[NSRCA-discussion] HV Direct Drive

[James Oddino]

I see other folks have cautioned that you must tap across the correct two cells and ONLY the correct two.  I’d like to add that you better use a regulator between 2s backup and the receiver if you want the 5s pack to be the primary and the 2s the backup if you do use a backup, and you really should. The voltage on the bottom two cells of the 5s can get quite low near the end of a long flight when they are under a high fluctuating load, and the noise level can be quite high causing erratic receiver behavior.  And by the way, if you put a regulator on both, you can set it up for a six volt (LV) setup.

Now if you are running an ESC with a BEC you can connect it directly to the receiver and also connect the 2s backup pack directly to the receiver (through an on/off switch).  I set the BEC to 8.0 volts and the system keeps the backup charged to 8.0 so it should last for years.  See the wiring diagram for my Acuracy Pipe.



Jim


> On Oct 16, 2018, at 5:21 AM, tim pritchett via NSRCA-discussion <nsrca-discussion at lists.nsrca.org> wrote:
> 
> A friend of mine suggested that with high voltage equipment, a dedicated battery is not needed for the receiver and servo's.  Plugging in the balance leads from the 5s power packs directly into the on/off switch to the receiver provides the same voltage.  This is true; the red/blue wires (on my packs...) in the balance leads produce 8.4v.  A simple 5s plug and a two wire harness could be easily made to supply power to the controls, and could even be 'doubled up' to supply power from both 5s packs.  My flight pack usually only drains ~30mah per flight, so that equates to ~7mah per cell in the power pack per flight - almost unnoticeable. 
> 
> So the question; is anybody doing this with success, and is it recommended?  It eliminates some complexity maintenance and weight, so it seems worth asking. The math seems to work...
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