Are there rechargeable batteries which don't discharge when idle?

Question

This is kind of a peripheral question — not exactly about photography, but about the batteries for my camera, which uses AA batteries.

I have tried every known brand (to me) of rechargeable battery, and I find that no matter what brand, the batteries discharge when left idle for more than a day or two, whether in the camera or out. This is tremendously frustrating to me, because every time I pick up my camera to take a spontaneous shot, I see that the batteries are flat — so I waste a minute changing the batteries... only to find that the spares are also flat... this despite the fact that I had them in the &$*&! charger for about 36 hours straight just three days before!

Does anyone else have this problem, or is there some charge-eating poltergeist inhabiting my home? Is there some brand or type of rechargeable AA battery that actually keeps its charge for a reasonable amount of time?

Answer 1

I have conducted quite a lot of testing to find out how the low self-discharge cells keep their charge. You can see the results here.

Sanyo claims the self-discharge pattern follows inverse S curve, meaning that you lose first some 10-20% rapidly in first 1-2 weeks or so, and then it levels, and the batteries retain some 70-75% of charge after one year. My tests this far span only to 2 months, but this far it would look like Sanyo was correct.

I am hesitant to mention any brands, but if you really want some, Sanyo Eneloop XX and Ansmann maxE seem to offer more actual capacity (after some time in storage) than the rest, while Varta Ready2Use performs worse than the rest. The rest, Sanyo basic Eneloop, Maha Imedion, GP ReCyKo and Sony CycleEnergy are pretty much even. In practice the differences are smallish, so any LSD battery, with possible exception of Varta, will work, and work a lot better than regular NiMH batteries if there is more than 1-5 weeks between last recharge and usage.

Here is another study, comparing Sanyo basic Eneloop and regular higher-capacity NiMH batteries. With these two brands the basic Eneloop wins in actual capacity after 3-4 weeks of storage. However, basic Eneloop was the very first product to hit LSD market, and the capacity is a bit low by today's standards, so for example Eneloop XX would win already after 1-3 weeks.

(I'm not affiliated with any of the included brands, I'm just a fellow amateur photographer who wanted to know which cells exactly are worth buying.)

If you need to store batteries for extended periods before using, you can also wrap them to watertight bag and put them to freezer. The lower temperature will slow down self-discharge.

I also have anecdotal data on this: For example, I had matched set of six ReCyKo/Eneloop batteries 2-3 months in my camera bag and then I switched them to use in my Canon 450D, and shot some 400-600 images before they depleted. Fresh batteries would do more, but still, that's a lot better than old-style NiMH would do.

Answer 2

As noted by others, if you want a battery that is a straight replacement for rechargeable AA cells then LSD (low self discharge) NimH will meet your need.

LSD cells have more, not less, lifetime cycles than standard cells. A first generation Sanyo Eneloop cell offers about 1000 cycles (compared to less than 500 for a standard NimH cell) and their new 2nd generation Eneloop cells offer 1500 cycles. And a 3 year shelf life to 70% capacity.

Eneloop home page

Eneloop information

• An extra of 500 charging cycles - instead of being rechargeable 1000 times, the new eneloop is even rechargeable up to 1500 times.

• Improved self-discharge. Even though the self discharge of the old eneloop was already very impressive, you can store the new eneloop for 3 years and still it will retain 75% of its capacity.

• You need a battery, which is reliable even when having cold temperatures? Before eneloop was suitable for temperatures as low as -10°C - now even until -20°C.

LSD capacity is about 2000 mAh compared to about 2600 mAh from the top reputable AA NimH standard cells. You can buy cells with higher claimed capacity than 2600 mAh, but not from reputable manufacturers.

A typical LSD AA cell has about 70% charge remaining after one year.

If you look at non AA cells you can get better performance. LiIon (Lithium Ion batteries) have extremely good shelf lives. The very large majority of the charge is retained after one year. You can buy AA size (14500) LiIon cells but these have 3V - 4V+ output and are not suited to direct drop in replacement.

I have personally been using GP (GoldPeak_ brand LSD NimH lately - sold under the ReCyko" label. Capacity from new is about 2000 mAh and they so far seem very well behaved. (I have no involvement with Gold Peak).

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Other chemistries have somewhat better shelf lives but are not available in a direct drop in replacement for AA cells. eg LiIon (Lithium Ion) AA cells = 14500 size are available. However, these have a 3V to 4+V voltage so are unsuited as direct consumer replacement.

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Available LSD cells -

Prolife from Fujicell

Ready2Use Accu from Varta

AccuEvolution from AccuPower

Hybrid, Platinum, and OPP Pre-Charged from Rayovac

eneloop from Sanyo

eniTime from Yuasa

Infinium from Panasonic

ReCyko from Gold Peak

Instant from Vapex

Hybrio from Uniross

Cycle Energy from Sony

MaxE and MaxE Plus from Ansmann

EnergyOn from NexCell

ActiveCharge/StayCharged/Pre-Charged/Accu from Duracell

Recharge from Energizer

Pre-Charged from Kodak

nx-ready from ENIX energies

Imedion from Maha

Pleomax E-Lock from Samsung

Centura from Tenergy

Ecomax from CDR King

R2G from Lenmar

LSD ready to use from Turnigy

Enesuper from BTY

Answer 3

Yes! This is a normal problem with rechargeables, and there is a type of battery made to solve it — low-self discharge NiMH. These will hold a charge for months sitting idle. The downside is lower capacity, but I find that a small price to pay for actually being useful. The main brand is Sanyo Eneloop, but there are others, too.

Answer 4

Also check on buying a better charger. Most of the chargers that are sold together with the batteries are really cheap, can't properly charge the battery, and can also damage it.

The BC-700 charger sold by LaCrosse may be an option. You have complete control of the charging and discharging on each of the 4 batteries. It will display voltage, current and accumulated capacity. It also has multiple modes including a discharge refresh mode that will cycle multiple times until optimum capacity is reached.

Answer 5

You are looking for low discharge rechargeables.

Sanyo Enloop are the best known variety of these shelf stable rechargeables, but other brands include:

Duracell Rechargeable "Pre-charged"
Energizer 'Recharge"
Rayovac "Hybrid"

Note that some of these brands offer both low discharge and 'regular' so carefully read the label. Look for 'pre-charged' 'ready to use' etc in the descriptions. Most battery vendors use the low discharge battery to eliminate the need to charge the batteries prior to use.