WHATS a UBEC ? and Who Needs Them ?

[TheSelf]

it seems the hobbyking UBECs only go up to 7.5 A though- I just ordered the castle creation 10A UBEC- not sure if it's even needed with teh stock set up of my P51 or will even still be 'overkill' if i upgrade to a bigger ESC, motor and 4S lipos.. but better safe than sorry- I still don't know how to choose what Amp rated UBEC i would need in general, but this will do for now- thanks to all

[CHELLIE]

Originally Posted by TheSelf

it seems the hobbyking UBECs only go up to 7.5 A though- I just ordered the castle creation 10A UBEC- not sure if it's even needed with teh stock set up of my P51 or will even still be 'overkill' if i upgrade to a bigger ESC, motor and 4S lipos.. but better safe than sorry- I still don't know how to choose what Amp rated UBEC i would need in general, but this will do for now- thanks to all

Hi its best to always over kill the UBEC IMHO here is what i do, it works great for me, its a bit of a over kill, but thats a good thing for every mini servo i give them 3/4 of a bec/ubec amp rating, for every mini digital servo i give them 1 amp bec/ubec rating, for every standard size servo i give them a 1 amp bec/ubec rating, and for every digital standard size servo i give them 1 1/2 amp bec/ubec rating,

4 mini servos give them 3 ubec amps or more
4 mini digital servos give them 4 ubec amps or more
4 standard servos give them 4 ubec amp rating or more
4 standard digital servos give them 6 ubec amp rating or more
always use a ubec with a 2.4 radio, its cheap insurance against a brown out, Take care and have fun, Chellie

[tctdrummer]

hello-new to the forum, seem amazing so far, just to confirm (as i am paranoid on launching a new plane) it is currently sock with a no name ESC with BEC, i am wanting to buy a Turnigy 50A esc with 3a 'switching' BEC, would i be pleased with this for my 4 (active)9g servos, or should i get a higher amp BEC?

reason i ask is because my plane has vector thrusting that runs on 2 additiona 9g servos, i hate to loose this mid-air because of a burnt ESC, i was thinking the Turnigy would be a great upgrade from the stock one, but in reading this thread, i am thinking an additional BEC wouldn't be a bad idea

[kyleservicetech]

Originally Posted by tctdrummer

hello-new to the forum, seem amazing so far, just to confirm (as i am paranoid on launching a new plane) it is currently sock with a no name ESC with BEC, i am wanting to buy a Turnigy 50A esc with 3a 'switching' BEC, would i be pleased with this for my 4 (active)9g servos, or should i get a higher amp BEC?

reason i ask is because my plane has vector thrusting that runs on 2 additiona 9g servos, i hate to loose this mid-air because of a burnt ESC, i was thinking the Turnigy would be a great upgrade from the stock one, but in reading this thread, i am thinking an additional BEC wouldn't be a bad idea

Check out the Castle Creations 10 Amp uBEC. It weighs in at perhaps 1/2 ounce, and will put out 10 amperes. I've got 4 of them, one in a 19 pound electric model with seven Hitec 645 MG servos. My onboard voltage monitor shows that the CC uBEC never sagged below 6.0 VDC, its set to 6.6 VDC.

Thing to be aware of on the BEC's with a linear voltage regulator, those regulators are designed to be used with a heat sink. A LARGE heat sink that would be larger than the ESC itself. Since no heat sink is provided on these regulators due to space considerations, these regulators can get hot. And when they get to hot, they turn them selves off to protect them selves. And when you get to the scene of the crash, the regulator has cooled off and starts working again.

I've seen this happen in my club twice this year so far. Got them to put in the CC uBEC units, no more problems.

[craigrs84]

Hi, can someone point me to a good reliable brand of UBEC?

I have heard you can get a good one for about $10, but not sure which brand to trust. Thanks.

Also, when factoring the amount of amps your servos require, do you also need to factor in amperage for the receiver itself?

for example, does the receiver draw 750 milliamps, similar to a micro-servo?

[rcers]

I like Dimension Engineering BEC's but they are more than $10.

Most 2.4GHz RX's draw around 200-300ma. I assume that is what you are using. Some 72Mhz receivers are a tenth of that.

http://www.dimensionengineering.com/index.html

Mike

[kyleservicetech]

Originally Posted by craigrs84

Hi, can someone point me to a good reliable brand of UBEC?

I have heard you can get a good one for about $10, but not sure which brand to trust. Thanks.

Also, when factoring the amount of amps your servos require, do you also need to factor in amperage for the receiver itself?

for example, does the receiver draw 750 milliamps, similar to a micro-servo?

I've used both Castle Creations and Common Sense uBEC's. Both have worked well.

If you buy the Castle Creations ICE series of ESC's these units use a switching type of uBEC rated for five amperes. And some of the other ESC suppliers are going the same way. IMHO, I'd NEVER use a linear BEC for receiver power on any ESC running on more than two LiPo cells.

The current pulled by the receiver is fairly low, less than 50 milliamperes, depending on who made it. That current is fairly constant. The various servos also pull fairly low currents. Until they have to push an elevator or something. I've measured peak currents on my Hitec 645MG servos at 2100 (thats 2.1 Amps) on EACH servo, when pulling maximum current.

That's why using the linear BEC's often used in low cost ESC's can lead to problems. The voltage regulator IC in these units can overheat, and shut off to protect itself. By the time you get to the crash site, that regulator has cooled off and starts working again. I've seen it happen in my club three times this year.

As to what's involved with these battery elimination circuits, take a look:
http://www.wattflyer.com/forums/showthread.php?t=63779

[CHELLIE]

Originally Posted by craigrs84

Hi, can someone point me to a good reliable brand of UBEC?

I have heard you can get a good one for about $10, but not sure which brand to trust. Thanks.

Also, when factoring the amount of amps your servos require, do you also need to factor in amperage for the receiver itself?

for example, does the receiver draw 750 milliamps, similar to a micro-servo?

if your in the USA here is a great vendor to work with, Tell Jeff that Chellie sent you

http://www.headsuprc.com/servlet/the...BEC/Categories

here is what i do, its a bit of a over kill but thats a good thing

for each micro servo i allow 3/4 of a UBEC amp for it, so with 4 micro servos use a 3 amp UBEC

with mirco digital servos or standard servos even if they are digital, i allow 1 AMP from the UBEC for it, so use a 4 to 5 amp UBEC for 4 servos of this type, dont worry about any draw from the Receiver, its already calculated in Hope that helps, Chellie

[E-Challenged]

I added a Park BEC to the E-Flite 30 amp Pro ESC bypassing the 700ma rated switch mode BEC in my Park Zone Stinson ( five micro servos with flaps) after an "unexplained" crash. I have used Park BEC's in all of my smallish models with 3S lipos and four or more servos with no unexplained crashes for the last 4 years. I have not invested in CC ICE or other ESC's with built-in higher amp capacity switch mode BEC's due to the much higher cost. Hobby King offeres a lot of ESC's with high amp rated switch mode BEC's and add-on BEC's but I don't patronize them. Why PZ used the 30amp Pro with puny 700ma BEC in the Stinson is a mystery.

I think that the indented foam control surface hinges on foamy ARF's put too much strain on servos causing higher than normal amp draw. I think that possible defects in servos and variations in BEC circuit amp capability, plus sensitivity to low voltage from overheating BEC's in 2.4Ghz receivers, operating with 3S lipos, with four or more servos lead to brownouts. Too many fliers still don't know the difference between ESC amp ratiing and BEC amp rating re brownout crashes.

PS: The name "Ultimate Battery Eliminator Circuit" (UBEC) was originally a specific product name for one of the early add-on switch mode BEC devices. Nowadays the terms "Universal BEC" (also UBEC) and Switching BEC ( SBEC) are all used interchangeably.

[Mtrchs]

Dont know never used them

[GooberRC]

Thanks for the great info here Chellie and everyone else who contributed. I think I know the answer to this but I wanted to double check with the experts

I'm about to start putting together my Hyperion 25e P-51. I'm going to be using a Hyperion HP-S3025-08 motor with a CC Phoenix Ice Lite 100 ESC on 4S. The ESC is a little overkill so I can use it in larger configurations later on. I will likely be drawing no more than 50A. The servos are as follows :

Ailerons: Hitec HS-65MG x2
Tail : Hitec HS-82MG x2
Retract : Hitec HS-75BB

If I'm understanding this right, I should be fine without a separate BEC with this setup. On the other hand a separate BEC such as the CC 10A would provide a little extra insurance against a blown ESC. Sound about right? What would you recommend? I've seen some comments suggesting the seperate BEC can also help prevent brown-out but I must confess I'm still not sure when or how that happens. My radio is a Futaba 8FG in case that's relevant.

Thanks, as always!

[CHELLIE]

Originally Posted by GooberRC

Thanks for the great info here Chellie and everyone else who contributed. I think I know the answer to this but I wanted to double check with the experts

I'm about to start putting together my Hyperion 25e P-51. I'm going to be using a Hyperion HP-S3025-08 motor with a CC Phoenix Ice Lite 100 ESC on 4S. The ESC is a little overkill so I can use it in larger configurations later on. I will likely be drawing no more than 50A. The servos are as follows :

Ailerons: Hitec HS-65MG x2
Tail : Hitec HS-82MG x2
Retract : Hitec HS-75BB

If I'm understanding this right, I should be fine without a separate BEC with this setup. On the other hand a separate BEC such as the CC 10A would provide a little extra insurance against a blown ESC. Sound about right? What would you recommend? I've seen some comments suggesting the seperate BEC can also help prevent brown-out but I must confess I'm still not sure when or how that happens. My radio is a Futaba 8FG in case that's relevant.

Thanks, as always!

Hi The CC lite 100 AMP is a Great ESC, it has a 5 AMP BEC, the more cells you use, the less AMPs you get from the built in BEC normally, also the BEC is built into the ESC, and HEAT from the ESC sometimes will reduce the BEC amp output, also using a seperate BEC will give you a cleaner voltage, since its not built into the ESC and being affected with the electronic of the ESC, and its just Darn good cheap insurance to use a UBEC, if you have a 2.4 radio, and use 4 or more lipo cells, use a UBEC, you will be glad you did. Hope that helps, Chellie

http://www3.towerhobbies.com/cgi-bin...XXXU0&P=8#tech

This is the Phoenix Ice Lite 100 25V Electronic Speed Control
from Castle Creations.



FEATURES: Recommended for aircraft where space or weight are at a premium such
as sailplanes and pylon racers
Onboard Data Logging
Switching BEC
Handles up to 6S LiPo (25.2V) maximum input


INCLUDES: Phoenix Ice Lite 100 25V Electronic Speed Control with universal
receiver connector, pre-tinned motor and battery leads and
instruction manual


REQUIRES: Installation between motor, battery and receiver

SPECS: Length: 2.5" (63.5mm)
Width: 1.1" (27.9mm)
Height: 0.5" (12.7mm)
Weight: 1.12oz (31.7g)
Max Amps: 100A, 5A BEC
Max Volts: 25V (6S Lipo, 20S NiCd/NiMH)

[CHELLIE]

If you dont use a UBEC with a 2.4 radio, use a voltage protector, its cheap insurance against a brown out, its almost as good as using a seperate UBEC, it will save your plane. these voltage protectors were designed for rc cars using a 2.4 radio, but people have found that they work just as well for planes too, the voltage protector does not know if its in a plane or a car, electronics is electronics a Charged capacitor is a Battery, and will feed a little current back into the system to prevent a Low voltage Brown out problem, Hope that helps, Chellie

Spektrum Receiver Low Voltage Cutouts and Damaged LiPo Batteries

I Hate Brown Outs
There are a few things you can do to help prevent a 2.4 brown out.

1. Always use a UBEC with 2.4 Period its cheap insurance
2. Always use a Full range 2.4 Receiver Period its cheap insurance
3. Use a Receiver Low voltage Protection Capacitor if your to Cheap to buy a UBEC it will supply voltage for the few seconds that the battery is drawn down to low and prevent a Brown out, a Charged Capacitor is a battery, there has been some debate here on that, But thats Why Spektrum made the darn thing for, to prevent a brown out on rc cars, but it will ALSO work on planes too, it does not know if its in a Plane or a car it will just do its job and supply voltage if it goes down.
4. Dont allow your plane to get bewteen a object and you, like a tree, building etc to prevent a Masking of the radio signal.and a brown out.
5. if your using a non full range 2.4 Receiver, good luck to you, keep your plane in close to you or else, by by plane
6. And thats the Truth

http://www.hobby-lobby.com/voltage_p..._2212_prd1.htm

[JetPlaneFlyer]

Originally Posted by CHELLIE

3. Use a Receiver Low voltage Protection Capacitor if your to Cheap to buy a UBEC it will supply voltage for the few seconds that the battery is drawn down to low and prevent a Brown out, a Charged Capacitor is a battery, there has been some debate here on that, But thats Why Spektrum made the darn thing for, to prevent a brown out on rc cars, but it will ALSO work on planes too, it does not know if its in a Plane or a car it will just do its job and supply voltage if it goes down.[/IMG]

Actually Spektrums official statement on these things is:

This Voltage Protector is not intended for Aircraft use.

Bottom line is they simply don't work in planes (I'm guessing they probably dont do much in cars either). The electricity stored is only good for hundredths of a second, nothing like 'a few seconds'.. just not enough to make a difference.

Here's a video I shot a while ago to show how long the capacitor works for when I disconnect the battery. As you will see the servo stops the instant I pull out the plug, and this is WITH the capacitor installed, and this is only one 5g sub-micro servo that I'm powering.

YouTube Video

[CHELLIE]

Originally Posted by JetPlaneFlyer

Actually Spektrums official statement on these things is:

Bottom line is they simply don't work in planes (I'm guessing they probably dont do much in cars either). The electricity stored is only good for hundredths of a second, nothing like 'a few seconds'.. just not enough to make a difference.

Here's a video I shot a while ago to show how long the capacitor works for when I disconnect the battery. As you will see the servo stops the instant I pull out the plug, and this is WITH the capacitor installed, and this is only one 5g sub-micro servo that I'm powering.

YouTube Video

The capacitor is not designed to operate a servo its designed to work with the available voltage and keep the voltage up, it only has to supply millivolts at a voltage to where the 2.4 receiver will not brown out and reboot, remember the Voltage protector is working with the available voltage and supplying just enough voltage even if it millivolts, to keep the receivers memory alive Hope that helps to clear up things, Take care, Chellie

[JetPlaneFlyer]

This is just going over old ground. Here is the response I posted to the same question last time it was asked, based on actual calculation of the capacity of the capacitor:

Chellie,

The numbers still don't stack up. Lets say the capacitor just provides half an amp to slightly 'top up' the power supplied by the BEC for a few moments.. Is that what you have in mind?

The 4700 cap providing just half an amp would be exhausted in about two hundredths of a second. Basically a capacitor of that size just does not have enough storage capacity to make any significant difference in preventing a voltage drop in an RC system. You would need about 200 capacitors of that size to make any worthwhile difference.

the original thread with all the math: http://www.wattflyer.com/forums/show...ight=capacitor

It's possible that a capacitor 'might' protect in a very limited way from transient (as in hundredths of a second) dips in voltage. But low voltages lasting 'a few seconds' the capacitor would have no hope of helping with. If a cap gives any protection at all is highly debatable but if it gives any then it's in such a limited way as to be not a reliable form of protection. The best solution is to install a reliable power source that will never drop to low enough voltage to cause a brown-out. the castle 10A BEC that you recommended is great, most quality ESC's these days have decent BEC's built in too.

[GooberRC]

Thanks a lot Chellie - The CC 10A seems like a good investment

[kyleservicetech]

Originally Posted by GooberRC

Thanks a lot Chellie - The CC 10A seems like a good investment

I've been using the CC 10 amp BEC now for five years. Did have an issue with one of them where its output voltage started sagging about 1/4 volt below its set voltage at a 5 amp load. It still worked OK, but I replaced it.

Since you have the CC ICE ESC with its built in 5 amp BEC, it's a fairly simple job to use BOTH the ICE's BEC and a Castle Creations 10 Amp uBEC. That would be the best of both worlds.

These two uBEC's must be isolated from each other with a Shottky diode. Do not substitute the Shottky diode with a silicon diode. The silicon diodes have more voltage drop. Directly parallel connecting them is usually a no - no.

Take a look at this thread. Use your 100 Amp ICE ESC as one input, and the 10 Amp CC uBEC as the other input. The 10 Amp CC uBEC would be powered by the same 4 cell LiPo used on the 100 Amp ICE ESC. The white signal cross over wire is not used with the CC 10 Amp uBEC. Let me know if you'd like a drawing specifically for a 100 Amp ICE ESC and a 10 Amp uBEC.

http://www.wattflyer.com/forums/showthread.php?t=67094

[kyleservicetech]

Originally Posted by JetPlaneFlyer

This is just going over old ground. Here is the response I posted to the same question last time it was asked, based on actual calculation of the capacity of the capacitor:


the original thread with all the math: http://www.wattflyer.com/forums/show...ight=capacitor

It's possible that a capacitor 'might' protect in a very limited way from transient (as in hundredths of a second) dips in voltage. But low voltages lasting 'a few seconds' the capacitor would have no hope of helping with. If a cap gives any protection at all is highly debatable but if it gives any then it's in such a limited way as to be not a reliable form of protection. The best solution is to install a reliable power source that will never drop to low enough voltage to cause a brown-out. the castle 10A BEC that you recommended is great, most quality ESC's these days have decent BEC's built in too.

Agreed:
I've been using the Castle Creations 10 Amp uBEC with complete success for the past five years.

As for using a "Backup" capacitor, I've got a few that WILL do the job, including powering the servos for a few seconds.

In case you want to order some, take a look:
http://www.digikey.com/product-detai...221-ND/2269430 (Yeah, this $100.00 two pound capacitor is what it takes to briefly power the receiver and servos a second or so. )

[GooberRC]

Thanks Dennis. I think I get it, but I'll run it by you before I start soldering!

[kyleservicetech]

Originally Posted by GooberRC

Thanks Dennis. I think I get it, but I'll run it by you before I start soldering!

Here you go!

Just a note, before giving this to a club member, I covered the solder connections directly with a piece of shrink tubing, then covered the entire diode/solder connections with another piece of shrink tubing. Got to make certain those wire/solder connections have proper support!

These two assemblies just plug in between the ICE ESC and the uBEC. Do not use the white wire between the two units. It's not required.

Let me know if you have questions.

DennyV

[GooberRC]

Thanks a lot Dennis. I'm assuming that the receiver is fine with having voltage connected to both inputs? Does it draw current from both or does it switch to the second one as a backup if it can't get enough power?

[kyleservicetech]

Originally Posted by GooberRC

Thanks a lot Dennis. I'm assuming that the receiver is fine with having voltage connected to both inputs? Does it draw current from both or does it switch to the second one as a backup if it can't get enough power?

Connecting two uBEC's to a receiver in this manner is just fine. These receivers have three connections per servo, Battery minus, battery plus, and signal. All of the battery minus connections are connected directly to each other, same for the battery plus connections. Each signal connection is different.

So, you can connect your battery cable to any of the receiver's servo connections. Makes no difference. Just be certain to not plug in any connector upside down.

With this setup, which ever input has slightly higher voltage will be the one that powers the receiver. If you really load down the servos, then both might be powering the receiver.

[GooberRC]

Got it, thanks!

[kyleservicetech]

Originally Posted by GooberRC

Got it, thanks!

Just had a thought. Might be a good idea once or twice a year to unplug one DC input to your receiver. Then cycle the servos. Then do the same for the other DC input.

This verifies both uBEC's are doing their job, and you really have dual DC inputs.

(I've got undervoltage alarms on both my giant scale models for my receiver DC uBEC and A123 supplies.)