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Old Oct 18, 2009, 05:23 PM
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Monitoring multiple battery voltages with OSD Pro

There have been several requests for multiple battery monitoring with the OSD Pro. Eagle Tree plans a new "Advanced FPV Expander" to make it easy to monitor up to three battery voltages, but it is possible to do this now, with a relatively small amount of "techie" work.

Here are the instructions for monitoring up to 3 batteries, with both numeric and graphical displays.

First, note that the main pack (the one plugged into the eLogger) is already monitored, and its status can be displayed in two ways: the voltage is displayed numerically, and the "mAH used" is displayed as a graphical battery icon. Nothing new here. We'll refer to this as "Voltage A".

Now, two additional battery voltages can be monitored, each from 0V to 16V, by using a simple resistor probe connected to the "Temperature 2" and/or "Temperature 3" inputs. We'll refer to these as "Voltage B" and "Voltage C." The voltages can be displayed numerically, as above. And, the voltage (not the mAH) can be displayed with a graphical battery icon. The "full" and "empty" voltage inputs of each additional graphical battery is configurable.

See the image below: in this case, the main battery voltage, labeled "ESC", the video pack voltage, labeled "Vid", and the BEC voltage (you guessed the label) are shown. Additionally, 3 graphical batteries are configured.


To monitor up to two additional batteries, follow these instructions:

1) Install our latest beta software. Be sure to read the installation notes.
http://www.eagletreesystems.com/Support/apps.htm
2) construct a probe for each additional voltage to monitor, consisting of a wire that connects to your battery, a 15K Ohm resistor (preferably 1%), and a servo plug. See schematic below. IMPORTANT: the resistor MUST be inline with the probe, and the pack voltage must not exceed 16V, or the eLogger will be damaged!

3) Connect the resistor probe(s) between the + lead of the additional battery pack(s) to be measured, and the Temperature 2 and/or Temperature 3 inputs on the eLogger (center pin of Temperature input connects to probe). Note that this configuration assumes a common ground exists between the eLogger, and each additional battery to be measured. In most cases, ground is already shared. This will be true of the video battery, assuming the camera is connected to the OSD Pro, and is true of the BEC/Receiver battery, assuming your receiver is connected to the OSD Pro.
Note that neither the other two pins of the temperature inputs is ground!
4) In the OSD Pro on-screen menus, under the "Sensors and Units" menu, configure the temperature 2 input as a voltage monitor, by setting "Use Temp2 Input for Voltage B." If two additional voltages need to be monitored, enable the Voltage C option also.
5) If graphical battery monitoring is desired, set the 0% and 100% endpoints of the batteries by changing the values of "Set Voltage X Minimum" and "Set Voltage X Maximum" (where "X" is either voltage B or voltage C).
6) Select the appropriate graphical batteries to display, under the "Configure OSD Display" menu.
7) If you wish to display the numeric voltages of Voltage B and Voltage C, run the Data Recorder software, and add "Temperature B" and "Temperature C" parameters, relabeling them to indicate the voltage that is being monitored.
8) Do an "Antenna Down" range check!

Post any issues/questions here.

Regards,

Bill, for Eagle Tree
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Last edited by billpa; Jul 02, 2011 at 03:12 PM.
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Old Oct 18, 2009, 05:46 PM
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Since we're gonna measure separate batteries, it wouldn't be likely the ground is already shared (if not on purpose), so it would be more convenient to share the ground just there... i mean running the negative cable to the tmp input as well (on the top pin..)?
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Old Oct 18, 2009, 05:54 PM
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Hi npole,

I suspect that in most cases, ground is already shared. This will be true of the video battery, assuming the camera is connected to the OSD Pro, and is true of the BEC/Receiver battery, assuming your receiver is connected to the OSD Pro.

Note that neither of the other two pins of the temperature inputs is ground.

Regards,

Bill, for Eagle Tree
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Old Oct 18, 2009, 05:58 PM
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Lewis Center, OH
Joined Jun 2006
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Looks like I'm going to have to pick up some 10K resistors!

Very cool, Bill.

Tim
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Old Oct 18, 2009, 06:00 PM
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Quote:
Originally Posted by billpa
Note that neither of the other two pins of the temperature inputs is ground.
I would remark this part before someone would end to make a mistake like i were going to do (but saved in time).
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Old Oct 18, 2009, 06:03 PM
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Mr Pibb, thanks!

Npole, good point. I updated the text in the description above.

Regards,

Bill, for Eagle Tree
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Old Oct 19, 2009, 12:50 PM
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Good work's bill

I use 10k 5% resistor look on video compare with tester, with 10k 1% and more accurate?

http://www.youtube.com/watch?v=rataYeJ0rxU
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Last edited by Neo360; Oct 19, 2009 at 02:47 PM.
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Old Oct 21, 2009, 01:17 AM
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well, it's all about probability, so a resistor with a 1% tolerance is more likely to be closer to "perfect" than a resistor with 5% tolerance. If you want to be sure, I'd use an ohm meter (measures resistance) on the resistors you have and see which one is closest to exactly 10 kiloohm.
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Old Oct 21, 2009, 01:20 AM
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Bill, would you mind copying & pasting this into another one of your PDF "white papers" for us to download?

Thanks,

Victor
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Old Oct 21, 2009, 03:01 PM
KF7JBN
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I love you Bill. Truely. Now if I just hadn't crashed my EZ* last weekend...sigh.
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Old Oct 21, 2009, 04:34 PM
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Bill,

In the Data Recorder settings for "Set Votage B Maximum/Minimum", it has 111/100, respectively. Is this a x10 value, (so 111 = 11.1v)? Or just some wacky default? I assume I should set 8.7 and 12.5, roughly for my 3S lipo, and the values I set are used for scaling the battery display, so 87 and 125?

edit: Never mind. I just hooked everything up and configured it on my video/live model, and then brought it back in and checked the values on the computer (yes, they are x10). It might be nice to indicate that in the Data Recorder menu settings (same goes for HDOP, it is a x10 value).

Thanks!

Jhondra

P.S. I haven't looked at what the eLogger data values for Temp B are yet, but I'm guessing the OSD changes to represent/use it as a voltage do not apply to the data logger? If not, is there plans to have it accurately reflect the raw voltage level, rather than a "temp"? Maybe it is already taken care of, I'll need to check.
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Last edited by Jhondra; Oct 21, 2009 at 05:33 PM.
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Old Oct 23, 2009, 06:17 PM
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Victor,
Quote:
Bill, would you mind copying & pasting this into another one of your PDF "white papers" for us to download?
Yes, once we get enough feedback to be confident that the feature is fully documented, will generate a PDF. As a stop-gap, I posted a "permalink" to these how-tos here:
http://www.rcgroups.com/forums/showthread.php?t=1130792

JHondra, thanks for the kind words! Sorry to hear about your EZ*. Hope the rebuild is not too painful!

You are correct that the voltages are x10. I just checked the code for the PC software support of on-screen menus, and sure enough it is not correctly adding the decimal. We'll get that fixed. It's displayed correctly on the OSD's on-screen menus.

The software will try to interpret the logged tempX values as temperatures still. As part of the "Advanced FPV expander" project we'll be supporting the new parameters fully, including AHI, RSSI, and the multiple pack voltages. With AHI a graphical display will be available in the software.

Regards,

Bill, for Eagle Tree
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Old Oct 24, 2009, 08:35 AM
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Quote:
Originally Posted by Neo360
Good work's bill

I use 10k 5% resistor look on video compare with tester, with 10k 1% and more accurate?

http://www.youtube.com/watch?v=rataYeJ0rxU
Bill i have change the resistor with 10k 1% but, voltmeter see 11.4 and osd read 11.0v.

Have 0,3-0,4v difference.
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Last edited by Neo360; Oct 24, 2009 at 09:23 AM.
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Old Oct 24, 2009, 10:12 AM
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North vancouver, B.C. Canada
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18,502 Posts
Dang
i thought
seeing at least two voltages were stock for the ET

I have not tested my ET pro system out yet
but would be very disapointed if a modification was required
to see what my video or rx bat. was doing.
while looking at my main battery voltage

ET are the sailplane experts, no?
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Old Nov 01, 2009, 02:06 PM
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Neo, are you doing the test with the eLogger powered with your main pack, or just by USB? There could be voltage reading errors if the power is coming just from USB.

David, the only modification required to measure Rx voltage with our eLogger based OSD Pro is the resistor probe described below.

Regards,

Bill, for Eagle Tree
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