Need Help! which battery do I need?

[leighb2282]

Hey Folks, i'm currently doing a scratch build which involves a couple of 68mm EDFs and I kind of want to get some help on battery choice to avoid the walk of shame (or at least a walk of shame because I fry everything with poor battery choice)

So the plan is:

2x Alloy DPS Series 68mm EDF (66amps max, 4000kv motor, max 1000w, cont 900w) - 1 will be running with a normal impeller/rotor.

These would be each be paired up with a:

Dr Mad Thrust 60A ESC for EDF (w/ SBEC) (cont 60amps, 80ampa burst) - maybe underpowered?
or
HobbyKing 70A BlueSeries Brushless Speed Controller (cont 70amps, 90amp burst) - maybe best option?
or
Turnigy Brushless ESC 85A w/ 5A SBEC (cont 85amps, 100amp burst) - overkill?

so 2 ESCs from the choice above (or if someone has an opinion on a better ESC) will then connect with a Y-Adapter to ???

Here's where i'm a little lost, I'm not sure what the best option here for a battery is, I for sure want it to be a 4-cell battery as that is what the EDF needs but I don't know what the best mAh would be (the largest is the obvious but possibly impractical answer) and I don't know what C-rating I would need.

I was looking at the Turnigy Heavy Duty 5000mAh 4S 60C Lipo Pack but I don't know if this will be to much or to little in terms of mAh to give me a decent length flight and I don't know if that C-rating is to low (or conversely to high and I could get away with a lower c-rating)

Please Help!

 

[Flyingninja]

Go with the Hobbyking 70 amp esc. I would do a 4000mAh or 3000mAh 4S 40-60C pack. I think the 5000mAh could be too heavy, but is is just a guess.

Hope this helps!
Flyingninja

P.S: What plane are you building? from the way the power system sounds I want one too

 

[leighb2282]

Awesome! thanks for your input! I appreciate it!

I'm building my take on a DTFB cargo plane, twin EDF, swept wing (roughly 66inch wingspan), T-Tail configuration, engines under the wings, (or maybe even above like on the YC-14) with a modular bay on the bottom for various things (dropping stuff but also maybe even extra batteries for extended flight - the bay is (I think) under the CG location so more batteries hopefully won't make to much of a difference (but that is just a purely uneducated guess from someone that STILL hasn't maidened his Tiny trainer but got bitten by the design/build bug)

Go with the Hobbyking 70 amp esc. I would do a 4000mAh or 3000mAh 4S 40-60C pack. I think the 5000mAh could be too heavy, but is is just a guess.

Hope this helps!
Flyingninja

P.S: What plane are you building? from the way the power system sounds I want one too

 

[Flyingninja]

Sounds pretty awesome! Could post pics of the build process?

 

[leighb2282]

Sounds pretty awesome! Could post pics of the build process?

I Actually just finished taking pics from the first part of the build, I'll be starting a new thread up in the Mad Scratch builders corner!

 

[stay-fun]

When it comes to hobbyking stuff I'd go for the overkill

I'm not sure what your plane can carry, but if you want to go light: calculate using the C rating and capacity which light battery can still provide enough continuous power for your motors