What battery size and rating would be recommended for a large hexa?

I have a Tarot Ironman 680 hexacopter (hex-x) with 6x 3508 700KV 198W disk motors and 1355 CF propellers. 6x 30A Opto Oneshot125 ESCs.

The flight controller is a cube orange+ set with a Here3+ GPS. There’s also a GoPro Hero 3+ on a Tarot 3D gimbal.

All together this weighs 2476g without battery.

I’m currently using a 4S 5200mAh 30C battery which weighs 561g – but it’s only giving me a few seconds of flight before battery low failsafe. I have followed these instructions for settign up the power brick mini: The Cube User Manual V1.0 - CubePilot

What size battery should I be using for this setup to get 5 to 10 minutes of flight time?

When I put some of your figures into ecalc I get almost 10 minutes hover time, so you have something wrong like the battery is never fully charged, or measured voltage is wrong.
Some of the ecalc output is not ideal, like electrical power, but your combination of components should still be useful.
Please provide a link to your exact motors.

Perform the manual voltage calibration as per this link (set the sensor to Other and enter the exact measured battery voltage)

A .bin log will help us see what happens during flight.

In ecalc you exact motor is not listed so I chose a discontinued Multistar which is extremely similar - in fact yours is probably a copy of the old Multistar motor.

the motors are these: https://www.aliexpress.com/item/1005001431336546.html?spm=a2g0o.order_list.order_list_main.5.7b0e1802XzVv79

More Detail:
Motor KV: 700KV
Shaft: 4.0mm
No-load Currency (A): 0.4A
Maximum Currency (A): 18.0A
Power: 198W
Weight: about 90g
Input Voltage: 2-4S LOPO
Suitable Propeller: 12"-15" Props

That is how I calibrated my voltage. I attached a power analyser to the balance port while the battery was connected to the power brick mini.

Not sure how to get those logs but will try when I next give it a try

What should my minimum voltage per cell be for failsafe?

Yes that’s the motor I assumed it was - it comes with one of several different brands on the label.

In MissionPlanner Data screen, go to the “Dataflash Logs” tab and download via mavlink.
Once you have a .bin log (in your MissionPlanner logs directory) upload it to dropbox or some suitable file sharing service and paste the link in here. You may need to get a link for “anyone” or turn off restricted access.

These are the battery-related settings you should have:


Thank you so much for your help with this 

My motors probably aren’t the best quality but I am on a budget. I looked for motors of the same shape/size/type as the Tarot recommended ones. If I get serious I will buy better quality as and when I can afford it.

My battery settings are the same as yours except for BAT_FS_LOW_ACT which was 1 and has now been changed to 3

I’ve put log and settings files here: https://www.dropbox.com/scl/fo/z3xu1c1o9xmvppxfrrj9g/h?rlkey=es02p4n0r327yh50ljawem2h5&dl=0

Please let me know if you have trouble with permissions. I think it is set to view mode for anyone with a link?

That battery is dead - you can see the voltage is going down to below 11v when it should never be allowed to go below 14v.
This can happen if the battery has been over discharged multiple times, or never been charged properly.
It is not going to come good and work, it will only get worse.
What charger do you have?

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Thanks again for looking in to this. I guess it’s time to buy a couple of new batteries. Do you think a 4S 5000mAh or greater branded battery from a reputable outlet will suit my needs?

My charger is a Robbe Power Peak Infinity 3 with Robbe balance charger. Each of my batteries has a programmed BID chip that the charger reads for cell count, total current, charge current etc. I have no concerns with the charger. Works brilliantly for all of my helicopter batteries (3S & 6S2P) which don’t suffer with this problem.

I had been using Turnigy 3S 5000mAh batteries in this hexa setup with the same problem but I had smaller motors (A2212/13T 1000KV) from an old quad with 10” props. I had thought the whole setup was just too under spec’ed

I upgraded (?) the motors and props so I could start using this 4S battery that I’ve had for a while. Looking at the battery it is no name so I should not be surprised it’s garbage :frowning_face:

Yes probably. I wouldnt go over about 5000mAh

You can actually get the same flight time, about 10 minutes, with 12inch props and electrical load is more acceptable than with the 13 inch props.
Increasing the battery capacity does give you slightly more flight time but with the expense of electrical load. A smaller battery gives only a little less flight time but with less electrical load.
The sweet spot is going to be 12inch props with 5Ahr.

The smaller 12inch props spinning a bit faster (than the 13inch props) will give better attitude control too. There will still be plenty of thrust to weight.

That would be a great charger! Use the charger to give it a charge/discharge/charge cycle to check what capacity the battery really has before you start using it.

I’ve found the Master Airscrew MR 12 inch props to be excellent and they dont require balancing. Order their prop adapter rings at the same time if you get those. They are not CF but will certainly take a load.

Thanks again xfacta

That sounds like excellent advice on the props and I’m actually going to take it! I am guessing you mean these: Multi Rotor Drone - MR 12x4.5 Prop Set x2 Black

I will try to find some in the UK before ordering direct from USA.

I can probably sell my 13” CF props as new as they only flew for less than 1 minute without incident.

I am having trouble identifying a battery I can trust though. There are so many brands that I’ve never heard of and have no idea whether they are reputable. I can’t find Turnigy 4S 5000mAh anywhere in the UK that has stock :frowning_face:

I’ve only used the discharge function once on my charger and destroyed the battery. I think I discharged it too much. Is there a rule of thumb for discharging batteries?

Huge second for the Master Airscrew props - I use them almost exclusively. Yes, the MR series is what you want.

I’ve had good luck with Race Day Quads’ house brand. They have an LiHV series that gives you a little extra energy density (just make sure your charger supports the higher voltage spec). Not sure what their UK shipping policy/costs might be.

RDQ Drone Batteries for Sale - RaceDayQuads

I’ve also had good luck with Zeee branded batteries. They’re probably made in the same sweat shop as a dozen other brands (and possibly even the same place as those RDQ ones), but they haven’t let me down, despite the “budget” branding.

As for discharging, generally don’t fly your batteries past about 3.5V per cell, and that’s probably a good place to stop a discharge cycle. You can push it to 3.3V/cell, but you’re flirting with disaster and possible battery damage if you’ve misjudged at all, and repeated deep cycling a LiPo cell will destroy it in short order.

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3 sets of Master Airscrew 12x4.5 MR ordered and hovering over the trigger on these: Zeee 4S Lipo Battery 14.8V 5200mAh 100C with EC5 Plug Soft Case for RC

I’ll need EC5 to XT60 adapters for the power brick mini.

I have a couple fo 3S 5200mAh Zeee batteries and I must say that I am quite impressed with their build quality. Only had 2 cycles as I bought them for hex-rotor before deciding to move to 4S motors

I always just (carefully) clip any non-compatible power connector off and solder an XT60 or XT90 in its place rather than dealing with adapters. It’s not terribly difficult, though you’ll want a higher wattage soldering iron than those used for PCB pins.

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Yes and their prop adapters too, the thousands of prop adapter rings that you already have are different.

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You should have a lipo discharge mode that discharges down to say 3.6v per cell (to stay within safe limits). You could discharge down to 3.3v per cell but I’d only do that for serious testing and it might be an unnecessary risk with a new battery.

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Your power configuration is not the right fit for your frame. It is recommended that you replace the motor with a 400KV, 3510 motor; the ESC uses a 40A motor. The propeller uses a 14~16 inch, 6s 10000~15000mAh battery. This configuration flight time can reach 40~60 minutes. For ordinary batteries, the single-cell voltage should not be lower than 3.5V.

I think in this case we want to work with what’s there already as much as possible. Also I believe 13 inch props are the largest you can fit with the Tarot 680 frame.

Shawn is correct. I’m not looking to replace motors now.

From my recent experience 13" is probably the maximum for an ironman 680 hex.

The spec for my motors is also 4S max.

I really do only want 5 to 10 minutes flight time at this stage. I’m flying by RC for hobby and practice. I’m not flying missions or for any commercial need. 5 to 10 minutes is probably the extent of my concentration span :slight_smile: but thanks for the feedback Cuav_le - maybe on my next upgrades I’ll change motors and try 6S

You are right, he only needs 5-10 minutes of flight time, based on which optimization is a better choice.

What kind of battery do you use? Using an 18650 battery pack with higher capacity and lower weight may be a better choice. 5-10 minutes is very easy to do.

I think so that you use 4s 5600mah battery pack.

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