6S and AQ

[ABL]

Hello,
didn't found such topic, so will ask here (already done on RCG but...).

I would like to use AQ6 with 6S batteries. If i understood correctly, onboard SMPS are limited to 4S only (16.8V fully charged, and they're rated only up to 18V). So, for anything above 4S we need different solution, right?

For now i think about such workaround - ESC's (--> motors) are powered by 6S flight battery. Middle wire (5V) from ESC SBEC is removed.
Everything else is powered by separate 3S battery (VTX, OSD, gimbal, AQ6). This would allow to use copter without serious modifications.
Another alternative is to use one powerfull SMPS, 6S -> 12.5V for everything on board. This would eliminate needs for separate flight battery, but noise, reliability and other factor remains...

The problem here - can't monitor flight pack, because AQ6 is not rated for this. What's proper solution? Add voltage divider (let's say 2:1 and configure 6S pack as 3S pack)? Fully charged 6S pack is ~25.2V (4.2*6), maybe i can get around this problem by changing voltage dividers on board (i have both, rev0 and rev1 boards)?
How others are solving this problem with > 4S setups?

[Astudillo]

Hi ABL,

From what i understand is that you can replace the recoms on the AQ board with ones that have a higher voltage rating.

Check out this link :

Hope this is what you are talking about.

Cheers,

Ray

[ABL]

Thanks. It's easy to swap SMPS on board, but what about monitoring? Is rev1 change (one resistor in onboard divider) enough for 6S monitoring?

[LPR]

Currently the AQ board will not arm if the input voltage is greater than 21 volts. Newer firmware may have changed it to a higher setting.
It's important to have the voltage to the AQ board be the battery voltage because the board changes some flight settings to correspond to changes in battery voltage.

[ABL]

Thanks for answers, but i still do not get, what i should do to be "compatible" with 6S?
If board won't arm, then i probably need voltage divider and configure battery as 3S (instead of 6S), right? If so, can i connect that divider to another pin on board (not "main power" plug) and keep board powered with another power source (3S battery or another SMPS)?

Or i'm limited to 5S in any case (no use then on this copter)?

[JussiH]

As I remember, the voltage divider should support up to 35V on R1 boards (post october 2012). You will have to replace the recoms (current ones are max 18V).

I´ll get back to you on how to configure the code to accept 6S input voltage to board. To be completely honest I was not aware that a 21V limitation even existed....perhaps Bill can jump in and clarify?

[ABL]

If i understood correctly, i can swap recoms (both) on board to 'R-78B5.0-1.0L'. Then (as i have rev0 for this task) i have two possibilities:
- replace resistor to rev1 alternative (8.45K)
- replace resistor to bit higher (let's say 10K) - to get lower voltage divider value
In first case i'm limited to 24.25V, so full battery won't be measured. In second case... Upper limit should be higher, but could i perform proper battery calibration to get correct voltage values?
I also found this in board_6_1a.h:
#define ANALOG_VIN_RTOP 8.45f
#define ANALOG_VIN_RBOT 1.33f
So, i probably can define own voltage divider?

I can't find 21V limitation for arming, maybe looking in wrong place?

EDIT: oh, i just noticed JussiH response. Now i do not get anything. If built-in voltage divider can measure full 6S voltage and i do not have limitation on arming - then replacing SMPS and voltage divider resistor to 8.45K is 'easy mode'

[Max]

I've never heard of the 21v limit either. Larry?

Yep, you can replace R5/6 with whatever values work for your setup, and use the ANALOG_VIN_Rxxx macros to define the values. I think Jussi was saying the newer rev board (post October '12) already have proper resistor ratio to measure up to 35v.

There is some cell count detection code in analog.c, but recent versions already handle 6 cells. I think you should be all set by replacing Recoms and R6.

-Max

[bn999]

[LPR]

Max

Yes I know that there was no discussion of a 21 volt limit. Messing with the 28 volt Dewalt battery and V2 AQ board made me aware that four months ago the firmware did not let you use over 21 volts and still arm the board. It took 11 diodes to lower the voltage to under 21 volts and then arming was fine.
The firmware may be different now.

Larry