some excavator questions... esc,bec, radio and battery

[schmoking]

soo... i blew up 3 esc`s for my escavator (4200xl v1),
also think i may have damaged 2 more, but they work... for now.
i had a light swich short out, that burned 3 of them to death... then during some testing i accidently hooked up a shorted out servo,
heard some sounds i didnt like and there was an electrical smell,
but the pump motor esc and my last turn motor esc are working now after i hooked up a bec for power supply and pulled the red wires from the esc`s.


1. i want to get the sabertooth esc, and im planning on some other upgrades,
but for now i gotta make some other priorities... so i was looking for a cheaper alternative, just to get the tracks running.
im clueless when it comes to electro motors and esc`s, so i have been looking around and found a few that i thought might work...

https://hobbyking.com/en_us/quicrun-...5-brushed.html
http://www.rcmart.com/1040-brushed-c...?cPath=1560_51
https://hobbyking.com/en_us/hobbywin...-for-1-10.html
http://www.rcmart.com/tritronic-wate...?cPath=1560_51

they range from 25a to 60a... the rc4wd replacement is 40a(i think), but no way these motors draw 40a?
my pump motor a robbe 5055-45 has a 50a esc... but from reading the manual a 30a esc is recomended.
the sabertooths i think are 25a. so the motor are drawing these amps? not the esc feeding them? right?
anyways... does any of these esc look usable for trackmotors? or does anyone have a suggestion for a cheap alternative?


2. after some searching i figured out that when having 4 esc`s hooked up to the receiver its not good to have them all power it...
and after me hooking up the shorted out servo, the pump and turn motor esc`s wouldnt work right until i hooked up the bec.
this is the rc4wd yellow bec that came with the 4 valve upgrade kit.
i hooked red and black to the battery, and got 5 volts for the receiver... works fine, but it also has a white wire, what is this for?
did i hook this up right? after searching i couldnt find any other bec`s with 3 wires...?


3. the transmitter i have is the fly sky th9x... that came with the excavator
in aux channels i have
channel 5 as pit trim(the pot on the front) i use this to control pump motor.
channel 6 as hov pit (left lever) for track 1
channel 7 as hov throttle (right lever) for track 2

i used to have the pump motor revving up sometimes when i used the tracks, i finally figured out why...
if i take the left lever down then release it, then take the right lever up then release it channel 5 will changer rpm on motor...???
this is also visible in the display menu,
when i only have the radio powered that channel 5 will change when i do this... (but only if i have it set to pit trim)
to set it back to normal i can repeat the same movements or pull the left lever down twice.
this seems oddly specific to be some interference causing it,
but i been through the settings on the radio and i cant figure out if this is a setting,
even in a fresh profile it will do this, but only with these channels and selections.
anyone else have this happen? is it supposed to do this?


4. this is probably a stupid question... but im tired of burning my electronics.
i bought some lipo batteries i planned on using for my transmitters, but they are 25c and have really thick wires...
the old one i used have thin wires and is just 1c... could the 25c ones burn my transmitter?

sorry about the long post, but this stuff is confusing me...