Robert’s Photography Blog

The La Crosse AlphaPower BC-900 Battery Charger has been getting rave reviews from users. The term ‘charger’ is a bit of a misnomer. That’s because it’s not only a battery charger but also a battery tester and battery refresher. It has four modes: charge mode – slow or fast charging with selectable current; discharge mode – fully discharges the battery before charging; refresh mode – discharges and recharges up to 20 times to bring old batteries back to life; and test mode – measures a battery’s discharge capacity. All modes switch to trickle charge at the end of the cycle.

Before the BC-900 came on the market, photographers were at the mercy of the battery manufacturers. Whatever was printed on the battery label, we assumed to be the capacity. The fine print was always suspicious. Terms such as ‘nominal capacity’, ‘typical capacity’, and ‘minimum capacity’ were rarely defined. Only a few geeks with expensive or homemade test equipment were posting independent test results. We had only field experience to go by. Now all that has changed!

I have had a BC-900 for about six months now so I can offer you some advice to shorten the learning curve. Here are some tips:

Tip #1: Use 500mA as your standard current for charging high capacity AA batteries. The BC-900 default charge current is 200mA. In my opinion this charging current is just too low (less than 10% capacity for 2,500mAh batteries) and probably is a legacy setting.

Do you really want to wait 14 hours to charge a set of batteries? At 500mA, charging takes about 5 hours and generates minimal heat. Even 1,000mA is still below the current used by most ‘fast chargers’ on the market. Once the batteries are charged, the BC-900 automatically applies a trickle charge current so you can leave a set in the charger ready for quick use.

Tip #2: Use the refresh mode to test battery capacity. It has been established that a new set of batteries require several charge/discharge cycles to achieve full capacity. The BC-900 will do this for you automatically. (Note: Discharge capacity can only be measured in the Test Mode or the Refresh Mode.)

I recommend setting the discharge current to 500mA, and then the BC-900 will automatically set the charge current to 1,000mA. Thinking about lower currents? Think twice! Even with discharge/charge of currents 500mA/1,000mA, a new set of NiMH AA batteries can take 2-3 days to reach a consistent capacity. Ok, if you don’t mind waiting nearly a week – use 250mA/500mA. Worried about excess heat ruining battery life? The BC-900 has a temperature sensoring circuit that interrupts charging at 127^oF until the batteries cool to a safe temperature.

Tip #3: Use the measured capacities to sort your batteries. The better ones can be grouped together and used for more critical applications. For example, I measured the capacities of (8) Sanyo 2500 AA batteries. They ranged from 2,420mAH to 2,520mA. Four of the eight measured over 2,500mAh.

Regardless of the time required, one might ask ‘what are the test conditions that best simulate real life applications’? Digicams drain batteries continuously at low currents during use. A Speedlite flash, however, grabs power at the max discharge rate briefly to refresh a capacitor. No test protocol will perfectly simulate the various discharge conditions required by different devices. That said, a discharge current of 500mA applied continuously will drain a set of 2500mAh batteries in about 5 hours. This is a reasonable simulation of real life. And, applied consistently to different batteries will allow us (at least) to evaluate which batteries will last the longest or which batteries offer the best price/performance ratio.

I won’t list minor complaints about the BC-900. You can find those in the photography forums. Only one glitch is worth mentioning though. The BC-900 refuses to charge over-discharged batteries. That is, batteries with less than zero volts. The BC-900 simply displays ‘NULL’. You need to charge them for a few minutes in (yes) some other charger.

For me, the reasonable price of BC-900 offsets the minor design and operation flaws.

The BC-900 is available at EastGear if you live in Singapore or from Amazon.com if you are in the USA or Canada. The power supply is universal (100-240v, 50-60 cycle) so (with a plug adapter not included) you can use this device anywhere in the world. It comes with a nifty black travel bag as well as ‘C’ and ‘D’ size battery adapters. Included in the box are also a set (4) AA La Crosse 2000 and a set of (4) AAA La Crosse 700 (Mignon) rechargeable batteries.

A copy of the La Crosse BC-900 Instruction Manual (pdf format) can be download here: Instruction Manual.

Shop for the BC-900 on eBay.
Are you in the UK? Go here.

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