Aqualab: Research: Which Kind of Battery?

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Research Topic: Which Battery Will Do?

Last updated:	Overview & Terms 31 May 2007	Single Use 8 November 2007	Rechargeable 29 May 2009	Suitable Uses 24 August 2008	More Info & Links 24 August 2009
Original article by Ian Mander, 22 July 2002.		Single Use Test 6 November 2007	Rechargeable Test 13 April 2008
		Battery Analyser 12 April 2008

On this page: Further reading | Shopping for batteries | Emerging technologies

Energizer has continued to generate bad feelings with their 2500 mAh NiMH cells, widely regarded as the worst high capacity cell available, and that hasn't changed with the latest version, available in 2450 mAh and 2500 mAh. Tests are hard to come by because almost no one in their right mind wants to buy the pathetic things, but one three week self discharge test does investigate the claim they last up to six months. It seems very unlikely - they lost 13% in three weeks, more than twice the other high capacity cell tested.

For more information on rechargeable batteries have a look at this battery article at Extreme Tech or for single use D cells I quite like this battery test by a couple of home-school students (you'll have to scroll about two thirds of the way down to find it).

Imaging Resource has a very good test/review of AA rechargeable batteries, covering a huge range of NiMH battery brands and models. It's unfortunately somewhat out of date (stopping at 2300mAh) but it does include three brands of alkaline batteries for comparison - and they do not compare well when run at 1 amp in the test.

Robert's Photography Blog has a Battery Round-up that lists a few brands of AA and AAA NiMH cells and notes how much capacity they actually have as measured by the La Crosse AlphaPower BC-900 - a nifty charger that can cycle NiCd and NiMH cells and measures their capacity as it discharges them. I don't know how accurate it is, but it's interesting to note how poorly a couple of brands of the AAA cells performed, having only around 78% of their claimed capacity. One of those brands, Moden, is commonly available in New Zealand. Robert found that the supposedly 1,000mAh AAA cells he tested actually failed to reach even 800mAh. It's particularly bad because the BC-900 discharges straight after charging, without resting the cells at all, which leads to unrealistically high results as far as real world usage goes, where cells are not normally used hot off the charger. One of the footnotes is also interesting:

Where are the other major brands? Most Sony, Energizer, and Kodak rechargeable NiMH batteries are re-labeled Sanyo batteries (Sanyo OEM). You can confirm this by looking for the small ‘HR’ stamped on the bottom of the battery.

Imaging Resource has a Great Battery Shootout (that's it's name, too) by Dave Etchells. It lists a large number of NiMH cells, some of which are available in New Zealand. Very interesting is his inclusion of three leading brands of alkaline battery, which don't compare well to the NiMH cells at the 1 amp test current.

Eneloops and Imedions are compared in a camera flash cycle-time test by Calvin Foo. He writes: Eneloop completed at 1564 shoots and Imedion completed at 1660, approximately 100 shots more than Eneloop, which is pretty much expected as it is a 2100mAh vs 2000mAh, with approximately 5% extra power. ... On cycle performance point of view, Eneloop out performed Imedion from 4rpm to 14rpm with an amazing everage of 6rpm on a consistant performance. In this experiment, it is concluded that the Sanyo Eneloop is a better performer than PowerEx Imedion, at least on a [S]peedlight point of view.

Shopping for batteries and chargers

GP Digi1 (NiZn) is apparently now sold out from Dick Smith Electronics. This is a great shame - they were good batteries.

Sanyo Eneloop cells are available in New Zealand from PB Technologies: 4-packs of either AA or AAA cells are NZ$22.39 (cash price), and a four pack of AAs with a charger is NZ$32.63. (Note that the charger charges pairs of cells.) Because of the varying exchange rate online purchases from overseas web sites may not be not good value.

Sadly Dick Smith Electronics has sold out of Eneloops and it's a great pity they didn't recognise their value. Their replacement - a DSE-branded low self discharge cell - are more expensive than PB Tech's Eneloops, and look like a relabeled version of a certain brand of poor quality cell. I don't recommend them. Stick with Eneloops - they still have a few Eneloop AAA cells.

The Powerex brand, which Dave Etchells (of the above-linked Great Battery Shootout on Imaging Resource) calls the "longtime champion" of his testing is available in 2500mAh and 2700mAh versions at a pretty good price in New Zealand from Ian Jenkins at Ecobatteries. Note that no high capacity batteries have a long service life. He also sells the excellent Maha MH-C9000 analyser/charger for a good price, and Maha's Imedion batteries which are a low self discharge NiMH battery along the lines of the Sanyo Eneloop and are reputed to be very good batteries. International customers may want to try Thomas Distributing, where I bought my original unit, although their shipping prices for non-US customers are quite high.

Emerging rechargeable battery technologies

Zinc Matrix Power in the Unites States has created the Silver Polymer™ battery (available in several models). They love to point out how the gravimetric storage density is about the same as lithium ion batteries but the volumetric energy density is much greater because the materials are far denser than those in lithium batteries. Their standard cells can be recharged only about 100 times, which doesn't sound all that wonderful at all, but supposedly compares well with lead acid. A 12V 15Ah battery made from 8 silver polymer cells would weigh 1.4kg - supposedly a quarter of what a similar spec lead acid battery weighs. However, the Silver Polymer battery has "only" 80 amps peak, probably costs several tens as times as much, and has very fussy recharging requirements.

Update August 2008: Now known as ZPower Battery, they are pushing the technology as silver-zinc batteries, which "are inherently safe", for mobile electronics. They say they will provide laptops with 40% longer than lithium ion batteries, and expect them to be available in 2009.

NEC Corporation in Japan has shown off the world's first proton-polymer battery - using protons (hydrogen ions) instead of lithium ions. They say the battery takes just five minutes to recharge - nice! Storage density is a bit low for my liking (just 10-15 Wh/kg, or half that of lead acid). However, specific power is quite good (1 kW/kg), so fast discharging goes hand-in-hand with its fast charging. These properties mean that it may have important uses in electric and hybrid vehicles, where very high pulse currents are often needed and batteries need to be able to take sudden rapid charging to reclaim energy from braking. (These fast charge/discharge characteristics mean they have some features more like super capacitors than normal batteries.)

Power Paper has figured out a way of printing batteries onto just about anything, making a 1mm thick flexible battery. They claim 2.5 mAh/cm², which is about a third of what lithium ion polymer cellphone batteries have for the same volume. So they're not likely to be used for normal cellphones but the flexibility and thinness could find uses in other areas.

Yuasa Delta Technology (Taiwan), a subsidiary of motor battery giant YUASA, is first company in the world to develop nickel-hydrogen AA batteries which can be charged in just 15 minutes. Yuasa has started mass production of two types of battery: AA (2,000 mAh capacity) and AAA (850 mAh capacity). Sanyo Electric, the world's largest manufacturer of nickel-hydrogen batteries, has released a 30 minute chargeable product and was expected to launch a 15-minute charger version in (northern) spring 2004.

Carbon Air batteries look quite promising also. As explained in a May 2009 article, the STAIR cell (for St Andrews Air cell) uses a block of porous carbon and draws in oxygen from the air, a bit like a zinc air battery as used in a hearing aid. By having one reactant outside the cell, more energy can be produced from the same size cell. The porous carbon is also cheaper than the lithium cobalt oxide used in present batteries. Sadly someone has stuffed up the units in the 3rd to last paragraph.

Other companies making some headway are mentioned in this article from May 2005.

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Last updated:	Overview & Terms 31 May 2007	Single Use 8 November 2007	Rechargeable 29 May 2009	Suitable Uses 24 August 2008	More Info & Links 24 August 2009
Original article by Ian Mander, 22 July 2002.		Single Use Test 6 November 2007	Rechargeable Test 13 April 2008
		Battery Analyser 12 April 2008

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