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.
will MEMORIZE instantaneous low voltages DOWN TO 3.4 VOLTS!
Voltage is the absolute lowest voltage. It shows if your
switch, wiring, connectors, battery/regulator are really doing
their job with your servo amperage.
VoltMagic 2Y-20 EX
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:
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.)
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.
SPECIFICATIONS - VoltMagic 2Y-20 EX
Specifications subject to change and/or improvement. For previous versions, please download the appropriate instructions.
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.
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.
VoltMagic - Don't take off without it.