I just bought a BC-900 from thomasdistributing.com about a month ago and I’m loving it.
If you’re thinking about getting one, there are some precautions to be taken, though.
This charger uses a -dV primary charge termination algorithm, so it’s highly, highly recommended that you don’t charge at a rate below C/3. It’s actually better if you charge anywhere between C/2 and 1C. That means for a 2000 mAh battery, your charging rate should be at least 1000mA (C/2) but not greater than 2000mAh (1C). If you don’t do this, you run the risk of missing charge termination and damaging your batteries to the point that you’ll get way fewer cycles out of them.
Also, the circuitry inside this charger is pretty inefficient, so quite a bit of heat is generated at higher charge rates. It’s a good idea to prop the back of the charger up on something to increase air flow under it. Otherwise, you’ll get your batteries so hot that the thermal cutoff point will be hit and charging will temporarily stop to let the cells cool.
And finally, there have been several reports of people with firmware v32 having melted batteries and charger because of the aforementioned thermal problems. Please make sure that you get this charger with v33 firmware. The thermal cutoff is lower and therefore safer on the newer version. I don’t know about amazon, but thomasdistributing only keeps the latest firmware version in stock.
Anyway, it’s just good to keep in mind that all rechargeables are somewhat dangerous, especially so when charging. NiMH are not nearly as dangerous as Lithium-based chemistries, but it’s still a good idea to keep an eye on your batteries when they’re recharging.
Great writeup, as always Jeff. I completely agree that Eneloops or any other hybrids with low self-discharge are the way to go.