BEC's and Discharge rates.... PLEASE HELP!!!!

[4x4Jay]

OK, so I have a Zagi-33, It came with a 2100mah 25C 3S Thunder Power RC lipo. It also has a 3300kV outrunner motor powered by a 40C BEC.

My question is, can I use a lipo rated at 40C with 50C bursts, with this setup?
If the motor is only really constantly pulling say 25-30C, will that damage the larger C rated pack? Or is it more like, the battery can handle 1C-40C constantly, with 50C burst?

I guess I'm really wondering if I can run a 40C constant with a 50C burst rating, on a BEC that is rated at 40C max.

I feel like this is a rookie question, but I would rather know now, vs when this thing is up in the air and it turns into a fireball.

[k7zpj]

Read this link if you haven't already done so.
Understanding RC LiPo Batteries

The Zagi-33 ESC is rated at 40A cont/45 burst but the motor isn't going to draw anything like that so the battery you have will be fine.

I would check out some of the forums with people experienced flying the Zagi-33. You will get a lot more responses there. Also find someone local to help you learn to fly it if possible. I would also consider joining the AMA Academy of Model Aeronautics

Be careful with the rotating prop. A trip to the ER will buy a whole wheelbarrow load of VP parts.

[JokersWild]

^^^^^^ x eleventy billion! I got things that go up too

[Trubble]

Originally Posted by 4x4Jay

OK, so I have a Zagi-33,

Interesting.
I started with a Commanche coaxial 'copter, hated it couldn't ever get it under control. Now have a Blade Nano QX quad-copter, love it.

It came with a 2100mah 25C 3S Thunder Power RC lipo. It also has a 3300kV outrunner motor powered by a 40C BEC.

You mean a 40 amp ESC?
BTW, your 2100 mAh battery (times 25c) should be okay for 52.5 amps. Your current battery isn't having problems now, is it? Then putting batteries in that have more capability than the rest of the system shouldn't be a problem, (as that's what you're already doing now). At 2100mAh, stay above 20c, at 1800mAh, stay at 25c or above. But there's no problem with running more. I personally like having more battery then I really need, but I can get away with that in ground-pounders. In flight, because of weight, I don't usually go nearly as overkill.

My question is, can I use a lipo rated at 40C with 50C bursts, with this setup?

Provided they're 1,000mAh or more, sure.

If the motor is only really constantly pulling say 25-30C (amps?), will that damage the larger C rated pack? Or is it more like, the battery can handle 1C-40C constantly, with 50C burst?
I guess I'm really wondering if I can run a 40C constant with a 50C burst rating, on a BEC (ESC?) that is rated at 40C (amps?) max.

Is your motor actually pulling 40 amps, though? Lesser amp draw motors run just fine on bigger ESCs than they need, FYI.
And in an aggressive vertical climb, is your motor temporarily exceeding 40 amp by a little bit? Until you install something like a Watts-Up meter (or similar), we can't really be certain. So be careful how much absolute and blind faith you put in those numbers.

I feel like this is a rookie question, but I would rather know now, vs when this thing is up in the air and it turns into a fireball.

You're getting your terminology mixed up, this could lead to problems for you down the road. Might also want to be careful how much faith you put in those C numbers. I cringe when I see people banking on those 'burst' numbers.

[Calderwood]

Trubble hit the nail on the head.

You are mixing up C and A ratings. While they both describe current, they are not interchangeable. A stands for amps. C also describes amps but can't be used as a stand alone number. You must also know the capacity of the pack to convert C to A. For instance a 2000mah 30c pack is capable of delivering 60A. It goes like this, 2000mah = 2ah. 2ah x 30c = 60a.

Remember that the motor draws current. Having more current available from the battery than the motor needs keeps the packs healthy. They can't force current to a motor that isn't drawing it. The ESC must be rated to at least what the motor can draw. Again, it won't force current to the motor. It only provides what the motor is drawing. So a motor that draws 30a should be paired with an ESC that's rated to at least 30a, a little room for safety is good so a 40a ESC is a good match for a 30a motor. The battery must be able to provide the 30a to the motor but again its not healthy to require the pack to discharge at maximum capacity so a battery that can provide 40a or more would be a good choice for a 30a rated motor.

I fly too. Although I fly planes and not copters, my planes spend most of their time in high alpha or hovering so I guess they get used a lot like a copter.

[4x4Jay]

Originally Posted by Trubble

You're getting your terminology mixed up, this could lead to problems for you down the road. Might also want to be careful how much faith you put in those C numbers. I cringe when I see people banking on those 'burst' numbers.

Yeah, as I look over it again, I did mean to say amps when talking about the draw from the motor. But you just confirmed what I was thinking. Thanks!!!

I fly heli well, and this plane was a gift from my GF. I'm going to be taking it to burning man this year. I have been flying for many years, so I have experience with the aircraft. I'm just new to Lipo's. It's been all nitro, or Nimh stick packs for me.

Thanks for all of this info everyone! I'll be sure to post the videos I capture from the flights!