The right batteries for 800e trekkers

[delirium_knight]

So i have a electric Trex 800e thats setup with a photoship one camera gimble. Standard motor in it. I have been using 5000Mah 45c batteries in it setting up the helicopter. I have a boom battery mount to hold 2 of these. Which i have been using to make 44v. I stumbled across some 12,400Mah 35c 6s batteries. I know that they have a lower c rating, but almost twice the Mah rating. Obviously my ap heli is weighing more now with the gimble, fpv equip and what not so there will be a slightly higher load on the batteries. But this heli was meant for 3d. So im not going to be straining as much doing ap. Given in a hover i was getting a. Good 10+ min of the batteries. My question is. Would these 12,400/35c batteries work for my large heli to give me a longer flight time. Keep in mind that i would be using at least 2 to obtain 44v and even thought that i could run two in series and 2 in parallel with a total of 4 batteries to up flight time.
Here are the batteries that i have found
http://www.readymaderc.com/store/ind...oducts_id=2324

[Khosravi]

How many amps do you pull in a hover? My 700 pulls around 20 amps. I use 20C 5000mah batteries since they were cheap and it would be a waste to get anything higher in C rating. 5000 mah at 20C is 100 amps. If my heli was pulling 100 amps I have some serious problems. I would bet your heli is no different. 20C would be overkill, 35C is even more overkill

-Chris

[R_Lefebvre]

IMO, a good rule of thumb is that you should be using at least twice as much battery capacity as a typical acrobatic setup would use.

[delirium_knight]

as in battery capacity are you talking mah or c rating?

[R_Lefebvre]

Capacity as in mAh.

Well, really, Watt-Hours is really what we should be talking about. But nobody seems to be looking at this scientifically.

I think most people's setups are completely off the mark. Way too much voltage, way too high head speed, and not nearly as much battery capacity as they should have. For example, typical Protos 500 battery is what, 6S 3300? For my mapping heli, I'm using 2 4S 5000 20C batteries in parallel, so 4S 10,000. Using the standard motor, head speed is low, and I'm flying for 20+ minutes, even though the AUW with the camera is double the standard Protos weight. 3200g vs. 1700g.

Completely standard, with the only change being a single 4S 5000 battery instead of the 6S 3300, it flew for 17 minutes (with no payload).

My 600 machine, I'm flying with 2S2P 4S 5000 20C batteries. So effectively 8S 10000 mAH. And I'd add another set giving me 15,000 if I needed it.

For an 800, I'd be doing 8S 20,000 to start. And if you didn't need 20,000, then you should be using a 700 anyway, or maybe even 600.

Typically, it seems people aren't operating anywhere near the sweet spot for efficiency.

[thielecg]

Has anyone thought about using four 5000MAH batteries? Two mounted in the frame and two on the boom? I have no experience in this but I run a 700 and and I think if I end up needing extra run time this would be my first experiment.

[R_Lefebvre]

That's basically what I'm doing. But I have 2 on the frame, and two up front.

[thielecg]

Do you see an increase on flight time?

[R_Lefebvre]

Compared to what exactly? I've never really seen people talking about flight time. There are lots of things that affect flight time on a heli.

As it stands now, the typical battery load on a heli is nowhere near the peak for efficiency.

With a double battery setup, I'm getting at least 15 minutes flight time at 1900 RPM with a Nex camera on a 3-axis brushless gimbal. And preliminary testing with reduced rotor speed is showing no vibration, so the flight time will get longer. Anything beyond 15 minutes just seems to be gravy.

This is 16.2lbs AUW. So it's a heavy 600.