bec getting really hot!

[jebster]

i recently upgraded to a dual esc setup on my xr10 since I got a new radio (MT-4) that is capable of running it. i have dual fxr's. got things wired up and it seems like it is all good except for one thing. the cc bec started getting hot to the touch while i was syncing the escs to the radio to check things out. any one of you electrical gurus out there see a problem in the pics below? when I was running my fxr/punk i had the bec hard wired to the esc battery terminals the same as I have here. not sure how the new setup is causing the issue. input welcome. a couple stats:

dual fxr, battery input hard wired between the two escs with a single stock fxr cap. when hooked up both escs run fine.
cc bec (repackaged to reroute the input wires) set to 7V running a 7950 servo. even though it gets hot is still works.
whole system is running on 3S

pics:

[Olle P]

I can't see any pictures.
One potential problem source though is if you have different "low" potential for the input and output side of the BEC.
That can happen if one battery is used to feed the BEC and another to feed the Rx (through the ESC).

[Charlie-III]

Does the CC BEC go to the RX? If so, did you pull the red wires from the ESC's to RX & tape off?
There should only be 1 BEC going to the RX.

[jebster]

Originally Posted by Olle P

I can't see any pictures.
One potential problem source though is if you have different "low" potential for the input and output side of the BEC.
That can happen if one battery is used to feed the BEC and another to feed the Rx (through the ESC).

I'll have to see why the pics aren't coming up.

To your comment I'm not sure I follow (I'm a little thick sometimes!). Everything runs off the main pack. It connects to esc#1. Hardwired battery lines from esc#1 to esc#2. That is where the bec connects on.

[jebster]

Originally Posted by Charlie-III

Does the CC BEC go to the RX? If so, did you pull the red wires from the ESC's to RX & tape off?
There should only be 1 BEC going to the RX.

I have the bec dedicated to the servo so it doesn't go thru the rx. (I did pull the red wire from one of the escs so only one esc provides power to the rx).

[Charlie-III]

Originally Posted by jebster

I have the BEC dedicated to the servo so it doesn't go thru the RX. (I did pull the red wire from one of the ESC's so only one esc provides power to the RX).

Excellent, you did it correctly. Does the BEC get hot if disconnected from the servo?

Since it was just sitting there, I can't think of anything right now. If it was running I would look at steering EPA's.

[jebster]

Originally Posted by Charlie-III

Excellent, you did it correctly. Does the BEC get hot if disconnected from the servo?

Since it was just sitting there, I can't think of anything right now. If it was running I would look at steering EPA's.

Hot with or without the servo. Just had a thought. When I repackaged the bec I replaced the original input wires because the had gotten too short. What are the chances the wires I replaced them with are heating up because they aren't able to handle the current/voltage? I haven't pulled it open to see exactly what is heating up. Might explain why it is still working and hasn't just blown up.

[Charlie-III]

The BEC input wires are pretty thin to begin with, can't imagine you would go much (if any) smaller in size.

[jebster]

Originally Posted by Charlie-III

The BEC input wires are pretty thin to begin with, can't imagine you would go much (if any) smaller in size.

yeah, i thought that would be a stretch too. just grasping at straws here! after work tonight i'm going to dig in again. sucks because i wanted to get the rig set up for a comp in a couple weeks and wanted some run time with the dual escs to get use to it in advance.

[Kylar]

Could just be a faulty BEC, try another one if you have one. I've seen plenty of new and almost new electronics be faulty or go bad in a short amount of time.

[jebster]

Originally Posted by Kylar

Could just be a faulty BEC, try another one if you have one. I've seen plenty of new and almost new electronics be faulty or go bad in a short amount of time.

fair suggestion. i have another one so i'll wire it up and see if it has the same issue. in the past becs seem to just fail. the fact this one is still working but just getting really hot has me stumped.

[Kylar]

Also double check for any shorts or nicked wires, maybe bad solder joints.

[Kylar]

Originally Posted by jebster

fair suggestion. i have another one so i'll wire it up and see if it has the same issue. in the past becs seem to just fail. the fact this one is still working but just getting really hot has me stumped.

Electronics can be a pita to troubleshoot, so i feel your pain. I had a bad esc that would get hot just sitting there, the bec ended up dying on it after about 15 mins. Luckily it was just a cheap brushed esc.

[jebster]

Hooked up another bec and no issues. I pulled off he shrink wrap of the bec that was getting hot to take a look. Seems like the cap going through the bottom board was the source of the heat. Probably still nothing I can do to fix it and I'm not sure why it crapped the bed but at least I can get the rig running.

[Charlie-III]

Sorry for the issue, glad you have a resolution.

[jebster]

Originally Posted by Charlie-III

Sorry for the issue, glad you have a resolution.

yeah, just sucks whent he resolution is a new item!

but that is the way electronics go.

[Olle P]

If that new item is a new capacitor it's no big deal.
Have you tried replacing the cap?

[Charlie-III]

Originally Posted by Olle P

If that new item is a new capacitor it's no big deal.
Have you tried replacing the cap?

+1.

If it was fine before working on it, double check your solder connections for shorts/bridging. If that does not show anything bad, then try replacing the cap.