Maximum current drain

Hi,

I apologise if the answers to this post are obvious but if somebody wouldn’t mind humouring me that would be great, thanks.

Please see below an extract from a log from a recent flight. I’m flying a Pixhawk on a Sky Hero Spy Y6 with T-Motor MT2814-11 770kv motors that, according to their site (copy of data sheet also below) can draw up to 21A.

Questions:

  1. The extract shows max drain of 60A in stab mode, full throttle at take off. Does that mean I’m only utilising half the power of these motors?

  2. If so, can I adjust the params to release some more power or even max out the power available? I have maxed the PILOT_VELZ_MAX param in alth mode and the power is less than when in stab mode.

  3. The power cables on the power module are 13awg which I don’t will be very happy with 120A so assuming a positive answer to No. 2 above, would I be best advised to upgrade all the wires lipo side to say 10awg?

Thanks…

Peter.

Oh well, I decided to change the wires to the pdb and power module to 10awg and start using EC5 connectors just in case there is a way that I can release the full power to the motors…

I have to say that I found the EC5 connectors a pain to fit but they feel much more user friendly than XT60s…

Ok, so I see that the 3DR power module will limit the current 60A hence the above issue although it is rated to 90A…

I found this from a year ago:

  • there should be a new bespoke Pixhawk power module under development with
    a higher current and voltage input tollerance

Does anybody know if these were ever produced or is there another unit that I can use instead of the 3DR power module?

Thanks…

There’s some echo in here… :slight_smile:

Problem sorted, I’ve ordered one of these which should release 50% more power, 90A:

buildyourowndrone.co.uk/ardu … ctors.html

I was going to use one of these but I couldn’t find one in the UK:

buildyourowndrone.co.uk/atto … board.html

Over and out…

Hi Peter,

You are right, the power module only can measure 60A when it is used with Pixhawk (90A when used with APM).

An alternative is the AttoPilot:
copter.ardupilot.com/wiki/common … nt-sensor/

Many thanks Roger, I couldn’t find the Attopilot in stock over here so I chose the 90A module for the time being…

She’s pretty quick at ~half power: youtu.be/GUh88VGxUPk

Heaven knows what she’ll be like afterwards: youtu.be/GUh88VGxUPk

:smiley:

Best laid plans…

Despite it’s Mega title, this transpires to be a standard 3DR power module so won’t change anything:

buildyourowndrone.co.uk/ardu … ctors.html

So I’ve found the 180A AttoPilot here:

coolcomponents.co.uk/attopil … -180a.html

and intend powering the Pixhawk using one of these:

coolcomponents.co.uk/adjusta … 20alv.html

I suspect that I’ll be posting for help with the AttoPilot later!

[quote=“RogelioN”]Hi Peter,

You are right, the power module only can measure 60A when it is used with Pixhawk (90A when used with APM).

An alternative is the AttoPilot:
copter.ardupilot.com/wiki/common … nt-sensor/[/quote]

Hi Roger,

You may not have had time to read my first post in this item but just because Pixhawk can’t read above 60A, does that mean it restricts the current to 60A? I assumed that it does restrict the current via the ESCs but may be I’m wrong and in fact there has been no restriction…

Thanks,

Peter.

So I can confirm that Pixhawk does not restrict the current, it merely cannot sense anything higher that 60A with the 3DR power module.

This shows a flight this evening having fitted an Attopilot 180A power module…

Just in case this is of interest to anybody, as part of the upgrade of the power wiring, whilst fitting the AttoPilot 180A sensor, I used 10awg 200C silicone wire from the lipo connector to the AttoPilot then direct connected the power wires to the motors rather than rely on a power distribution board. These were then insulated using self amalgamating insulation tape (what a great invention that is) and then separated from each other using a piece thick polythene sheet…

You could fix the current limit with a voltage divider made from resistors you can get from radio shack, if you were so inclined. I like your power distribution - I’d probably put connectors on it so that I’d never have to take it apart though. PDBs aren’t a reliability issue, but they are bulkier than necessary.

Thanks… I’m not a lover of connectors and avoid them if at all possible so I took the view that a simple cut and solder joint would be better in the event of having to swap out an ESC.

Anyway, she’s flying really well, just a little clip from my (juvenile) son’s phone the other evening:

youtu.be/2PAtExD-Kqc