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Pumpkin drop event

What went wrong?

#1
I am trying to build an RC glider for the first time, but i encountered a problem.

I plugged a 7.4v Li-Po battery (180 mAh) into my receiver (with bind plug), paired it, worked fine, plugged a servo into it, no problem

The next day, when i plugged my Li-Po into the receiver, the red light did not come on. So I tested the battery on another receiver, and it worked perfectly. That means the problem must be with the receiver.

What did I do wrong? How can I fix it and make sure it never happens again?

here are the parts i used:
AF5203E2-88FA-40B6-940B-25D921EAC29A.jpeg
 

Merv

Well-known member
#3
I can’t say specificly for your receiver (Rx) but 7.4 v is a bit high for most Rx’s. Most Rx run a 5v, we use a battery elimination circuit (BEC) to bring battery voltage down to Rx voltage. The BEC can be a stand-alone device or it can be built into an electronic speed controller (ESC).

You may have fried your Rx.
 

kilroy07

Well-known member
#5
I can’t say specificly for your receiver (Rx) but 7.4 v is a bit high for most Rx’s. Most Rx run a 5v, we use a battery elimination circuit (BEC) to bring battery voltage down to Rx voltage. The BEC can be a stand-alone device or it can be built into an electronic speed controller (ESC).

You may have fried your Rx.
Doh, I missed that!
Yea, you might be right about that... 👍
 
#6
I can’t say specificly for your receiver (Rx) but 7.4 v is a bit high for most Rx’s. Most Rx run a 5v, we use a battery elimination circuit (BEC) to bring battery voltage down to Rx voltage. The BEC can be a stand-alone device or it can be built into an electronic speed controller (ESC).

You may have fried your Rx.
Oh, that might be it.... :/

Anybody know where to buy cheap receivers and BECs? i already spent way too much on this project :(
 

Merv

Well-known member
#9
I can’t say specifically for your Rx but most Rx attach the bind plug 90 degrees from the way yours is attached. Most Rx have a row of negative pins a row of positive pins (the center row) and a row of signal pins. All of the positive pins are connected and all of the negative pins are connected, with a separate signal pin for each channel. To bind you short any of the signal pins with any negative pin.

So how did you plug in the battery, into which pins?
 
#11
To continue my project, I am going to need to buy a new receiver. Either I use the same battery and buy a BEC or use a couple of aa batteries or something. Would that work?


I can’t say specifically for your Rx but most Rx attach the bind plug 90 degrees from the way yours is attached. Most Rx have a row of negative pins a row of positive pins (the center row) and a row of signal pins. To bind you short any of the signal pins with any negative pin.

So how did you plug in the battery, into which pins?
The bind port is actually at a 90 degree angle on this one. I plugged the battery into the Batt port. does the polarity matter? image.jpg
 

Merv

Well-known member
#14
Polarity matters, but if you plugged your battery into the signal pin and the positive pin, you may not have hurt anything. It just would not power on.

Show a pic of your battery plug
 
#15
Yes, polarity matters. You do not want to reverse it.

oops..

So, in conclusion:
I fried my receiver by overvolting it and/or reversing the polarity. To make sure it doesn't happen again:

- What colors mean what polarity on my battery's wires?
- Can I use two aa batteries as a replacement for a Li-Po?

Thank you for all the help!!
 

Merv

Well-known member
#17
oops..

So, in conclusion:
I fried my receiver by overvolting it and/or reversing the polarity. To make sure it doesn't happen again:

- What colors mean what polarity on my battery's wires?
- Can I use two aa batteries as a replacement for a Li-Po?

Thank you for all the help!!
Red is always positive. The darkest color is always negative, usually black or brown. The lightest color is always the signal, usually white or yellow.

Yes, aa battery will work just fine, any source of 5v will work. For bench testing I cutoff the end of an old USB charger and solder on the servo lead from an old servo.
 

Wildthing

Well-known member
#19
That is the balance plug for your charger I am thinking. If you look at one of you servo or esc connector that goes into the rx you will see the colored wires are in a different sequence. black (negative) , red (positive) and then white (sometimes yellow) (signal) on the top . Positive (red) is in the middle not on the top.
 

Merv

Well-known member
#20
Your 3 wire lead is called The balance lead. With balance leads, only the out side colors matter. Red is positive and black is negative. The other wires can be positive or negative, it depends on which other pin you are comparing it to.

So when you plug in the balance lead, if you plugged in the red to the signal, I think you will be Ok. If you plugged the red into the negative, you may have fried the Rx. Either way you only apply a maximum of 4.2v to the Rx.

I would recommend as a first set testing with a good 5v source to see if you hurt anything.