gus6464

iTrader: (2)

I have a basher that I use with 3s batteries. My esc can only output 6v on the internal bec but my new servo can handle up to 8.4v. I was thinking of doing a test and powering the servo off of its own 2s lipo as I have some super tiny 550mah 2s batteries. Based on a calculator I used it says that if the servo draws 5a I can get a runtime of ~7 mins. Now this is of course based on the servo drawing that amount of current nonstop which wouldn't happen if I'm not turning.

Would it be safe to assume that I can triple the runtime of the servo in a normal bash session?

the rc guy

You can subtract all you want . You will never really know till you install lipo and go run the truck...I know from personal experience a servo will use alot more than whatever the numbers say! I ran a Hitec servo with max 5 amp.. ran it on its own battery with a watts up meter it was using 10.22 amps on some high speed corners. It blew 2 CC 10 amp ubec s..

GerryH

iTrader: (26)

The other problem you might run into is you don't have any low voltage protection. Run it too long and you ruin your lipo. And not that having one would do you any good. Don't want the servo to shut off while you're driving.

If you want to run the servo at HV, I'd suggest using an adjustable BEC from either Hobbywing or Castle. I'm sure others make them, but I've used both. The Castle is smaller and you can very finely set the output voltage, but you need the Castlelink, that's just additional cost. The 10a Hobbywing has dip switches to set the output from 5-8.4v

Bry195

this is probably the case. the problem is in the ratings. a description and standard for rating isnt usually provided. the rating that I respect the most is one that specifies the average current limit that you can continuously use without damaging or overheating something. during acceleration a servo can use 4 times the current it uses at maximum continuous stall current. so you have standstill continuous, work current, and peak acceleration current. if they all average under a 5a continuous you wont break anything. that is allot of tech talk to tell you that you probably have to test it and see but it is the most complete way to calculate what the draw is to see if you plan makes sense. test it.

billdelong

iTrader: (33)

The extra drain from a servo is negligible, the added weight for an extra LiPo pack isn't going to be worth it, nor the hassle. What you can do instead is power the servo from the primary LiPo off the balance port to draw 2S off the 3S pack, while it's true the cells won't drain equally, I have found the cells to still be within a few tenths of a volt by the time I hit LVC. Just be sure to unplug the LiPo when you're done, I once left mine plugged in and the servo decided to go full lock after the radio was turned off and the servo was extremely hot to the touch after an hour or so. Fortunately I didn't kill the servo or battery, so I just went back to using the BEC to play it safe

• How to wire HV Servo from 2S LiPo