bigger lipos for belt cp?

[niteflyer]

greetings! currently im havin the 3cell1800amh pack.im juz wondering whether how long should the flight tome be with that capacity?so far ive only managed a meagre duration of under 10mins.hovering only!should i get a bigger lipo pack?or is there an esc malfunction?pls advise

[damyxz]

An 1800mAh lipo should give you about 5-6 min on a stock belt CP heli, just hovering around. To get longer flight time, get a 2100 or a 2200 mAH pack.

[dumbass]

OK, so I know that the 11.1 is the voltage of the bat. but what is the 1800 mah and 20c? I have seen 11.1 v x hgher mah and higher/lower c (10c, 15c, 20c and 25c). But they were all 11.1 volt bats. Can I use a 11.1 v 2200 mah 15c or 25c bat.?

[JustPlaneChris]

Battery analogy 101:

The mah (milliamp-hour) rating is the "size of the gas tank". The c-rating is the "size of the fuel line", which determines the rate at which "fuel" can flow out of the "tank". For example, a 10c 2200 mah pack will be able to provide 22 amps of current (2.2ah x 10). But a 10c 1800 mah pack can only provide 18 amps of current. What c-rating you choose depends on how much current your motor can pull. You always want "overhead" when you choose your battery (and ESC) so it doesn't have to work at its rated capacity all the time. Forcing it to do so will dramatically shorten its useful life.

[dumbass]

Great explanation....(Battery analogy 101) however, it brings up another question. Using your calculation a standard Belt CP would be 1.8*20c=36 amps of current flow. I have read several postings recommending upgrading to a 2100 or 2200 bat. to increase flight time. Of course doing this makes it impossible to maintain the standard 36 amps of current. Examples; 2.2*10c=22 amps, 2.2*15c=33 amps, 2.2*20c=44 amps 2.2*25c=55 amps. and so on. So what are the real limitations if using the standard ESC? Can I install say a 2200 x 25c? I would thing that it would be important to maintain the 20c. Is this correct?


Here's another curious question, has anyone tried using 2 standard 1800x20c batteries simultaneously? If connected together in parallel it should equal a bat. Size of 3600x20c. Of course it would add a lot of weight to the heli. but then so would any larger battery.

[JustPlaneChris]

Originally Posted by dumbass

Great explanation....(Battery analogy 101) however, it brings up another question. Using your calculation a standard Belt CP would be 1.8*20c=36 amps of current flow. I have read several postings recommending upgrading to a 2100 or 2200 bat. to increase flight time. Of course doing this makes it impossible to maintain the standard 36 amps of current.

Nope, you've got it kinda mixed up. Just because you are using a 20c 1800 pack, that does not mean your Belt CP is drawing 36 amps. Look at it this way: Installing a different size gas tank in your automobile does not change the amount of horsepower your engine makes, or the amount of fuel it consumes. You are only changing the amount of time you can drive it without refueling. Along those lines, using a higher c-rating won't make your engine burn more fuel. It just gives it the ability to (bigger fuel line, more flow) should you ever install "hotrod parts". Make sense?

[dumbass]

Chris,


Yeah, your explaining it exactly the way I am thinking of it. Unfortunately, I do not know what the amperage draw of the stock 450 motor is. Because they supply a 20c with the bird shouldn't I stay with a 20c to ensure the needed flow rate? Or can a less expensive battery (15c) be used without sacrificing motor power?


Would you agree as crazy as it sounds (baring the big weight problem) 2 - 1800x20c batteries could actually work? The only reason I keep asking this is because a 2200x20c bat .only offers 22% more flight time over the standard motor.

And by the way thanks for all your help. Bob

[JustPlaneChris]

If your CG works out ok with 2 1800's in parallel, sure... it'll work. Keep in mind that a 20c 1800 (capable of 36 amp output) could be safely replaced with a 15c 2200 (capable of 33 amp output.... almost the same). It is highly unlikely that your Belt CP is drawing more than 25 amps at full power/pitch. Average current draw is probably 10-12 amps while hovering, based on my experience with similar size helis.

[psilo]

Don't forget the Esky ESC is only rated at 25A so you are not pulling more than that. Therefore a 2000 Mah 15C would do the job fine, however I tend to stick to the 20C personally and have a selection of 2250May 25C and 2100Mah 20C batteries for use on my belt.

[JustPlaneChris]

Originally Posted by psilo

Don't forget the Esky ESC is only rated at 25A so you are not pulling more than that.

Not for long anyway.