RCCrawler Forums

norco kid · 11-24-2015, 08:21 AM

Noobie question... Why is it that when you run an external BEC (or 2 ESC for Dual motors) that one ESC BEC has to be disabled? Wouldn't the 2 BECs working together provide MORE power?

johnnyh66 · 11-24-2015, 08:24 AM

Generally, only the steering servo runs off the BEC.
If you are running 2 steering servos for 4ws, you'd want either 2 10 Amp BEC's or 1 Castle Pro 20 Amp BEC.

micro racer · 11-24-2015, 08:52 AM

Also, the esc bec and a CC bec are generally providing different voltages. One will fry the other if the red wire isn't pulled.

phillyb · 11-24-2015, 11:03 AM

Also people usually run higher volts to their servo but the radio usually can't handle higher voltages reliably. So maybe 6+ to servo, while the radio gets 4.8V usually.

Olle P · 11-25-2015, 12:07 AM

To sum the previous answers up:

It's bad to have two BECs running in parallel to feed the same appliance.
At best they'll be out of sync with their PWM causing extra strain on the electronics.
At worst they're trying to feed different voltages resulting in the one with the lower setting being fried.
The typical way to wire things, at least for us running crawlers, is to actually use two BECs; the external and the internal.
ESC's BEC is used to power the Rx, lights and other minor power consumers.
The external BEC is used for steering servo(s), whinch(es) and other more "hungry" devices.

11-24-2015, 08:21 AM	#1
norco kid Pebble Pounder Join Date: Oct 2006 Location: Montreal Posts: 199	Why only 1 BEC? Noobie question... Why is it that when you run an external BEC (or 2 ESC for Dual motors) that one ESC BEC has to be disabled? Wouldn't the 2 BECs working together provide MORE power?

11-24-2015, 08:24 AM	#2
johnnyh66 Scale Detail Engineering Join Date: Apr 2010 Location: Turtle Island Posts: 5,573	Re: Why only 1 BEC? Generally, only the steering servo runs off the BEC. If you are running 2 steering servos for 4ws, you'd want either 2 10 Amp BEC's or 1 Castle Pro 20 Amp BEC.

11-24-2015, 08:52 AM	#3
micro racer Rock Crawler Join Date: Jan 2013 Location: San Diego Posts: 605	Re: Why only 1 BEC? Also, the esc bec and a CC bec are generally providing different voltages. One will fry the other if the red wire isn't pulled.

11-24-2015, 11:03 AM	#4
phillyb Rock Crawler Join Date: Nov 2004 Location: roanoke Posts: 550	Re: Why only 1 BEC? Also people usually run higher volts to their servo but the radio usually can't handle higher voltages reliably. So maybe 6+ to servo, while the radio gets 4.8V usually.

11-25-2015, 12:07 AM	#5
Olle P RCC Addict Join Date: Jan 2012 Location: Sweden Posts: 1,809	Re: Why only 1 BEC? To sum the previous answers up: It's bad to have two BECs running in parallel to feed the same appliance. At best they'll be out of sync with their PWM causing extra strain on the electronics. At worst they're trying to feed different voltages resulting in the one with the lower setting being fried. The typical way to wire things, at least for us running crawlers, is to actually use two BECs; the external and the internal. ESC's BEC is used to power the Rx, lights and other minor power consumers. The external BEC is used for steering servo(s), whinch(es) and other more "hungry" devices.

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