Combination of step up and step down feasible?

Question

I have a model aircraft on which I am installing a LED kit of the same manufacturer. The EDF jet is powered by a 6s Lipo (22.2V nominal). The LED kit connects to the balancer plug of the battery and taps the first three cells (approx. 12V) to provide input to the LED kit. The kit has a step up converter to power the 24V LEDs, the step up also contains a circuit which drives the LEDs according to throttle position which is the reason I cannot simply replace the step up converter.

I am already using the battery balancer plug for voltage telemetry and generally do not like the LEDs being driven by the first three cells only as this causes these cells to age more quickly.

Can I take a 12V step down powered directly from the 6s lipo (like this one: https://a.aliexpress.com/_mPv3amO ) to power the original step up in my LED kit, e.g. power the step up by a step down? The aircraft has flight times of about 4 minutes and pulls around 70A at full throttle so efficiency driving the LEDs is of no concern whatsoever.

Answer 1

Combination of step up and step down feasible?

yes. You can build that from two independent steps, or there's SMPS architectures that can do both at once.

The EDF jet is powered by a 6s Lipo (22.2V nominal). The LED kit connects to the balancer plug of the battery and taps the first three cells (approx. 12V) to provide input to the LED kit.

That's a terrible design.

The kit has a step up converter to power the 24V LEDs, the step up also contains a circuit which drives the LEDs according to throttle position which is the reason I cannot simply replace the step up converter.

Simply bypass the step-up and directly drive from your system 22.2 V.

Get the throttle position to enable the LEDs separately. This sounds like all you need to do is connect some "throttle" output of the central flight controller to a low-side N-Channel MOSFET. That would still be the same amount of effort, and far less added weight, complexity, heat problem and power inefficiency than step-down followed by step-up conversion.