NiZn–NOT!

It’s one thing for the fast recycling NiZn batteries to fail and another thing for the failure to occur at Grandparents’ Day!  After unexpected problems in mid-August, I sorted through my NiZn batteries with a volt meter, discarded a few and gave the remaining ones another try. A month later, I used those batteries at my granddaughter’s birthday party and my confidence in NiZn returned.  Today, six weeks later, two of the four batteries in the 580EX II (right, not yet using the YN565EX mounted on my 7D) let me down.

I admit to not recharging the NiZn batteries last night before using them  today.  I think the last time the batteries were charged was mid-October and they’ve been used for perhaps 10 flashes since that re-charging.  Still, I’m unhappy to get only five flashes from the NiZn batteries today before I noticed my wife waving her arms and mouthing, “The flash is not working!”.  I immediately removed the 580EX II and popped up the little built-in flash in the 7D.  Fortunately, my granddaughter’s small classroom was well lit and, with the 7D set for ISO 1600, the built-in flash generated sufficient fill flash.

Why didn’t I simply change batteries once I realized that the NiZn’s had failed?  Because I foolishly, but intentionally, left my camera bag in the car – that’s why.  I didn’t even drop a spare set of batteries in my pocket.  After all, we were only to be there for an hour. 

Tonight I checked my supply of NiZn batteries.  Of the 13 spare batteries, 2 were bad.  So of 17 total NiZn batteries, 4 were found bad today.  For all I know, the remaining batteries are fine but I no longer have faith in NiZn.

PowerEx 2700 mAh NiMH batteries served me well for several years and were my battery of choice before NiZn.  I’ve also tried Sanyo Eneloop 2000 mAh batteries.  The Eneloop batteries definitely hold a charge longer than the PowerEx but also do not produce quite as many flashes.  My strategy now is to first use PowerEx but to have the Eneloops in my pocket.  Of course, I can’t really bring myself to toss out all those NiZn batteries so I’ll keep them around for a while as unreliable extras.

Signing off to order Eneloops …

Pixel TD-381 Battery Pack

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Continuing my current fascination with batteries for external flashes, it was only natural to try an external battery pack. In addition to recharging the flash more quickly, an external battery pack provides more flashes without changing the batteries. After a bit of browsing and reading in POTN, I decided on the 3rd party Pixel TD-381 rather than the more expensive Canon CP-E4. I was especially curious as to how an external battery pack would compare to the rapid recharge from NiZn batteries.


Whereas the NiZn batteries will fit into any flash that uses standard AA batteries, an external battery pack requires a special connection on the flash. Not all flashes have this special connection but my Canon 580 EX II has it. My old Nikon SB-24s also have a connection for external batteries but, of course, the Canon and Nikon connections are different. I decided to order the version for the Canon and also decided to order from a US supplier, Cheetah Stand, instead of an eBay supplier -- just in case something went wrong.

As shown above, the TD-381 is a hard plastic case with connection cable and a cloth carrying case. The carrying case has a belt loop; the cable is long enough to reach the flash when the TD-381 is belt mounted. The plastic case has a hole through it so that it can be attached to the bottom of the camera; a thumb screw is included.

The TD-381 holds eight AA batteries that are wired into a “dual circuit” charging system. The batteries are in a tray that is removed for changing batteries. I'd read of problems with flimsy latches and loose battery connections but mine seemed fine. The tray can only be installed in the proper orientation.

So, how well does it work? I installed eight freshly charged NiMh AA cells and tested the TD-381 in the same manner as I did the NiZn batteries. That is, I fired off five shots as quickly as the 580EX would indicate it was charged. In previous tests, the 580EX with NiMh batteries could get off five shots in 15.7 seconds or 8.1 seconds using NiZn batteriers. With the TD-381, I could get of five shots in 5.9 seconds. Naturally, I couldn't resist putting the NiZn batteries into the TD-381. Using NiZn batteries in the TD-381, the time required for five flashes was reduced to only 5.5 seconds!

Repeating my warning: Be patient and don't fire off many shots in a short time because the flash may overheat!

I normally have no need for rapid fire flash or even for hundreds of flashes in event photography but now have the equipment to do so. My plan is to use the NiZn batteries installed in the 580EX for normal use and, when necessary, use the NiMh batteries in the TD-381.
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NiZn in the Canon 580EX II Flash

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After a few other tests, I finally felt brave (or foolish) enough to try the NiZn batteries in my Canon 580EX II flash. Before trying the NiZn batteries, I checked the performance of standard 2700mah PowerEX NiMh in the 580EX II at full power. With the flash mounted on my 7D and both flash and camera in full manual mode, I photographed the XNTimer on my computer screen. My procedure was to get off a shot as soon as the ready light of the flash came back on. Five shots took 15.7 seconds.

Next, the NiZn batteries were installed. Five shots took 8.1 seconds.

From this and a few other tests, my conclusion is that the recycle time with NiZn batteries is roughly half the recycle time of NiMh batteries.

I intend to further test these NiZn batteries in normal use and will report the experience.

Again, a warning: Be patient and don't fire off many shots in a short time because the flash may overheat.
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NiZn AA

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The cryptic title for this post will be very readable to a few die-hards (pun intended) and perhaps become increasingly recognizable in the future. This post is about the rechargeable nickel-zinc size AA batteries that I just could not resist.

The great thing about NiZn batteries is that each battery has a nominal voltage of 1.6V. In comparison, the old zinc-carbon and alkaline batteries are 1.5V; nickel-cadmium (NiCd) and nickel-metal hydride (NiMh) are 1.2V. Although there is a lot more to batteries than voltage, higher voltage can mean better (usually meaning faster or longer) performance in some devices.

The bad thing about NiZn batteries is that each battery has a nominal voltage of 1.V. This higher voltage can damage some devices.

Cowardly Disclaimer: These NiZn batteries can damage your equipment. Don't blame me! 

My interest in NiZn was initialized months ago by a now-forgotten discussion thread somewhere on the Internet claiming that recycle time on battery powered external flashes could be halved or better by using NiZn batteries. The unfortunate side effect – quickly pointed out – was that NiZn batteries recharged the flash so quickly that there was no time to cool and the flash “burned out” or went into a thermal overload lockout. The possibility of losing a flash for the sake of a few seconds kept me from buying NiZn at the time but the temptation did not go away. Finally, I conceded and placed my order.

I just received a set of four PowerGenix NiZn AA batteries with their own special quick charger. It is not recommended to charge NiZn batteries in NiCd or NiMh chargers or to charge other battery types in the NiZn charger. Each battery is marked 1.6V; 2500mWh. Note that 2500mWh is not exactly the same thing as the more standard 2500mAh listed on some NiMh batteries because the NiZn voltage is higher. The NiZn batteries are green in color because (I suppose) they are 100% recyclable and also non-toxic (according to the packaging).

As the batteries came inserted in the charger and I was anxious to get them charged, I immediately plugged it in. To my dismay, the LED lights blinked and then went off. Nothing. Tried again, again nothing. Then I noticed and removed the small strip of plastic preventing the batteries from making contact. The red LED came on. After about an hour the green LED came on to indicate that the batteries were 80% charged. This is the “quick” portion of the charging cycle. The charger, said to be “intelligent”, then changes to a slower “trickle” charge. Charging is complete after four hours. The batteries did not feel hot during charging (but I did not keep my hand on them).

According to my handy little multimeter, the freshly charged NiZn batteries were all 1.87V whereas my usual PowerEx NiMh batteries are 1.36V (open circuit voltage). But would the NiZn flash and destroy?

Taking a deep breath, I picked up my Canon 580EX II flash – no, wait a minute; how about that old Nikon SB-24?  I set the SB-24 on manual and full power. With one finger on the SB-24 trigger and another on a stop watch, I got 3 flashes in about 10 seconds with PowerEx NiMh batteries. The NiZn batteries could trigger 3 flashes in about 5 seconds – noticeably faster. They work!  No smoke!

For more information, check out the Wikipedia article on NiZn batteries.  Meanwhile, I'll do a few more tests without attempting to set the world record for flashes per minute.
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