Fans-External BEC-& Batteries

[N.Mango]

OK I know what a BEC is and what it does...but I don't know how to use it...if its a good idea to use it....and what type of battery is used.

I plan to add fans at some point. I run on grass mostly and been lucky that the parks are cared for and have had no heat issues as of yet but at some point I'll come across some taller grass and may have some heat issues. I also have a raw 500 servo that the voltage from what I'm running now can be turned up.
Does this setup justify using an external BEC?
Does the BEC use a separate battery?
Pro's & cons of using/not using an external BEC?
Wiring diagram for using a BEC?
Some suggestions for a decent BEC?

Loaded question I know but thanks in advance for any tips, opinions, and suggestions

 

[eyeopenher]

I used BEC’s on all my crawlers…. The biggest problem I see is the extra wires and such. Other then that they are smart to use I think…. I usually cheated and used these instead of clipping the red wire…

But I am starting to run an extra battery… tower has them on sale for $5-7 each. Biggest problem I see about running off a second battery. Is charging, maintaining and securing the battery….

The 2200 is for the infraction and maybe the Mojave… the 800 is for the kraton or Mojave…. I have 2 of each of these to run….

 

[eyeopenher]

And no, the BEC runs off of your battery for the rig…. It just steals power from the lead you solder into the black and red esc to battery wires….
I ran cheap ones from chyyyyna mostly. Only used the waterproof castle creations one in my Trx4…

 

[N.Mango]

And no, the BEC runs off of your battery for the rig…. It just steals power from the lead you solder into the black and red esc to battery wires….
I ran cheap ones from chyyyyna mostly. Only used the waterproof castle creations one in my Trx4…

So an extra battery for it is optional? If running the BEC from the battery for the rig what would be the benefit of it if the internal BEC from the ESC has the voltage needed...is it just to not use the internal BEC?

 

[eyeopenher]

I mean I guess you could run a BEC to a second battery to fine tune the voltage…. But At that point I would just power everything off a second battery as I am starting to do now…. The internal BEC doesn’t always fair well running high demand servos…. So running straight from the battery/BEC would give the motor full power and the BEC full power (without pulling from the esc….) all while stressing the esc less….

 

[L3phturn]

So an extra battery for it is optional? If running the BEC from the battery for the rig what would be the benefit of it if the internal BEC from the ESC has the voltage needed...is it just to not use the internal BEC?

Your ESC has it's own BEC built-in. The question is, will your servo, receiver, and fans pull more current than your BEC can provide? What ESC are you talking about here? You only need an external/additional BEC if you are drawing more current from your ESC's BEC than it can provide. You mostly run on grass... what truck? What are the electrical specs on the servo - IE at the voltage it is running, how much current does it draw? The receiver is easy to find and isn't a big number. How many fans and what are the electrical specs for the fans?

 

[Jon NC RC]

Your ESC has it's own BEC built-in. The question is, will your servo, receiver, and fans pull more current than your BEC can provide? What ESC are you talking about here? You only need an external/additional BEC if you are drawing more current from your ESC's BEC than it can provide. You mostly run on grass... what truck? What are the electrical specs on the servo - IE at the voltage it is running, how much current does it draw? The receiver is easy to find and isn't a big number. How many fans and what are the electrical specs for the fans?

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HERE are the questions to ask when it comes to getting an external BEC or not

 

[N.Mango]

Your ESC has it's own BEC built-in. The question is, will your servo, receiver, and fans pull more current than your BEC can provide? What ESC are you talking about here? You only need an external/additional BEC if you are drawing more current from your ESC's BEC than it can provide. You mostly run on grass... what truck? What are the electrical specs on the servo - IE at the voltage it is running, how much current does it draw? The receiver is easy to find and isn't a big number. How many fans and what are the electrical specs for the fans?

Sounds like I need to get my $hit together then ask.
I have no idea what fan/fans I plan on running so it would be pointless to ask until I choose what I'll use huh?
I have a MMX8 and I don't know off hand what it puts out and I think the servo I have (raw 500) is set to 7.5 now but can go to 8ish I believe...?
When I get all the specs I'll hit you guys up again.

 

[Jon NC RC]

Sounds like I need to get my $hit together then ask.
I have no idea what fan/fans I plan on running so it would be pointless to ask until I choose what I'll use huh?
I have a MMX8 and I don't know off hand what it puts out and I think the servo I have (raw 500) is set to 7.5 now but can go to 8ish I believe...?
When I get all the specs I'll hit you guys up again.

Nahhh....we learn as we go.....

I had to learn all of that with a crawler that had a gimpy internal bec.....

 

[L3phturn]

Sounds like I need to get my $hit together then ask.
I have no idea what fan/fans I plan on running so it would be pointless to ask until I choose what I'll use huh?
I have a MMX8 and I don't know off hand what it puts out and I think the servo I have (raw 500) is set to 7.5 now but can go to 8ish I believe...?
When I get all the specs I'll hit you guys up again.

Ask away, the questions spur discussion and we all learn. A quick search on Castle’s site turns up this on the MMX8s

• Powerful Integrated 8A Peak Adjustable BEC (5.25V-8.0V)

That is I think as good or better than any BEC circuit you can find. I don’t think you need to worry about a BEC - but it depends on the vehicle and how you drive it. Speed running and drag racing will have different demands, but I think that ESC will handle almost any application. The only reason for separate power I can see is if you want to run 12v fans. Instead of a BEC that puts out 12v you can run a little 3S battery just to run the fans directly, but your ESC will run at 8v and it will spin a 12v fan well enough. I run a Hobbywing Max6 at 8.4v and it’s more than enough for the 12v fan I run on my motors in the Notorious and KEXB.