Current draw of ELogger V4, OSDPro, GPS V4 - RC Groups
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Feb 27, 2011, 09:53 AM
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Current draw of ELogger V4, OSDPro, GPS V4

Hello to all EagleTree users out there,
I live in Germany and starting flying model aircrafts again in 2009 after a break of about 25years, due to my job. Half a year ago, i discovered FPV in the web and now got me a Eagle Tree System.
First of all let me tell you, i am not a greenhorn concerning electronic systems and equipment. Since 30 years i am working as an engineer in electronics and i've got some experience in all kinds of electronics including high frequency applications.

Just received my brand new EagleTree system consisting of:
ELogger V4
Airspeed V3
Altimeter V3
Eagle Eyes Ground Station

Additionally i got the following parts for my FPV project:
Pixim GF-PX-540 camera
Airwave TX Module AWM661T, 14dBm / 5.4GHz (the only legal in Germany)
Two Airwave RX Modules AWM682RX
Antenna tracker for azimuth and elevation
Two planar antennas horizontal and vertical polarized, each of 19dBi gain
Headplay Googles

After studying all manuals yesterday, i put the system to work today.
I connected all parts on my workbench, to start my first system investigations. Everything is working so far. I see the Eagle Tree texts overlayed to the cam video. But i experienced the following problem:

When connecting the ELogger V4 to a 12V regulated power supply via the Bat+ and Bat- terminals (no ESC and brushless connected) i measure a current draw of the logger of 17mA, pretty good value.
Now after shutting down the PSU, connecting the OSDPro to the ELogger via the OSD/LCD connector i measure 156mA, oops ! No additional loads at the OSD.
Finally connecting the GPS V4 to the ELogger via the GPS connector i measure 220mA. These 64mAmps are also a good value for a GPS.
After about 5 minutes the ELogger got a temperature of 65 C, measured with a infrared thermometer. Got an uneasy feeling, that there is something not working correctly and stopped all tests. For me it seems that the OSD is drawing to much current for the regulator in the ELogger. Guess it is a linear regulator not a buck switcher to retrieve the 5Volts for the whole system.
The linear regulator will dissipate 1.54 Watt when powered with 12v.
Any help will be appreciated.
Thanks and greetings from Germany,
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Feb 28, 2011, 06:25 AM
Registered User
Since there are no answers until now, i investigated the ELogger's internal power supply and found out, that a LT3012 250mA, 4V to 80V Low Dropout Micropower Linear Regulator is used. Datasheet:
This regulator is able to supply max. 250mA and has an internal thermal protection with shutdown when overheating.
If one would supply the ELogger with 70V as stated here:
the total power dissipation would be (70V-5V)*0.22A = 14.3 Watts. Assumed the current consumption of the devices (ELogger V4, OSDPro, GPS V4) are correct as measured in my last post.
When operating the ELogger V4 with 70Volts the linear regulator will no more work because of overheating all the time in fractions of seconds.
My questions now are:
1. Is the current consumption of the OSDPro of about 140mA correct, or is something wrong with the unit?
2. Am i correct, when assuming that the OSDPro and other peripheral units must be supplied from the receivers battery or a BEC?

Hoping for any answers from the specialists out there.
Greetings Roland
Mar 02, 2011, 08:25 AM
Registered User
Thint1's Avatar
hi Roland,
yes, you should power the et-components not from the e-logger. with your osd comes the "battery harness" - the short (~10cm) connection with two wires and 2 different plugs (3, 4). use this between the receiver and the usb-port on the logger.
i use an other solution: a 5A (peak 7,5A) turnigy ubec is soldered to the esc-connections of the logger (together with the 12V for video tx). so ive a bec with very low noise, high output and measure the current and consumption of the complete system.
the output of the ubec is splitted to three "branches" rc, e-logger, video cam.
this way prevents that the current for the et-components dont flow over the tiny strip-lines in the rc-rx.

ive about 250mA reading in my osd (same et-components like you + cam + rc-rx; no video tx, no servo movements). that means that your measures are in the same range.

greetings Thomas
Mar 02, 2011, 09:29 AM
Registered User
Hello Thomas,
thank you very much for your answer. That's exactly what i thought, just wanted a confirmation.
I am also happy, that you measured the same power consumption as i have.
Now i know, that i am on the right side.

Best regards, Roland

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