Need help choosing batteries.

[ScarabChris]

OK most of you know I'm building a 54" Bonzi Fountain. Its a twin motor build using two Leopard 5692 1090KV motors.

Let me start with the ESCs, I'm having a hard time with this as well. I really want the ability to have reverse (please no more reverse cable drive comments :tape: ) I want reverse incase I need to back out of a tight space and I understand about running a cable in reverse. Idle speed for short durations will not hurt the cable.

But it seems that all the big ESCs don't have reverse as an option. Now the specs on these particular motors indicate that they will draw 160 amps max if I'm reading it right. So in theory can't I use this 180 amp ESC?

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8937

It has reverse and 360 amp burst. But it says it will only take up to a 6 cell battery.

So that brings me to the battery question. Will a 6s battery be enough for these motors?
:help:

[scullyeng]

You should buy the 1340 kv version of the leopard motor for best results on 6s.

[ScarabChris]

I already have the 1090s. I was going to get the 1340s but the general consensus here was to use the 1090s. So that is what I have to use.

What about 2 batteries per motor to get the voltage? This way I wont have to buy a new charger as the one I have only does up to 6 cells.

Maybe two 4 cell batteries together to get the 30 volts?

[Fluid]

First, the motor spec of 160 amps does not mean that is the maximum amps the motor will draw, it is just what the makers feel is safe. Put on a big enough prop and you'll pull well over 200 amps.

I don't know what to say about the voltage to use. What are your expectations for this big boat? Speeds, run time, and reliability all have to be considered. I am not intimately familiar with the Leopard motors, but based on what I've seen I'd estimate the following:

6S2P - x455 prop - speeds probably mid/high 40s - amp draw in the low/mid-100s.
8S2P - x455 prop - speeds in the mid/high 50s - amp draw in the high-100s.

These are conservative guesses as I have not directly worked with an FE hull that large - few have. Estimates are based on a well-trimmed hull aired out, not running wet.


.

[ScarabChris]

This boat will have two motors so the loads will be less but I hear you.

My goals....I would like to see over 50 MPH and a decent run time. If I can get a good 10 minutes run time I'll be happy.

[ScarabChris]

OK I have made a decision. I am going to go to the 1340 motors, hopefully Steve can do an exchange for me.

This way I can use the 180 amp ESC and save a bunch of money and I'll have reverse. Plus the batteries will be cheaper and I can use the charger I already have since I will be using 6s batteries.

Now the question.

Do I go for the 5000 mAh 40C or the 5800 mAh 25C?

[igottalongone]

Hey Chris...
I just finished a Aeromarine Outerlimits XXX 45"
I'm running a single 1340KV on 6S, through a 240Hydra... 62mph
I think you MAY be ok with twins, thats takes alot of load off and will help with amps.. With my single set-up, I wouldn't run anything less than this 240, I don't think it would take it...
Here is my $0.02 on batteries HYPERION!!!!!!!!
My XXX vid
http://www.youtube.com/watch?v=0emLvQWuPHE

[forescott]

ATTA BOY!!!!!! Get the turnigy 180's then, but use an rx pack instead of the BEC. Just dont overprop!! 52-55mm props at best IMO!

[ScarabChris]

Hey Chris...
I just finished a Aeromarine Outerlimits XXX 45"
I'm running a single 1340KV on 6S, through a 240Hydra... 62mph
I think you MAY be ok with twins, thats takes alot of load off and will help with amps.. With my single set-up, I wouldn't run anything less than this 240, I don't think it would take it...
Here is my $0.02 on batteries HYPERION!!!!!!!!
My XXX vid
http://www.youtube.com/watch?v=0emLvQWuPHE

Yup....saw your vid, very impressive.

But Hyperion batteries? There goes all the saved money...LOL


ATTA BOY!!!!!! Get the turnigy 180's then, but use an rx pack instead of the BEC. Just dont overprop!! 52-55mm props at best IMO!

Oh yeah I always use an RX pack.

I grabbed 2 of these to see where it takes me. Can't beat the price.
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14986