Power System Rethink / thinking out loud


#1

Morning Guys / Gals

I was thinking yesterday about the issues that some of you are having with the electrical high current (this is a problem for switches, cables, interconnects).
Why if we are running 4 motors, 4 ESC’s and 4 batteries (for the bonka guys) don’t we run 4 “separate” systems. This can also work for the guys building 18650 batteries by just build 4 batteries.
My thinking is that we could monitor the voltage in all 4 packs. We could then give the readout of the lowest value on the hand controller.

Pros:

  1. Cheaper electrical interconnects
  2. More reliable interconnects (less current)
  3. System redundancy if 1 motor / ESC combo goes down
  4. Max current should then be around 75A peak (according to the figures i have read on here “peak 300A”)
  5. As there is less current for the cables we may have better efficiency as there should be less heat in the system.

Cons:

  1. Less flight time as we cant eek out the last of cell, by spreading power throughout system
  2. More complicated switch on system
  3. At present the controller only reads one voltage, i’m sure we could program in to monitor all 4 and then give the read out of the lowest pack

Let me know your thoughts


#2

Just another thought.
Bonka guys obviously can’t do this as we need 12s power…
Guys building 18650 could or using different lipo packs…


#3

4 x 12S with the same capacity, and it makes perfect sense, plus gives the redundancy promised by Revolt. Alternative for Bonka guys is 2 x 12S, and control the motors across the diagonal. Reduces max current, and square root of power loss. Control unit is still pretty trivial to do.


#4

I have been doing a little research and 12s battery while they are available become unfeasible as I can’t find a 12s charger.
So the option is 4x18650 packs, then you need bms’s for each pack. Or 8x 6s 10000mah lipo packs.


#5

I plan to use 14s LiPo to reduce current but also because i already have them :wink:

As for the charging there’s actually few 12s chargers but pretty costly, higher than that you either want to get a separate bms or charge cells separately.

Also higher voltage will means lower kV, so different esc’s and motors.

I’m considering the t-motor flame 100HV esc (as they support 14s) with the U12 motors for now. But it’s probably overkill… Maybe for a tandem version :wink:


#6

The 80hv ESC we use now support 14s and we havent had any problems with them.