logo
Thread Tools
Old 03-17-2019, 06:58 PM
rcfs is offline
Find More Posts by rcfs
Better - Faster - More Fun!
Joined Mar 2006
30 Posts
Discussion
ESC using external battery question

I have a 90amp Castle Creations Talon ESC.  Can anyone help clarify the manual statement "Always disconnect the red power wire on the throttle lead when an external battery is employed in the receiver circuit."  

It appears the statement says to cut the red wire on the plug from the ESC that is plugged into the throttle channel of the receiver if I use a NiMh to power the rx and servos.

Thank you
rcfs is offline Find More Posts by rcfs
Reply With Quote Quick reply to this message
Sign up now
to remove ads between posts
Old 03-17-2019, 07:02 PM
lrb75 is offline
Find More Posts by lrb75
Registered User
United States, VA, Springfield
Joined Aug 2010
42 Posts
Exactly. Dont cut the wire. Get a 3" extension and remove the red wire or pull the pin out of the plug and heat shrink it out of the way.
lrb75 is offline Find More Posts by lrb75
Reply With Quote Quick reply to this message
Old 03-17-2019, 09:15 PM
Philkoury is offline
Find More Posts by Philkoury
Registered User
United States, MS, Picayune
Joined Feb 2007
420 Posts
No need for the extension. Look at the side of the ESC connector where the crimped terminals are showing. Push in on the red wire and you should see the little plastic tab clear the terminal. Use an Exacto knife blade or a straight pin to slightly raise the plastic flap and you will be able to pull the red wire out of the housing. Fold the red wire back and cover the terminal with heat shrink or electrical tape.
How to disconnect a wire from from a servo plug (1 min 53 sec)
Philkoury is offline Find More Posts by Philkoury
Reply With Quote Quick reply to this message
Old 03-20-2019, 02:18 PM
Pilotpete is offline
Find More Posts by Pilotpete
Registered User
Pilotpete's Avatar
Lyndonville, VT
Joined Nov 2008
1,054 Posts
The Talon 90 ESC has a 20A peak, 9A continuous. No Nimh battery that uses AA size cells can match that performance. Why not just use the BEC?
Pete
Pilotpete is offline Find More Posts by Pilotpete
Reply With Quote Quick reply to this message
Old 03-20-2019, 02:35 PM
Judge is offline
Find More Posts by Judge
Team Futaba
Judge's Avatar
United States, CA, Ladera Ranch
Joined Jan 2006
11,311 Posts
I normally use a separate RX power rather than the ESC because I still want power to the radio if anything happens to the motor, ESC, or power pack. Would it be OK if your radio dies when the engine went dead stick on a gasser? That's my logic.
Judge is offline Find More Posts by Judge
Reply With Quote Quick reply to this message
Old 03-21-2019, 07:17 AM
lrb75 is offline
Find More Posts by lrb75
Registered User
United States, VA, Springfield
Joined Aug 2010
42 Posts
Dead stick on a gasser is not the same. The built in bec is hundreds of times more reliable than your gas engine. That being said I normally use an external bec for mid sized planes and a separate battery for giant scale. For giant scale the hv escs dont have a bec anyway.
lrb75 is offline Find More Posts by lrb75
Reply With Quote Quick reply to this message
Old 03-21-2019, 09:40 AM
Judge is offline
Find More Posts by Judge
Team Futaba
Judge's Avatar
United States, CA, Ladera Ranch
Joined Jan 2006
11,311 Posts
Quote:
Originally Posted by lrb75 View Post
Dead stick on a gasser is not the same. The built in bec is hundreds of times more reliable than your gas engine. That being said I normally use an external bec for mid sized planes and a separate battery for giant scale. For giant scale the hv escs dont have a bec anyway.
Conceptually it is. I do not want to lose radio power if the motor, ESC/BEC, or main pack have any issues. As far as reliable? Well, I have a number of burned up ESCs that stand in opposition to the idea that ESCs are super reliable.

It is amusing that people will go on about needing dual receivers, but then seem ok with a set up with a series single point failure mode that will kill power to their radio.
Judge is offline Find More Posts by Judge
Reply With Quote Quick reply to this message
Old 03-27-2019, 09:21 AM
rcfs is offline
Find More Posts by rcfs
Better - Faster - More Fun!
Joined Mar 2006
30 Posts
What would be the harm if the red wire was not disconnected?
rcfs is offline Find More Posts by rcfs
Reply With Quote Quick reply to this message
Old 03-27-2019, 10:20 AM
apriliamille is offline
Find More Posts by apriliamille
Registered User
apriliamille's Avatar
United States, UT, American Fork
Joined May 2008
179 Posts
Interesting question I always thought it was "the rule" I never questioned it
apriliamille is offline Find More Posts by apriliamille
Reply With Quote Quick reply to this message
Old 03-27-2019, 10:30 AM
BarracudaHockey is online now
Find More Posts by BarracudaHockey
Multi Platform Pilot
BarracudaHockey's Avatar
United States, FL, Jacksonville
Joined Dec 2007
9,667 Posts
It's like crossing the streams
BarracudaHockey is online now Find More Posts by BarracudaHockey
Reply With Quote Quick reply to this message
Old 03-27-2019, 10:38 AM
suds is online now
Find More Posts by suds
indywestrc & viehercfliers
suds's Avatar
United States, IN, Zionsville
Joined Jul 2014
509 Posts
Quote:
Originally Posted by rcfs View Post
What would be the harm if the red wire was not disconnected?
If lipo voltage < BEC voltage - it would try to charge the connected lipo and exceed max BEC output potentially taking out the BEC.

If BEC voltage < lipo voltage, Lipo voltage would backflow into BEC, also not good.

If BEC and Lipo were isolated with diodes, you could probably use both for redundancy.
suds is online now Find More Posts by suds
Reply With Quote Quick reply to this message
Old 03-27-2019, 11:00 AM
rcfs is offline
Find More Posts by rcfs
Better - Faster - More Fun!
Joined Mar 2006
30 Posts
If the 2nd battery powering/backing up the servos was a NiMh would there be a potential problem?
rcfs is offline Find More Posts by rcfs
Reply With Quote Quick reply to this message
Old 03-27-2019, 12:09 PM
apriliamille is offline
Find More Posts by apriliamille
Registered User
apriliamille's Avatar
United States, UT, American Fork
Joined May 2008
179 Posts
I saw this on break at work

I wonder if this applies to RX battery

Https://www.rcgroups.com/forums/show...r-multiple-ESC


'm not an EE either, but I frequently listen to Lucien Miller on the ATTF podcast. Lucien is an electrical engineer. This is from memory and not verbatim from the show.

Apparently, there is a feedback loop in the circuit of an ESC's internal BEC. It reads it's own output voltage and when it see's this voltage get out of tolerance, it adjusts to compensate. When two ESC's are connected in parallel, if there is even the slightest difference in output voltage, it can trigger the feedback loop in the other unit to adjust it's output and then the conflict begins. One goes up, the other goes down etc. Basically they fight each other. If the two units were assembled with the exact same production run of components and the output voltage was very closely matched, then I think you might get away with it.
apriliamille is offline Find More Posts by apriliamille
Reply With Quote Quick reply to this message
Old 03-27-2019, 01:56 PM
suds is online now
Find More Posts by suds
indywestrc & viehercfliers
suds's Avatar
United States, IN, Zionsville
Joined Jul 2014
509 Posts
To hook the two toghether (rx pack and ESC) the best bet is the 'battery buffer'
http://www.western-robotics.com/BBFR
suds is online now Find More Posts by suds
Reply With Quote Quick reply to this message
Old 03-27-2019, 07:35 PM
rcfs is offline
Find More Posts by rcfs
Better - Faster - More Fun!
Joined Mar 2006
30 Posts
Thanks guys! I'll just remove the red wire
rcfs is offline Find More Posts by rcfs
Reply With Quote Quick reply to this message


Quick Reply
Message:


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools