Valokuvaaja Ville-Veikko Tulkki

Mulle täsin tuntemattomuudesta tuleva firma on julkassu uudenlaisen sarjan ladattavia akkuparistoja. Noiden erikoisuus normaaleihin paristoihin verrattuna on noin 1.6v jännite joka on 0.4v suurempi kuin tavallisten ladattavien paristojen. Tavalliset alkaliparistot antavat noin 1.5v jännitteen ulos, mutta ne eivät anna tehoa ulos aivan niin nopeasti kuin mitä akut.
Strobistissa on huomattu näiden paristojen kätevyys esim. salaman latausaikojen lyhentämiseen. Hillittömän nopeasti tuntuu tuo videon sb-900 lataavan itsensä täydellä teholla, reilu sekunti ja taas saadaan täysi teho ulos. Haittapuoliakin tuolla on lämmöntuotannon muodossa, toisen videon sb-900 kestää 13 nopeaa väläystä täydellä teholla ennekuin salaman oma lämpörele pistää pelin poikki, salaman kärtsääminen on siis jo aivan oikea riski varsinkin niiden salamien kanssa joissa tuollaista relettä ei ole.

amazon
$20/8kpl

Käyttäjän kommentti amazonista:

[Energy Density]
The PowerGenix AA cells are marketed as “2500 milli-WATT-hour” (energy capacity). Most people may confuse this with “2500 milli-Ampere-hour” (charge capacity). But the data sheet for NiZn AA cell shows that its current capacity is only 1500mAh (this is verified by my own testing). It turns out that an 1500mAh NiZn cell actually contains the same amount of energy as a 2000mAh SANYO eneloop AA cell:

- Energy in eneloop AA cell: 1.25V * 2000mAh = 2500mWh
- Energy in PowerGenix AA cell: 1.65V * 1500mAh = 2475mWh
…

[Cycle Life]
Technical data found on PowerGenix web site says NiZn cells are rated for 200 cycles (at 100% deep-discharge). This is much shorter than the 1000 cycles cited for eneloop cells.

I have tested a set of 4 PowerGenix AA cells. After subjecting them through 12-16 deep discharge cycles, the average charge capacity already dropped 5% from original value. In comparison, I have a set of 4 eneloop AAA cells that have went through about 100 cycles in the past 2.5 years, and they still exhibit over 95% of original capacity.

[Self-Discharge Rate]
In my long-term storage test after two months, a set of four NiZn cells retained 74% original charge capacity on average. This translates to about 13% loss per month, which is much better than that of ordinary high-capacity NiMH batteries (with capacity > 2500mAh). But it cannot compare to low-self-discharge NiMH cells.

Previously, I have conducted storage test for several brands of LSD cells, including Sanyo eneloop, Rayovac Hybrid, and Kodak Pre-Charged. All those cells can retain 85-90% of original capacity after FIVE months in storage.

[Recharging Time]
The PowerGenix NiZn cells must be recharged using a specially designed PowerGenix NiZn Charger. The charger is called ‘1-hour’, but it actually takes 2.5 hours to fully recharge a set of four 1500mAh cells.

Eneloop (and all other brands of LSD cells) can be recharged using any good quality ’smart’ NiMH charger. Depending on which charger you use, the charge time can be as short as 15 minutes, or as long as 8 hours.

[BOTTOM LINE]
The only verifiable benefit for PowerGenix NiZn cell is its higher operation voltage. However, even this may turn out to be a curse rather than a blessing, as higher voltage can cause unregulated appliances to burn out.

If you have a digital camera that works well with eneloop, stay with it. Switching to NiZn will not offer more power nor longer run time. Only if your camera does not work well with eneloop, then it is worthwhile to try NiZn cells as a last resort. But you better contact PowerGenix, and ask whether they will assume warranty liability for the use in your camera. Otherwise, try it at your own risk!

Strobist