Morning,
Perhaps one of you could shed some light. I feel like I have tackeled this problem correctly. Setup 2 x 3000mah 35C batteries. Each battery runs 2 motors. So both batteries ends up powering 2 X 2 sets of motors. Hope that is clear. Battery config is Batt A -> powers FL, BR and Batt B _> powers FR,BL.
Here is the problem:
During flight battery A uses alot more power than Battery B. So say the duration of the timed flight is 5 minutes, Battery A will consume 2000mah and battery B will consume 800mah. I know these numbers because of the charge input of mah after flight. So basically one set of motors is consuming largely more power than the others.
This is what I have done so far to trouble shoot.
- Replaced all motors with a different brand, different type.
- Re-Programed each ESC manually to ensure there is no timing issue leading to power wastage...
- Tried different batteries to make sure that I didnt have a bad battery...
- Put a wattsup meter between the battery and esc on test bench, fired up each motor individually to check the A pull on each whilst unloaded and loaded. Each motor with its own ESC. The figures are within 0.2/0.3A for each motor so no real variance between them. Not enough to cause the power drain difference between the two batteries....
So the only time I can see the power difference is during flight and only because the power consumtion is so radically different. I have balanced props, CG is dead center. Nothing weighs more on one arm more than the other etc.
Any suggestions would be appriciated.
Regards,
Solo.
Replies
Right, to report back. I think my power issue was more than likely a solder joint, however now that I have shared the CW, CCW motors, 1 set per battery in the process, its hard to tell if that was the cause itself. I have a hunch that for some weird reason ccw motors do use more juice at higher throttle settings.
Thanks for the feedback and assistance.
Morning,
Ok, so I am starting to re-wire my battery harness. I have shortened the harness further as I said I would. Haven't quite decided on how to deal with the parrallel battery as yet. Also the battery that is being more used was powering the counter clockwise props as suggested by Mike, however this might just be a co-incidence as the bench test did not indicate this being a problem. With the new wiring I have shared the CCW CW motors. So both are now going to power a set of CCW & CW motors sets.
If I still dont have any luck after that, I will replace the FR motor first as it seems to be the one getting the hottest. I always buy my test motors in 5's so that if I have a dud its not the end of the world. So will finish the harness this afternoon. Test and if the problem persists then I will replace FR motor and test. I will report my findings sometime over the weekend. I havent replaced my labels yet. Its all about references... :D
Maybe one of you guys can check my apm log and see if there is anything perhaps showing more throttle applied or something like. It looks pretty uniform, but them I an not sure what you guys would consider normal. Please find file attached. It only gets interesting around 70%, took for ever to get a GPS lock.
2011-09-29 05-30-53.tlog
Using such a setup for a quad is not a good idea. It will not give you more reliability if a battery fail and each battery will never discharge exactly at the same rate.
More you would need two separate voltage monitoring modules to get right telemetry informations.
I would connect them in parallel.
Is there any issue with connecting these batteries in parallel and just letting them balance?
The side that consumes more power ... it also carries the ESC that supplies the BEC?