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ESC & No BEC Help

Old 01-31-2021, 01:49 AM
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Default ESC & No BEC Help

FRUSTRATION is mounting!!! Trying not to admit a mistake, BUT, I am in the process of moving up to a much larger electric model than previously. I find myself now using 2ea 6S batteries in series, now a 12 S system I believe. I had used an 80 amp ESC and ONE battery to build the plane and check out control servos with no issues. At completion and final check out I used both batteries and quickly found out that I had needed an ESC with 12 S capability, oops. SO, I bought a 120 amp, 6-12 S ESC from Hobby King(maybe, grrrr). I just tried to power things up and all I got is a constant beep, beep, beep.

Next checking my receiver and found that it was not getting power, hmm? Read the user manual and found that the section for "bec output" for my model was BLANK! Went back to the HK site and read more about my ESC- Aerostar 120A OPTO HV, and it says in the fine print, opto couple, no BEC. Groan, does this mean that I now have to have an additional battery onboard to power my servos and receiver??

If so, which port do I plug this small battery into? #3 is where I have plugged the ESC into. OR, should I "TRY" and send this back to HK for credit and claim ignorance?

Sorry to expose myself as somebody that probably should have stayed at 6S and smaller. The kit I bought in the mid 80s just got built due to the Corona virus and, boy, has this been an expensive undertaking, both $$$$ and emotionally.

Thanks for the, after the deed, advice.

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Old 01-31-2021, 08:09 PM
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Most HV ESCs are OPTO. A battery or a UBEC is what's needed. Plug it in to any open servo slot on the receiver if the receiver doesn't have a dedicated batt slot.
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Old 01-31-2021, 08:41 PM
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Agreed with Pat above. As the HK page says, the ESC is the OPTO type which does not include a BEC. So you will need to do one of two things:

1. Get an RX pack and plug it into an open slot on the RX (or Y it in with the throttle lead). If you use anything over 6v (like a 2S LiFE pack), make sure your servos can handle the higher voltage.

2. Get a UBEC and tie the power leads into the battery connection. One of the following would work for 12S:

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Old 01-31-2021, 09:10 PM
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Thank you both for the advice. I was blissfully ignorant of these differences from my smaller/single battery power systems. I hope the added education and financial hit are worth it IF I ever get this EDF plane into the air. TBD.
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Old 02-04-2021, 11:29 PM
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I does sound as if you are making a big leap going to a 12s EDF system. I hope you have the necessary monitoring equipment (at least a Watt meter) as if anything you have is not up to the job it is likely to fail quickly and expensively! .
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Old 02-05-2021, 01:29 AM
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When you say "monitoring equipment", I am not sure what you mean. I do have a balancing battery charger, a voltmeter to check voltage(duh) of the batteries, and I don't plan on long flights to deplete the batteries during flight. What else am I suppose to "monitor" while flying this plane?

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Old 02-05-2021, 02:07 AM
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Originally Posted by crxmanpat View Post
As the HK page says, the ESC is the OPTO type which does not include a BEC. ...
In a true optocoupled ESC a BEC would make no sense, it would defeat the purpose using an optocoupler: reducing electrical interference by eliminating all electrical connections. Used in higher power controllers.
Of course the Chinese marketing had to mess this up, like the did with the concept of Kv, by calling all BECless controllers opto, including the ones without an optocoupler.
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