Receiver Amp Draw Limit?

[Jamr]

There are a lot of devices you can plug into your receiver for power. From LED lights to LED bars to winches to whatever you want.
Does anyone know how to figure out how many watts or amps you can draw from a receiver before it starts to fail or prevent your servos from working correctly or stop working all together?
I ask this because I like accessories. I use them alot and sometimes I worry about drawing too much from the receiver so I often attach a fused lead to the battery and a voltage regulator to adjust the voltage to whatever I want, usually 3 or 6 VDC. Then most of my accessories attach to that for power.

I usually use this receiver. It's specs show nothing of a draw amount limit.
Am I being too paranoid about this?
Has anyone else had this issue come up where too many accessories screwed up your receiver?
What are some of the other ways people have fixed this problem?
How do I tell at what amperage the receiver can put out?
Just curious.
Thanks. Have a great weekend.

 

[J’sCrawler]

Usually it’s listed it the specs like 7.4V @ 3 or 5A. Simply use a power regulator that plugs into your receiver to power things like lights. I like powering lights with mytrickrc stuff, I get a cheap kit intended for the scx24 and it will do low power 3V lights and high power 5V lights. Never had any issues.
If it’s the servo you worry about, for that I like direct power servos, nothing heats up an esc faster than a servo that’s maxing out the BEC in that esc.….in a rock crawler application anyway.

 

[tntpoof]

Your bec limits that not the rx so if you bec is 20 amps or 25 my fav. ubec i use older bec to power all my rx .esc servos and anything else I plug into the rx..
The bec limits what you can plug into rx rx is just a way to control the plugged in devices

 

[nino]

Your receiver doesn't power anything, it's just a distribution box. You can find the max current in your ESC's specifications.

 

[Jamr]

Usually it’s listed it the specs like 7.4V @ 3 or 5A. Simply use a power regulator that plugs into your receiver to power things like lights. I like powering lights with mytrickrc stuff, I get a cheap kit intended for the scx24 and it will do low power 3V lights and high power 5V lights. Never had any issues.
If it’s the servo you worry about, for that I like direct power servos, nothing heats up an esc faster than a servo that’s maxing out the BEC in that esc.….in a rock crawler application anyway.

Their light kits are to expensive for me I usually get the light kits off of AliExpress for a third of that price and use those. They are still drawing power off of the receiver so if they draw too much, things should not work. This brings me back to my question as to what the receiver limits are.

Your bec limits that not the rx so if you bec is 20 amps or 25 my fav. ubec i use older bec to power all my rx .esc servos and anything else I plug into the rx..
The bec limits what you can plug into rx rx is just a way to control the plugged in devices

BEC? What is that?
Is that something you are adding, like my buck DC-DC step down converters that change the voltage from whatever the battery is to whatever I choose?

Your receiver doesn't power anything, it's just a distribution box. You can find the max current in your ESC's specifications.

Here are the specs for my ESC

• Continuous Current: 140A
• Burst Current: 880A
• Battery: 2-4S Lipo
• Built-in BEC: 6V/7.4V @ 5A(Switch-mode)
• ESC Programming: Independent programming port
• Motor Supported: Sensor and sensorless brushless motor
• Motor Limit:
  • 3S Lipo: Kv <4000 3665 size motor
  • 4S LiPo: Kv <2600 4268 size motor
• Application: 1/10 4X4 Short Course, Truck, Monster Truck
• Cooling Fan: Powered by BEC
• Size: 53x39.5x37.2mm (LxWxH)
• Weight: 120g (Including weight of wire)

The BEC current (In Switch Mode), whatever that means, is 5 amps.
Are you saying I can pull 5 amps at 6 volts through my receiver?

 

[J’sCrawler]

Well that is what the ESC is rated for Not the transmitter…. But essentially yes, for example a servo could be powered with 6V at 5 amps draw, No need for the fuses and all that.
the kits for an scx24 are cheap and really good, and the controller is compact. It’s basically a power regulator/BEC in itself. That’s about as cheap as it gets, for the quality you get. They’re more expensive stuff out there. I don’t buy from aliexpress so I couldn’t say how good that stuff is.

 

[tudordewolf]

There are a lot of devices you can plug into your receiver for power. From LED lights to LED bars to winches to whatever you want.
Does anyone know how to figure out how many watts or amps you can draw from a receiver before it starts to fail or prevent your servos from working correctly or stop working all together?
I ask this because I like accessories. I use them alot and sometimes I worry about drawing too much from the receiver so I often attach a fused lead to the battery and a voltage regulator to adjust the voltage to whatever I want, usually 3 or 6 VDC. Then most of my accessories attach to that for power.
View attachment 172672
I usually use this receiver. It's specs show nothing of a draw amount limit.
Am I being too paranoid about this?
Has anyone else had this issue come up where too many accessories screwed up your receiver?
What are some of the other ways people have fixed this problem?
How do I tell at what amperage the receiver can put out?
Just curious.
Thanks. Have a great weekend.

I think you'd be hard-pressed to overwhelm an RC with accessory current draw.

What you're really limited by is the current traces on the receiver's circuit board - all the "+" and "-" pins are connected in parallel. Power isn't flowing "from" the receiver circuitry to the accessories, the section they plug into is more like a power strip. You've have to exceed the current capacity of this miniature "power strip", which would take a lot of current through a single input plug.

Worst case scenario, you can wire up an RC to power accessories and even servos without passing current through the receiver at all. You connect the positive and negative wires from your accessories directly to the battery, and only the signal line goes directly to the receiver. The receiver also needs the + and -, but it won't be passing the current "through itself" in the process.

 

[Jamr]

I think you'd be hard-pressed to overwhelm an RC with accessory current draw.

What you're really limited by is the current traces on the receiver's circuit board - all the "+" and "-" pins are connected in parallel. Power isn't flowing "from" the receiver circuitry to the accessories, the section they plug into is more like a power strip. You've have to exceed the current capacity of this miniature "power strip", which would take a lot of current through a single input plug.

Worst case scenario, you can wire up an RC to power accessories and even servos without passing current through the receiver at all. You connect the positive and negative wires from your accessories directly to the battery, and only the signal line goes directly to the receiver. The receiver also needs the + and -, but it won't be passing the current "through itself" in the process.

Yes, this is exactly why I asked. There has to be a limit of current you can pump through a receiver. The pins circuitry are pretty small. Not to mention all that power is being delivered from the ESC with only the small 3 con throttle cable which powers the receiver and all of the accessories plugged into the receiver.

I agree. This is what I do with my fused lead from the battery, but unfortunately most LED's are 3 volts and will not last very long connected to a 2s/7.4v battery unless they have a resistor attached and not at all to a 3s, 4s or 6s batter. This is why I use a buck DC-DC regulator to get whatever voltage I want from whatever voltage battery I choose to use.

I still do not know if a BEC is safe to guard against shorts so I am still going to use a fused lead from the battery, It is cheap insurance and a quick way to disconnect power to diagnose issues if I need to.
It would be sad to lose a 1000$ rig due to fire when a .75$ fuse would have saved it.

 

[J’sCrawler]

Yes, this is exactly why I asked. There has to be a limit of current you can pump through a receiver. The pins circuitry are pretty small. Not to mention all that power is being delivered from the ESC with only the small 3 con throttle cable which powers the receiver and all of the accessories plugged into the receiver.

I agree. This is what I do with my fused lead from the battery, but unfortunately most LED's are 3 volts and will not last very long connected to a 2s/7.4v battery unless they have a resistor attached and not at all to a 3s, 4s or 6s batter. This is why I use a buck DC-DC regulator to get whatever voltage I want from whatever voltage battery I choose to use.

I still do not know if a BEC is safe to guard against shorts so I am still going to use a fused lead from the battery, It is cheap insurance and a quick way to disconnect power to diagnose issues if I need to.
It would be sad to lose a 1000$ rig due to fire when a .75$ fuse would have saved it.

I think you are overthinking it here…..just what exactly are you running that has you this worried?

 

[9x19]

Did I miss the power requirements for your accessories (amp draw, not voltage). It's hard to picture leds drawing enough current to be an issue.

 

[Jamr]

I think you are overthinking it here…..just what exactly are you running that has you this worried?

Lots of Led's and electric motors in a winch and some other devices.
With the ESC having only a 30 watt limit for the entire receiver which includes the servos, I am curious as to where I will start having problems.
One LED bar I bought a while back had so much heat coming off of it, I could not pick it up so I know some of those light bars are drawing some power.

 

[J’sCrawler]

The heat was probably due to voltage, if it was running at 6v instead of 5V that would heat it up, light bars run warm typically anyway. I don’t use winches so I don’t know if you could direct power those but if you are really worried I would personally get a direct power servo to eliminate that from the circuit at least.

I have to add an edit, if the light bar is rated for 5v and it’s being ran on 6V it will generate more heat. That’s all I was trying to say. LEDs dont draw a crazy amount of amps. Servos and winches can though. I never fret on my receiver being over taxed, it’s my esc.