Added bec and now have problems

[squish72]

hey everyone lets start out with what i have done. im running 2 mamba micro pros, 7990th, castle bec, 4pl, and its all in a xr. i was running just 2s lipos in my rig and had the servo soldered direct to the batt. I never had a problem with it.


So I decided to rewire my truck and add a bec so i could add the option of running 3s. I took the cases off the micros and "shrunk" all my electronics in one bundle. heres some pics of it Spiffy XR10 Electronics shrinkage

well after getting everything soldered up i plugged a 2s lipo in it and everything armed and works great except if you quickly turn the servo left or right it ignores your imput and slowly turns right. if you turn it left or right at normal speed everything is fine. I drove the truck for 4 mins and everything works like before except if you try to wiggle the steering quickly. Its like the servo draws too much and wigs out. Is the bec possibly flawed or something? please give my some things to try

[ax-10 crazy]

Originally Posted by squish72

hey everyone lets start out with what i have done. im running 2 mamba micro pros, 7990th, castle bec, 4pl, and its all in a xr. i was running just 2s lipos in my rig and had the servo soldered direct to the batt. I never had a problem with it.


So I decided to rewire my truck and add a bec so i could add the option of running 3s. I took the cases off the micros and "shrunk" all my electronics in one bundle. heres some pics of it Spiffy XR10 Electronics shrinkage

well after getting everything soldered up i plugged a 2s lipo in it and everything armed and works great except if you quickly turn the servo left or right it ignores your imput and slowly turns right. if you turn it left or right at normal speed everything is fine. I drove the truck for 4 mins and everything works like before except if you try to wiggle the steering quickly. Its like the servo draws too much and wigs out. Is the bec possibly flawed or something? please give my some things to try

The 7980 and 7990 both draw close to what the bec's max output is. The 7990 draws slightly more current than the 7980 as it uses a magnetic digital encoder. The stall rating on the 7980 is about 9 amps, so the 7990 would be a little higher.

Also remember that even though it is a 10 amp bec when you up the output voltage the amount of amps the bec can deliver goes down. Also he more voltage you but into the bec the more the amp rating will go down.

I have been running my 7980 off of a 10 amp cc bec for a couple months now and the only problem has been that the bec gets fairly warm but it keeps on runnin'

Hope this helps

[JeremyH]

Is the red wire pulled from the harness of your ESC?

[squish72]

makes sense about the amperage but i have a buddy running the same servo and has the bec set at the same voltage and his works as it should.

i have the bec directly wired to the batt then hooked to the servo with a dean micro plug and just the yellow wire plugged into the rx. i do have all three wires from the escs running to the rx. thats how i have had it running for almost a year now with out fail but if for some reason the addition of the bec messes that up i can pull a wire from the esc plug

[TSK]

Originally Posted by squish72

makes sense about the amperage but i have a buddy running the same servo and has the bec set at the same voltage and his works as it should.

i have the bec directly wired to the batt then hooked to the servo with a dean micro plug and just the yellow wire plugged into the rx. i do have all three wires from the escs running to the rx. thats how i have had it running for almost a year now with out fail but if for some reason the addition of the bec messes that up i can pull a wire from the esc plug

I would pull just one red witre from one esc.

[squish72]

Pulled the wire and its still the same

[ax-10 crazy]

Originally Posted by squish72

Pulled the wire and its still the same

Have you tried a 3s lipo? Maybe the voltage is dropping below what you have the bec set for and the bec is not liking that.

[squish72]

didnt even think about that but i plugged in a 3s i had (still need to solder connectors on my crawler batts) and wamo no more problem whoo hooo.............................................u ntil i tried driving the truck throttle it forward and everything is fine hit reverse and only the rear esc/motork spins plug 2s back it forward/reverse works fine but servo glitches like it used to starting to get grumpy

[ax-10 crazy]

Originally Posted by squish72

didnt even think about that but i plugged in a 3s i had (still need to solder connectors on my crawler batts) and wamo no more problem whoo hooo.............................................u ntil i tried driving the truck throttle it forward and everything is fine hit reverse and only the rear esc/motork spins plug 2s back it forward/reverse works fine but servo glitches like it used to starting to get grumpy

Do you still have one of the red wires pulled out from one of the esc's? is the front esc set up for 3s lipo?

[squish72]

yep still have the wire pulled and i have both escs set to auto lipo

[JohnRobHolmes]

What is the BEC voltage? Do you have a common ground from servo to RX?

Sounds like the RX is browning out. Since you are using the ESCs for the radio power (and they are 5.1v if I recall) you may just need to bump up the voltage for the RX power. Additionally, you may be experiencing some interference by having all your electronics crammed together so tight.

[squish72]

Bec is set at 8v and the bec does not go through the rx at all.

[JohnRobHolmes]

Try pulling it down to 7.4v and then use it to power RX too. Remove the red wires from both ESCs RX plug so they don't get force fed some current.

[squish72]

ok ill try it. Might take me a bit gotta do some cuttingand soldering lol

[squish72]

well i dropped the voltage on my bec and decided to try it again without hooking it up to my rx and same thing happened but since i had everything opened up i decided to unplug the rear esc and try and see what the front does on its own. well reverse still didnt work but at least i could hear the esc try to work for half a second then nothing. i tried throwing it in reverse a few times and it would spin the motor every once in a while. i grabbed the tires and turned them and noticed the drag brake was super weak if workin at all (edit: theres way more drag when no batt is hooked up). I hooked the castle link up and it was still set on crawler drag. so maybe this esc is messed up (still dont explain the bec/servo problem)

[squish72]

well i ordered up another esc who knows how long this has been like this cause ive never ran anything bigger than 3s on them and havent checked my drag break in forever on them. so theres one problem down and one to go

[ax-10 crazy]

Originally Posted by squish72

well i ordered up another esc who knows how long this has been like this cause ive never ran anything bigger than 3s on them and havent checked my drag break in forever on them. so theres one problem down and one to go

Maybe you just ended up with a faulty esc? Send it back to castle and see what they have to say

[squish72]

i think im gonna try that