Eagle Tree Electric Expander - Manual (Page 2)

Copyright © 2003-2010 Eagle Tree Systems, LLC
http://www.eagletreesystems.com
Page 2
you still have problems fitting it, you might need to lightly sand the top of the connector (nearest the red wire) with sandpaper, but this
should not be necessary.
EXTREMELY IMPORTANT:
The Electric Expander Connector **MUST** be connected correctly
to your Recorder, or severe damage to the Recorder and other equipment could occur, which will void the
warranty. The Expander connects as shown in Figure 1A, to the right of the USB connector, with the RED wire of
the connector facing UP. If you are uncertain as to how to connect the expander, don’t hesitate to email us at
[email protected]!
Connecting the Electric Expander to Your Battery
To measure current the hall effects current sensor ring can be installed around either the positive or negative wire leading from your
battery to your speed controller. It works through the wire’s insulation, and hence no cutting of the wire is necessary. It can be
installed facing either direction, as it is not polarized.
The alligator clip is for measuring battery pack voltage. It should be attached to an exposed part of the positive (normally red) battery
wire or terminal between the battery and the speed controller. It must be in direct electrical contact with the positive battery wire.
Alternatively, the alligator clip can be removed and soldered to the wire leading to the ESC for a more permanent installation.
If an easily removable installation is desired, one convenient way to do this is to have a removable wire “section” with Deans or other
plugs on either end (male/female). Both the current and voltage leads of the Electric Expander can attach to this wire section (the
alligator clip is normally cut off and the voltage wire soldered), and the section can be removed easily from the model when electric
measurement is not desired.
ESCs with isolation between BEC/Throttle ground and Main Battery Ground
Note that there must be electrical conductivity between the ground wire of your main battery and the Recorder’s internal ground, for
voltage measurement to work correctly. Normally, when the Recorder is connected to your receiver via one or more of the
Recorder’s servo connections, the
ground wire of the ESC’s BEC/Throttle
output results in the correct grounding.
However, some ESCs isolate battery
ground from the ESC/BEC throttle
output ground. The easiest way to tell
if there is ground isolation is, with
everything disconnected from your
ESC, to measure the resistance between
the main battery negative input of the
ESC, and the BEC/Throttle ground
wire. If the resistance is greater than an
ohm or two, there is isolation.
In these cases, for the Recorder to
measure voltage correctly, the
recorder’s ground must be connected to
the ground of the battery to be
measured.
There are two ways to do this:
a) RECOMMENDED: Disconnect all connections between your Receiver (including BEC/Throttle output of the ESC) and
your Recorder, and power the recorder from a separate small battery. Then, connect a small ground wire between one of the
Recorder’s servo ground pins, and the negative lead of the battery being measured, as shown in Figure 2. Note that the
resulting connections should not bypass the ESC’s isolation between the BEC/Throttle ground and the ground of the battery
being measured, since the BEC/Throttle ground is NOT connected to the recorder. Note that servo position logging will
not be possible in this scenario.
b) If you want to continue to power the Recorder from the ESC’s BEC output or the battery you are using to power the
Receiver (and to be able to log servo positions), you will need to leave the servo connections from the Receiver to the