What to do? Switching from 4S to 6S

[Bartman]

Moving along with the evolution of my kopters, I'm considering switching out to 6 cell lipo packs. The Turnigy Plush 40A ESC's that I have are compatible with 6S packs but do I necessarily have to switch motors to a lower KV? I'd guess no but by not switching motors I'd expect to have my heli hover at a lower position on the stick. Maybe keep the same KV but switch to smaller props and let them run at a higher rpm?

Any input on this?

 

[DucktileMedia]

I was always confused by this as well. with smaller helis I think you spin a smaller prop faster but on your average to large heli I think the idea is to spin a larger prop with lower KV motors. I would think it all works out to be the same but everyone I know uses 15" or 16" props on their 6s setups. Ill be curious to hear what people have to say on this. I've been contemplating going to pancake motors and doing the same. I think there is a timing issue though. Denny keeps bringing this up but I dont know exactly what to watch for. Something about the amount of poles.

make sure you use a bec for your vtx if you are running it straight from the main packs.

 

[Bartman]

the trick is to use lower KV motors because kv and torque are inversely related and having high torque (and therefore low KV) allows the FC to make the control inputs for control more easily and more instantaneously.
the pancake motors are a nice idea to put the props closer to the mounts thereby lowers the amount of wobble at the prop (less efect of motor's runout) and reduce vibration. there are probably other factors but i'm a mechanical type of guy so that's what i see first.

my mount and vtx are on a separate switched battery/circuit so no problems there. will probably try yeehawnow's idea of pulling 3S power through the balancing taps to power the FC.

bart

 

[DucktileMedia]

Pulling power fromt he balance taps sounds risky. Im sure the wire can handle the current but who knows how well those wires are attached in there. Clever though.

I like the pancakes because they are all lower kv motors. I would like to spin the 14" apc's reliably. I think on 5 or 6s that might be a magic setup. As nice as the Xoars are, the Apc's have worked really well for me and are cheap and easy to get anywhere anytime.

 

[Bartman]

Pulling power fromt he balance taps sounds risky. Im sure the wire can handle the current but who knows how well those wires are attached in there. Clever though.

i plan to wire a harness so both batteries will supply 4s power in parallel to the FC. should be ok if one connection is iffy although a bad connection should show up during charging/balancing.

http://epbuddy.com/index.php?main_page=product_info&cPath=26_14&products_id=205

 

[yeehaanow]

Are your motors actually rated for 6s? Most of the higher kv motors go up to only 4s or 5s. Tabb told me even though the freefly motors are rated to handle 6s, it wouldn't be a good match.
I'm using the 400 kv tiger's and CC ice esc's with apc 14X4.7 props on a CS6 and couldn't be happier. Everything runs cool and it has plenty of power and flight time.
The only problem is that tricky little FC powering issue. Haven't been brave enough to try my idea yet.

 

[kloner]

why wouldn't you just use a bec that does 6s?
http://www.castlecreations.com/products/ccbec.html

the motor thing would be important to prop so the max watts the motor is rated for doesn't go over. amps times volts...... theres no capacitor or anything to grenade except overloading a motor into submission from making too many watts from too big of props, burns em like a fuse. usually when a motor gets a volt rating like 4s, 6s, whatever, it is a recomendation for the marketed application. not necesarily a engineering problem...... ie, this motor is made for 12s in this heli or this is the 8s motor for that heli, etc. it's to achieve a desired head speed in this case rpm while it's lifting and the props that'll do that if are even available then how that handles carrying the load you want to fly.

the general rule is lower kv and bigger props make more torque, faster spinning smaller props make more hp, they slow less with a load

don't have any specifics for your gig, but that's basic brushless motors as i have been using them with no problems. I fly 3s motors on 4s, have been forever. my helis are all weird custom built electric conversions, they all have a different motor than what is marketed to them

 

[Bartman]

Are your motors actually rated for 6s? Most of the higher kv motors go up to only 4s or 5s. Tabb told me even though the freefly motors are rated to handle 6s, it wouldn't be a good match.
I'm using the 400 kv tiger's and CC ice esc's with apc 14X4.7 props on a CS6 and couldn't be happier. Everything runs cool and it has plenty of power and flight time.
The only problem is that tricky little FC powering issue. Haven't been brave enough to try my idea yet.

it's a great idea.....make a parallel harness though so you can tap into both balancing taps in case one slides off or has a loose wire in there. it'll also deliver better power longer if the cells get low.


great point on the motors, i thought my Tiger 2814's were good to 6S but they're not. gotta start a new thread on 6S motors.