Robert’s Photography Blog

In an earlier post, Robert promised more detailed information on the new Sanyo 2700 rechargeable battery. I considered testing them in a flash unit or digicam. However, such an experiment is too difficult to implement meaningfully. Therefore, I decided to measure the capacity of the batteries in the conventional way. Measuring rechargeable battery capacity is much easier to do since the La Crosse AlphaPower BC-900 Charger came on the market. It is available at EastGear if you live in Singapore or through Amazon.com if you live in the USA or Canada.

Now for the good news! A new set of (4) Sanyo 2700 NiMH batteries were measured at 2,654mAh +/-3% with an end voltage of 1.46V. Sanyo does claim the batteries have a nominal capacity of 2,700mAh; however, they also give a minimum capacity of 2,500mAh. A previous study of lower capacity rechargeable AA NiMH batteries yielded capacities often well below their nominal capacities. Some credit goes to using the charger/tester in the refresh mode. I noticed that the batteries did not reach maximum capacity until they had been through several discharge/charge cycles.

Important: The LaCrosse BC-900 does its discharge and measurement in the Refresh Mode immediately after fast-charge termination, which means there’s still a little bit of capacity left that could be filled by extra time spent trickle charging. The capacity could be boosted by an additional 50mAh or more by leaving the battery on tickle charge for an hour or so after the initial charging is finished.

Sanyo OEM batteries: Some of the rechargeable batteries sold under the labels Energizer, Kodak and Sony are manufactured by Sanyo. Sony batteries from Sanyo have “HR” imprinted on the bottom of the battery.

GE/SANYO: Sanyo NiMH batteries are available in the USA under the GE/SANYO label. The GE/SANYO 2700 NiMH batteries are available here.

Addendum (April 8th, 2006): I have tested a new set of (4) Sanyo 2500 NiMH batteries using the same tester and conditions. They had a measured capacity of 2,468mAh +/-1%. Also, see the Battery Round-up page.

Addendum (May 27th, 2006): I have posted tips for using the LaCrosse AlphaPower BC-900 Charger here.

Notes: Batteries were tested using the LaCrosse BC-900 in the ‘Refresh Mode’. I used a charge current of 1,000mA (0.4C) and a discharge current of 500mA (0.2C). Capacity (C) is measure by discharging the battery to an end voltage of 0.9V under constant load. Batteries were repeatedly discharged and charged until the capacity was stable. The discharge current is similar to that used by the manufacturers to spec their batteries. Also, manufacturers use a lower charge current over a longer time. IMHO, not practical for routine use.

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