Fc not powering with battery power

[Ian_FPV]

I recently had to switch flight controllers because one had fried. When I switched to the new fc, I found that it came with a 8 pin harness to connect my 4 in 1 esc to the fc. I had to re pin a few cables but when I tried to plug a battery in, I only got 3 beeps from the esc and no lights on the fc, rx, or tx. When I plug it into the computer however, I got power. I then provided to try to solder jumpers from the battery leads of the esc to the vbat and ground pads underneath the 8 pin connector. I still have the same problem. I am not sure what else to do, any help would be appreciated.

 

[HighTechPauper]

Hi @Ian_FPV,

There are 2 ways that an FC can get power, so it helps to know the difference between the 2 when troubleshooting issues like this...

One way it can get power is from the 5v rail being fed by the USB connection/cable from you PC.
The second way is from a step down voltage from your battery by way of whatever BEC/Voltage Regulator is making and feeding 5v to the FC.

Sometimes that 5v BEC is on the FC and it gets fed vBat from somewhere, sometimes that 5v BEC is on the ESC and 5v out needs to be wired to the FC correctly, and sometimes there isn't one at all and we have to add a separate vReg board and wire it correctly.

So USB fed or BEC fed, they feed the FC from 2 different directions, and when it works off USB but not off Battery, it is because the BEC is bad, or bad wiring so the BEC isn't working.

The first thing I would do is figure out where your FC is getting its 5v BEC from, and double check your 8 pin harness.

If vBat comes from the ESC to the BEC on the FC, it could be the harness, and if the ESC has the BEC, then maybe the 5v/G in the harness isn't wired correctly to get up to the FC, or maybe the BEC is bad altogether.

 

[Homelesscpgamer]

I recently had to switch flight controllers because one had fried. When I switched to the new fc, I found that it came with a 8 pin harness to connect my 4 in 1 esc to the fc. I had to re pin a few cables but when I tried to plug a battery in, I only got 3 beeps from the esc and no lights on the fc, rx, or tx. When I plug it into the computer however, I got power. I then provided to try to solder jumpers from the battery leads of the esc to the vbat and ground pads underneath the 8 pin connector. I still have the same problem. I am not sure what else to do, any help would be appreciated.

I obviously don't know what the situation was with you original flight controller getting fried, but given the issues your having with the replacement I'm curious if the original was really the issue or if it comes from your esc's side. It Could be ethier one of the power or ground wiring between you f.c. and esc has a unnoticed break in them. ( I've had this happen and for me the wire looked fine on the outside because the silicone coating was still attached and looked undamaged but inside the metal came unattached from the little end connector breaking the connection so I wasn't getting power to my f.c. and it took me alot of trial and error to figure this out but finally did right before it went in the trash bin ) also could be just a lose/broken wire harness connector on your esc, that's not the issue it's most likely the esc regulator that's giving the f.c. power like stated in the previous post witch I might add was all great advice aswell
Ethier way if I were you I would start out by making sure that that the power is making it to the end of the power and ground wires in the harness that gose from the esc in to the f.c. first and if your not getting any power, work your form the f.c.'s end of the wires back to the esc regulator to see what's not working.
For me its usually something easily fixable but the hard part if finding what the issue is in the first place as everything I know I've learned from trial and error as well as the internet. I know one thing for sure about all this though,when you find the issue it will always be the last thing you checked that gets it to work!

 

[RENOV8R]

It's all just a guessing game until we know which flight controller and 4 in 1 ESC you are using and a diagram of how you have them connected

 

[Jetty]

Hey guys I'm having the same problem with my all in one F4 Beta FPV Brushed FC ... Any suggestions? I have no power coming from the battery lead but when I plugged it in the Beta flight and I pulled the battery in it registers as having a battery, so I don't understand it...