Jeti Mezon 130 BEC measurements in helicopter

In my 700 size Compass 7HV helicopter, I did some tests on the jeti mezon130 bec, similar to the tests at Mikado ( www.vstabi.info/de/node/1316 or www.vstabi.info/en/node/1327 )
The bec voltage is programmed to 5.5V.
The pitchpump of Mikado Vstabi is used to maximize the movements of all connected servo’s during fast pitchmovements.
The used servo’s are : JR DS8915 (=JR DS8717), tail is the JR DS8900G.

In this system I have measured peakcurrents until 23A ! During this condition the BEC voltage will drop, without any extra capacitors, until 3.5V, which is not good. According Mikado the critical supply voltage for Vstabi equals 3.7V minimum .
If extra capacitors on the BEC output are connected, starting at 2x2200uF/16V (in parallel), then the bec voltage drop is significantly less. Increasing the capacitorvalue doesn’t give a big improvement anymore. The ESR of the capacitor seems also not dominant in this matter.
The minimum values are now between 4.2V and 4.4V which is safe.
So it is recommended to use at least 2x2200uF as extra buffer for Vstabi. Of course the value can vary when other servo’s are used.

Furthermore I did some tests with extended bec cables of 35cm, of which the diameter of the leads are the same as the original BEC wires.Of course this influences the bec voltage at the side of the vstabi/receiver.
Now it revealed that the extended bec cable can give an extra voltage drop of 0.5V, of which the main cause probably is the series resistance of the servoconnector. When soldering the extended wire, this should be almost zero (but beware of the void of the warranty when doing this !).
So please take this into account when using extended bec cable !

regards/mfg

Sebastien

As i am planning to use a Mezon 130 with my Diabolo , i am also faced with the problem how to power the RX parts.
Thre options are on the table still.

1. Mezon 135 SBEC
2. Mezon 135 Opto and a 2S Lipo
3. Mezon 135 Opto and the Jeti 40A external Bec

The servo Setup is MKS 950/980 HV on HC3SX with Linus Caps
The Motor is a HK 4525 LE
I am planning on using the internal governor too.
Any ideas ?

Thanks for the good test.
How did you measure ?
Did you connect both BEC plugs into the V-Stabi and measure the voltage as well at the V-Stabi output ?

The JR are very good servos but very ampere-hungry. A few years ago I tested them at 6,5A peak per Servo when I planned to put them into my TDR together with a Jive BEC. After my test I changed to Futaba BLS (they have only half the consumption) because I was in doubt the Jive BEC will not stand that much amps.

@ArguZ:
If you're using Linus Caps I would take the Mezon 135 SBEC, wich will be defineately sufficient.

ArguZ wrote: As i am planning to use a Mezon 130 with my Diabolo , i am also faced with the problem how to power the RX parts.
Thre options are on the table still.

1. Mezon 135 SBEC
2. Mezon 135 Opto and a 2S Lipo
3. Mezon 135 Opto and the Jeti 40A external Bec

Any ideas ?

My opinion is that the differences are not so big, it's more a matter of convenience :

Some years ago I used 2s lipo and SBEC to get 5.5V, this worked fine , but I had to charge the lipo too after some flights and had to take some extra weight into the air for the 2s lipo.

Then, for the ease of use, I used a Western robotics superbec connected directly to my 12S lipo mainbatt's and this also worked out pretty well. More convenient since I only had to charge the mainbattery and a little less weight to take into the air. This appeared to be as reliable as the 2s lipo.

Nowadays I use the jeti mezon internal bec and uptill now also runs flawless. It has a little less wiring so also looks better.

Regarding the internal governor: I have read that the governor behaviour of firmware version V1.23 / 1.24 is better than v1.27 (which is the latest). So it might be worth a try to downgrade to v1.12/1.24 ...

My personal experience is that, when I choose more rpm settings and the values are closer to each other the governor is working better, than when they are not close to each other, eg.
min=1500rpm / max=2000rpm ; governor not so good
min=1800rpm / max =2000rpm; governor is much better

Sebastien

AlexBonfire wrote: Thanks for the good test.
How did you measure ?
Did you connect both BEC plugs into the V-Stabi and measure the voltage as well at the V-Stabi output ?

The JR are very good servos but very ampere-hungry. A few years ago I tested them at 6,5A peak per Servo when I planned to put them into my TDR together with a Jive BEC. After my test I changed to Futaba BLS (they have only half the consumption) because I was in doubt the Jive BEC will not stand that much amps.

@ArguZ:
If you're using Linus Caps I would take the Mezon 135 SBEC, wich will be defineately sufficient.

I did measure with BOTH bec leads connected to v-stabi.
The voltage is measured on the (non-used) connectors of the vstabi. The current is measured by means of a current probe on both bec cables.

Sebastien

23A really is a lot for the small servo connectors.
I guess a significant amount of voltage drop is caused by them - even if you use two of them.

With this high power setups a better connection between BEC and V-Stabi would be nice.
Like the MPX-connectors at jeti recievers.