Dedicated receiver battery

[Timothy L]

In my surface vessels I normally use a dedicated LIFE receiver battery to avoid potential sensitive voltage fluctuations caused by interim high current draws on servos, crapped out esc’s, etc.

However, it appears to me that most rc submariners routinely take rx power off of the esc. I am wondering what others see as pros snd cons of using a dedicated rx battery. Thank you.

[MFR1964]

Using a dedicated rx battery gives you more power to run stuff, using the ESC gives you about 1A, other thing can be room, inside a SD you don't have the luxery of plenty of room.
For me it depents on the model, my dryhull boats have a seperate rx pack, those with the SD run of the connection from the ESC.
There is also the fact that some micro servo's don't like higher voltage as 4,8 V, on the long term they will be smoked, using the rx connection of the ESC will give you allways a stable voltage.


Manfred.

[Timothy L]

Thank you Manfred. I am not an electronics person so I want to make sure I understand - you are saying that NOT
using the BEC connection would be conducive to greater voltage fluctuations to the servos (as compared to current surges)? That confused me a little bit. Again, thank you for your response.

[He Who Shall Not Be Named]

Thank you Manfred. I am not an electronics person so I want to make sure I understand - you are saying that NOT
using the BEC connection would be conducive to greater voltage fluctuations to the servos (as compared to current surges)? That confused me a little bit. Again, thank you for your response.

Often the 1-1.5 Ampere's available from the (usually) motor driven ESC is adequate to cover the maximum 'hotel services' demanded by the various devices that dine off the receiver bus: The angle-keeper, depth-keeper, servos, sub-system ESC's, V-tail mixes, etc., all drawing current from the BEC.

IF everything is working to specifications!

But, toss into that once happy circuit one or two stalled servos and maybe a current hungry solenoid valve or two and you quickly over-load the ESC's poor little BEC.

Bad Ju-Ju. Glitching and total hotel service break-down is in your immediate future.

Best to use a dedicated BEC board, dining off the main bus, qualified to carry a continuous 3-5 Ampere load; that board still a much smaller package than a dedicated receiver bus battery.

This picture illustrates the small foot-print of a typical dedicated BEC board:

[RCSubGuy]

I've been pretty lucky with onboard BECs thus far, but... there have been a few instances where the ESC is fine, but the BEC inside them craps out. In terms of capacity, the only 1A BECs I know of in modern ESCs are from super low capacity, cheap POS ESC's. The Pythons I usually run are actually 4 to 5A capacity, so plenty of capacity for normal guts and gizmos.

I am not a fan of a separate battery. Too big. Too much hassle.

If you don't want to use the onboard BECs, disconnect the red wires and run a standalone BEC. Those units can offer high output, steady current without the need for a separate battery.

[Timothy L]

I've been pretty lucky with onboard BECs thus far, but... there have been a few instances where the ESC is fine, but the BEC inside them craps out. In terms of capacity, the only 1A BECs I know of in modern ESCs are from super low capacity, cheap POS ESC's. The Pythons I usually run are actually 4 to 5A capacity, so plenty of capacity for normal guts and gizmos.

I am not a fan of a separate battery. Too big. Too much hassle.

If you don't want to use the onboard BECs, disconnect the red wires and run a standalone BEC. Those units can offer high output, steady current without the need for a separate battery.

Thank you David. I wasn’t even aware that standalone BEC’s existed. Excellent approach!!!

[He Who Shall Not Be Named]

Thank you David. I wasn’t even aware that standalone BEC’s existed. Excellent approach!!!

Amazon is your friend.

Amazon.com : r/c, BEC

[Timothy L]

To add to my earlier comment, I didn’t realize that there was something referred to as a “standalone BEC” - but, by function, it’s what I normally would’ve called a voltage regulator - which I use, for example, when I’m applying a specific voltage to a sound system in a surface boat.

But I see that these products are marketed using the two separate terms. The only significant difference I can determine is that a “stand alone BEC” might be equipped to handle a really high Input voltage like you might find in a race boat. Otherwise they basically appear to be the same thing - am I missing something? Thank you.

[redboat219]

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