Spektrum SPMR4400 DX4e - Manual (Page 15)

15
EN
voltage to the receiver during flight loads are the number-one cause of in-
flight failures. Some of the power system components that affect the delivery
of adequate power include: the selected receiver battery pack (number of cells,
capacity, cell type, state of charge), switch harness, battery leads and, if used,
the regulator and power bus.
While a Spektrum receiver’s minimum operational voltage is 3.5 volts, test the
system per the guidelines below to a minimum acceptable voltage of 4.8 volts
during ground testing. This compensates for battery discharging or greater actual
flight loads than ground test loads.
RECOMMENDED POWER SYSTEM
GUIDELINES FOR LARGE PLANES
1. When setting up large or complex aircraft with multiple high-torque servos,
you should use a current and voltmeter (Hangar 9 HAN172). Plug the
voltmeter in an open channel port in the receiver. With the system on, load
the control surfaces (apply pressure with your hand) while monitoring the
voltage at the receiver. The voltage should remain above 4.8 volts even when
all servos are heavily loaded.
2. With the current meter in line with the receiver battery lead, load the control
surfaces (apply pressure with your hand) while monitoring the current. The
maximum continuous recommended current for a single heavy-duty servo/
battery lead is three amps. Short-duration current spikes of up to five amps
are acceptable. If your system draws more than these currents, you need to
use multiple packs (of the same capacity, cell number, cell type and state of
charge) with multiple switches and multiple leads plugged into the receiver.
3. If using a regulator, perform the above tests for a 5-minute period. When
current passes through a regulator, heat is generated. This heat causes
the regulator to increase resistance, causing even more heat to build up
(thermal runaway). While a regulator may provide adequate power for a short
duration, you should test its ability over time as the regulator may not be
able to maintain voltage at significant power levels.
4. For really large aircraft or complex models (for example 35% and larger or
jets), multiple battery packs with multiple switch harnesses are necessary.
In many cases one of the commercially available power boxes/ busses is
recommended. No matter what power system you choose, always carry out
test #1 above. Make sure the receiver is constantly provided with 4.8 volts or
more under all conditions.
5. Nickel-Metal Hydride batteries, when charged with peak detection fast
chargers, have a tendency to false peak (not fully charge) repeatedly.
These include all brands of NiMH batteries. When charging, make sure the
battery is fully charged. You should use a charger that displays total charge
capacity. Note the number of mAh put into a discharged pack to verify it has
been charged to full capacity.
FREqUENTLY ASkED qUESTIONS
ON USING 2.4GHz SYSTEMS
1. Q: After I’ve bound the receiver to my transmitter, which do I turn on first
when I want to fly?
A: Either one, unless you are using a Smart Bind receiver such as the
AR6400 or AR6400L. With a Smart Bind receiver, the transmitter must be
turned on approximately 5 seconds before the receiver.
2. Q: Sometimes the system takes longer to connect or doesn’t connect at all.
Why?