BEC question need help for a classified add to buy

[83trekker83]

There is this for sale near me for a friend who wants it
Selling my new build thats never even been on the trils yet, only inside the house. Its RTR
Build list
Proline bronco body with custom rear canvas roof and scale accessories
Led super bright light bar
Scx10.2 chassis
Full build Steel OG transmission
Aluminum axial oversize lower links
Gunmetal aluminum upper links
Aluminum sterling links/ drag link
Airtronics steering servo
Losi lipo esc
12t monster 550 can traxxas motor
2.4 ghz radio
Aluminum chubs and knuckles
Aluminum axle lock outs
Front steel CV axles
Juncfac rear carbon steel driveshaft
Aluminum adjustable front progressive shocks
XD aluminum adjustable read shocks
Aluminum body posts
3ch set up to use winch if wanted

has NIMH battery

I asked if it can use 2 and 3 cell lithium and he said "With a BEC yes"

Can anybody explain this bec needed im lost with that. My TRX4 i can choose eaither batts and have no BEC

[HumboldtEF]

You'll always have a BEC, its either an internal BEC in the ESC or a separate external BEC. Usually an External BEC is used to run a servo with higher amp draw or in some case to run a different voltage than what the ESC's BEC can put out.

Battery voltage shouldn't have anything to do with the BEC unless something like lights or servos run directly off the battery. If thats the case a BEC might need to be added to drop the voltage back to a specific voltage.

[83trekker83]

Thanks, i mis took what he said , all good now.