Need Help! SBEC, UBEC and Reciever Packs

[Gregor77]

OK, I understand most.. but here is my question...

I wanted to have a sep reciever pack.  But I want to make sure the pack is good to last a long time. 

What can I do on this set up.

10S 2X5S 4000 packs running into a HV100 ESC.  Running a separate SBEC (CC).

But I want the RX and the Servos running on a separate battery pack?  Could I use a 3S, 2200 if needed?  How to I wire this up?  Is there going to be a conflict if the SBEC runs into the RX and the ESC red wire is unplugged? 

So I see a connector the 3S, 2200 to the SBEC, then to the RX, then the ESC to RX, but red off.  ESC powered by the two 5S packs.

My other big plane has an RX battery that I have to keep checking and charging.  But there is no SBEC, it goes right to the RX.  I think the SBEC will just make sure the current is balanced and I don't have a brown out?

Am I on the right course or way off?

Think we need a class on this!

[sts41]

What ESC and what SBEC are you using or planning to use?

Steve

[piker]

Are you saying you want to use the SBEC to maintain and charge the separate Rx pack from the main flight pack...though the receiver? 

Years ago I built and used this scenario in a couple of planes.  A separate circuit was wire to the main battery pack and to the Rx pack to maintain it's level.  That way the small Rx pack worked as a sort of reserve tank.  I don't remember the exact wiring, but it worked well.

But if you're thinking what I think you're thinking, as stated above, I think you'll over charge your 3s pack as there will be no peach detection.  With old Ni-cads, you could trickle charge them forever without a problem.

I guess you could have the 3s pack connected to the ESC AND the SBEC connected to the ESC as long as both have a diode, or something to prevent back flow (which would over charge you 3s Rx pack and perhaps namage the SBEC).  They would be wired in parallel and share the load, therfore allowing you 3s Rx pack to last longer.  I wonder if the greater (higher voltage?) of the two supplies (perhaps the SBEC) would provide most of the power and the Rx pack could just sit back and relax until needed, like when the SBEC gets over loaded, or dies 

Am I understanding your question correctly?

Robert

[Ededge2002]

Quote"So I see a connector the 3S, 2200 to the SBEC, then to the RX, then the ESC to RX, but red off.  ESC powered by the two 5S packs."

That's right.
You could run a 2S pack to the SBEC as it's going to sink down to the set voltage (I would recommend setting the CC SBEC to 6V). You will be able to do everything with the motor pack disconnected safely.

[Bobmic]

If you want to use a 3s 2200 for the Rx, first you will need to disconect the power from the main ESC to the Rx ( red wire ) and connect the 3s through through an SBEC to the Rx, a 2s battery for this job will be better though.

I am not sure if your plan was to keep the Rx battery charged from your 10s setup, in this case the best thing will be not to use a LiPo for the Rx, that way it will be easier if you want to charge it from the main 10s battery through the SBEC. Charging a LiPo with no control will not be smart
If you just what to have some kind of a reserve tank you can use NiCads or NiMH Connected to the 10S SBEC and setup the output voltage of the SBEC per pack size. The smaller pack in this case does not necessarily need a separate SBEC (one less part that can fail..

As for brownouts.... The SBEC will not have any effect here as brownouts are caused by under voltage and if the battery voltage drops too much your plane is gone.

[piker]

Ed,

I think he wants more than a Lipo Rx pack through a regulator.  I think (correct me if I'm wrong, Greg) we wants some redundancy.  A BEC AND an Rx pack with the load being shared so the Rx pack last longer.  It sounds like his preferred scenario is what I described above.  A BEC with a reserve tank that doesn't have to be maintained (is automatically maintained by the power pack).

As Bobby says, maybe an old school Nicad pack is the way to go, and have it set-up with a low current trickle charge from the power pack.  Would require some circuitry though.  Who knows.  Maybe something's available.

Robert

[Papa]

I think you are making things way too complicated. The draw on a separate 2S LiPo powering the Rx and all servos is very small.
Depending on the size of LiPo you could probably fly every day for a week and still have lots of voltage. What exactly is the problem you anticipate?

jack.

[fprieto]

Hey...
At least what I had on my Tucano is:

8s 2x4s -> ESC (HV120 OPTO) -> RX <- SBEC <- 3S

From the ESC / SBEC to the RX, there was no need to cut or isolate the red wire.
And worked okay !!!

[Gregor77]

That is the system I am trying to do.  I want to still have a separate lip to run the servos and rx.  Keep the esc on a separate battery.  I know that if the    esc has a built in bec.  The red has to be removed. 

[Bobmic]

Hi Greg,
You are correct about the wiring unless you are using an ESC with no SBEC (...some are called OPTO...).
It might work without removing the positive wire from the ESC side but it depends on the two SBEC's used. If they both have identical Vout and some protection for Current flowing back it might be fine and than you end up with somekind of redundancy but this is not what you described as keeping the Rx battery charged.
Anyhow I would not count on HK's parts for that and would remove the red wire from the ESC side.
Is this some kind of a super expensive plane or you just want a separate battery for the Rx to allow more current to the servos and/or be able to control the plane if the ESC fails?
The easiest is to use a separate SBEC from your main 10s input. This way if the ESC fails or the voltage drops too much and the ESC cuts off you still have control

[Ededge2002]

Just for numbers I'm using a separate pack to run the RX and 5 small HS65 sized servos in a glider. Recharge numbers on +10 minute flights are under 50mA on 2S LiFe 1100 pack without regulator.