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VoltMagic R/C Voltage Monitor with Glitch or Failsafe Counting and Peak Low Voltage.  Super- Fast sampling and accuracy.  VoltMagic uses a proprietary voltage indication algorithm that even works with 2-cell A123 / LiFe, as well as nearly all R/C servo-receiver Batteries (LiPo, LiFe, NiCd, NiMh), and Voltage Regulators or BEC.

See the Video on YouTube

VoltMagic will MEMORIZE instantaneous low voltages DOWN TO 3.4 VOLTS!  Peak Low Voltage is the absolute lowest voltage.  It shows if your switch, wiring, connectors, battery/regulator are really doing their job with your servo amperage.
  March 2011: VoltMagic EX released and in stock at all our retailers!  EX stands for EXtreme.  Higher rated components and faster sample rates.

4 or 5 cell NiCd or NiMh

4.9 - 7.0 Regulator / BEC

2 cell series A123 / LiFe (6.6)

2 cell series Li (7.4)

Averaged Voltage / Battery Gauge with 20 ranges

Adjustable low battery warning

Adjustable Peak Low Voltage ranges

1200-1600 samples per second

Glitch or Failsafe counting

Calibrated within 0.015 volts

The ultimate radio control battery or regulator voltage monitor,  plus glitch counter.  Record abnormal low voltages, display the current average voltage, and count glitches or failsafes.  It's even a data logger that stores the glitch or failsafe count and abnormal low voltages even after the power is turned off.  The previous flight's data is played back on power up.

   Designed & Assembled in the USA

VoltMagic 2Y-20 EX

Upgrade exchanges available.  Do the DEMO...

Custom configure VoltMagic for your setup -- 4.8 volt,  6.0 volt, 7.4 Lithium, 6.6 A123, or voltage regulator.  There are 20 ranges for Voltage (AV).  Two selectable ranges for Peak Low Voltage (PLV) record low voltage.  There's even Glitch or Failsafe detection.  Here are the details:

Averaged Voltage (AV) —  An adjustable battery gauge, to indicate low mAH remaining in a battery, or incorrect output from a regulator.  It shows a steady display of the current voltage. Each LED represents a 0.1 volt step. 4-cell Nixx, Regulator, 5-cell Nixx, 2-cell A123 and Lithium each have multiple ranges.  One monitor for all applications, plus you can fine-tune the colored LED bar graph to match your system, and your personal preference. [Table 1]  Click to expand the example graph.   .

Peak Low Voltage (PLV) — This is what indicates whether the electrical system is capable enough for the servos.  Below a certain threshold, shows the lowest voltage at the receiver (or wherever it’s connected) in 0.1 volt increments [Table 2]. There are two ranges, Normal or Low, to select from.  The Extended PLV feature temporarily shows an extra 0.2 volts of PLV range on the high end for an early warning, displayed on LED 5 if the switch VoltMagic is connected to is toggled quickly 5 times (after 1 minute of run time).  The new EX version sample rate is 1200-1600 per second.  The fastest on-board monitor available.

Overvoltage (OV) — For regulated systems, shows if the voltage went above a certain threshold [Table 2] which would indicate an overvoltage failure of a regulator / BEC.

Glitch and Failsafe Counting — Selectable for Glitch (PPM) or Failsafe (PCM or 2.4 GHz with an adjustable failsafe). The counting is smart, so several within a short time period are counted as the same glitch. [Table 3]  A glitch (missing or bad signal pulse) from a PCM or 2.4 GHz receiver indicates a fault (possibly a reboot).  With a traditional PPM receiver, a glitch usually indicates a failure to receive the transmitters signal.

Data Logger — This feature plays back any PLV / OV plus any Glitch or Failsafe counts from the previous flight when the power is turned on.


Average Voltage (AV) is shown by which of the 8 LEDs is on.  Peak Low Voltage (PLV) is shown by blinking LEDs 5-8.  The glitch or failsafe count blinks on LED 1.  Note: A LED will blink off if it is already lit displaying the Average Voltage (AV).

See Table 1 and Table 2 for the available voltage trigger points for each range.  (The version with 2 yellow LEDs is depicted. The 2 red LED version operates similarly, LED 7 being red instead of yellow.)

LED 8 AV extra Low

1-2 blinks = PLV extra Low

LED 7 AV very Low 2 blinks = PLV very Low
LED 6 AV Low 1-2 blinks = PLV Low
LED 5 AV Normal 1-2 blinks = PLV near Yellow or OV
LED 4 AV Normal  
LED 3 AV Normal  
LED 2 AV Normal  
LED 1 AV Normal Blink = Glitch (Failsafe) count

AV = Averaged Voltage              PLV = Peak Low Voltage  OV = Over Voltage

At least one LED will always be lit showing AV.  Normally, that's all you should see.  You could have up to three LEDs lit at one time: one showing the AV (any of the LEDs), one blinking to show the PLV or OV (LEDs 5-8), and one blinking the Glitch/Failsafe count (always LED 1).  If the AV is lighting up the same LED that blinks, it will blink off quickly instead of on.


Application:  Battery types: 4 or 5 cell Nixx (NiMh / NiCd), 2 cell A123 (LiFe), 2 cell Li (Lithium), 4.9 to 6.2 and 6.7 to 7.1 voltage regulators.  20 ranges for averaged voltage, each with 2 peak low voltage ranges.

Input Voltage:  2.8 to 8.5 VDC

Voltage Sample Rate:  1200-1600 per second

Frame Rate:  12 to 23ms (for glitch & failsafe detection)

Connector:  Universal (Futaba, JR, Z).

Accuracy:  Calibrated within 0.015 vdc.

Weight:  7.3 grams (1/4 OZ)

Size: 48 x 19.5 mm, and 5 mm thick (1.89" x 0.77", and 0.20" thick).

NO switches or pots to fail, all configuration is via your transmitter.

Warranty: Two years

Specifications subject to change and/or improvement.  For previous versions, please download the appropriate instructions.

Peak Low Voltage (PLV)

Modern servos for radio control are more powerful then ever, and they draw more peak current then ever too.  A battery can have a good charge, yet the voltage can dip quite low.  Voltage regulators have their limitations.  There can also be excessive  voltage drop in wiring, connectors and switches.

There are no rules of thumb that always work to select batteries or regulators.  Peak amps differ substantially between servos.  Voltage drop under load differs greatly among batteries that have similar ratings.  Regulators typically have amperage ratings, but what are the peak servo amps, and can the supply battery keep the input voltage sufficiently above the output?  Can the regulator handle fast transient load changes of your servos?

The only way to know how low the voltage really goes is to check it with a high speed monitor like VoltMagic.

It is not uncommon for a pilot to be shocked at the peak low voltage after installing VoltMagic on a model that had been flying well.  Typically there are no symptoms, until something finally draws the voltage down a little further.

A less obvious advantage of being warned about peak low voltage is that troubleshooting intermittent problems becomes easier when you can either rule out low voltage, or seek the cause of it and verify a repair before flying.  Even if your setup is very tolerant of voltage drop, a unusual decrease might indicate a battery cell, regulator, switch, or connector going bad.  Low range PLV works well in situations where the voltage drop normally runs high.

Another advantage is stirring the sticks on pre-flight.  Quickly reversing the direction of servos produces current spikes (and voltage dips) that are similar to flying (but shorter in duration).  VoltMagic has a very fast sample rate, so you'll likely catch peak low voltage problems on pre-flight.

2.4 GHz

Under voltage on 2.4ghz receivers is notable for the time to re-link with the transmitter.  XPS lists their voltage requirements at xtremepowersystems.net.  The Spektrum receiver power requirements are detailed in this article at spektrumrc.com.  To summarize this article, 3.5 volts minimum operational voltage.  There are also guidelines and procedures for testing both current and minimum voltage to check that there is a sufficient safety margin.

VoltMagic makes this kind of testing easier, and more accurate (because it's a high speed monitor that captures the lowest voltage). You can also stir the sticks before every flight and check the peak low voltage (minimum voltage), plus it monitors while you fly. 


Is My Radio's Power Supply Adequate?
by David E. Buxton

Peak amperage of digital servos may be more than you think. 
Whether using a voltage regulator or a straight battery, the voltage may dip extremely low.  Click the pic.

Graph showing momentary abnormal low voltages that the VoltMagic voltage monitor easily detected.

Troubleshoot low PLV with this FAQ.

VoltMagic Advantage

It's high speed sample rate will record the actual lowest voltage that other monitors and data loggers just miss.

Why is this important?

When you stir the sticks on the ground (quickly reversing the servo motors), peak current and peak low voltage will be close to in-flight values.  However, the duration of the voltage dips will be shorter.

Slower volt meters, monitors and data-loggers miss these dips because they don't sample often enough.

With VoltMagic you can stir the sticks and get comparable readings to in-flight, WITHOUT THE  RISK.  It makes a great pre-flight check.


Averaged Voltage is
useful to estimate the charge remaining, or monitor a regulator output voltage. With multiple ranges you can fine tune when the LED's turn on, as well as select ranges for different battery types and regulators.  Sudden voltage changes from servo movement are filtered out for a steady reading.

Peak Low Voltage can  detect problems with batteries, switches, wiring, servos, etc.  Great for monitoring the output of a voltage regulator or BEC.

Glitch and Failsafe Counting monitors the condition of your radio link.  Detect problems with noise, interference, and radio gear.  The count is binary weighted for quick reading.
1 blink = 1 glitch
2 blinks = 2 to 3 glitches
3 blinks = 4 to 7 glitches
and so on.

Data Logger:   If you turn off the receiver, or the battery becomes disconnected, your data is still there.

The ultimate R/C voltage monitor and glitch counter.  Record abnormal low voltages, display the current average voltage, and count glitches or failsafes.


VoltMagic - Don't take off without it.

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