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Is a higher C battery worth it?

#3
Nice!

I know higher C makes a huge difference with EDFs; I flew my Viggen with a 2200mah 35C versus a 50-60c, and it made a world of difference.
Great video Nic!
 
#4
Good job Nic, although I already knew the answer i like facts. Now if we can just get the manufacturers to tell us the truth on their batteries. Side note, don't buy into the current Lithium Ion battery hype you might be seeing around, those just don't have the ability to give the amps most of us need currently.
 
#5
I would agree that batteries in the smaller sizes (in the sub 1800ma range) the higher C-ratings maybe worth the extra money.

However if you are getting above 1800ma in 3-cell batteries, you have to run the numbers.
Paying for more than 35-C in these larger sizes may not be worth it.

A 2200ma 35-C Zippy battery is about 2.66 oz. heavier than your 1000ma 65-C Graphene.
But...if the math holds true, it will provide the equavilancy of 77-C in a 1000ma size battery.

If you want more pizzaz at these 1800ma and larger sizes...paying for higher C is not going to get the desired results that you see at the 1000ma size.
In these cases you need to go from "3-cell" 35-C 2200ma battery...to a "4-cell" 35-C 2200 battery.

But for smaller battery sizes in super-fast planes and quads...it's definately worth paying for higher C-ratings.
 
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PsyBorg

Fly Angry
Mentor
#6
I have to agree the higher c batteries are worth it no matter what size. I got two 3s 20c 2200mah batteries when I started on my runner 250. When I built the Versa Copter I got two 3s 25c 2200mah Floureon batteries for the price of one of the walkera batteries. There was a noticeable difference between the two specially when I started doing flips and rolls. The sag on the Walkera batteries was horrendous and I ended up draining them and getting rid of them because they started to swell more each week. The 25c batteries had decent punch for the first minute or two but then you could feel it drop off quickly after that. I imagine if I had 35c or higher they would never sag the time limit I flew the Versa Copter.

Once I swapped over to 4s grahene batteries I had to change my timers as I was running the pack flat before noticing any change at all. Even the 35c 4s batteries I got for my airplane ran the whole allotted time before any noticeable change right before the beeper went off.

Like anything I guess the amount you spend on batteries will greatly effect performance other then just by their ratings. Buying a Tattu or a Lumenier graphene battery vs. Joe's bargain basement battery of the same rating will also prove different I am sure.
 
#7
Nice job Nic. Your data proves that higher C rating equals lower internal resistance. Lower internal resistance means less voltage drop in the cell and more power to the motor. Generally speaking, the higher C rated batteries have heavier plates (conductors) and therefore lower IR (internal resistance). The difference in IR is small but power is current squared times resistance so there is 56 watts more power being dropped across the 35C pack than across the 65C. That's significant.

Very well done video! Thanks.

Mike
 

nerdnic

nerdnic.com
Mentor
#8
I would agree that batteries in the smaller sizes (in the sub 1800ma range) the higher C-ratings maybe worth the extra money.

However if you are getting above 1800ma in 3-cell batteries, you have to run the numbers.
Paying for more than 35-C in these larger sizes may not be worth it.

A 2200ma 35-C Zippy battery is about 2.66 oz. heavier than your 1000ma 65-C Graphene.
But...if the math holds true, it will provide the equavilancy of 77-C in a 1000ma size battery.

If you want more pizzaz at these 1800ma and larger sizes...paying for higher C is not going to get the desired results that you see at the 1000ma size.
In these cases you need to go from "3-cell" 35-C 2200ma battery...to a "4-cell" 35-C 2200 battery.

But for smaller battery sizes in super-fast planes and quads...it's definately worth paying for higher C-ratings.
I think the needed mah size really depends on the load. I have 2200 and 3300mah 4s batteries in 20-60c ranges, the higher C definitely still makes a difference when your load is 80a.
 

nerdnic

nerdnic.com
Mentor
#9
Nice job Nic. Your data proves that higher C rating equals lower internal resistance. Lower internal resistance means less voltage drop in the cell and more power to the motor. Generally speaking, the higher C rated batteries have heavier plates (conductors) and therefore lower IR (internal resistance). The difference in IR is small but power is current squared times resistance so there is 56 watts more power being dropped across the 35C pack than across the 65C. That's significant.

Very well done video! Thanks.

Mike
Knowing the batteries IR up front would be really nice huh? :)
 
#10
Some chargers measure IR but I question their accuracy. Here's a video explaining how its done manually. Also, the on resistance of the ESC can make a big difference too. That's the one thing I don't like about the EMax ESC's. They seem to have higher "on" resistance and therefore run hotter and lossier.

Mike
 
#11
Great article and quite informative. I think you did a great job explaining that it's a balance. If I don't need the current (smaller plane, or if I fly it more "scale"), I go lower C rating for weight and cost savings. My 40C batteries are much heavier than my 25C batteries of the same mah. I am anxious to try out one of those graphene batteries though.

sconner
 
#12
This subject is extremely important to me right now. I recently arranged some battery samples from a manufacturer & my calculations led me to order a battery with a relatively low C rating.

As it is a 6S battery with as low as 6000mAh but as high as 6500mAh, a 10C battery would comfortably deliver a peak of 60-65A to my motors. Collectively, my motors will only pull a max of 45A. That is close to 30% extra power.

My application is a slow flyer & any extra minutes would be precious. It's use would never include acrobatics or really anything fast.

From this thread I think it would be safe to assume that though a higher C value means more on-demand power, there would be diminishing returns in larger (or all) batteries due to more mass from thicker conductors that deliver that extra power.

Greater power doesn't mean greater efficiency.

Am I barking up the right tree?

megabotz
 

PsyBorg

Fly Angry
Mentor
#13
I don't know.. efficiency is all dictated by throttle management IMHO. I can run a 1300 75c battery dry in under 4 minutes of hard flight, I can take that same battery and easily get over 10 minutes with moderate flight and if I really milk the throttle I can get over 12 in the air.

Add in properly tuned gear specifically set up for extended flights and you can do pretty well.

What the advantage of higher C rating would be in that case is the likely hood of sag nearing the end of flights becoming a problem like on low C batteries that go pfft really fast at the end of flights.
 
#14
I think it would be safe to say that this thread is really dedicated to C rating of batteries in racing type multirotors.

For an example, let's take out the human element. Let's assume that the ship in question is being controlled by autopilot. All the same variables, just different batteries.

My position is that if you fly slowly (not racing) from point A to point B, the ship with the lighter battery (but same capacity) is going to fly further. If this isn't true, I missed the battery class entirely.

The conclusion I draw is that the higher C rating is proper if you need power in huge surges but if you are designing something that isn't meant to tear around corners at breakneck speeds, you are adding weight unnecessarily.

If you haven't guessed, I am not designing a racing quad.

megabotz
 

nerdnic

nerdnic.com
Mentor
#15
This subject is extremely important to me right now. I recently arranged some battery samples from a manufacturer & my calculations led me to order a battery with a relatively low C rating.

As it is a 6S battery with as low as 6000mAh but as high as 6500mAh, a 10C battery would comfortably deliver a peak of 60-65A to my motors. Collectively, my motors will only pull a max of 45A. That is close to 30% extra power.

My application is a slow flyer & any extra minutes would be precious. It's use would never include acrobatics or really anything fast.

From this thread I think it would be safe to assume that though a higher C value means more on-demand power, there would be diminishing returns in larger (or all) batteries due to more mass from thicker conductors that deliver that extra power.

Greater power doesn't mean greater efficiency.

Am I barking up the right tree?

megabotz
This will be case by case but yes, the extra weight can possibly have negative effects.
 

nerdnic

nerdnic.com
Mentor
#16
I think it would be safe to say that this thread is really dedicated to C rating of batteries in racing type multirotors.

For an example, let's take out the human element. Let's assume that the ship in question is being controlled by autopilot. All the same variables, just different batteries.

My position is that if you fly slowly (not racing) from point A to point B, the ship with the lighter battery (but same capacity) is going to fly further. If this isn't true, I missed the battery class entirely.

The conclusion I draw is that the higher C rating is proper if you need power in huge surges but if you are designing something that isn't meant to tear around corners at breakneck speeds, you are adding weight unnecessarily.

If you haven't guessed, I am not designing a racing quad.

megabotz
I've never flown a multi so I don't know if that is true :)

For a lighter pack, based on how lipo technology works, you're looking at less C (however you want to measure it). I agree that the punch might not be needed so lower C is fine. However the lower C battery will also sag more toward the end of the pack and eventually to the point of having to land. The higher C battery will hold voltage longer and in theory give the higher C more 'usable' mah.

I'm working on some tests to show this in real life situations.
 
#18
My limited experience with the Graphenes is the following:
A 3000mAh 15C 3S graphene has a flatter discharge curve than a Nanotech 2200mAh 35-70C 3S.
It also weights about 30gr more and has (on paper) 800mAh more capacity than the Nanotech.
According to test, the Graphene give about 20C in real test and the Nanotech about 26C, more or less make them equal in max Amps.
I can attest that when I use them on my 260 quad I can feel the better punch-out from the Graphene when I'm low on energy.
But on my planes I'm not even close to using 30A so there I only can use the higher capacity.
 

nerdnic

nerdnic.com
Mentor
#19
After using Graphene lipos for a few years, I've now decided to not purchase them anymore. I don't know if I got a few bad batches or what, but nearly all of my Graphenes have had a failed cell crop up.

For my performance batteries, I've been sticking to Turnigy Heavy Duty 60c lipos. They have the power I need and seem to hold up better over time.

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