Hello, I want to use Tmotor U11 motors with A2 DJI flight controller. Problem is that U11 runs on 12S and DJI A2 max operativo voltage is 6S (22V).
I was thinking about Having a 12S set of batteries just for the U11 motors and a separate 6S battery for The A2 controller only.
Anyone has tried that out before?

Just get a bec or step down. The a2 operates on 3s-6s, so you could even get a small 3s battery just for flight controller.

Or plug flight controller into balance plug.. Black wire is always ground and find which positive wire gives you 15.8 volts when the pack is fully charged. This is how I run my lower voltage stuff off higher voltage packs and have never had an issue

You will take power from 4 of the 6 cells in the pack then..  I wouldn't hook something up like this if it draws more than 1 or 2 amps because of the thickness of the wire on a balance lead. But just like they are there so each cell can be charged separately they also give power from each cell seperately.. Balance wires are connected to a protection circuit unlike the main leads on the pack too do I doubt you can damage a pack by doing this for small current draws, just make sure you balance charge the pack each time which we should all do anyway

The A2 is powered from the PMU. If I use a 3s battery to power the controller, will it disrupt component readings, or everything will be intact via canbus ports.

I have seen a 2S2P setup with four 16000mah batteries. Anyone know the max voltage the A2 PMU can handle? It has been done, I just want run 44.4V with the U8s or U10s, but without frying the flight control system.

Any help/insight is greatly appreciated.

Blade_Strike Posted at 2014-12-31 00:44
Just get a bec or step down. The a2 operates on 3s-6s, so you could even get a small 3s battery just ...

The A2 is powered from the PMU. If I use a 3s battery to power the controller, will it disrupt component readings, or everything will be intact via canbus ports.

I have seen a 2S2P setup with four 16000mah batteries. Anyone know the max voltage the A2 PMU can handle? It has been done, I just want run 44.4V with the U8s or U10s, but without frying the flight control system.

Any help/insight is greatly appreciated.

AlexBilous Posted at 2015-1-7 02:22
The A2 is powered from the PMU. If I use a 3s battery to power the controller, will it disrupt com ...

I use 2 banks x 6s in series, call it bank A and B, you can determine the mAh of each bank as long as each bank is 6s.
Wire the ESC's for 12s use.
Connect the A2-PMU  to bank A + and - and you will have real time readings of battery bank A 6s.
When connected in series (12s) both batteries run down at the same time effectively giving the A2 a true reading of both banks.
Discipline yourself to always connect bank A first then bank B, when disconnecting always disconnect bank B first then bank A, the reason for this is, should bank B be connected first the polarity to the PMU is reversed, no problem as the  A2 PMU is reverse polarity protected, but not the OSD and other units.  You can connect the OSD to a separate 4s battery until you are disciplined to connect and disconnect the banks in the correct manner.

Ok, so I guess my theory was right. The A2 power supply will not affect the flight controller just because I use two banks of 6s batteries to power the U11 motors? I will put a few 6S in paralell and and call it bank "A". Then I will do anothher bank "B" of 6S and put it in series with the bank "A" batteries. That gives me enough current and voltage to power up the U11 motors and have all of their thrust. I can do like I read above - grab bank A (22 Volts) and plug to the A2 controller or have a dedicated battery to it. I am thinking about using Futaba voltage telemetry just to read the full battery bank voltage. I am building a octa X8 with U11 to use for oil rigs inspections at the sea, Brazil 150 moles from the coast - will take off from supply vessels. It will have 29" props. Will be a little monster.
Not sure that has been built before.
The ESCs are PWM generators controlled by the A2. The ESCs will just deliver the battery bank power to the U11 motors. My concern is that this set up could screw up the A2 flight control precision. I guess not right?

I would go the BEC route

have a look at http://www.castlecreations.com/products/ccbec.html

They will do a 12s to 12v step down BEC
hope this is of help

Hi sombra y speack spanish Her
I nerd help for mi phantom fc40 and mi Fatshark

I need used mi phantom fc40 with the Fatshark the problem is the Fatshark is frecuenci  5.8 ghz and the phantom is 5.8 ghz how i do

Dronesolutions. Posted at 2015-1-7 16:48
I use 2 banks x 6s in series, call it bank A and B, you can determine the mAh of each bank as long ...

ok, so the 2,3,4... banks are not an issue.

My main concern is can the a2 read true voltage of 50V-100V(software made for 6s).

And if it does... will Go Home still work when 1st and 2nd level protection are input correctly?

As for ESCs, what do you mean by "wire ESCs for 12S use"?   I plan on using YGE 160V ESCs. Don't ask why ... have a prototype to build for a client with predator 30-8s.

Thank you so much for your help!

project41@me.co Posted at 2015-1-10 19:12
I would go the BEC route

have a look at http://www.castlecreations.com/products/ccbec.html

What does this do to the Go Home feature and 1st and 2nd low voltage protection? How can the A2 Read exact voltage through a BEC?

What Happens to the A2 Low Voltage protection feature with the BEC?
Same with a separate 4S power source to the controller...

Does anyone know 100% if the A2 PMU can handle 12S  (So two 22.2V Banks in Series = 44.4V)?

The DJI Wiki says it supports 4S-6S, but i refuse to quote wikipedia

Any help is appreciated. Thank you.

Any update on this? Can we wire the A2 with 12s

ant.lagarde.gma Posted at 2015-2-19 17:35
Any update on this? Can we wire the A2 with 12s

I can't make any promise.
Have not seen a successful case ever.
If the voltage is too high, a breakdown might occurs. Do not recommend.

If you use a BEC to power the PMU  the flight module will not see low battery voltage and will not be able to initiate a battery failsafe.  OSD values will be the BEC voltage which will be fixed.  Using a separate battery you would also lose battery failsafe and have the additional issue of that battery dying before the main batteries and you would not have a indication of main battery status. I personally don't like separate batteries for flight controllers since it introduces another potential failure point.  On a multicopter if you lose the main battery the flight controller can't so anything.  You are a rock falling.  

I can't comment on the 12S direct wire compatibility.  Have not tried and will follow specs in manual.
The method mentioned by Dronesupply should give you battery failsafe and a usable (but 1/2) voltage reading.  Just make sure all equipment requiring 6S or below is wired in the same way.  I would probably put a separate connector on the battery to plug in after both batteries are installed.

In my case only the A2 will be powered by the 6S "bank A", so is it really true and tested that if I fail to plug them in the correct order it won't blow up the A2?

any news on that? I want to be sure I don't blow my A2 if I plug the wrong bank first

Hi there.
I also have been thinking about this. I would like to use the low battery voltage on the A2 controller and I do not want to use separated battery for the controller.I am using 8s with 2x 4s in series.
Dronesolutions, is this like your setup look like?   https://www.dropbox.com/s/k0k6zumwt4nsznk/A2%20on%2012s%20setup_1p.png
Sorry about the drawing. Drawn on my phone.
Also AlexBilous, were can I buy this DJI power management module for 4s-12s?
My best
Johannes

project41@me.co Posted at 2015-1-10 19:12
I would go the BEC route

have a look at http://www.castlecreations.com/products/ccbec.html

DJI has a BEC to step down 50v to 12v

I tried to connect 12S battery pack (2x 6S LiPo) to DJI A2 PMU directly. It worked (not burned out), but PMU gets a little hot after 1 minute. I think it is ok, but not sure.