Flight times, temperatures and all that

[Droider]

@krleas.. is there any modifications needed to the MK FC/BL dis board to go from 4cell to 5cell?

Dave

 

[krleas]

Yes, check if u have brown big capacitor on FC, if u have switch ti black one (same on blctrl) and replace 2 x dc/dc (black ones) to traco 5V red ones.

Thats all.

 

[seattle_helo]

2x 4S/5000mah, Canon 5D mk2, SLR2 ( and HDMI converter because I couldn't be bothered to remove it)
Total weight ........... 5974g (5881g without HDMI converter pcb)
Average amps......... 63A
BL temp range ....... 35-78°C
Flight time ............. 10:30 (MKTool low batt. setting 33 : 4S = 13.2v)

As a point of comparison I've got a Cinestar8 with an AUW of 5602g using two 4S/45C/6600mAh batts and I typically get a flight time of 12:30 (low batt setting of 14v) with average BL-CTRL temps of 50°C (max temps ranged from 49 to 62°C) and average current of 53A. Ambient temp was 9°C. Using 12AWG wire from PDB to APP connectors. Batts are 10AWG from cells to APP connectors. None of the connectors, cable or the parallel harness ever get warm.

10:30 seems very reasonable for your AUW and setup.

 

[MombasaFlash]

So how do you think you got it from under 6 mins to 10 and a half?

I would say the most significant thing was taking the low battery warning down to the minimum of 13.2v. Whether double 10AWG cables and better connectors made any difference I do not know but those were the only three things that were changed. The second pair of battery cables were soldered to the opposite side of the PDB by scraping away the black paint to leave two squares + & -, rather than try to squash that much cable onto the designated tabs.

Now switch to 5s with 1 batterie 8000mAh 30c ...

The jury is still out on this subject. Other than your assurances I have yet to find any other definitive evidence that it would be a change for the better. MK says that running the higher voltage will only increase the BL temps. I don't know. My basic understanding of electricity is that running a higher voltage reduces the current and that it is the current that causes the high temperatures. But of course all circuits and motors etc. have to be comfortable with a higher voltage as well.

I also have no idea whether changing to the higher voltage of 5S packs would necessitate changes to certain parameters within MKTool. As I have absolutely no desire to get embroiled in experimenting with settings I know nothing about, I will stay with preset 'Easy' setups and within the designed limits of 4S for the time being. Carrying the NEX gives around 13 minutes flight and that can always be bumped up a bit by using 2x 6600 packs. That sort of flight time is adequate and long enough to be useful.