The Battery Clinic
Red Scholefield | red@rcbatteryclinic.com
In the Lithium-Only Category
Tejera Microsystems Engineering, Inc. (TME) (www.tmenet.com/xtrema.htm), known for its SmokePump and CHARGEminder products, has introduced the Xtrema Lithium charger/wattmeter to address the needs of the more sophisticated electric-power modeler.
As larger models become more common, they will be well served by the Xtrema. It has a charge capability up to 10 cells at 4 amps (four cells to 8 amps). TME is one of the first companies to address the newly introduced A123 Racing Lithium batteries, which require a lower end-of-charge voltage cutoff. The Xtrema is easy to program for cutoff voltages from 3.60 volts per cell to 4.20 volts, in 0.05-volt increments. This allows the user to employ a more conservative cutoff on packs, which is reported to enhance cycle life.
The Xtrema’s large four-line, 20-character LCD lets you easily jump around programming and set-up features using a small joystick. Operation is intuitive, but for the charger-challenged an excellent 17-page manual is provided to guide you through the process and answer questions such as “What are the 12 error messages trying to tell me?”
The display interrogates you once you start the charge; it shows all the charger parameters you selected and asks, “Are you sure?” It gives cell count, cutoff voltage, temperature, and time safety cutoffs. If you confirm the settings, a flick of the joystick begins charging with a real-time display of charge status, input voltage, pack voltage, charge current, time on charge, and mAh input. If your selection does not match what the charger senses, it notifies you with a low- or high-voltage message.
The Xtrema is unique in that it incorporates a wattmeter function, which is essential for the serious electric-power modeler who wants to know how much the setup is demanding from the battery and ESC while experimenting with different configurations. It is a great tool for optimizing setups and selecting propellers. It remembers maximum readings until disconnected from the 12-volt source. Voltage, current, watts, horsepower, and temperature are displayed, as are the maximums of each on a separate screen.
The Xtrema features an expansion port that will accommodate the following planned future options:
- A computer interface for data logging and free lifetime software updates (USB/serial)
- An integrated and stand-alone cell balancer
- An add-on integrated tachometer
- Extra temperature probes
- Add-on expansion memory
The Xtrema manual is available at www.tmenet.com/pdf/Xtrema%20Manual-1-1-0.pdf. Street price: $189.99.
Charger specifications:
- Number of cells: 1 to 10
- Input voltage: 10.5–15.0 V DC at up to 20 A
- Input connectors: Super heavy-duty alligator clips with 3-foot cord (excellent quality)
- Case size: 6.25 x 3.25 x 2.25 inches (159 x 83 x 57 mm)
- Weight: 22 ounces (624 grams)
- Charger output connections: 14-gauge fine-strand silicon wire (add your own connector)
- Volts per cell: 3.60 (A123 M1 cells)–4.20 in 0.05-volt increments
- Charge rate: 50–8000 mA in 50 mA increments (4000 mA max at 10 cells)
- Battery types: Lithium-Ion, Li-Poly
- Safety timer: 10–990 minutes (120 default)
- Fan: On only when needed for longer life
- Safety temperature cutoff: 60–130 °F (104 °F default)
- Audible alarms: Piezo speaker alarms, 15 seconds, beep once or disable
Xtrema wattmeter specifications
- Input supply voltage: 6.5–15.0 V DC < 40 mA
- Output connections: 14-gauge fine-strand silicon wire (add your own connector)
- Voltage measurement: 0.00–60.00 V, resolution 0.01 V
- Current measurement: 0.00–100.00 A peak, 50.00 A continuous, resolution 0.01 A
- Power measurement: 0.0–6000.0 W, resolution 0.1 W
- Horsepower measurement: 0.00–8.00 HP, resolution 0.01
- Temperature measurement: Up to 302 °F (150 °C)
Even more notable: this state-of-the-art charger is designed and manufactured in the U.S., with support by an English-speaking American engineer (the designer).
The Triton Trilogy: Great Planes
ElectriFly follows the success of its popular Triton charger by introducing the Triton Jr., priced at $79.99. The Triton was phased out at $89.99 and replaced with the Triton Z, which should be available for $129.99. Following that is the Triton ZX for $239.99. From preliminary specifications (www2.towerhobbies.com/cgi-bin/wt/01p01?&P=1&LAXMAJ1&P=7) the ZX promises to be an advanced charger; shipment was reported for November 2006.
I received the Triton Jr. to review and found it to be a decent entry-level, multifunction charger that accommodates Ni-Cd, NiMH, Pb, and Li-Poly packs. It is a close competitor to the similarly priced Multiplex LN-5014.
Programming with the Triton Jr.’s four buttons is intuitive; the well-written 27-page (5.5 x 8.5-inch) manual isn’t really needed. There are four pages of flow charts to guide you through sequences—these clarify operation much more than text instructions.
Triton Jr. specifications (my comments in parentheses):
- Input voltage: 11.0–15.0 V DC
- Input connections: Large alligator clip (I replaced these with banana plugs on chargers I test.)
- Number of outputs: One
- Battery types / number of cells:
- Ni-Cd/NiMH: 1 to 14 cells
- Li-Poly / Li-Ion: 1 to 4 cells (3.6- or 3.7-volt cells)
- Pb: 2, 4, 6, 8, 10, 12 V (2 V per cell)
- Fast-charge current:
- Ni-Cd/NiMH: 0.1–5.0 A (0.1 A increments, 63 W maximum)
- Li-Poly/Li-Ion: up to 1C (63 W maximum)
(With 14 Ni cells the charge rate is roughly 3.5 A to stay under the 63 W limit; roughly 3.75 A for a 4S Li-Poly pack.)
- Fast-charge termination:
- Ni-Cd/NiMH: Zero deltaV / Peak Detection
- Li-Poly/Li-Ion: CC/CV
- Peak sensitivity: 8 mV fixed Ni-Cd, 5 mV fixed NiMH (If NiMH packs terminate early, try Ni-Cd mode with higher sensitivity.)
- Peak delay at start: 3 minutes fixed (helps avoid premature peak cutoff)
- Trickle-charge current: Charge current / 20 — NiCd/NiMH only (useful for maintaining balanced packs)
- Fast-charge safety timer: Ni-Cd/NiMH, 1.5 hours; Li-Poly, 2 hours (I would prefer an option to disable for formation charging or gentler charge profiles.)
- Thermal cutoff: Unavailable
- Discharge current: 0.1–1.0 A (0.01 A increments, 5.0 A maximum) (adequate for checking pack capacity across many cell sizes)
- Discharge-cutoff voltage:
- Ni-Cd/NiMH: 0.1–1.6 V (0.1 V increments) (can be used to take Li-Polys down to a reasonable storage level)
- Pb: fixed at 1.8 V per cell
- Li-Ion/Li-Poly: fixed at 3.0 V per cell
- Cycle count: 1 to 5 (remembers and displays only the last cycle)
- Battery memories: 1 (remembers the last battery charged)
- Programming controls: Membrane touch pad, four buttons (good for dirty-field environments)
- Display type: 2 x 16 LCD, blue backlight
- Displayed information: Input and output volts, peak volts, average discharge volts, charge and discharge capacity, currents and time, errors
(Because of the fixed timer cutoff, information may be lost if you restart the fixed time.)
- Audible indicators: Beeper (continuous until the pack is removed)
- Output connectors: Banana jacks
- Case material: Extruded aluminum
- Current overload: 10-amp spade fuse (automotive type)
- Case size: 4.7 x 3.6 x 1.2 inches (118 x 92 x 30 mm)
- Weight: 13.1 ounces (371 grams)
Promises, Promises — A tour of The Battery Clinic
Look at the photo. Maybe I’ll include more details next time if I can dig my way out from under chargers to review. Don’t forget that we are starting our prime flying season. Just so you know I don’t spend all my time trying to let the smoke out of new products, here are two photos of my latest endeavors.
The Rascal, owned by my brother-in-law, originally had a SuperTigre .40 but was never flown. It ended up in my hangar and got an attitude change when I installed an AXI 2826/12 motor with a 3S 4400 Li-Poly pack.
That worked out so well I canceled my plan to build a 70% Tango for electric power and instead put another AXI 2826/12 in my old .40 FP-powered Tango. I may be slowing down a bit, but both models’ performance more than keeps the adrenaline flowing.
I’m still at 12219 NW 9th Ln., Newberry, FL 32669. Send an SASE, please. I answer e-mail faster.
—MA
Transcribed from original scans by AI. Minor OCR errors may remain.
