Proper High Current Setup

[sarpilot]

OK here is the concensus from Team Compass... We have several pros that are flying the living daylights out of HV servos with no issues. Recommended has been adding a seperate power supply to main beast buss which I plan to do. This wire chopping and soldering is in my opinion for the birds. Either Microbeast can handle high voltage servo loads or it cannot. I asked for documented failures and no replies. If Microbeast cannot handle hv servo applications then they should produce documentation to the fact and expect dissastisfied purchasers.....

[Helico-pteron]

I agree with the wire chopping comment, especially when there are available pass through regs.

That being said, MB has told me specifically that it won't carry the high currents.

[nexgen]

Originally Posted by egicar

About the high voltage / high current servos, here is what Stefan (BeastX Team) answered me:

Hey Egidio,

... the MB was designed for the future to use 2s Lipo directly and this also worked out in our tests. I also hear more and more of problems with such servos. So at this time there are real power servos on the market and especially some new HV servos can draw an extreme amount of peak current so it really is better to supply the servos with a separate power line.

Ciao

Stefan

Ciao,
Egidio

Originally Posted by sarpilot

OK here is the concensus from Team Compass... We have several pros that are flying the living daylights out of HV servos with no issues. Recommended has been adding a seperate power supply to main beast buss which I plan to do. This wire chopping and soldering is in my opinion for the birds. Either Microbeast can handle high voltage servo loads or it cannot. I asked for documented failures and no replies. If Microbeast cannot handle hv servo applications then they should produce documentation to the fact and expect dissastisfied purchasers.....

Originally Posted by Helico-pteron

I agree with the wire chopping comment, especially when there are available pass through regs.

That being said, MB has told me specifically that it won't carry the high currents.

Edgicar has the answer for you above. I bet the pros arent stalling out all their servos and pulling peak current for any length of time. some lesser skilled pilots may be hammering on the sticks and stalling out their servos which as we all know will draw a much greater amount of current than in normal flight.


Helico-pteron I agree here. thats why I didn't want to chop any wires, just add connectors for the pins. plus it ends up being less wires the way I did it.

[Helico-pteron]

+1

Not sure why people are so adamant about not doing this.

It's pretty simple reasoning to me.

[JustPlaneChris]

Yep, and in fact it's standard procedure for other units on the market. Skookum offers a power bus for their SK720 for use in large helicopters with big servos.

I'm not sure what the big deal is... <shrug>

[HugoCraft]

On my fusion 50 running (3) DS610's and a DS650 I'm running a hobbico LiFe1100mAh pack. It has 2 servo leads and a main lead which I split into 2 more servo leads. I have (2) double switches and I have the servos plugged into the MB just like the manual shows using a normal RX. I have 3 power leads going into the AR7000 and one into the MB. So the MB is getting one direct lead of power and two more power inputs from the RX which is getting 3 power leads.

Kinda crazy but I figure I would make use out of all the leads coming from the RX pack and it was easy to make it redundant.

So far after (2) five minute flights I'm only using 400-600mAh and then I recharge the RX pack.

[nexgen]

Ok so I was able to get more clarification on the capabilities of the BeastX unit itself, and reasons why offloading power for the servos may be a good idea in some cases. You will see (and I did not know this originally) that the unit will have no trouble with current distribution, rather its more about getting the current to the BeastX efficiently. If you can reliably feed current to the BeastX itself then there should be no reason you couldn't power the servos directly from the unit. Read on:

BeastX power bus

Hi Stefan, I just had a quick question on the power bus in the BeastX. I know the unit is rated to run off of up to a 2s lipo, so can also handle the voltage that today's HV servos require. there seems to be some confusion as to how much current the power bus is rated for or can handle. See this thread at HeliFreak for more info. https://www.helifreak.com/ showthread.php?t=259794&page=7 Do you know if there is a rating for max current over the bus on the BeastX?

Thanks
-Rob

-------------------

And Stefan replied:

Hi, you can send 60A over the interconnect then the PCB will start to burn. Typically it can handle 15 to 20 A and only getting sligtly warm. Of course this is like an electrical resistor and the voltage will drop the higher the current. At about 2-3A the voltage drop will be in the range of millivolts. The problem is not the power BUS/PCB. The problem is connecting your power source to the Microbeast unit as this is usually done with only two 0,25sqmm servo wires, AIL and ELE between Microbeast and receiver. These servo plugs only can handle a constant load of 2,5A each without nearly any resistance otherwise the voltage will drop very rapidly. So modern power servos (not especially HV servos, this also applies for example to JR8717 or ACE DS1015) take peaks of 5A what makes 15A peak for 3 swashplate servos and then additionaly you have the tail servo. If you do not supply these with a constant power supply this will lead to extreme voltage drop switching off receiver and Microbeast for a short time. So where should the servos get power from? You have 4 servos with 4 servo plugs pulling the maximum possible load so you should also feed in 4 servo plug style power lines. But there are only 3 ports left -SYS, AIL, ELE. Additionally the longer the power line is and the smaller the diameter of the power lines is the higher will be the loss of voltage from source to servo. Unless the Microbeast has no high power input (for example some DEANS connector at the side) like some receivers do, you should not connect such "extreme" servos directly to the unit. The problem especially with HV servos is that they will consum even more current as on 6V. But as said you can also get in trouble with "standard" servos. I heard that new Savox BLS HV servos will be very very power efficient (even better as Futaba BLS). Such servos can be plugged into the Microbeast directly without any problems.


Sent from my brain using technology.

[Helico-pteron]

Great info!

I plan to power my Fusion with one power lead in the SYS slot and one in the CH7 slot on my Rx.

[JustPlaneChris]

Yep, same here, except my RX has a dedicated "batt" port so I'll put one there and one in the SYS slot on the MB. I'm also using Hyperion servos, which aren't quite as power hungry as some of the newer ones so I should be good to go!

[nwmtech]

700n, Synergy N5, Fusion 50. All at 8v and all directly into the MB. Over a hundred not so easy flights between the three on MB with zero issues. I'm going to choose to keep it simple. I agree with everyone that technically on paper a power buss is by far a better solution however I also like to take into consideration what actually works and the theory that the more connections you have the more potential for failure you have. Servo choice is probably the biggest key. My HV Hyperions only draw about 250mah for a 6min flight of beating it where as the 8717's in the 700 drew about 575mah per the same flight style.

[Stickey]

A set of 3 servo plugs wired to a miniboard that plugs straight into the MB. Then off that board you have the opposite connectors to plug the servos into. Overall just about 1/2" long and just large enough for those three servos (you could add in the rudder too).

Then pull off the + and - to a dedicated, higher amp connector. That way you're pushing the power out from an enlarged bus to the servos and to the MB.

Would simply adding a decent sized capacitor to each main servo lead help dampen the load enough?

Lots of clean, easy ways to accomplish things.

[egicar]

Reading Stefan's considerations, I can find 2 very important informations:

• the MB PCB can manage from 10A to 20A without conseguences;
• the connectors can manage 2.5A; over this current, the voltage drop becomes important.

With these two informations we can take an objective decision.

Ciao,
Egidio

[naif_r/c]

thnaks...............

[Roger Palacio]

Originally Posted by airjawed

Why the GY701 on there? Thats a tail gyro right?

Would you mind posting more pictures of you set up ? maybe you can help me with the set up ?

[Helico-pteron]

Originally Posted by Roger Palacio

Would you mind posting more pictures of you set up ? maybe you can help me with the set up ?

It's the gov unit, no gyro.

I currently have that heli torn apart to install a S.Bus system preparing for the next firmware with the gov feature. The GY701 will be removed when the gov option is available on the MB.

What did you need help with?

[James Kovach]

The problem in these situations is not really the current carrying abilities of the MB as mentioned above, but the effectiveness of getting the current thru the system to the servos and MB. The bottle neck in all of this is all the servo connectors that the power has to travel thru to get where it is needed. These connectors are horrible for passing current. As mentioned above, at around 2.5 amps, they will start dropping voltage rather quickly. The more you have in-line, the worse things get.

In the picture I attached, the top wiring setup is what it typically done. Before the power even gets to the RX, it passes thru 3 servo connectors. Then it passes thru 2 more to get to the MB. Then another to get to the Servo. That is a total of 6 servo connectors to get to the final destination. Even though there are two power feeds going between the RX and the MB, it is all still being supplied thru a SINGLE feed. So the multiple connections really do not do much for you here. Your servos start wanting 3-5 amps, the MB another .5 or so and finally the RX needs another .5 or so. So you are trying to pull all that current thru a single line of servo connectors. Not a good situation.

The bottom wiring is my solution to all of this. As stated the MB's power buss is more than able to handle all the current that is needed. You just need to get it there in an effective manner.

[rembard]

Hello,

In my configuration I put the power directly on the Beast and the power to the receiver is linked with the serial bus cord.

On the receiver is only connected the power regulator.

Regards.

[Philip Clemmons]

Guys,

If you look at post 45 and the few before it, you will see the kiwi regulator by fromeco. It's a perfect fit for this scenario. It has a deans in, and supplies power directly to all the cyclic servos. (It's fairly cheap too, around 75.00 bucks.) The beast ends up with signal only, except for rudder (in my setup). Works flawlessly and it's plug and play......no splicing or soldering. It also serves as a 5v regulator. Only downside is it passes battery voltage OR regulated 5v, so use with an life (a123) pack, or lipo with hv servos gains best performance. It can regulate everything at 5v, but who wants that

[DannyvG]

I did some logging with the Jlog2 on my Jive that is used in a Outrage Fusion with BLS251 on 333Hz and BLS451 on 200Hz all on 5.6V

As you can see I had peaks of around 5,5A and most was around 2A to 3A
This is actually a lot lower then I expected because of everybody (inclusing myself) thinking of peaks of 3~4A per servo.
I now have 1bec wire into the RX and 1bec wire on a ycable into the MB and a extra power cable from the RX to the sys port and a 4cell eneloop pack as backup in the RX.
So I guess the need for powerbus systems is not really as big as I expected.
As long as your bec is capable of 5A continuously and 10-15A peaks then your good to go. Most important is a constant voltage from the bec under load and as you can see the Jive can deliver that.


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[Helico-pteron]

I've also removed all regulators and the like. I run a power lead to the Rx and MB.

Good info, thanks!