Battery size question

[sresener]

I can get some gens ace 4000mah 30c packs quite cheap, Will these work with the x7 or should I just stick with my 5000mah 40c's

[Chris Sexton]

Check the weight. Other than the obvious shorter flight times, 4000s might be too light for CoG. My Hyperion 4200a were all the way forward in the mounts and I was still tail heavy a few grams.


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[sresener]

What is the best way to check cog on a fbl heli.

[beeflyer2]

Hold the headblock/grips and turn the machine up so the main shaft is horizontal. The boom will hold level when balanced.

[sresener]

So turn the heli sideways and see if the boom turns up or down.

This may sound like another dumb question, but how does it effect sport and 3d flying if your CoG is out.

[Chris Sexton]

Gravity is going to fight you. More present in a hover but will mess with flight and aerobatics.


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[ragtop01]

im running the 4000's tons of pop and its pretty light. i get 4:20 per pack.

[kenlanham]

I was just about to make a post about my 4000mAh Gens Ace batteries. I have the 25C versions. I'm very new to the X7 and 700 size helicopters altogether, but I had some strange issues with the Gens Ace batteries today.

I also have a set of 35C 5000mAh Nanotechs that I flew side by side with the GensAces.

I had the motor cut out on me twice while running the smaller packs today. I can only assume that I pulled enough current to pull the voltage down to the low voltage cutoff. After a moderate vertical climbout for about 1-2 seconds the motor just died. I was autoing unexpectedly. Luckily the motor came back alive about 50 feet above the ground.

I I didn't have this problem with the bigger and higher C rating Nanotechs.

I'm running 1900 rpm on the 10t pinion and the HKIII-500 motor. I thought I was playing it safe and trying to get some longer flight times. I was shocked to have a problem like this on the first day of flying. I went through my Castle ESC settings and I didn't see anything odd. I have not made up my mind about the 4000 size batteries yet.

[Levitbe]

What motor? If ur using a big motor u need at least 5000. My motor starts to cut out when my 5000s reach about 30-35% - when i fly it hard

[kenlanham]

I'm running the "stock" 4035-500.

I'd think another pair of 5000-5300 batteries are in my future.

[frito169]

Its not the mah causing the issue its your c rating. Get at least 45/90 c batteries and youll be happy, no motor cutting out.

[Matt Nasca]

What Frito said, and/or lower your LVC in your ESC. When the voltage sags under load, it can go to LVC and shut down. I keep my LVC at 3V/cell and use a timer.

[kenlanham]

That sounds like a nice strategy and I did drop my LVC to 3.1 volts after that event hoping that I could still make use of these battery packs for a while. Maybe I'll go to 3.0 volts per cell. I haven't tried to fly again since then. These 25C Gens Ace packs were supposed to be pretty robust and closer to a true 25C discharge capability than some companies inflated C ratings. But really, at 4000mAH and 25C, thats only 100A continuous dicharge. They were a good size for my 550 size heli, but now its Welcome to the big leagues I guess.

Anyways, I was just trying to give some feedback on the 4000 size Gens Ace since that was the original question. They are good quality batteries, but that size and C rating just isn't going to cut it in the X7. There are some new 60C Gens Ace that look promising though.

[Rob Cherry]

Originally Posted by Matt Nasca

What Frito said, and/or lower your LVC in your ESC. When the voltage sags under load, it can go to LVC and shut down. I keep my LVC at 3V/cell and use a timer.

Agreed! Although 45c isn't necessary, the Gens 25C 4000's just can't deliver the needed power, they aren't up to the task (and shouldn't be expected to). I have them and tried, I only run them at lower rpm, with less pitch. The Gens 30C 5300's are perfectly capable of hard 3D for 3.5 minutes, mine put out 150+ amps without breaking a sweat.

4000 @ 25C is 100 amps.
5300 @ 30C is 160 amps, that's 60% more potential, no comparison.

Voltz 5100 @ 65C is 331 amps.