Receiver Battery with ESC (w/ BEC)

[beefmuffin 1156]

Hi folks. I apologize if this topic has been raised elsewhere... but I couldn't find the angle I was curious about.

Basically, is there any advantage / disadvantage to using a receiver battery pack (4AA or NiMH) in a setup with an (Tamiya) ESC that HAS BEC?

Does anyone have any experience regarding this? Mainly, sometimes I feel like the voltage needs of the motor being pulled from the ESC are disrupting the receiver function, particularly when the battery runs a little low...or when using a powerful motor. I don't do LiPo with my cars and I'd prefer not to daisy chain batteries. So I was toying with the idea of using the old school 4AA setup to keep the receiver fully powered regardless of the ESC/NiMH situation. Or maybe use a NiMH receiver battery instead of the 4AAs.

Thoughts? Advice? Ridicule?

THANKS!

snoop beefy beef

[TA-Mark 195]

It is possible to do. Connect the receiver pack to the BATT connector of the receiver, and remove the +ve (usually red) from the 3pin connector that goes to CH2. Having the receiver powered by both the ESC and an external pack at the same time can cause issues. To remove the red wire you need only back it out of the plug, then insulate it and secure it out of the way (fold it back on itself and put on some shrink wrap).

The big disadvantage of using a receiver pack is the extra weight. Another is the limited spaces in some chassis to mount the pack.

The Tamiya ESCs will usually cut power to the motor when the voltage sags below 5.0v so that the receiver power isn't compromised. Can't say I've had any issues with using TEU101-BK ESCs and low discharge rate Ni-Cd 1400mAh/1800mAh packs. Neither loss of signal or intermittent servo operation caused by low voltages (Futaba R122JE/R162JE receivers and S3003 servos).

[Maximus Desimus 4]

Im also thinking about this,

First reason extend the life of the main battery pack,

And the second, to use the extra weight over the front wheels of my buggy!

[beefmuffin 1156]

i've had problems at times with really slow servo response that cleared up when i changed ESCs. which sounds to me like a receiver power issue. the servo would lag to begin turning, then keep turning after i had told it to stop. other cases i've had all functions of the car die after a minute or two of high speed running, then come back after some time or after a switch off and on. it isn't an ESC thermaling issue, since i've had that happen in the past and the steering servo still functions at least. again, this problem would respond to changes in the ESC and motor. the ESC and motor were always compatible turns-wise, and everything ran at 7.2v... so my conclusion is that separate steady voltage to the receiver might fix both of these issues. but i had thought that since the power from the BEC and from the receiver battery would (i believe) run in parallel that it wouldn't result in an over-voltage issue. it would just extend the overall battery power, and maintain voltage any time the BEC cuts out.

what issues have been caused by having both power sources connected to the receiver?

thanks for the replies!

[TA-Mark 195]

What model ESC are you using that has an internal BEC? TEU105-BK?

[beefmuffin 1156]

the one that's given me by far the most trouble is a duratrax unit specs are here: http://www.duratrax....s/dtxm1070.html

i like the power i was getting from it with a superstock BZ and a trinity slot machine... but had this problem even with a silvercan in another setup after i got tired of it and decided to try using it as a basic ESC.

i do notice that on the specs it lists BEC voltage as 5v. shouldn't this be 6v?

[TA-Mark 195]

i do notice that on the specs it lists BEC voltage as 5v. shouldn't this be 6v?

4x "AA" Ni-MH cells, or a shrink wrapped receiver pack is only 4.8v. 4x dry cell alkaline batteries is 6.0v. Internal BECs are usually anything from 5.0v to 6.0v.

The 1.0A current rating of the BEC will have a bigger bearing on how much it can power rather than the voltage. A fast or high torque servo may want more than that.

[beefmuffin 1156]

that's good info, but i wasn't using any special servos. just the $10 futaba variety. tried changing servos to, didn't help. no two runs were exactly the same, but it because unreliable enough it was very frustrating. hence the considering using a dedicated receiver pack.

also, as maximus states above added weight isn't always bad. i don't race so a little better traction wouldn't be a bad thing.

[hammerstien 187]

had same prob i had with BEC receiver turn out to be the receiver was faulty new quick change end everything was fine and a powercap helps as well

[beefmuffin 1156]

hey hammertime - by powercap do you mean one of those capacitors you plug into the BATT pins on the receiver?

[hammerstien 187]

yep thats what i mean nice and cheap as well .... off to play in snow now with my mad bull i may be some time