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So I finally picked up a bunch of these from Amazon.com, shipped them to my brother in California, and he brought them up for Christmas. NiZn is "nickel zinc", and alternative chemistry to NiMH batteries we're all used to. There are several differences, but the one that most people here are probably interested in is the increased voltage: 1.6v instead of 1.2v. It also has low internal resistance, which results in the ability to deliver much more current. This translates to faster flash recycling times:

http://www.youtube.com/watch?v=kLcPsGkA1_Q

The best I've been able to do with NiMH AA's is about 2.5 seconds at full power on an SB-900 and fresh Eneloops. This is measured as the time between doing a full power dump and the red LED lighting up again. They eventually settle down to around 3 seconds to recharge.

By comparison, as shown in the above video, even NiZn batteries fresh out of the package can cycle an SB-900 in about 1.2 seconds! There is no top-up charge, no break-in period, nothing. Rechargeable batteries also tend to perform better after a few discharge/recharge cycles too, so I'm wondering if I'll be able to hit the magic 1.0 second mark. Normally, you need the $275 SD-9 external battery pack with an extra 8 AA's to get that sort of recycling performance.

You'll also hit the SB-900's thermal cutoff in record time... 13 shots.

http://www.youtube.com/watch?v=VGWpjrtrTL4

It's still too early to tell how these perform in the real-world. I will likely be doing some casual shooting with the family in town for Christmas, and then I'm off for a couple of photography conferences in January. That will give me a good opportunity to uncover any caveats about the system. For now, though, these NiZn's are very impressive and the price/performance beats everything else out there.

Thanks for the update Taob! Hummmmmmm......

Cool! seems like a good and affordable way to improve performance of your electronics.
Can I ask what brand you bought?

I did not have good results using NiMH's in the battery grip of my D700's before, although I did not do much investigation into why. I would get less than 100 shots, and the D700 would switch to its internal battery. I'll try the NiZn's in the grip to see if they do any better.

Just as long as you remember the saying "the candle that burns twice as bright, burns half as long". If you're not careful, you can easily fry equipment that isn't expecting 1.6v per cell.


There is only one producer of NiZn AA cells right now (at least one that is easily accessible in North America), and that's PowerGenix. I had a hard time finding them in Canada. Amazon.ca had them, but the ship date was uncertain, and I wanted them before Christmas. I ended up buying them on Amazon.com:

http://www.amazon.com/dp/B0029NZVZ0/

Why not just get 'em from Amazon Canada?

http://www.amazon.ca/Chrgr-Rechrg-Nizn- ... B002NJUJ2K

- Sabesh.

How long do they hold a charge?

Ok answering my own question not too bad at all....

Long Shelf Life - Superior to lead-acid batteries which will sulfate over time limiting their shelf life, the PowerGenix NiZn battery has a significantly longer shelf life than ordinary batteries with approx 50% residual charge after one year.

Last time I looked, the various pieces were either "out of stock" or "will ship in 2-4 weeks". Since I live on Internet time, I wanted them ASAP. I also had a $50 GC with amazon.com and free 2-day shipping, so the whole purchase (charger + 16 batteries) came out to about $8.50 total, no tax.

Better than regular NiMH's, but not as good as Eneloops. Still, if NiZn's hold a fairly decent charge after even a month or so, that's good enough for me. I just don't want them discharging themselves into oblivion after just a few days sitting on a shelf, like some of my old NiMH's did.

The other concern is the number of recharges they can take before the performance degrades beyond an acceptable limit. PowerGenix claims each cell can be recharged 200 times. Sanyo claims 1000+ cycles for Eneloops. I don't know if both companies used the exact same criteria to determine that number, so it's impossible to tell if they are comparable. Even with 200 cycles, that means I can recharge them every week for almost four years before I have to throw them out and buy new ones. That's fine by me.

I brought my D700 + MB-D10 + 8xAA + SB-900 + 4xAA (all PowerGenix NiZn cells) to the family Christmas dinner.

On the camera side of things, these cells performed much better than the NiMH's I tried when I first got the D700's, which lasted less than 100 shots. I tripped the shutter 551 times tonight. The D700's battery meter does not appear to record estimated capacity or number of shots with AA's, so I don't know how depleted they are. My BC-900 charger shows the cells at around 1.75 volts, down from about 1.85 volts when freshly charged. I'll keep shooting until the camera switches over to the internal lithium ion pack.

On the speedlight side of things, I was quite pleased with the recycle times, but I wasn't blown away by the endurance. I was shooting in a typical suburban home, so not really all that challenging to begin with. I did not want to make things too easy, so I kept the ISO at 400 and shot at f/2.8 or f/4 most of the time, bouncing every flash. I took a couple dozen family group shots at f/5.6 and ISO 200.

The SB-900 shutdown with the low battery indication after 541 shots. But since I don't really know how powerful each flash was, I can't really tell whether that's better or worse than NiMH batteries. Nikon claims 190 full-power dumps with 2600 mAh NiMH batteries, waiting 30 seconds between shots (95 minutes total). This was 541 shots over 4.5 hours at unknown flash power. So that might be good, or it might be bad. It doesn't strike me as being any worse than NiMH's, but I'm not that excited about it either.

It's too bad that the SB-900 cannot estimate the remaining charge capacity on the AA cells, nor can the D700 record flash power in the EXIF information of each shot. The latter would be particularly useful for experiments like this, and also to analyse your own shooting performance for areas of improvement. Alas!

Thanks for the field testing report Taob. That's a huge jump from sub-100 shots to over 551 shots! The NiMH's that you used before, were they the eneloops?

No, I think they were the Energizer 2650 mAh NiMH, which were great in a flash. I didn't really look into why they died so quickly in the camera (and still worked fine in the SB-900 afterwards).

very informative thread...
i'm sure i have a few sets that will need replacing soon

is there a way of testing the "resiliency/life left" of batteries? i have about 20 "sets" of rechargables and i'd kinda like to know which ones are on their way out and which ones still have a lot of life still in them

using groups of energizer 2450s/2500s

tia

Brian if you can get a hold of the manufacturer's discharge curves depending on the technology you could gage the remaining capacity by the voltage on the cell

http://www.powergenix.com/docs/powergenix-specs-aa.pdf

Yeah, I can get a very rough idea of how much usable capacity is left, but those curves assume a constant discharge rate. I don't know how much current a D700 or SB-900 draws. Also, those curves are pretty flat, so it's difficult to pinpoint how, say, 1.6 volts translates into remaining capacity. Also, I can only measure unloaded voltage... I think the graphs in your link show voltage under load.

There isn't too much information out there yet about using NiZn AA's in camera gear, so I'm doing some experimentation myself to figure out how they behave. It looks like when the cells get to around 1.55 v, they are effectively "dead" (just like how my NiMH's get below 1.1 v). A fresh charge puts them up around 1.85 to 1.90 v.

Can't say I'm a fan of 200 recharges before they expire.

Yeah, that's very low compared to the claimed 1000 recharges on Eneloops. However, I don't think I've ever owned a AA cell that I've recharged more than 150 times anyway. I will have lost them or replaced them by then. I keep several sets of batteries so I'm never caught with any dead cells, so they are rotated in and out. On average, I figure each cell is only recharged 15 or 20 times per year. Even 200 recharges will take ten years. Besides, none of the battery manufacturers say what happens when you hit the limit... it's not like the cells suddenly stop working. It's sort of like shutter lifetime ratings in cameras, I guess.

In any case, since I often need faster recycling times, I'd rather have twice the recycle speed and half the lifetime, than the other way around.

Yeap, if the battery is pushing three years, time to replace it. It's not like these things will last 5-6 years and offer the same capacity as day one if you're only charging it once a month.

Also, if the reduction in performance is proportional, NiZn cells may still end up ahead of NiMH. I expect 2.5 seconds or faster with new Eneloops. Maybe that is reduced down to about 4 seconds at best after a few years. Since NiZn's start out at around 1.2 seconds, perhaps they drop down to "only" 2 seconds after a couple of years. That's still better than a brand-new NiMH battery.

There are a lot of assumptions, though, and the PowerGenix batteries have not been around long enough for anyone to report back with real-world numbers yet. I guess I'll update this thread in a year's time.

It does seem whatever batteries I get they are next to useless after a couple of years regardless of the number of cycles, the only exceptions are those big old gel cells using ancient lead acid technology.

Brian for testing I usually measure the voltage while loading the cell down with the correct load resister.

I ran a flash endurance test the other day. The D700's intervalometer was set to fire once every 30 seconds. The SB-900 was set to 1/1 manual power. I set the exposure to ISO 100, 1/250s, f/22 so it was obvious from the resulting images when the flash fired. This ran until the SB-900 reported a low battery warning and stopped firing.

The PowerGenix AA's lasted 143 shots, while the Imedion AA's lasted 184 shots. Given that the charge capacity between the two is approximately 1500 mAh vs 2100 mAh, these numbers make sense.

So the NiZn cells definitely do not have the capacity of NiMH cells yet. I typically can get through 8 hours of wedding coverage on a set of Imedions or Eneloops quite comfortably. Given the above numbers, I might only get 6 hours from NiZn's. But since they recycle much faster, I won't have to change them out as soon, so in reality the endurance may be comparable. I bring several sets of AA's with me anyway, so that won't change.

You made it on Strobist Brian .. congrats!!

http://strobist.blogspot.com/2010/01/ne ... -fast.html

Yep. I was a bit surprised over the lack of information on these NiZn batteries, even though they've been available for almost a year. I decided to do a bit more investigation, and found a thread about them on the Strobist Flickr page. I posted my videos there, and that's where Dave Hobby picked up the links and e-mailed me about including them in a upcoming Strobist post.

D'Oh - you beat me to it. I just started reading this and thought I should mention Brian's work on the subject and as soon as I hit the jump on Strobist.com, there you were!

Nice going Brian!

So, these cells can be charged via third party chargers like your Lacross & Maha chargers? How do you like the Powergenix charger?

I have some doubts. These chargers are made to follow the charging curve of the NiCd/NiMh batteries which I bet is much different than the NiZn.
I think at best you'll get a partially charged battery.

Disclaimer: this is some educated guess, I don't have any actual facts to backup this statement.

Yeah, the thresholds are different on a NiZn cell, and if the charger isn't expecting that, it won't know when to start or stop charging. For instance, when my LaCrosse BC-900 detects at least 1.45 volts across the terminals of a cell, it assumes it is full. This assumption holds when you insert a NiMH AA. But if you stick in a NiZn cell, even when it is "empty" it will report 1.6 volts or higher. Thus, the charger will think the battery is already full, and will not recharge it.

The same goes for determining when to stop charging a cell. Since there is no direct, instantaneous method of figuring how much charge is inside a cell, chargers use other telltale signs that indicate a cell is "full". They might watch for a slight drop in voltage, or a sudden rise in temperature. Those measurements are calibrated for NiMH cells in NiMH chargers. So even if you trick your NiMH charger into charging NiZn cells (which you can with the BC-900), it may not necessarily know when to stop charging them. It might end prematurely, or it might just keep going until the cell explodes and burns your house down.

I haven't linked to this video from anywhere yet, but here is some footage of an SB-900 with an SD-9, filled up with NiZn AA's. Keep in mind that the SB-900 normally takes about 4 seconds to cycle with normal NiMH's, and perhaps as fast as 2.5 seconds with Eneloops. Adding an SD-9 pack with Eneloops brings it down to a 1-second recycle time. But check this out:

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Pretty impressive.