Running BEC with Seperate RX Pack ?
 

Hi, just wondering if you can run a seperate receiver battery pack [ 6 volt nimh ] with the esc ,s BEC as well. my reason for asking is incase one of the two pack up i still have radio power. thanks.

Hi,
You can't just plug both in without adding some sort of protection. If the battery pack would short closed that will shut down the regulator and then shut down the receiver.
You could make a circuit using diodes or you could just add a Batshare unit and use separate switches for each power source.
http://smart-fly.com/index.php?route...&product_id=97

Just disconnect the red wire between the ESC and the receiver and plug the 4 or 5 cell NiMh/NiCad into any unused channel on the receiver to power the receiver and servos. Do not connect an external battery to the receiver without first disconnecting the red wire between the ESC and the receiver or you risk damaging the ESC. It is fairly easy to remove the red wire from the connector between the ESC and throttle channel of the receiver, just use a small pin to release the little plastic flange that holds the metal end of the red wire into the connector case and pull that red wire out of the housing. If you ever decide to use the ESC to power the receiver again, it will be easy to just plug that red wire back into the housing and be back in business.

thanks. so you can,t use both the bec power and a seperate receiver battery together ?

Yes you can BUT you need to either make a circuit or buy the BattShare unit to isolate each power source for your redundant set-up.

The reason you need to do this as I stated earlier , is that if the battery or the bec in the esc should fail closed then it will short out the other power source and crash the receiver. The circuit that you build or the Battshare will prevent this from happening and give you true , safe, redundant power.

I would suggest the Jeti DSM-ESC
http://www.espritmodel.com/jeti-elec...y-dsm-esc.aspx

i understand now, i think i will just use the esc for motor and use a seperate LiFe 2 s for rx power. thanks for your help guys.

I think you have made a smart decision; however, you still have to be sure to DISCONNECT the red wire from the connector between the ESC and your receiver.

IMHO, it is a better option to have an active element in series (diode or MOSFET) to prevent the 2 voltage sources from being connected together directly at the Rx bus.
This allows for true redundancy; the ESC BEC powers the radio and in the event of failure, the backup battery takes over.

Another option would be a Scorpion or OptiPower Backup Guard
http://www.experiencerc.com/store/op...s-p-16831.html

yes thats what i did want for my model, esc / bec rx power plus seperate 2s rx power. if one goes bad i still have the other for safety. i suppose this being for electric boat use maybe i am going overboard with this extra power security.

Understood.
you can use the Jeti DSM-ESC, Scorpion or Optipower Backup Guard, WesternRobotics BatteryBuffer, SmartFly BattShare, a Boomarc hidden dual battery redundancy switch with pin flag, Boomarc DualBatt 2x10 isolating circuit
or a simple DIY with a common cathode diode circuit.
or as mentioned pull the red wire from the ESC BEC and get 2 small Rx batteries; one each in an available Rx port.
its whatever you feel most comfortable with.