful of photos.

Low current application, but a high storage density means the battery won't have to be changed very often. Interestingly, most of the locally available sizes of hearing aid batteries cost the same, although there's quite a difference in capacity. This tends to indicate the manufacturing and distribution costs are significantly greater than the cost of the raw materials, or maybe it's just supply and demand.

NiMH

Alkaline or modified alkaline if NiMH not available

Moderate current draw. Modified alkaline may be better if the device is particularly power-thirsty, but probably won't be worth the extra expense for most equipment.

If the equipment is used frequently LSD NiMH cells will be much less expensive. If the item is used infrequently with alkaline cells left in it, check them to make sure they're not leaking.

Despite having low capacity compared to NiMH, NiCd actually has a more robust chemistry behind it. That means they can tolerate the environment and duty cycle (a daily charge) better than NiMH cells would. They also tolerate overcharging by a continuous trickle charge better than NiMH cells, which they might get from the solar panel on a long sunny day.

Because the solar panel probably won't give a complete charge (especially in winter or on cloudy days) it can help if you periodically remove the cells and give them a complete charge on a proper NiCd charger. Clean all contacts before reinstalling.

Expect them to last about three years. They do wear out eventually. Recycle them when they do wear out, don't just throw them away.

Whatever works, whatever you can find, whatever you can afford.

Note that most torch bulbs are rated in increments of 1.2V, not 1.5V. In other words, your five D cell Maglite will have a 6V bulb, not a 7.5V bulb. A twin AA torch bulb is rated at 2.4V not 3V. This means that with new alkalines, torch bulbs are run slightly overpowered. That's alright - if they burn out early, replacement bulbs are normally pretty inexpensive. It also means that rechargeables (with their even voltage output) are well suited to torch bulb ratings.

Also, rechargeables have a flatter discharge curve than alkaline or zinc-carbon, so non-regulated lights will maintain a more even brightness until they go flat.

3rd gen. Eneloop

Alkaline or
lithium iron-disulfide

The reasonably long shelf life of alkalines (when kept cool) means you will have power when you need it, while lithium cells have a very long shelf life, and cope with cold conditions extremely well.

Zinc-carbon batteries do not have a very good shelf life, so most of their useful life will have expired before you use the torch, especially if stored in a car or other vehicle which gets very hot during the day.

Most rechargeable batteries self-discharge quickly, meaning they are likely to be dead when you want to use the torch. (I know a couple of people who used to find this quite often – it took them a while to learn.) However, 3rd generation Eneloop cells will still have plenty of charge after a few years of sitting on a shelf (70% after 5 years). The expense of low self-discharge NiMH cells might make them seem unattractive for this purpose – they'd just be sitting around doing nothing – but so would any batteries bought for the purpose. In New Zealand Eneloops cost less than the leading brand of lithium cells, and it costs a pittance to recharge them – which can be done at any time.

NiMH rechargeable

Alkaline as a backup if not using LSD NiMH

Many headlamps are designed to work within the ideal current output of alkaline batteries (which is actually quite low, <500 mA for AA, <250mA for AAA), so don't have 800-1,000 mA bulbs running off AAA cells, for example, a situation that has apparently arisen with some 3 W Luxeon headlamps running off 3 AAA cells. Bizarre.

However, some cavers love lithium primary batteries for their light weight* and long life when used hard and are willing to pay the premium for that. (Of course, some cavers are happy spending $200 on a $50 headlamp, bless them. When one's life depends on having light, reliability equals security.)

A set of modern NiMH AA cells such as the Sanyo XX low self discharge NiMH cells can drive an LED at 350 mA for over seven hours, and depending on how the LED is driven may dim gradually or die suddenly. Some regulator boards die very quickly when dropping out of regulation, so it's good to know beforehand what to expect. Non-LSD rechargeable batteries also have a tendency to die suddenly and completely when using incandescent bulbs** (neither is good in a cave), which means spare alkaline batteries should be carried if not using reliable LSD cells. An easy to reach alternative light source is also important for changing batteries. Also see the notes under "extra bright torch" below.

Extremely flat rechargeables may have enough power to drive a LED at very low current but continuing to use them may damage the rechargeable cells. Flat alkalines will almost certainly still have enough juice to run an LED for many hours in an emergency, will be unlikely to leak in that time, and it doesn't matter if they get damaged internally since they will be discarded after use anyway.

Since cadmium in NiCd batteries is so bad for the environment it seems almost sacrilegious to enjoy the great outdoors using them. If using them, make extra sure none get lost on the trip. They also don't have the capacity that NiMH do.

I had one multiple LED caving headlamp which used a dropping resistor that I couldn't change. I found that single-use nickel-zinc AA batteries, with their slightly higher voltage, was just what I wanted to run the LED array on more current, and therefore run brighter. While using them with the headlamp's half-voltage setting, the LEDs drew twice as much current as they did with alkalines, which was very nice.

Very infrequent use:
Alkaline or
lithium iron-disulfide

Frequent use:
NiCd or NiMH
rechargeable

Sealed lead acid

At high current drain lithium cells "can exceed the power output of alkaline cells by 260%" – which can begin to make the lithium cells about the same value for money as top brand alkalines (since in New Zealand they cost at least that much more). The reduced weight* of lithium batteries coupled with less frequent battery changes and longer life (meaning fewer spare batteries to carry around) can make them quite attractive if the torch is not used very often.

If the torch is used often the high current output of rechargeable batteries make them ideal (and much more sensible) for a high current torch. Their voltage stays relatively constant over their output life, so the light output of the torch will also be quite constant. NiCd might not suit security work because of voltage depression and the need to have charged batteries at the start of each shift, but NiMH is great for this use.

Rechargeable handheld spotlights use sealed lead acid (SLA) batteries with bulbs that may draw as much as 20 amps. Heavy, yes, but give great light for everything from possum shooting to boating. (Although I'm told that some spotlights these days are so bright they make the opossums close their eyes, which makes finding them hard.) SLA batteries have a pretty slow self discharge, so will be fine if not used too infrequently.

Low current application. The size of the battery is important, because it will often be the greatest factor in the torch size. If designing a single-LED seldom-used torch, it might use so little current that the shelf life of the battery also needs to be considered. (Sadly, this tends to rule out zinc air cells for almost all applications, which is a shame, since three zinc air 675 cells would have quite a nice size, voltage, and capacity to drive a single white LED.)

As an emergency light in a cave zinc air cells might work well.

A long life is needed at a low current drain.

Don't even think of using rechargeable batteries in a smoke alarm – most self discharge (and so have a short shelf life) then die suddenly. You might too if your smoke alarm doesn't work.

If you do not presently have a smoke alarm GET ONE! They save lives.

Rechargeable, reliable. Weight isn't an issue since these things aren't designed to be highly portable. Needs to be tested regularly to ensure proper functioning.

 
Last updated:  

Recommended Batteries
for Particular Uses
16 May 2014

Original article by Ian Mander, 22 July 2002