Автор: GenaDP
Дата: 10-02-09 13:12
1. SIZE:
First thing you'll notice is that the Maha C9000 is HUGE for a 4-AA-cell charger. It is about twice as large as the BC-900 (see my Customer Image for size comparison).
Larger size makes the C9000 less suitable as a travel charger. However, as a home charger this is actually an advantage. Extra spacing between cells allows better cooling, and also makes it easier to remove individual cell.
2. CHARGING CURRENT:
The BC-900 can provide charging current from 200 to 1000mA for 4 cells, or up to 1800mA for two cells. The C9000 can charge from 200 to 2000mA for all four cells. So if you routinely need to charge cells in a hurry, the C9000 is better.
However, due to the complicated key sequences involved (for example, to charge 4 cells at 2000mA, you need to punch in 48 key strokes!), most sane people will probably leave the C9000 at its default current of 1000mA.
3. DISPLAY:
The BC-900 has a 4-column LCD panel that shows the status (capacity, voltage, current, or time) of all four cells either simultaneously, or individually. The C9000 sports a LCD display with back-light. It is BIG, it is BRIGHT, and it works really well - as a NIGHT LIGHT!
The biggest problem with the C9000's display is that it can only show one status for one cell at any one time. It constantly toggles from one status to another, then from one cell to the next. If you have 4 cells in the charger, it takes 48 seconds or more (depending on the current activity) for the display to cycle through all 4 cells. There is also no way to pause the display. So if you missed one reading, you have to wait for it to cycle through again.
4. ANALYZING / CONDITIONING FUNCTIONS:
The BC-900 has an easy-to-use 'DISCHARGE/REFRESH' function that can be used to recondition old cells. The C9000 has a similar function called 'CYCLE', but it is very tedious to use (see the USER INTERFACE section for details).
In addition, the C9000 also has a 'BREAK-IN' mode which supposedly should be applied to new cells before first use, or to really old cells that have not been charged for years. Beware that this operation takes at least 39 hours to complete, so I doubt many people would actually use it.
5. DEAD CELL DETECTION:
If a cell is completely drained (battery terminal voltage drops below 0.5V), the BC-900 thinks it is shorted and therefore refuses to charge it. This has caused a lot of frustrations among users, but there is a way to work around it (see my BC-900 Customer Image for details). The C9000 is smarter in this aspect. If the battery terminal voltage is too low, it automatically starts charging at 125mA until the voltage rises above 1V, then it continues with the programmed charging current.
The C9000 also measures battery internal resistance when a cell is first inserted. If the user inserts an alkaline cell (which has much higher internal resistance), the C9000 displays 'HIGH' and refuses to charge it. This is a good safety feature, except that it also incorrectly rejected most of my NiMH cells bought four or five years ago. So I cannot use the C9000 to charge or recondition those old cells, even though the BC-900 reports that they still have around 1000mAh of capacity left.
6. USER INTERFACE:
With the BC-900, you can select the operation and current for all cells simultaneously, or you can change them indivdually by using the cell-selection buttons. The only limitation is that once the charging current is fixed, you cannot subsequently select a larger current without removing all cells.
The C9000 has four completely independent charging circuits that can be programmed to different currents. This may sound great at first, but in practice it soon becomes a burden, because you often need to press dozens of key stokes to program all four cells.
For example: If you want to recondition four cells on the BC-900, you'll go through the following sequence:
- insert in all 4 cells at once
- press MODE to select DISCHARGE/REFRESH (2 keystrokes*)
- press CURRENT to select charging current (2-3 keystrokes)
* Note: need to press and hold MODE for 1 second for the first keystroke
On the C9000, you can insert in all 4 cells at once, but you have to program them one at a time. Which means:
- press UP/DOWN to select 'CYCLE', then 'ENTER' (2-5 key strokes)
- press UP/DOWN to select charging current, ENTER (1-11 key strokes)
- press UP/DOWN to select discharging current, ENTER (1-6 key strokes)
- press UP/DOWN to select number of cycles, ENTER (1-13 key strokes)
Congratulations! You just finished programming the first cell. Now repeat that for the other three cells.
BOTTOM LINE:
The Maha MH-C9000 is, without a doubt, the most powerful NiMH AA battery analyzer/charger in the consumer market. However, certain design issues (such as a single-status LCD panel and ridiculously long programming sequences) make it difficult to use for multiple cells. For most of my routine charging and maintenance of NiMH cells, I'll continue to use my old La Crosse BC-900.
Nevertheless, I don't regret buying the C9000, because it was a lot of fun for me to try out all its functions. Plus I now have a really cool (but expensive) night light.
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