Possible to run High Voltage servo from 2*2s packs in series?

[Zoea]

Hi there

I bought a high voltage servo for my new 1/8 ebuggy and the ESC only outputs 6v.

Today I had a bit of a disaster when I tried to get the servo running at 2s volts. What I tried (do NOT do this) is use a servo extension, cut the red and black wires from the extension socket, extend the ESC signal wire to channel 2 of the ESC, and use the extension plug black and red wires to wire to the ESC positive and the bridge (jumper to make the batteries series) of the 2s lipos negative/positive.

This quickly caused smoke and a melted negative receiver extension wire. I think the circuit was trying to charge each lipo with 4s volts via the receiver - I'm not sure I've figured out what actually happened, it's complicated and I'm not

Is it possible to run a 8.4v servo/receiver from 2 2s packs and still get the throttle signal from the ESC? I do not want to spend £25 on a BEC for this, rather swap the servo. I am learning now that these HV servos are really designed to run in nitro 1/8 from the 2s receiver battery.

I was thinking, if I tap the balance ports of each lipo, wire that up to the power of the extension wire for the receiver, and ignore the ESC bec, would that do it? Bear in mind to run the 4s car on 2 2s lipo I have them connected in series. So the balance ports would be either 2 cells one from each lipo, or the other two cells and any load from running the car (?).

I'm not sure that's much different than what I tried before though, just moving the circuit a little bit on the battery end. It's also not ideal from a wiring point of view, with every port of both 2s batteries used.

I've read on an aviation forum that's it's not possible to get 8.4v from 2*2s packs easily. Others use balance ports etc. with success I think, probably with a real 4s battery.

Opinions welcome.