s-chester

Hi
I am useing the powerbox Digi-switch unit for the sevos .
I recently change the esc to kontronik jive 80 HV that includes a Protectid BEC(as I understand from it's Manual) .

Will it be o.k to connect the Digi-switch & BEC to the receiver in parallel, for backup, without damage to the Digi switch or 2s lipo?



Chester

rm

My Feedback: (27)

I wouldn't. If your running 5.6V then use a 4 cell nicad or nimh. 6V use a 5 cell. This is origninally designed as a buffer, as an automatic backup for when servos draw more then the amperage the bec can provide. You can use an unregulated switch, but you should match the bec voltage with the batt pak used, not another regulator.

Henning

Hi Chester,
Yes it works. If you adjust the BEC from the Jive to 6.0V the RX will be powered by 6.0V. If the the ESC should fale the 5,5 V backup from the Power Box will take over. I have used this configuration myself without issues.

Regards,
Henning

s-chester

hi Henning,

I'm really glad to know that thes set-up works without fault
How many flights have you done with JAVI BEC and the Digi switch ?

Chester

Henning

I have had 100+ flights with this configuration. I don’t use the Jive for F3A anymore. I still fly with Pletty Advance and that motor and the Jive don’t work very well together. The startup is ruff and the transition from break to power has some synchronization issues.
I only use the Jive now for offseason winter practice in a Sebart Wind 50. The Jive works flow less with the OS 50 motor and 6 cells. I only use the BEC and it just works.

Which motor do you use? Are you still using Pletty Advance?

Regards,
Henning

Rendegade

Well guys I kind of nicked Jim Oddino's idea, and I'm currently using it, I have to say it's inspired thinking.

I am however having one problem. Unplugging the balance leads is painfull at best. I've even gone so far as to cut the barbs of the locating pins on the leads, but they're still a PITA to get apart.

Anyone have any good ideas on how to make them easier to disconnect?

s-chester

Henning My friend ,

Yes I am still using the same motor Pletty Advance it is great, I also feel that the motor & kontronik jive ESC are not functioning well on ground at the beginning of propeller rotation but in flight I do not hear the same sounds, that's maybe because always the propeller is spinning and ESC do not have to search for the location of the magnets relative to the coils
The brake logic is unclear to me to

Thank you for the information on the ESC & BEC
Regards,
Chester

pvogel

Here's where I've currently ended up on the redundant HV RX power setup:

Jeti Mezon 90 ESC with BEC set to 8v (actually delivers 8.2 at minimal loads according to my volt meter and my RX telemetry) I modified a servo extension to tap off the pwr + gnd lines to a deans connector, signal for the throttle goes to the receiver normally. Deans connector goes to one of the two inputs on a Fromeco Wolverine switch. The other input on the wolverine comes from a 2S lipo as would be normal. I checked the wolverine and even with all outputs connected in parallel on the RX power bus, the input voltage sources are isolated (enough) from each other, about 1v leaks from the BEC input over to the battery input side and vice-versa, not enough for me to be concerned about the switching regulator fighting the battery. The wolverine's outputs all plug into the RX power bus. RX gets turned on first and all controls can be checked, etc. with power coming from the battery, when the main ESC is armed from the arming plug the wolverine switches over to drawing power from the BEC and the battery is just there as a backup.

The only thing I need to worry about is the potential for the BEC to fail and dump full 10S voltage onto the RX I'm looking at the CSM BECSafe to see if I can make that concept work for an HV system.

Peter+

OhD

Peter,

Do you have any detailed specs on the CSM BECsafe? It sounds like it is what everyone who is using a BEC needs. I was told by a Castle guy that one failure mode of BECs is FET shorts that put the full input voltage on the output. He added that Castle is adding circuitry to prevent this in their devices. I'm running a Jeti BEC set at 8.0 volts right into my receiver and also have a 2s LiPo directly in. I worry about the BEC going high.

Jim O

pvogel

Hi Jim,

I agree, the BECSafe is exactly what we need, the current specs of the BECSafe are really only suitable for LV setups:

Max BEC voltage: 6.1v
Max current: 20A
Max unregulated input: 50.4v (12S lipo)

Fundamentally it's a pair of STB55NF06L MOSFETs that switch in about 20-40ns, I think some fairly minor modifications would make it suitable for 8V setups and I've been talking to CSM about that. If they won't do it, a buddy of mine and I may.

Peter+

OhD

After reading about the BECSafe, I got even more worried about using BECs. Apparently they fail going high, enough that Colin at CSM felt we needed a circuit to protect against that burning up our RC systems. It sounds as if the BECSafe will do that if it can be set for the desired voltage. However, I read where it won't switch over to the backup battery if the BEC output goes completely low as it would if your motor battery fell out as mine as done or the ESC burned up as I have observed. So I would not use the BECSafe as the switchover device but only as disconnecting the BEC output if it goes too high.

The net result of all this is that I removed the BEC from my plane and went back to the Jaccio regulator at 8.2 volts. Let us know what you finally end up with.

Jim O

pvogel

The BECSafe WILL switch if the voltage goes completely low (I've tried it). Where did you read that it won't?

Peter+

OhD

Peter, try this:

http://www.scottishbordermodels.co.uk/0030_02bbdg.htm

This isn't where I originally saw it, but it does state the problem and shows a fix.

Jim O

OhD

Peter, did you ever get a HV BECSafe or modify one? I've been told that the CC BEC Pro has circuitry built in to prevent the BEC from failing in a high voltage mode. I've also asked Jeti if their SBEC and Mezon ESCs with BECs can fail high. Sure would be nice to plug in a BEC from an ESC and a backup 2s LiPo and be done with it.

Jim O

Dean Pappas

No, it is not.

Regards,
Dean Pappas

OhD

Peter,

I never did post the answer I got from Jeti so here it is. I conclude that we don't need a BECSafe type device.

I did see on another forum that Esprit told you not to use the BEC like I recommended where it charges your backup battery but they never said why. Any further info on this subject? I'm still running a Jaccio regulator at 8.2 volts and it is working fine. You do need to start with the backup battery charged or the regulator will try to charge it at 5 amps and overheat the regulator. It won't destroy anything but I try to make sure the backup is close to 8.2 at all times.

Jim


Dear Sir,

all our products with switching regulator have very fast high voltage protection.
For fast and brushless servos it helps to use additional high capacity capacitor at the output of BEC,

Best regards

JETI model s.r.o.
LomenĂ¡ 1530
742 58 PÅ™Ă*bor
Czech Republic


On 21.2.2013 18:09, James Oddino wrote:
After buying a Jeti SBEC to power my RC system in a two meter FAI airplane, I read about BEC failures where the output voltage went high, to the value of the input voltage. This would be disastrous, especially with $175 brushless servos. Apparently this problem has occurred often enough that at least one manufacturer has built a device to detect the output voltage of a BEC and disconnect it from the system (switch to a backup battery) if the voltage gets too high or too low. I was also informed that Castle Creations has added similar circuitry in their products. My question is, how safe is the Jeti SBEC and does it have sensing circuitry to eliminate a high voltage output failure mode? I am also considering the Mezon ESC with the built in BEC and have the same concerns about it.

Thanks, Jim Oddino

Jetdesign

My Feedback: (8)

Forgive me if this was already mentioned - just had this idea and not really in the right place to read through 4pgs:

I know people are using one Rx pack and the power batteries in parallel for redundancy. Are people using the small Rx pack for the main servo power, and the power packs on the backup circuit?

It seems to me that this would force you to monitor the Rx pack daily since it would need to be charged and balanced. Of course the power packs are already being monitored, so this setup to me seems safer.

Does this make sense?

cmoulder

No, just the reverse.

The Rx regulator is set to a lower voltage so that it kicks in only if there is loss of voltage from the primary, which in my case is a Dimension Engineering VHV BEC tapped off the main power, 10S.

However, it is still a good idea to check the backup LiPo regularly because there is some draw upon it in reality when theoretically there should be none with the Tech-Aero reg set at 5.75v. But I notice it after about 8-10 flights, so it is no issue at all for a day's flying.

dando

Hello everybody!

What is the State of the Art in redundant receiver/servos power?

I am using an older Castle Creations Ice 2 80 HV without BEC and a DigiSwitch with a 2S LiPo battery to power my RX and servos (non-HV).
I have a simple idea how I could introduce some redundancy in the system using the main power pack (lowest 2S) through a low-drop Schottky diode in parallel with the small 2S pack before the DigiSwitch.

I need to think about it a bit more and can attach a schematic. :-)

Kind redgards,
Nikolay

Brenner

I am using a high voltage Emcotec Dual Switch with an ESC BEC from a Jeti Mezon 90 feeding one input, and a 350mah Lipo feeding the other. The BEC charges the Lipo through a diode, and I have disconnected the power wire in my throttle lead. This is needed to ensure that power reaches the RX only though the Emcotec switch.

The diode drops the BEC voltage so that the BEC is the source that is used, not the Lipo. The Lipo lets me turn the RX on, and then the RX allows the ESC to be armed. When the ESC is armed the Lipo is charged by the BEC.

If the BEC stops supplying power the Lipo takes over.

Brenner ...

verezaandre

Brenner,

could you explain a little more about the diagram of “Diode” conections?

thanks

ltc

My Feedback: (3)

The simplest way is to use something like a Jeti DSM-10
DSM 10: JETI model s. r. o.
This provides dual Rx power to any downstream receiver. You can use any 2 voltage sources and they will be isolated from one another via the DSM-10 electronics (switching).
Very clean, easy to install.

If you just want a "dual diode" (common cathode configuration) device with no soldering, you can simply buy one of these devices:
Western Robotics Ltd. Battery Buffer
or
Booma RC Advanced Radio Control Specialists. DualBat 2 x 10A Isolating Circuit
or
Batshare

I use Jeti DSM's in all my 2m planes and have no issues
For my planes with OPTO (non BEC) type ESC's, I use a DSM-10 with 2 Rx packs
For my planes with BEC equipped ESC's, I use the DSM-ESC;
DSM ESC: JETI model s. r. o.
the BEC is primary Rx power and the small 2s Rx pack is backup power
(My radio telemetry tells me instantly when I have switched from primary to secondary Rx power since the voltage will be different)