Bests & Worsts Reviews from Amazon

[Full Disclosure]: Several months ago, a distributor sent me (unsolicited) two pre-production units of BT-C2000 Battery Charger Tester Analyzer for my feedback. I was reluctant to write this review since it may give people the impression that I'm now accepting free samples for 'honest' reviews. However, since I already spent time playing with this charger, I might as well share my findings for the benefit of others. Just keep in mind that the following observations are based on pre-production models. [End Disclosure] I have purchased several advanced battery charger/tester/analyzer in the past 7-8 years, including the La Crosse BC-900, BC-700, BC-500 , BC1000, Maha MH-C9000, AccuPower IQ-328 and BM200. Unfortunately, they all have either design limitations or features that I miss. The BM200, in particular, looked most promising as it combines the best features between BC1000 and MH-C9000. But it failed to become my ultimate 'go-to' charger due to poor thermal management. The BT-C2000 Battery Charger Tester Analyzer can be viewed as the 'version 2.0' of BM200. With new firmware and circuit board design, it claims to have solved the thermal problem, and added some useful refinements to the user interface. Here are my findings on this charger: [EXTERIOR] From the outside, the BT-C2000 looks exactly the same as the BM200. That means it is sized right in-between BC1000 and MH-C9000. The way to distinguish BT-C2000 from BM200 is to check the firmware version. During power up, the leftmost window shows a "2.0" briefly. [Power Supply] The BT-C2000 charger unit is powered by a 12V supply from AC wall unit, similar to that for BM200 and MH-C9000. They all share the same 2.1/5.5mm barrel plug, so I can freely interchange the adapters. The BC1000, on the other hand, requires a 3V supply to operate, so it cannot operate directly from 12V car battery through a cigarette lighter adapter. All AC adapters are designed for 100-240V AC input. [DISPLAY] The LCD display is identical to that of the BM200. It has four independent columns, showing the status of all four cells at once. This is much better than the MH-C9000's single-column display, which can only display one parameter of one cell at any one time. The display has a backlight which automatically times out after 10 seconds of inactivity. This is an improvement over both BC1000 (no backlight) and MH-C9000 (backlight stays on). [CHARGING CURRENT] The default charging current has been increased from 200mA (in BM200 and BC1000) to 400mA. This is a most welcomed change, since the new default current works well for both AA and AAA cells. In contrast, the BC1000's default current of 200mA is too low for AA, while the MH-C9000's default of 1000mA is too high for AAA. Naturally, you can press the CURRENT button to change all charging currents in 200mA steps (400 -> 600 -> 800 -> 1000 -> 200) before charging starts. When charging only two cells in slot#1 and 4, the charging current can be increased to 1200 or 1400mA. You can also select any one cell using the SLOT button, and adjust its current independently. Unlike the BC1000, you are free to choose current higher than that used by previous cells. [FUNCTIONS] The BT-C2000 shares similar features found in BC1000 and MH-C9000. The operation is controlled by pressing the MODE button: - CHARGE - DISCHARGE - REFRESH (called CYCLE in MH-C9000) - TEST (called ANALYZE in MH-C9000) In addition, the BT-C2000 added a "QUICK TEST" function, which measures the internal resistance of each cell. This is useful to screen for old cells that have developed high internal resistance. All my good-quality AA NiMH cells (Sanyo eneloop) have resistance around 50 mOhm or less. Some of my old Energizer cells have resistances around hundreds of mOhm. Those can still be used in light-drain appliances such as wireless mice. (The MH-C9000 does an impedance check whenever a cell is inserted, and refuses to charge it if the resistance is too high.) [DEAD CELL DETECTION] The BC1000 has a known bug: if the terminal voltage of a depleted cell drops below 0.5V, the charger cannot detect it and the display says `null'. The BT-C2000 has mostly resolved this problem. In my testing, it is able to detect a depleted cell with just 0.1V across. However, in case the cell is over-discharged to 0V or polarity reversal (negative voltage), the display will still say `null'. [THERMAL ISSUE] The over-heating problem found in BM200 seems to be mostly resolved in BT-C2000. The charger does not suffer from 'thermal hiccup' even when charging 4 cells at 1000mA. However, cells still get rather warm to the touch near the end of charging phase. The MH-C9000, on the other hand, keeps the cells lukewarm when charging at the same current. This is mostly due to its larger case and ventilation space between cells. [QUIRKS]: So far, I like everything I saw on the BT-C2000 - except for the following problems: 1. The DISCHARGE function is quite useless. It discharges a cell down to 0.9V, and then recharges it back to full automatically. The `mAh' number you see in the end is for the final Charging phase, not for the initial discharge. I rather have the charger stops after the Discharge phase, and preserve the 'mAh' number. This is how the MH-C9000 implements its DISCHARGE function. [Update: a reader confirmed that DISCHARGE function in the production model works correctly now] 2. During DISCHARGE/REFRESH operation, the 'mAh' reading from previous Discharge phase is not preserved. Instead, it shows the accumulated charge during the present Charge phase, which is useless information. This makes it impossible for me to measure the remaining charge in a cell, which is vital for my long-term battery self-discharge rate measurement. (The BC1000 preserves the 'mAh' reading from the previous Discharge phase, so I have a few hours to record the data) 3. I tried to charge two C cells through the C/D-to-AA adapters in slots #1 and 4. Although I can select the highest current of '1400mA', the actual current I observed varies all over the place between 900mA and 1200mA. Apparently, the extra resistance introduced by the adapter makes it difficult for the charger to regulate at higher current. I must stress again that my observations are based on pre-production models. It is possible that the final model may have addressed those issues. [CONCLUSION]: With the exception of the issues mentioned above, I consider the BT-C2000 to be the best advanced charger/analyzer I have found. Once those issues are resolved (hopefully through firmware update), it could become my ultimate 'go-to' charger for battery testing as well as daily charging. Maybe by then, I can finally get rid of the other half a dozen advanced chargers that I own. In the meantime, I will hang on to my BC1000 and MH-C9000. [Update on May 14, 2014] There seems to be a lot of confusions about the DISCHARGE function. For the final production model, DISCHARGE is supposed to stop right after cell voltage has dropped to 0.9V. But apparently, some people received older models which recharge automatically after Discharge is done (same as my pre-production model). Both models display firmware version 2.0 during power up. I strongly suggest people should look for the latest BT-C2000 Battery Charger Tester Analyzer with firmware v2.1. It made several improvements that I like. See my review on it for details.