6s v 7s batteries

[grejen711 (Greg Jensen)]

@flyingtiger56

Still waiting for my batch4, and looking for batteries, I see a lot of 6s available for sale from the internet and shipping to europe(France) but 7s are not really « out there » to find.
I was heading to 4x6s but I read here that the last batch is intended to run on 2x7s’s…?

I ordered 6s Bonkas for my batch 4. The reasoning was that the charger options are much wider and less expensive. So I have 6s chargers as well.

Still waiting for the batteries (over 2 months now:cry:) but I have my Batch 4 kit and assembly is underway. I’m not a big guy - 170lbs (77kilos) and I’m not looking for a skyrocket climb rate. May be OK. I do however live in a pretty mountainous area so I may have to go to the larger props at some point.

[jhair (Jonathan)]

The efficiency column you are quoting is the total system efficiency, including the prop.

You cannot make a conclusion on this that a throttle or duty cycle of 55-60% is the most efficient for the motor and ESC.

If you changed the KV of the motor to achieve a lower throttle %, I suspect you would have approximately the same efficiency (thrust / watt) for a given amount of thrust. In other words, I think the prop efficiency dwarfs any differences in losses of the motor based on duty cycle.

Charts like this are helpful for comparing props at a given speed, but you can’t make conclusions on the duty cycle from it.

[tarifachris]

@jhair

The efficiency column you are quoting is the total system efficiency, including the prop

I agree. The motor manufacturer charts aren’t good … How can you have constant 48 v with a load?
That is why I have my own calculations… and a different efficiency %.
I used real live numbers from GliderPilot with 66000 mAh batteries and KV180 motors with 12S.
For the propeller I used the Xoar PJN electric (same as the Gemfan) and the 23x13 it is a APC electric wide blade.

7590 gram thrust each motor is for level flight…
12980 g thrust each motor is for climbing…

OpenPPG with 22x10 prop / KV180 / 12S

OpenPPG with 22x10 prop / KV150 / 14S

OpenPPG with 23x13 prop / KV150 / 12S

OpenPPG with 22x10 prop / KV150 / 12S

To compare 12S and 14S you have to look at the wattage use!

I didn’t compare the KV150 12S with 22x10 because they don’ have the thrust like the other combinations.

We will see in the future how these numbers compare to real life since the Batch4 can
record the telemetrie data on a SD card.

[Privatreal (Christian Zelinka)]

@GliderPilot

I assembled a batch 4 for a local friend.

Did you or your friend try to use 2 x 7s setup?

Should it not stay cooler as it has nearly 20% more amperehours ?

I think thats one of the big + of the x4 possibilities?