How to connect FrSky Battery Voltage Sensor (FBVS-01)

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bob195558
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How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by bob195558 »

Hi
The instructions that came with the FrSky Battery Voltage Sensor say nothing about, NOT connecting the Black ground wires
to the FrSky D8R-XP Receiver and the single Lipo 3-cell 12v Battery Power source.

But at the Hobby King web file web page the FrSky Battery Voltage Sensor Manual
(http://www.hobbyking.com/hobbyking/stor ... stem_.html) (and/or (good manual (English))
says not to connect any of the Black Ground Wires to the FrSky D8R-XP Receiver and to my Lipo 3-cell 12v Battery Single Power Source.
Because there would be a Ground-Loop that will cause permanent failure to the Receiver and/or other Hardware Components.

This is the note from HK file: good manual (English): (http://www.hobbyking.com/hobbyking/stor ... 211X41.pdf)
:? (*note: if you are using only 1 battery in you RC-model (without separate battery for electronics) –
you should NOT use | connect black (Ground) wire of voltage sensor. Just do NOT connect it.
Throw it away or cut it, or just forget it. The only cable that should be connected to RX and battery – red (+).
In case of 1 battery, Ground is already supplied to the RX from ESC (and/or SBEC)
.
If you would supply another one Ground through the voltage sensor to RX telemetry port – you would have Ground-Loop
because electrons would follow the lowest-resistance route omitting long RX-electronic circuit.
It would eventually result into electronics (gyro, servo, etc) short-time or permanent failure.) :?

:idea: I am thinking that maybe one of the Black Ground Wires should be connected for the Battery Voltage Sensor to work.
I can see that the Black Ground Wires are a pass through connection for the Ground of the Voltage Sensor.

:?: Is there a need to have, ........ say one Black Ground Wire connected to the Ground for the Battery Voltage Sensor to work?

:?: And/or what is the proper wire connections for this Battery Voltage Sensor to the FrSky D8R-XP Receiver and the single Lipo 3-cell 12v Battery Power source?

:)
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by ShowMaster »

The BEC negative wire connects to the lipo negative and that's carried through to the receiver - buss when you connect the BEC. No negative wire is needed from the lipo side of the Frsky sensor because its already connected by the other - ( ground) connections.
Only connect the sensor input red wire to the red lipo connector and you're good to go. You do want to connect the ground and output side of the sensor to the A1 or A2 input (2 wires)
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by Kilrah »

I do the opposite, i.e. connect the battery's + and - to the voltage sensor, but then only connect the + (red) wire from the sensor to the receiver.

This following the logic that the measurement current flowing through the divider stays "local" to the voltage sensor. It comes out of the battery, through the divider, and back to the battery.
Doing like the document and SM say, the measurement current goes from the battery through the divider to the receiver, then back through whatever path you have (ESC usually). This is a long way.
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by MikeB »

This is my setup:
Vsense.png
Vsense.png (3.57 KiB) Viewed 31675 times
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by bob195558 »

:D
Thank You SM, Kilrah and Mike,

One of the two Black - Ground wires, is NOT to be connected to its Ground,
whether to the Receiver's A1 or A2 port or to the Black - Ground Side of the Lipo 3S Battery Power Source.

:D I like the logic of Kilrah to have the measurement of the current flowing through the divider to stays "local" to the Voltage Sensor.
So I will remove the Black Ground Wire from the Black Servo Plug that goes to the A2 port of the Receiver.
Though the other way there is less work and would be Cleaner with the wires.

(Side Note: I have been lifting the small plastic catch on the Black Servo Plugs to remove any unwanted wires from these Black Servo Plugs
and then I have been slipping a piece of heat shrink over the unwanted wire so that it will not make contact with any other electrical circuit,
which may cause damage. This is much better then cutting the wire and finding that you may have wished you had not cut them in the first place.)

Mike your setup has a 1K0 R3 between the Grounds. :?:
Dose this protect from a Ground-Loop damaging any other electrical Hardware Components?

:)
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by MikeB »

Yes, that is what it is there for. It should also provide a slightly more accurate measurement as it should remove some of the voltage drop that might occur in the black wire when it is carrying significant servo current.

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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by ShowMaster »

What I like about Mikes circuit is if you reverse the plug into the A1 analog port you don't direct short + to - besides providing a normal usage ground path.
Frsky should look it over.
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by Kilrah »

You never short anything, there's no "direct" + on the A1/A2 plugs.
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How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by ShowMaster »

There is if you use the red and black wire supplied on the sensor output and input instead of just the red. Some connect both not knowing about the ground loop concern.
Actually it's reversing the input/lipo side with A1 or A2 plugged in that will fry the black wire. Mikes added 1K limits the current to the receiver ground if this was to happen. If the divider was plugged into A1, A2 reversed the input divider resistor would limit current.
I think I'm correct in my thinking.

ImageUploadedByTapatalk1379891541.428890.jpg
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by Kilrah »

Ah, this way (reversing battery) is bad indeed. Your previous post sounded like reversing the voltage sensor in the receiver's plug, which is no problem (just grounds the ADC input).
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by bob195558 »

Hi,
Mike is it possible to add the 1K0 R3 into the - Ground of the FrSky Battery Voltage Sensor (FBVS-01) circuit,
so that it could work like your Battery Voltage Sensor Circuit?
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by MikeB »

Yes, just break into the black wire from the FBVS-01 that goes to the receiver and add the 1K0 in line. This will give you the same circuit I use.

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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by ShowMaster »

Kilrah wrote:Ah, this way (reversing battery) is bad indeed. Your previous post sounded like reversing the voltage sensor in the receiver's plug, which is no problem (just grounds the ADC input).
I thnk I did post it that way Kilrah. I was doing it from memory originally. All I know is some time last year I reversed one of my sensor plugs on my lipo and sparks flew. It was then that I actually read the posts about dropping the black lead on one side. I'm going to modify a Frsky sensor to use Mikes circuit and maybe start using the black wires in and out as a test. It's also a better strain relief to use both wires so why not connect then.
For deans lipo connectors I've started using the deans m/fm tap adapter with the orange JST connectors on it. It's all polarized so no more sparks. If the 1k in the sensor ground works as Mike says it does I think Frsky needs to add it permanently as a safety feature against reversing the plugs and voltage.
Maybe jumper pads next to the resistor to jumper the resistor or just drop the black wire connection, flyers choice. There is a spare clear shrink tubing piece provided for changes already.
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by MikeB »

The left end of my FrSkt voltage sensor looks like this:
Fvsense.png
Fvsense.png (4.54 KiB) Viewed 31585 times
It should be possible to add a small surface mount resistor from the pad to which the black wire is connected and the pad above. Then put the black wire on the pad below the red wire.

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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by ShowMaster »

Bravo Mike.
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by jhsa »

I have been using the ground on the receiver side.. I can see some advantages of using the ground on the battery side.. But if doing that I will just solder the sensor permanently to the power lines.. that will avoid reversing the polarity by mistake..

Would this be a good solution?

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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by ShowMaster »

I was moving mine around. Depending on the revision D recover I was using. Now I own extra sensors so I no longer move them. Soldering them could be an option for me now also.
What ever works as long as like in ghost busters, you don't cross the streams.
Or in our case the red and black wires.
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by tedbmoss »

This ground loop really does not affect the circuit and likely will not hurt anything. I have been ignoring this for two years now with no discernible effect, this is because the wires are short.

Ahem; however this is something that can get you in trouble with multiple sensors. Keep in mind that ground loops should be avoided.
Last edited by tedbmoss on Sun Jun 29, 2014 3:48 am, edited 2 times in total.
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by tedbmoss »

This ground loop really does not affect the circuit and likely will not hurt anything. I have been ignoring this for two years now with no discernible effect, this is because the wires are short.
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by ckleanth »

guys

can you please cast your eyes on this post?
from this thread?

I thought I knew how I'm supposed to connect the FBVS-01 but now I'm completely confused...
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by Clivew »

I don't use a FBVS-01. (It is only 2 series connected resistors anyway)
Mike's added decoupling cap is a good idea, though I haven't needed it (yet!)
I always fit R1 to the +ve connector going to the esc, with a thin wire going to A1 or A2 servo type plug,
with R2 connected there. Seems to work fine for me! No chance of massive current flow that way.
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by Wayne »

Am I correct in saying that the schematic that MikeB posted can be built and used as a substitute or DIY version?
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by ShowMaster »

Yes. Mikes circuits designs are well thought out. This is only for the D series receivers not the X series.
Use polarized connectors if you connect both + and - inputs. Mikes circuit does have some current limiting but we want to avoid reversing the input leads. Usually only the red + input lead is connected and the - is left off to avoid a ground loop condition.
Mikes added resistor helps avoid that with both connected.
One trap is the fact that A1 and A2 input connectors are NOT polarized and can be inserted reversed. Always focus when you plug in to avoid reversing the connector.
FYI,
When I use the Frsky version for club members I add the 1K R3 to avoid future trouble. Many will reuse it on other setups and this is insurance against them doing their own wiring and reversing the inputs or outputs.


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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by cilek »

bob195558, I’m not sure how a ground loop can fry the circuitry but it could be damaging for some protection circuitry if it is done when the all circuits are powered up. Since the ground loop is already closed, I don’t see any reason of connecting the lack wire to D8R-XP receiver. It might’ve been useful to generate a work around for any conditions where a ground sync would’ve been necessary but since there is no need, I don’t think many people will work on it.

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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by bob195558 »

Hi cilek,

Yes I agree :D , do not connect the Black Ground Wire to the D8R-XP and/or D8R-II plus Receivers.
FrSky instructions say to connect the Black Ground Wire on both ends,
but this could cause damage to the Telemetry Circuit in the Telemetry D Series Receivers.

I am not using this FrSky FBVS-01 Battery Voltage Sensor any more.

I have upgraded to the FrSky FLVS-01 Lipo Voltage Sensor with Display.
I like being able to quickly check the accuracy between the 3S Lipo battery cells
and the Telemetry Data Reading in the Radio for the Lipo Battery Cells.

Bob :)
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How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by ShowMaster »

Reversing the lipo sense (+) with the ground wire (-) connected at both ends should put a direct short across the lipo (+) and (-).
The added 1K on mikes circuit limits current to a safe level if this happens. I add it to my all Frsky sensors. Cut the ground trace and tack the 1K across it and replace the shrink tubing.

As for a ground loop frying something. If for any reason the lipo's (-) lead is disconnected or intermittent into the ESC, the total current will try and use the (-) sensor lead to carry the current. From a #12/14 wire to a # 22 gauge. The resistor limits this from happening.
I use my balance port as the input to my sensor so it's posable to have the lipo's main (-) lead disconnect due to breakage or bad deans, and fry my sensor (-) lead or the receivers (-) connection leads. That did happen one time. I've added the resistor since then.
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by ltb »

Guys,
I would like to measure 2 batteries with my X8R.
Till now I have just FBVS-01 which is pure analogue sensor.
But X8R haven't any analog ports - only s.port.
How can I connect ?
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by bob195558 »

With the X8R you can use this voltage sensor with the S.Port telemetry.
FrSky SP-FLVS - Smart Port Lipo Voltage Sensor:
(https://alofthobbies.com/frsky-sp-flvs- ... ensor.html) maybe can use two.

Also this may be what you are looking for and you can use two if needed:
(https://www.frsky-rc.com/product/mlvss/) with S.Port.


There is some hardware you can make or maybe purchase,
that will convert analog to the S.Port signal.
Have not done this myself,
maybe other's who have, will see this and help with this option.
Add an edit: Found some info here:
(https://openrcforums.com/forum/viewtopi ... nal#p62119).
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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by jhsa »

Or you can do the same as I do. Build your own sensors.
Search these forums for "oXs" or "openXsensor".
It is based on an arduino board. If you can do some simple soldering and program an arduino board, you will have voltage sensors in no time... And cheap :) ;)

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Re: How to connect FrSky Battery Voltage Sensor (FBVS-01)

Post by bob195558 »

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