You can get the newer version at Amazon, which now can charge at rates up to 1.8 amps!
This is the best battery charger I've ever used, and I've been using and designing them since the 1970s. It's a great, intelligent, flexible battery charger for AA and AAA Ni-MH and Ni-Cd batteries.
It also measures capacity and can rejuvenate and improve the performance of your batteries.
Separate AC power adapter, 100 - 240 V 50 - 60 Hz (runs anywhere on Earth with the right passive travel adaptor)
You may choose the charge rate: 200, 500, 700 or 1,000 mA. Default is 200 mA.
Discharge rate is half the charge rate: 100, 250, 350 or 500 mA. Default is 100 mA.
Comes with four AA and four AAA Ni-MH cells. It also comes with passive adapters to let you use AA cells in items that require C or D cells, and a great case to carry it all.
It determines end-of charge both by temperature and voltage drop.
Discharge cuts off at 0.9V per cell.
Also reads and tests the accumulated capacity of cells in most modes.
Solid Chinese construction. Simple operation, it's easy to figure out with the manual. The AC adapter seems to be an efficient switching unit; it doesn't get hot when left plugged in unused.
Four discrete charging channels, each with its own LCD display. Each cell is separately charged and discharged and measured. If you're really good you can configure other channels with new cells while another channel is working with another cell. If you're not as good you'll mess up and have to start everything from scratch.
No charge status LEDs: you have to read the small LCD for each cell to see if it's charging, discharging or done. I would have preferred LEDs for each cell: red for charging, amber for discharging and green for done. Oh well.
The LCD has a lot on it, and separate displays for each cell. The LCD is hard to see at some angles, like low across a desk.
It shows alternately:
Time on charge or discharge in hours and minutes
mAh display reads in units of 1 mAh up to 1,999 mAh, then in 0.01 Ah up several Ah. Thus some AA cells might read 1,653 mAh, and above 1,999 mAh will read something like 2.35 Ah.
The BC-900 will not charge a completely drained cell. The display will say "null" when you insert a totally dead cell and simply ignore it.
If you manage to charge the cell enough to get its voltage to 0.5 - 1 volt, then the BC-900 will charge it. The best way to do this is to pop it into a less sophisticated charger for a little while first.
If you don't have another charger, you can pull a little trick that may help (or may blow up your house). Here's how:
1. Unplug the BC-900.
2. Place a good cell and the dead cell next to each other.
3. Short the (+) terminals of the two cells together with a 1 Ohm resistor (or paper clip if you're man enough) for a few seconds. This will throw current into the other cell - WARNING: if the other cell is shorted and you use a paper clip or your keys, the whole mess could melt, burn your fingers, catch fire and burn down the neighborhood.
4. Remove the link.
5. Plug in the BC-900 and all ought to work properly.
It really works and works well. I was able to rejuvenate some old unused cells. I was able to improve the capacity of my five year old ones that I use all the time. I was able to confirm my suspicions that one brand of cell I had which never seemed to give me much run time on a charge really only had less than half its rated capacity.
Buy one if you want to keep your batteries in top shape and also want to test and monitor their performance.
Buy one if you have older or less used batteries to keep in shape.
Skip it if you just want something tiny to throw in a travel bag. This LaCrosse unit is bigger and has a separate AC adaptor. For a compact unit see this one that I use. I take the travel charger with me and keep the LaCrosse at home.
This charger always sits on my desk ready to charge whatever I've brought home at the end of the day. I always use the "discharge" mode, so regardless of the charge state of my batteries they'll be discharged and charged fully, which makes them happiest. Much more about batteries on my battery page here.
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