Building a hexacopter

Thanks for the responses. I DO have telemetry for voltage of the battery as a whole, and individual cells. First flight I ran it to about 3.75 per cell, next I did about 3.6. After hearing back from Pulse (the battery manufacturer) they recommend above 3.65 and even better 3.8. Opinions vary greatly on this subject it seems.
 
wkf94025 said:
Editor,

If you had in-flight access to either mAH consumed, or current voltage under load, but not both, which would you find more useful? Planning my telemetry / OSD game plan for next aircraft, and looking at various telemetry options for current/voltage.

Kelly

I'd have to agree with 'OI Photography' here and go with voltage over mAh consumed. I find voltage more useful and 'quicker' to glance at and take in whilst flying.

@Mediaguru - Are you sure they are 'under load' voltages quoted by Pulse? They seem very conservative! A big hexa can easily draw 100amps plus on full climb out and any lipo pack is going to exhibit a drop pulling that sort of current from it.
It's perfectly ok to fly down to 3.5v or 3.6v per cell as long as the recovered voltage bounces back up to your magic 3.7v.

My caveat to that statement above is, you should get to know your packs/aircraft over a period of time and fly to a particular voltage (you can be quite aggressive with your flying technique). Make a note of your voltage while flying/under load and then bring the craft back into land. Let the packs rest for a good 15-20 mins then charge them at 1C and keep a close eye on the number of mA you are putting back into the pack.
You will soon get to a point where you will work out thaty flying to a particular voltage under load as displayed on your osd correlates to a specific (fairly) charge taken out your packs. Then just stick to that.

In my case, I can fly for around 20 minutes and I land just as my osd is flickering between 14.3 and 14.2v (3.55v per cell). I know my packs recover around 0.7v after rest back up to 14.9v (3.725v per cell). when I charge I am putting around 3,900 mAh back in so circa 78% of pack used (I fly with two 5,000mAh packs in parallel). This method works for me.
 
mediaguru said:
Thanks for the responses. I DO have telemetry for voltage of the battery as a whole, and individual cells. First flight I ran it to about 3.75 per cell, next I did about 3.6. After hearing back from Pulse (the battery manufacturer) they recommend above 3.65 and even better 3.8. Opinions vary greatly on this subject it seems.

Yes, opinions do vary. I have 3.6 as my 2nd warning. As long as you stay above that, you should have no problems. The danger zone is when you approach 3.0 (or the LVC of the ESCs which on my machine is 3.15). I think the general consensus is that 3.6 doesn't hurt (based on experience) but you can set it anywhere you want. If you set it at 3.6, then be sure to be in the area - a 3.6 reading when you are 1000 meters out would probably mean an impromptu landing.

3.8 is quite high and you will find you have some fairly short flights with that. I was flying with some friends today (RC) and they were bringing back some FPV birds with 3.8 - and were calculating that they had used only about 1/2 the available power.
 
I've been landing at 3.7x on the lowest cell. When I balance charge the 5000mAh batteries back they're taking anywhere from 2400 to 3400 mAh. That would tell me I can fly a little longer without much of an issue, based on the 80% rule (which would be 4000mAh). When I power the bird down right after flight the cells are at 3.75 or a little higher.

Here's a shot of my hexa in a test flight this evening. I just picked up a NEX-5T and got it mounted on the Arris Zhaoyun 3-axis gimbal. Some jello issues to work on, but so far so good.

DSC_3818.jpg


For fun, I think I'm going to attach my Phantom to the bottom of this hexa and fly it around, just for perspective. That would be entertaining.
 
mediaguru said:
I've been landing at 3.7x on the lowest cell. When I balance charge the 5000mAh batteries back they're taking anywhere from 2400 to 3400 mAh. That would tell me I can fly a little longer without much of an issue, based on the 80% rule (which would be 4000mAh). When I power the bird down right after flight the cells are at 3.75 or a little higher.

Here's a shot of my hexa in a test flight this evening. I just picked up a NEX-5T and got it mounted on the Arris Zhaoyun 3-axis gimbal. Some jello issues to work on, but so far so good.

DSC_3818.jpg


For fun, I think I'm going to attach my Phantom to the bottom of this hexa and fly it around, just for perspective. That would be entertaining.

Nice looking rig.

I'm in the middle right now of sourcing parts for a Tarot FY 680 pro build. Not quite as big as yours, but still bigger than my P2V. I mainly want to do this with my brother; as both he and I helped our dad (he was a near lifelong RC airplane modeler). We got to where we enjoyed building them just as much as flying them.

Doesn't hurt that my brother is a journeyman electrician and has skills will the iron. :)

Enjoy your rig.
 
BigTulsa said:
mediaguru said:
I've been landing at 3.7x on the lowest cell. When I balance charge the 5000mAh batteries back they're taking anywhere from 2400 to 3400 mAh. That would tell me I can fly a little longer without much of an issue, based on the 80% rule (which would be 4000mAh). When I power the bird down right after flight the cells are at 3.75 or a little higher.

Here's a shot of my hexa in a test flight this evening. I just picked up a NEX-5T and got it mounted on the Arris Zhaoyun 3-axis gimbal. Some jello issues to work on, but so far so good.

DSC_3818.jpg


For fun, I think I'm going to attach my Phantom to the bottom of this hexa and fly it around, just for perspective. That would be entertaining.

Nice looking rig.

I'm in the middle right now of sourcing parts for a Tarot FY 680 pro build. Not quite as big as yours, but still bigger than my P2V. I mainly want to do this with my brother; as both he and I helped our dad (he was a near lifelong RC airplane modeler). We got to where we enjoyed building them just as much as flying them.

Doesn't hurt that my brother is a journeyman electrician and has skills will the iron. :)

Enjoy your rig.

Many thanks.

YES YES. A big part of this activity is the journey, the problem solving, and the creativity in building these awesome machines. I've been asking myself what I'll do when this big bird is flying perfect and the videos and photos are to the level I'm hoping for... The answer is probably to build another one!
 

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