Copter-3.5.0-rc2 has been released for beta testing

Aparetly the TI board i have uses same registry addresses as Maxell so they should be compatible. With 3.4 if i hook it up and fiddle with registries the flight controller freezes.
I was looking at the rc code and noticed that only current and voltage are defined for use so i guess the current aim is to make those Maxell batteries usable rather than making batteries smart? If i uncomment the registry values for other parameters then in user defined code i should be able to request state-of-health, cycle-count etc data?

@George_Muirhead On the SBS wiki article it says that its sort of a de facto standard. What the differet boards do internaly probably differs but the interface available to SMBus seems to be the same.

Nice work Karl.
Yes, the current Maxell battery driver is just a starting point with basic functionality (voltage and current) but the maxell battery itself also doesn’t provide as much info as say the Solo battery. Hopefully we can do more (with the maxell or these TI batteries) including what you’ve mentioned and also individual cell voltages, setting battery capacity, % of battery remaining.
Are the TI batteries readily available or is it still very DIY?

Its DIY as its custom made batteries with TIs SBS controller. This chip to be exact. I can get quite a bit of data from my batteries but not everything that the chip offers is imlpemented yet. Will be quite a while before it can become a fully blown product if ever. If you need someone to test the interface then from this chips perspective im happy to help.

Hi all,
I made a first test with 3.5 rc2.


  • Quad X
  • Pixracer
  • EKF3
  • MOT_THST_MID = 19


  • Autotune
  • windy conditions (4-10m/s)


  • Generally, Autotune would never have been possible under such conditions without PosHold
  • Turning into the wind works perfect!
  • Due to the higher wind speed during this test turning into the wind can look like a “flyway”. I guess this is the phase when wind direction is measured.


  • Autotune failed. At least there were no changes in the PIDs. There is no indication if it failed or finished successfully in the logs. Autotune logging simply stopped.
  • At that point the copter started drifing in the wind - it seemed like normal AltHold behaviour.
  • I landed and disarmend with autotune still on. But no changes in the PIDs.


  • What went wrong?
  • I can imagine that AT failed due to too high wind speeds. But, how can this be seen/determined?


PS: Uploading the log here failed… You can find it at:

Another thing - maybe related to Copter 3.5:
Getting Params over USB after connecting in Mission Planner is sometimes unusually slow. I saw this behaviour on different boards (Pixracer, AUAV-X2) and different USB cables. Downloading a log afterwards was as fast/slow as usual. I’ll make some further tests.

Thanks for the report. I think I know what this is. We throw away the first request-for-parameters if it arrives before all our internal objects have been created (it takes a few seconds after startup). I think you’ll find if it’s possible to wait a couple seconds after startup before connecting and downloading parameters it will be fast. Tridge has mentioned this issue to me and I think we have a fix in mind.

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When the auto tune completed, did you switch out of auto tune and back in?

  • Auto Tune runs. When complete, the ground station will provide the Auto Tune complete message.
  • It will sit there and wait in Alt Hold or Pos Hold, using the old PIDs.
  • Switch out of Auto Tune and back in. That will activate the new PIDs to try out.
  • If you like your new PIDs, you can keep your new PIDs. Land and disarm without switching out of Auto Tune again.
  • If you don’t like the new PIDs, switch back out of Auto Tune to go back to original PIDs. Then land and disarm.

I have never looked at or used auto tune logs. So no clue what they should/shouldn’t show.

been doing some googling and found this, it appears to use the ti chip you mentioned.

I wonder if something like that can feed 3DR Solo battery SMBUS data to the pixhawk too? It would pretty amazing to eventually see cell voltage and such in the Pixhawk telemetry and logs.

Cool board but, this is for a rather large battery. 15s will be something like 4kg battery.

Pulling SMBUS data from the 3DR Solo smart batteries would be pretty epic too. Imagine being able to see the cell voltages on the Ground Station in flight? Alerts and failsafes based on cell voltage could help prolong the life of batteries that get unbalanced. Having it in the dataflash logs opens up a lot too.

yea im really struggling to find anything 4-6s that does more than 30A

We should have read the posts closer. Though we thought the manual tuning for our copters was spot on we were so-so wrong. We upgraded our shop Centurion MKIII to 3.5.0-rc2 and gave autotune a whirll.

Our flight engineer Berlin envoked in Loiter and was surprised it was holding position through the first few twitches but then I heard a mess of expletives from her as the copter yawed off 90 degrees. Told her to hang on to it then realized it was by design.

We ended up with a large change in PID’s, Though the numbers looked scary to us we are amazed that a good flying copter is now an amazing flying copter.

Kudos to all the development team for this release candidate.

Where is the donate button?

Johnny Skoch
Aromas Robotics

Matt, thanks for having a look!
I am using autotune since the beginning and it is the first time that the new PIDs have not been saved. This is why I posted it here. However, from the log it seems that it completed Pitch, Roll and Yaw tuning. So this is a little strange to me. I am also not 100% sure but I guess there was no autotune complete message.
I had some problems autotuning this configuration before. But the result was wrong PIDs which had been saved. So, I hope for less wind tomorrow…


Solo battery was the first SMBUS implementation ArduPilot had for quite a long time. We have now added Maxell too (thanks to Tatsuya Yamaguchi for the contribution). Since this is a standard protocol we hope to generalize the driver in the future, but unfortunately both of these brands don’t completely respect the standard.

Hi John,

Great to read that everything is working even better!

Our donate page is in the wiki:

Test flew 3.5.0.rc2 on Auav Pixracer on F450.
Stab, Alt Hold, Circle, Loiter, Poshold, Auto Mision with RTL and Disarm, and AutoTune in Loiter.

Al worked great !, No problems. Kudos" to all.
Best Version yet. LOVE the new Autotune. Even in a 5~10 mph breeze, once it drifted downwind 20 feet or so and yaw spun around to face wind direction, it just stayed over a a 5 foot spot. Amazing !

Thanks for all the work you all have put into this.

Hi All,

Can anyone post a video later of the new autotune with position hold?


I made some further Autotune tests with different copters and 3.5 rc2. Today it worked perfectly on the small quad. But again I had one autotune on a bigger hexa where the new PIDs had not been saved. Apart from that tunes are perfect! The autotune waltz is nice to watch as well!

Please open new topics when you have specific issues - and, for better support, provide plenty of information, including logs.