Tarot zyx-s on single cell lipo?

[Design Engnr]

Hey folks,
Quick question on voltage range of Tarot ZYX-S. From the specs the operational voltage range dips as low as 3.5 volts. But I have to wonder has anyone tried to run this unit off a single cell lipo? Is it practical or am I asking for brownouts? Any advice is appreciated.

Thanks,
Dave

[Dr. M]

You're asking for trouble. I've done some testing and the ZYX gets flaky as voltage drops below 4V, and it will go dark around 3.44V. There's no way it will run reliably on a 1s lipo. For that matter, most servos won't run either with voltage so low.

What do you have in mind? putting a ZYX on an mCPX?

[Design Engnr]

Actually I am trying to retro fit a Nine eagles solo pro 180. If I could do it, it would give me a dsm2 compatible micro heli. I had concerns about one cell operation, which is why I had the question. It is possible to go 2s on the walkera v120d02s, but that means going with 4.8volt capable servos, motor, and ESC as well.

[Dr. M]

There's a small chance it could work if you have good flight packs that keep their voltage up and you don't fly them too long. You might also consider a boost DC-DC converter to feed the ZYX a constant 4.2V no matter the state of charge of the flight pack. The 1s servos should be able to handle it too. Look up Texas Instruments PTN04050c boost converter. It's pretty small too and could work nicely...

[RedOctobyr]

I would expect that under hard motor loading, the LiPo voltage drops below 3.5V while flying sometimes, even with good packs.

The voltage booster sounds cool.

Another option could be a small 1S LiPo to power just the FBL and servos, with the main battery for the ESC & motor. It probably wouldn't need to be very big. But the lower, much more constant drain (since you're not powering the motor) would likely help keep the voltage higher, avoiding a brownout. The idea of an RX pack on a micro is kind of funny, but it might be one approach for doing what you want.

[PcChip]

or maybe a smaller 2s battery (like the new MCPX BL) for the flight pack with a stepdown for the micro servos you're using?

[Design Engnr]

Thanks for the suggestions. I may look into the booster mentioned above. What step down would you recommend. I have not seen one that will step down 3.7 volts.

[Dr. M]

Originally Posted by Design Engnr

Thanks for the suggestions. I may look into the booster mentioned above. What step down would you recommend. I have not seen one that will step down 3.7 volts.

I don't think there are any. You could try a bunch of diodes in series such that their Vf adds up to about 4.2V. It'll be inefficient, but should work...

[Design Engnr]

Thats what I thought. Any idea the current drain from one of the boosters you suggested? It looks pretty straight forward to wire up.

[Dr. M]

2.4A, 12W. Be aware that it natively only goes down to 5V, but you can trick it to go lower. Gotta do some web searching to see how others have done it, or buy a converter that does output natively at 4.2V.

http://www.ti.com/product/ptn04050c