kb45 xl setup

[rmkymy]

will the kb 45 xl 700kv motor work with the super simple 100amp brushless esc (http://www.hobbycity.com/hobbycity/s...idProduct=7341)
also i will be running a 25c 2300mah 5s lipo. how many amps does this motor draw?
thanks

[ED66677]

impossible to say, the amp draw will depend on the size of what you spin!

[rmkymy]

il be using Turnigy 4mm AquaProp 43x26x9mm, the size of my boat is about a meter long and about 35 inches wide any guess as to what the draw would be?

[ED66677]

35" wide? what boat is this?
700KV under 5S will spin 13000rpm unloaded, you're not going to go fast with this!

[rmkymy]

sorry i ment 15 inches** lol that would be weird

its an old hull iv had for years just stitting there used to have a nitro engine in it but i got rid of it, its a copy of 1/1 cray boat hull. i dont really know much about rc boats im more into cars ect but when i took it to perth one time to get some parts and get the nitro engine set up the hobby guy said it was the best hull he'd seen (we tested it in the river), he couldnt roll it with the nitro in it so im guessing its pretty good. what prop / motor kv combo should i go with? the kb motors go from 700 to 1600kv and inbetween. thanks

[eboat]

I am running a KB with 1200KV on 6S2P 4350 lipos in a 36" long hydro
Using a X450/3 prop it is using an average of 90 amps and is getting me just over 50 mph

I do not think 5S 2300 battery is going to be enough unless you have 4 sets of them and can run it 5S4P you will not have enough amps to do much

[ED66677]

if you refer to this you'll see that a 40" long hull requires a bit more power and rpm than you expect, the KB45 700KV is not a bad choice, but you will certainly have to feed it with 10S lipo's, use an appropriate ESC that can support such high voltage, if you want to stay with 5S (witch is IMO a really bad idea) you will need to provide twice as much amp than under 10S to reach the same power, those "poor" 25c 2300mah 5s are going to suffer a lot!

[rmkymy]

oh ok how about two of these (http://www.hobbycity.com/hobbycity/s...idproduct=7295) linked up to make 6s would this be enough? im on a pretty tight budget

[ED66677]

3700x20=74000 so 74A max, I would at least use some 5000mAh 25C so you can pull 125A constant!

[rmkymy]

hmmm i cany find any esc's that go over 100amps that arnt over my budget cos im only 14 what speed can i expect from thoes 2 3s 3700mah 20c + 1600kv kb + a prop i have thats about 2 inches long 1 inch wide? thanks

[ED66677]

then start over from scratch, forget the 40" hull... what is your budget?

[rmkymy]

about $400 aus id rather put it into one of my rc cars then start over, i only decided to go brushless with the boat because all it needed was the motor, batterys and speed control.

[eboat]

I am using this esc
I got 2 of them when I ordered
I am using one on 2S and the other on my 6S setup

You will have to waterproof them
NAME: HiModel GX Seires 200A 3-7S Brushless Electric Speed Controller Type GX-200A-OPTO
SKU: GX200ALV

Customer Rating: (6) Rate
SUBCATEGORY: Brushless Speed Control (BL ESC) - Air/ Helis
MANUFACTURER: HiModel
WEIGHT: 124g / 4.37 oz
SIZE: 65 x 40 x 16 mm
PRICE(USD): $62.50 In stock
QTY:1234567891011121314151617181920

http://www.himodel.com/electric/HiModel_GX_Seires_200A_3-7S_Brushless_Electric_Speed_Controller_Type_GX-200A-OPTO.html

[rmkymy]

thanks i might get that! but how are you keeping it cool? water cooling? if so what one are you using?

[eboat]

If you are into the rc cars then look at 2S lipos and get 3 of them and hook them together to get 6S and when you are not running the boat you will still be able to use them in the cars
You should still look for something that will get you at least 100 amps
Boats take alot of juice to run and the smaller the battery(gas tank) the shorter the run will be