Battery Dilemma: Batt Capacity vs Amp Draw Capability

[randomtask]

Hi guys,

I was looking around to get new battery packs and now I am faced in making a decision between getting a battery with a higher capacity which has lower discharge rate and one with a lower capacity but has a higher discharge rate. I'm actually trying to find a suitable battery which will give me the best power and lifespan. If I am not confusing you guys already, let me give an example.

BATT A
2500mah
Discharge rate: 18C
Weight: 2150g (agar-ation )

BATT B
2170mah
Discharge rate: 20C
Weight: 200g (also agar-ation))

SCENARIO
Batts will be subjected to a constant amp draw of 40amps and burts of maybe around 50amps (or less). Flight time: around 6 minutes.

MY EXPERIENCE (thus far)
When I subjected these two types of batteries to the same scenario, I find that I needed to put in more juice to BATT A as compared to BATT B when charging. I fly both batts as aggressively and performance-wise I cannot tell the difference in the air for 3D flying. But I do need to have my throttle abit higher when flying with BATT A (slightly heavier). BATT B on the other hand does not have the same vertical pullout performance as compared to BATT B. I understand for 3D flying, lighter is "usually" better, but 15g difference on the CG won't make much difference right?

So once again, my questions are:
1) Which battery am I actually pushing harder?
2) Which battery should I actually go in the future for the same purposes?

To all the guys who read this, and think I'm talking nonsense , I'm sorry I cannot give back your 2 minutes . Any input from you guys is greatly appreciated.

Thanks,
Adnan

[hoppie]

I am flying pusher with High AMP drawn too. I actually tried the following BAttery config:

- 2100 20C
- 2200 15C
- 2200 25C

With my pusher drawing about 30 to 40A, i feel a difference with the 2200 15C which can only do 33A, not much punch. As for 2200 25C and 2100 20C, the difference is the flight time, 25C is slightly more punchy though.

Think with current drawn down, a higher discharge rate batt will hold the voltage higher at full throttle compared to lower ones. e.g. 3.6V per cell compared to 3.2V per cell, that may make a difference in the power.

Just my 2 cents, correct me if i am wrong.

[fuse]

my 2 cents worth, sinced you want the best of both world, light and power.

go buy yourself a 2200 25c batt.

problem solved

[baby_zyklon]

You have to look at the burst amp draw too. From the numbers you have posted, are you comparing the evo 25 with the evo lite? Their burst c rating are quite different.

[hoppie]

my 2 cents worth, sinced you want the best of both world, light and power.

go buy yourself a 2200 25c batt.

problem solved

I second to that

[simonwoo]

Your batt should have a max discharge right, so even the 18C should be able to give you that burst (provided it's not too long) of 50A. In this case, I would personally go for the lower discharge batt but with higher capacity - it should give you a longer flight time and the WOT should not be that much different since I believe both can boost that 50A, only that like you said it's a bit heavier so probably that's what accounts for the difference only.

On my Flash I use 3 types of batt :

1. 1000mah 20C
2. 1300mah 20C
3. 1500mah 15C

All fly pretty well, although with the 1000mah it does feel more shiok simply because the plane feels so light! But I hate to keep changing batts (and charging is a hassle) after only 6 mins flight. So also like to use the 1500mah one where I can fly for 11 mins or so...

Pros and cons loh...

[edmond22]

Hey Randomtask,

I just share my AJ330 experience with you so you can draw some conclusions.

First started out:

3s1p 2150 FP 20C
flight time: 5mins
wot amp draw: 40ish
Conclusion: Power not bad, pushing 14x7 prop but considered abusing battery and true enough lasted about 50 cycles only

Second setup:

3s1p 2170 FP25C
Flight time: 5mins
wot amp draw: 40ish slightly higher than above
Conclusion: Feels more punchy, battery is cooler, lasted well about 100 cycles

Third setup:

4s1p 2170 FP25c
Flight time: 5mins
WOT amp draw: 55amp! on a cc45 phoenix (with no issue lol)
Conclusion: A rocket already, batter is even cooler as less throttle needed to fly around using 13x6.5 prop, lasted well about 80 cycles

fourth setup:

4s1p 2500 FP25c
Flight time: 6mins (conservative)
WOT amp draw: 57 amp! still on cc45 no issues
Conclusion: Still a rocket like above despite weight increase. Battery is even coolest of all mentioned setup. Still same flight performance. Less throttle needed, more fun. Given the heat after flight, think can easily last of 100 cycles. Did not get to that number, AJ given away, now slightly bigger plane.


If you ask me if I were to do it all over again. I will gladly take the last choice and yet that is not the recommended size at first from the plane designers. The weight was never an issue for me. So if you can, try to get a bigger capacity without too much weight increase (though you can see from example above from 3s1p 2150 to 4s1p 2500 quite considerable diff) and always always take the most c rating your money can buy. If you are into 3D, give your plane the fuel to fly 3D. Dun haggle on that, power makes things easier to do, too often flyers of the similarly sized plane asked me how I do this and that so effortlessly, 50% of that confidence comes from the power at hand really, any mistake just a slight blip on the throttle to correct it vs full wot and panic recovery.