RCCrawler Forums

K.O.M. · 05-13-2010, 12:00 AM

Ok, I'll try to make this as short as possible, here it goes:

Most, if not all, competition crawlers (I'm referring to the people driving the rigs, that is), are running some sort of additional external BEC. This, at least to me, was quite fascinating. In my 20 years in the R/C hobby involved mostly with go-fast electirc machinery, I thought this was bit silly or redundant, because "Doesn't the ESC already provide that function?"

Now that I'm a few months into crawling, I've realized the need for an external BEC--servos draw a lot of amps, and that all to common bind draws a lot of current as well. All of the external BECs being used are using switching or switch mode to power the electrics--advantages are that it stabilizes the voltage/amperage input to the receiver, servo, esc etc...

The question is:

1. Which ESCs have a switching BEC built into the system that ALSO caters to the needs of crawlers (drag brake, instant reverse, etc...)

2. With the only example I've found being the Holmes Hobbies model, is the built in switching BECs of said ESCs be sufficient for say a 300-400 oz/in. or will I still need to run an external switching BEC?

P.S. Would love to hear JRH's thoughts on this.

oldhippie · 05-13-2010, 09:22 AM

The 5 amp bec in the HH is marginal. Most guys get by with it but I have heard of heat/glitching issues "votling up" and/or running big servos.

constantmotion · 05-13-2010, 10:27 AM

Yeah, mine doesn't seem to be as strong as it should with a Hitec 7950TH. I did check the voltage on the wires coming out of the servo, it was like 5.96V. It is truely getting 6V, but I'm not sure if that's true when under a load.

05-13-2010, 12:00 AM	#1
K.O.M. Quarry Creeper Join Date: Mar 2010 Location: SF East Bay Posts: 451	ESCs with switching BECs Ok, I'll try to make this as short as possible, here it goes: Most, if not all, competition crawlers (I'm referring to the people driving the rigs, that is), are running some sort of additional external BEC. This, at least to me, was quite fascinating. In my 20 years in the R/C hobby involved mostly with go-fast electirc machinery, I thought this was bit silly or redundant, because "Doesn't the ESC already provide that function?" Now that I'm a few months into crawling, I've realized the need for an external BEC--servos draw a lot of amps, and that all to common bind draws a lot of current as well. All of the external BECs being used are using switching or switch mode to power the electrics--advantages are that it stabilizes the voltage/amperage input to the receiver, servo, esc etc... The question is: 1. Which ESCs have a switching BEC built into the system that ALSO caters to the needs of crawlers (drag brake, instant reverse, etc...) 2. With the only example I've found being the Holmes Hobbies model, is the built in switching BECs of said ESCs be sufficient for say a 300-400 oz/in. or will I still need to run an external switching BEC? P.S. Would love to hear JRH's thoughts on this.

05-13-2010, 09:22 AM	#2
oldhippie I wanna be Dave Join Date: Feb 2009 Location: 20 miles southeeast of downtown Sacramento Posts: 2,373	The 5 amp bec in the HH is marginal. Most guys get by with it but I have heard of heat/glitching issues "votling up" and/or running big servos.

05-13-2010, 10:27 AM	#3
constantmotion On the lookout for Rocks Join Date: Mar 2006 Location: Monroe, Louisiana Posts: 3,711	Yeah, mine doesn't seem to be as strong as it should with a Hitec 7950TH. I did check the voltage on the wires coming out of the servo, it was like 5.96V. It is truely getting 6V, but I'm not sure if that's true when under a load.

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