Solved esc with bec or external bec?

The Hangar

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In a project I’m working on I may end up needing 4s power. I plan on flying it on the old emax 2215 c pack on 3s, but if that doesn’t cut it, I may need to move to 4s power. However, the old c pack motor (and the esc I’m using) are not 4s rated, but my stock power pack b is technically 4s capable. I can’t seem to find a good amp draw chart for it, but I’m skeptical that my emax 20 amp esc will be able to handle the 4s power and 9x6 propeller... The sites I looked at did recommend an 18 amp esc, so I think that it might be OK... what do you think - have you ever flown the stock old emax power pack b on 4s? I just want to make sure this is ok before I ruin all my gear😂. Thanks!
 

The Hangar

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i fly the old C-pack emax 2215 on 4S all the time with a 9x4.5 and a 30A esc. my mustang, my spit, my bushwacker, ....

laters,

me :cool:
Hmm, well issue is that I ruined all my emax 30 amp escs by flying off the water and so I picked up a four pack of cheapo eBay 30 amp escs for like $18! They are actually much smoother upon start than the emax escs which surprised me a lot. I mean that’s less than $5 an esc! But they aren’t 4s capable. My 20 amp escs are, but pretty sure it would be just as bad to run the 2215 of a 20 amp esc 4s capable esc than a 30 amp non 4s capable esc. Have you by any chance run a b pack on 4s?
 

moret

Well-known member
Hmm, well issue is that I ruined all my emax 30 amp escs by flying off the water and so I picked up a four pack of cheapo eBay 30 amp escs for like $18! They are actually much smoother upon start than the emax escs which surprised me a lot. I mean that’s less than $5 an esc! But they aren’t 4s capable. My 20 amp escs are, but pretty sure it would be just as bad to run the 2215 of a 20 amp esc 4s capable esc than a 30 amp non 4s capable esc. Have you by any chance run a b pack on 4s?

I show that using a 2215 on 4S with 9X45 prop I was drawing 18 amps.
With a 10X4.5 prop I was drawing 26 amps.

And with a 3S on a 10X4.5 prop I was drawing 18.5 amps.
The 2215 was in the C pack V2

I am using 35 amp ESC's and a 9X4.5 on my 4S 2215 to keep the heat down on the motor and ESC.

With the new radial C pack motor, I let the smoke out on the 35 amp ESC and am now using a 45 amp ESC.
I am using the FT ESC or a ZTW for the 45 amp.
Also the 3 amp BEC in the FT ESCs will not run 6 servos.

I might trying running one for a few seconds and see if it gets hot. Then try for a minute and check again????
But I am not paying for the ESC...

Good luck.
 

The Hangar

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I show that using a 2215 on 4S with 9X45 prop I was drawing 18 amps.
With a 10X4.5 prop I was drawing 26 amps.

And with a 3S on a 10X4.5 prop I was drawing 18.5 amps.
The 2215 was in the C pack V2

I am using 35 amp ESC's and a 9X4.5 on my 4S 2215 to keep the heat down on the motor and ESC.

With the new radial C pack motor, I let the smoke out on the 35 amp ESC and am now using a 45 amp ESC.
I am using the FT ESC or a ZTW for the 45 amp.
Also the 3 amp BEC in the FT ESCs will not run 6 servos.

I might trying running one for a few seconds and see if it gets hot. Then try for a minute and check again????
But I am not paying for the ESC...

Good luck.
Thanks! So I’ll have to at least get a bec because my project will require 6 servos. I have a couple extra escs I don’t care about, and I was wondering if I could somehow use the bec off one of those... thoughts? I hope to pick up a radial c pack one of these days, so I can throw 4s into that no problem then.
 

FDS

Elite member
You can use the bec in a spare ESC but separate ones are really cheap and tiny, you just piggyback the main battery wire to them. I have a couple of 3A ones that are really small and light.
 

The Hangar

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You can use the bec in a spare ESC but separate ones are really cheap and tiny, you just piggyback the main battery wire to them. I have a couple of 3A ones that are really small and light.
How would I wire up the esc? I might as well use something I got lying around...
 

The Hangar

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Would this be helpful and apply to using an esc? And also, where would my servos plug into? I plan on using 3 y harnesses for my ailerons all plugged into 1 port.
 

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FDS

Elite member
Yeah, that’s all you need, batt voltage goes in, 5v constant voltage comes out. They are super simple to wire. If you were using a spare ESC it would just replace the Bec in your diagram.
Unless you have digital servos you should get 6 running off a 3A bec, the 30A esc’s usually come with those already. If you go separate then a 5A should easily do 6 servos. Look at the max current draw of whatever ones you are using.
 

The Hangar

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Yeah, that’s all you need, batt voltage goes in, 5v constant voltage comes out. They are super simple to wire. If you were using a spare ESC it would just replace the Bec in your diagram.
Unless you have digital servos you should get 6 running off a 3A bec, the 30A esc’s usually come with those already. If you go separate then a 5A should easily do 6 servos. Look at the max current draw of whatever ones you are using.
These are the servos.
https://www.amazon.com/dp/B072V529YD/?tag=lstir-20
Are you saying I might not have to use a separate bec(esc)?
 

buzzbomb

I know nothing!
When using a separate bec, the red and black on the input side are soldered to the battery connecter, along with the esc power leads. The red and black on the output side plug into any available channel on the receiver. You remove the red wire from the esc receiver plug. Cap that off with some shrink wrap, so it doesn't short.

You're left with an esc that only provides signal (white and black, maybe) to the receiver. The power (red and black) comes from the bec.
 

The Hangar

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When using a separate bec, the red and black on the input side are soldered to the battery connecter, along with the esc power leads. The red and black on the output side plug into any available channel on the receiver. You remove the red wire from the esc receiver plug. Cap that off with some shrink wrap, so it doesn't short.

You're left with an esc that only provides signal (white and black, maybe) to the receiver. The power (red and black) comes from the bec.
So I could use something like the y connector used to fly twin engine planes off one battery?
 

buzzbomb

I know nothing!
You can't y-connect esc's. The signals would get crossed. You really can't serial esc's to increase their power capability. A separate bec just handles the power to the servos and receiver, so that the esc doesn't have to.

That frees up the esc so all it has to handle is the motor. I don't think that'll increase it's maximum amperage draw. That's pretty built in. It just means your servos won't fail for lack of power. I haven't run 4s, yet. If it were me, I'd get a beefier esc and make sure the motor could handle the voltage.

I guess that's what you're trying to do here. The short answer is, you need an esc and motor that handle 4s. If it's in doubt.... Don't do it. :)
 

The Hangar

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You can't y-connect esc's. The signals would get crossed. You really can't serial esc's to increase their power capability. A separate bec just handles the power to the servos and receiver, so that the esc doesn't have to.

That frees up the esc so all it has to handle is the motor. I don't think that'll increase it's maximum amperage draw. That's pretty built in. It just means your servos won't fail for lack of power. I haven't run 4s, yet. If it were me, I'd get a beefier esc and make sure the motor could handle the voltage.

I guess that's what you're trying to do here. The short answer is, you need an esc and motor that handle 4s. If it's in doubt.... Don't do it. :)
Thanks! Ill pick up a bec and maybe a power pack c v2 and then finish up this project!
 

moret

Well-known member
Yeah, that’s all you need, batt voltage goes in, 5v constant voltage comes out. They are super simple to wire. If you were using a spare ESC it would just replace the Bec in your diagram.
Unless you have digital servos you should get 6 running off a 3A bec, the 30A esc’s usually come with those already. If you go separate then a 5A should easily do 6 servos. Look at the max current draw of whatever ones you are using.

After trying 6 servos to add flaps to a mustang, I got to build another plane after all the servos locked up as I hit the flap switch. I did quiz FT store about the 35 amp ESC / 3 amp BEC and the number of servos I will post there answer below, It might work, it might not.

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

Thank you for reaching out. I am sorry to hear you have had issues getting it to function correctly. We do recommend 4-5 servos as this was a problem that was encountered. You can do 6 but you will have to use a secondary BEC. You may need to add something like this: https://www.amainhobbies.com/castle-creations-10-amp-adjustable-bec-cse010-0004-00/p18210

It sounds like the servos are just barely wanting to pull too much power. I look forward to hearing back from you. Have a great day!

Ticket: https://support.amainhobbies.com/helpdesk/tickets/104109

Best Regards,

Kyle F.
Customer Service Specialist
 

buzzbomb

I know nothing!
The 35amp esc is just to handle the battery power to the motor. I'd have gone to 40 amp. It's got a 3amp bec built in, which is not enough power for six servos. If they're recommending a separate 10 amp bec, I would go with that. I've also never run six servos before. I've also never needed a 10 amp bec! But I don't run on 4s.

I'm going to tag some friends to help out. @CarolineTyler, @kilroy07 ,@Sero. I would have tagged @Headbang, but he's already here.

Help is on the way. If they can't help, they'll know who to tag, so they can help. :)