Introduction
It's no secret digicams eat batteries, so rechargeable NiMH AA cells are a must if your camera takes that battery size. I've been playing around with batteries and chargers quite a bit lately (early Fall, 2001), and have discovered that having the right charger is at least as important as having the right batteries! Some chargers overcharge and can damage batteries, others drastically undercharge, making your high-capacity NiMH cells little better than garden-variety cheapies.

While my favorite charger (at least so far) for the NiMH AA cells I typically use is the Maha/Powerex C-204, there's another charger in the Maha/Powerex family that could be just the ticket if you also have a camcorder in the household. - The Maha/PowerEx C-2000 can not only charge standard NiCd or NiMH AA or AAA cells, but also handles a wide variety of other batteries, including Canon, JVC, Panasonic, Sharp, and Sony LiIon camcorder packs.

In the Box
Like many of the Maha/Powerex chargers, the C-2000 comes with both the usual wall-wart power adapter, as well as a cigarette lighter adapter as standard equipment. Very handy for trips! Internet battery experts Thomas Distributing also carry some European power adapters, if you're going to be traveling to a country with 220v power instead of the 120v we have here in the US.

Versatility
At least in terms of battery type and voltage, the C-2000 can handle just about any battery you're likely to throw at it. About all it can't manage is low- or high-voltage packs outside its 4.8 to 12 volt range. It handles both NiCd and NiMH cells, as well as LiIon rechargeables as used by many camcorders. (And when charging the LiIon cells, it's a good bit faster than most manufacturer-supplied chargers, with a charging current of 780 mA.) Here's a list of the types of batteries you can charge with the C-2000:

The photos above show some of the mounting points on the C2000 for various battery packs, and a Sony NP-F530 battery being charged.

What it can't handle:
There are unfortunately a few battery types I'd really like for the C-2000 to handle that it doesn't, at least not directly. Many of the new Sony digital still cameras use smaller LiIon packs (the "M" and "S" battery sizes) that the C-2000 doesn't have mounting points for. I've successfully charged both of the smaller Sony packs with the C-2000 by (carefully) connecting clip leads between the 7.2v terminals on the "Sony" mounting point and the terminals of the battery pack. (The small alligator clip leads sold by Radio Shack are just large enough to grab the spring-loaded terminals on the C-2000, and just small enough to jam into the hollow terminal ends on the Sony M-sized batteries. (S-sized batteries are a bit more of a challenge.) This worked quite well for me, but I'm not sure I'd want to recommend using clip leads for my non-geek readers...

Charging
The C-2000 is a "smart" charger, which means it applies a high rate of charge to the batteries when first inserted, then cuts back to a "trickle charge" when peak voltage is reached. Fast-charge current is 780 mA for battery packs, and 400 mA for AA or AAA cells, about as fast as you'd want to dump charge into the batteries. Once maximum charge is reached, the charging current drops to 40mA, a gentle level that can easily be tolerated by most any good-quality NiMH battery on the market. - You can probably get away with leaving high-quality NiMH batteries in the C-2000 indefinitely, but the 40mA maintenance current is a bit high for optimum charge retention. (You'll end up with your batteries in a perpetual state of slight overcharge, reducing their capacity.) LiIon batteries use a "smarter" charging algorithm, meaning that there's very little charge applied to the pack after it hits "full", so indefinite connection shouldn't be a problem there either. (Although the lack of self-discharge in LiIon packs means there's no need to leave them trickle-charging once they're fully charged.)

The "smart" charging means you can safely use the C-2000 to "top off" the NiMH cells from your digicam if you're about to head out with it, without worrying about over-charging them. (Although they will get hotter than cells brought up from empty.)

Depending on the capacity of the batteries you're charging, the C-2000 can bring a set of AA cells from "empty" to fully charged in three to five hours. (Figure five hours for the latest, high-capacity NiMH AAs.)

I'm hoping to do a more comprehensive set of tests on battery chargers in the near future, testing them for completeness of charge. - In my tests to date, I've found great differences between chargers in how completely they charge batteries. (The differences between chargers are much greater than between batteries of various capacities. The highest capacity NiMH AA cells on the market in the wrong charger will give you less run time than the poorest set in a good charger.) I don't have this information collected yet, and indeed it'll likely take me another month or two of running life cycles on batteries to develop accurate statistics in this area. Our preliminary results on the C2000 show that charge completeness is its achilles heel, at least with NiMH cells: It looks like it only brings cells up to about 60% of their maximum capacity when used by itself - Not nearly as good a job as its little brother the C-204F. With most any charger, I strongly recommend getting a couple of Maha's dirt-cheap 4-cell trickle chargers to just park your NiMH batteries in for storage - These little chargers do a great job of keeping the batteries "topped off", without overcharging or damaging the cells. They're also a great way to insure that you've got batteries that are running at 100% of capacity, in the face of other chargers that don't get them quite all the way there themselves. When used in conjunction with the 2A4 chargers, the C2000 is a good charger, bringing batteries up to that 60-65% charge point fairly rapidly, while not overheating them at all. Transferring the batteries to a 2A4 trickle charger at that point produces maximum capacity overnight, with very low stress to the batteries. - This sort of a two-step charging process may be more than some users want to deal with though...

Conditioning
Of greatest importance for NiCd users, but still useful for NiMH cells, the C-2000 includes discharge circuitry for thoroughly "conditioning" batteries to prevent the "memory" effect. Memory effect happens to NiCd cells when they've been repeatedly charged after being only partly drained, or when they've been left on a too-high trickle-charge for long periods of time. The batteries "remember" the amount of charge they've routinely received, and refuse to deliver more than that amount, even though their rated capacity may be much higher. This robs batteries of power capacity, reducing the maximum charge the batteries can deliver. Draining them fully to about 1.0 volts/cell helps restore full capacity.

There's some debate by the experts as to whether memory effect is real or not. We aren't equipped to get into that debate, but in our own experience have certainly seen NiCd cells lose capacity that was restored by a conditioning cycle or two.

Gentleness
This is an odd heading title for a battery charger review, but it's an important one if you want to get the maximum life out of your batteries. Some chargers seriously overheat batteries, which can shorten their life. Some (fairly significant) temperature rise is normal in charging batteries, and shouldn't cause a problem. Too much will definitely lead to early exhaustion. The C-2000 is quite a bit better average in this respect. The batteries get only slightly warm to the touch when they're charging, not nearly as hot as other chargers we've tested.

Operation
It couldn't be much simpler - With the charger plugged into its power source, insert four AA or AAA cells and away you go. The charger immediately begins rapid-charging the batteries, and the first indicator LED lights yellow. As the charge cycle progresses, the second yellow LED will light. When full charge is reached, the red LED lights up, and the charger beeps to indicate that its charge is complete. For NiCd or NiMH batteries, there's a "Discharge" button that starts the conditioning cycle. - As you can see from the photo below, there's not much in the way of controls to deal with!

When the rapid charge is complete, the C-2000 is supposed to switch to a 40 mAh maintenance trickle-charge. This should be enough to bring the batteries up to 100% charge and keep them there. In our testing though, there seemed to be little additional advantage to leaving the batteries in the charger overnight, so we wonder whether the trickle charge was operating on our test unit or not.

From the user's viewpoint, the process for charging LiIon battery packs is virtually identical to that for NiCd or NiMH cells. Internally, LiIon charging is very different. (NEVER try to charge LiIon battery packs on a charger not designed for them - Besides permanently damaging the expensive LiIon pack, there's a fire hazard as well!) The C-2000 automatically detects the type of pack attached to it, and adjusts its charging protocol accordingly. In the case of LiIon packs, the charger delivers current in little spurts, checking the battery's voltage in between. Once the pack is fully charged, it can be removed: There's no need for trickle-charging with LiIon batteries.

Cost
Pricewise, the C-2000 is a midrange charger, with a "street" price of about $45. A little pricey for just a AA charger, but dirt cheap when you consider its ultra-versatile NiCd/NiMH/LiIon capabilities.

Bottom Line
If all you use is AA NiMH batteries, the C-2000 is a little pricey, particularly in that it really needs to be used with a trickle-charger to achieve and maintain maximum charge. On the other hand, if you also have a camcorder with a battery pack ranging from 4.8 to 12 volts, it's a slam-dunk choice. Alternatively, if you're looking for a very gentle battery-charging system that'll get the maximum life out of your NiMH cells, combining a C-2000 with Maha's little 2A4 trickle charger works really well.

Ratings
As we go through various chargers on the market, we'll rate them in various areas. Here's now the Maha/PowerEx C-2000 stacks up:

Purchase/More Info
Here's a link to a Maha distributor, with a good price on the C-2000 charger.

For more info on the charger, here are some links to Maha's site:

Power & Batteries Q&A!
Questions about batteries, power, chargers, etc? Visit our Batteries & Power discussion thread! Questions or feedback on this review? Email us at [email protected].