Hi guys
I couldn't quite work out whether this should have been in the wings section, the batteries one, or motors- so I stuck it in general hope that's ok :)
I run a 60" zeph style wing and it's a beauty. She carries 2x 4000 4s and has good range. I'm about to stock up on a few spare batteries for her- and it has crossed my mind to move up to 6s.
Why? Well the 6s batteries are 30% cheaper for the same energy content
4000mah 4s * 16V = 64W of energy
64W /24V = 2666mah
I can buy 2700mah 6s for 30% less than the 4s 4000s and they are much the same size.
Are motors rated purely for specified cells? Or is it all down to the total wattage?
My 3820 1200kv is quoted as being a 3-4s motor- will running it on 6s damage it? I will downscale the prop appropriately of course! The OS spec quote it can handle 60A which is >1000W with a 4s and a 9x6 prop.m
I'm hoping with a parallel setup of 2* 6s 2700mah I will have crazy high punch if needed and a cruise speed with about 10% throttle :) Nice small 6-7" prop too instead of the 9-10" I use atm.
Am I missing something? Will the bigger cell setup be less efficient? I want the option of mental speed but also the ability for it to sip 8-10A and cruise around for a while.
Any advice would be great thanks :)
Quote from: Billy_boy_2010 on March 06, 2015, 06:03:21 PM
Why? Well the 6s batteries are 30% cheaper for the same energy content
4000mah 4s * 16V = 64W of energy
64W /24V = 2666mah
Hopefully someone will contribute something more helpful but there is an issue with your calculations in that you have mistaken mAh for mA. mAh is already a unit of charge stored or 'energy content' if you like where as mA is a unit of current. The formula I assume you were thinking of is P=IV.
Perhaps look at ecalc or similar to work out good motor/prop combinations
Ah yes I was thinking of P =IV
I was trying to calculate the total amount of stored energy in the batteries- hopefully it's still comparable even if my units are wrong?
Oh- I did check on ecalc a couple of days ago and it came back with an error saying my calculations were unrealistic. It was happy with a 9x6 on 4s but the moment I give it 6s even with a tiny prop it came up with an error. I have just tried again in case the website was having a moment but it can't find my motor now?! Anyway I tried all sorts of props on 6s and it wasn't liking it. Makes me think the voltage limit on a motor is pretty strict and this is a non starter unless I change my motor and I don't want to spend £££ on a new motor my OS is great.
If you want to go 6s for more efficiency then you'll need a lower kv motor and a larger prop. Small fast spinning props aren't efficient.
Ah right thanks Brucey- I suppose that's quite obvious really given how quick my skyfun guzzles the juice with its 6" prop.
I figured it would be quite efficient still as it was a fairly low kv motor (rather than a 2200kv on the skyfun)- but if I'm increasing the voltage the rpm will increase and it becomes less efficient.
Feel a bit of a fool now :D
I suppose I still could do it- but it would mean pigeon-holing the Zephyr to a huge screamer with 10 min battery life with the original motor and a 7-8" prop- or buying a 500kv motor and running a big prop for real efficiency- which would make the Zephyr pretty dull for anything other than really efficient flights and perhaps the torque from a 6s 13" prop would cause issues even for a big wing?!
I'm going to leave it as it is- I quite like it having a bit of a dual personality.