upgrade from 2200mAh 11.1 30 c

[doctormike]

After all these years of flying, I'm unclear on this... To upgrade from an 2200mAh 11.1 30c battery, which would be best... an 2200mAh 11.1 45c or an 2400mAh 11.1 30c? Which one will do what for me? Thanks, Doc

[Konrad]

RE: upgrade from 2200mAh 11.1 30 c

"C" Rating is not a real rating. With that out of the way, what it is trying to show is what is the maximum current (amps) you can safely draw out of the cells. So 2.200Ah x 45 = 99 amps max draw, 2.4Ah x 30 =72 amps max draw.

Generally the higher the 'C' rating the heavier the cell, also the internal resistance is lower allowing for more voltage to drop across the motor/ESC rather than the cell themselves. (Look up voltage divider network). This means that while both batteries are rated at the same voltage, under load the higher 'C' rated cells will deliver the same amps but at a higher voltage (your motor prop with spin faster with the 45C rated cell [it will also draw a bit more current]). And last the higher C rating usually costs more.

With what little information given 2400 mAh 30C battery will give you about 8% longer run time. The 2200 45C mAh battery will handle higher amp draw, good for higher performance set ups. At lower current draw the 2200mAh 45C cells should have a longer life than the 2400 30C mAh battery for any given current within the 2400's amp rating.

The 2200 45C will give you more power as a result of the lower internal resistance (impedance)
The 2400 30C will give you more energy as a result of its higher capacity

All the best,
Konrad

[doctormike]

RE: upgrade from 2200mAh 11.1 30 c

"C" Rating is not a real rating. With that out of the way what it is trying to show is what is the maximum current (amps) you can safely draw out of the cells. So 2.200Ah x 45 = 99 amps max draw, 2.4Ah x 30 =72 amps max draw.

Generally the higher the 'C' rating the heavier the cell, also the internal resistance is lower allowing for more voltage to drop across the motor/ESC rather than the cell themselves. (Look up voltage divider network). This means that while both batteries are rated at the same voltage, under load the higher 'C' rated cells with deliver the same amps but at a higher voltage (your motor prop with spin faster with the  45C rated cell [it will also draw a bit more current]). And last the higher C rating usually costs more.

With what little information given 2400 mAh 30C battery will give you about 8% longer run time. The 2200 45C mAh battery will handle higher amp draw, good for higher performance set ups. At lower current draw the cells should have a longer life than the 2400 30C mAh battery for any given current within the 2400's amp rating.

The 2200 45C will give you more power as a result of the lower internal resistance (impedance)
The 2400 30C will give you more energy as a result of its higher capacity

All the best,
Konrad

 Thanks, Konrad. I get it now! Doc

[Konrad]

RE: upgrade from 2200mAh 11.1 30 c

So which way are you going to go?

[doctormike]

RE: upgrade from 2200mAh 11.1 30 c

So which way are you going to go?

I'm going with the 2200 45c. This is for aerobatics. I'm not too concerned about flight time. I'm looking at the RocHobby MXS 3D plane, pretty seriously. Thanks, Doc

[Konrad]

RE: upgrade from 2200mAh 11.1 30 c

I too used a 2250 45C 4 cell battery for some of my 50 inch 3D ships pulling 46 to 48 amps with an APC 14x7. Other than the need for nose weight from the heavy 45C 258 grams battery they all would have flown better with the lighter battery.  So if not needing the current draw I would recommend the lighter of the two batteries. These 45C batteries were great for 64mm 70mm EDF models. But in lower amp draw set ups the 25 or 30 C rated batteries are often best.


In the 50 inch aerobatic/3D class of model, little beats the ply and balsa model. Not all Ply and balsa models are suitable.
http://rctruth.com/index.php?topic=1374.0

But the Edge 540 from Extreme Flight and Precision Aerobatics  are at the top of their class and well worth the price particularly if trying 3D for the first time. Actually I like some of the foam profile models if first starting out with aerobatic/3D models.
http://extremeflightrc.com/48-Edge-540-Blue_p_667.html


Please note that the Dynam, Freewing and FMS are not in the above mentioned class for ether flying characteristics or final price. 

While I understand the desire to try to fly 3D I actually think mastering precision aerobatic first is preferable.
These are some of the best models, no scale compromises just flight performance!
http://extremeflightrc.com/48-Vanquish-MKII_p_274.html
http://www.motionrc.com/fms-f3a-expl...-wingspan-pnp/


All the best,
Konrad

[Konrad]

RE: upgrade from 2200mAh 11.1 30 c

Disregard much of the above post. I messed up the math. I thought you were talking about 4 cell ships I see that you are looking into 3 cell models.

Looking at the Rcinformer video, I just might need a one of those 3 cell MXS models myself.

[doctormike]

RE: upgrade from 2200mAh 11.1 30 c

I own several Great Planes and FMS planes requiring 4 s batteries. I could not care less about 3D flying. This RocHobby MXS looks like it could handle any SCALE aerobatic maneuver one might throw at it, however. I think I could get it into a Lomy and flat inverted spin, easily. I really don't understand the facination with 3D flying. Whatever turns you on, I guess. I certainly appreciate your info! Doc

[fhhuber]

RE: upgrade from 2200mAh 11.1 30 c

I fly some extreme aircraft... 5000 watt (appx 6.2 hp) EDF conversion of what is supposed to be a 1.20 glow (appx 2.0 hp) pusher for example...

I find little performance increase with higher than 20C rated packs. I get mostly 20C rated because they deliver plenty of power. (Even for the big EDF which can drain a 12S 5000 mah pack set in under 3 minutes)

It wasn't that long ago that 20C was considered a premium LiPo and we were mostly running 8C to 12C packs.

You aren't going to see significant performance difference in the average model due to C rating, because 20C is now the lowest you are likely to find in RC hobby LiPos. There are some contest and record setting applications where the marginal performance increase due to higher C rating (lower pack internal resistance) could give a slight edge.

The big EDF model on 12S 5000 mah 20C hit 119 mph. (Eagletree logger pitot tube) on 30C it hit 120.

And then there's the labeled pack capacity vs what you can actually use, which varies significantly from one battery brand to another more than with C rating within one brand.

[WintrSol]

RE: upgrade from 2200mAh 11.1 30 c

You aren't going to see significant performance difference in the average model due to C rating, because 20C is now the lowest you are likely to find in RC hobby LiPos.  There are some contest and record setting applications where the marginal performance increase due to higher C rating (lower pack internal resistance) could give a slight edge.

There is one other time you may notice a difference with a (true) higher C pack, and that's when you are near the end of a flight, and need a short burst of power. The high C battery will likely give it to you (if you aren't too near LVC), while the lower C battery may just go flat.

[Konrad]

RE: upgrade from 2200mAh 11.1 30 c

...
The 2200 45C will give you more power as a result of the lower internal resistance (impedance)
The 2400 30C will give you more energy as a result of its higher capacity

All the best,
Konrad

Does anybody have an issue with what was posted in the above quote? I hear the term "not much difference" while I agree that in sport applications this is true. I also know that in performance application these differences become glaringly obvious. Even the NMPRA EF1 pylon class of racers even show this, with their low current daw (between 40 to 50 amps). Now the F5D racers are ridiculously hard on cells so any reduction in the internal resistance is easy to note. (I haven't flown FAI F5D in about 8 years, don't know the current current draws)

I too don't fly 3D much, I prefer precision aerobatics. I'm just old school that way.

Pusher glow ducted fan, that would point to Byron jets. Very nice entry level sport jets that actually flew well a 6k feet. We were limited to about 22k rpm with the glow 60/90 on pipe making over 3+hp. Most sport 1.20 cid make 2.1 HP. EDF has given these old glow kits new and sparkling life as we can now spin many of these rotors a 30K+ rpm.

I remember (mid90's) 5C Discharge as being high performance cells! The basic cells were 3C discharge

All the best,
Konrad