RE: RC Surfer
Yowsa
You can try your 6 cell 7.2 volt with your setup to see if it works - It won't hurt anything. If it can't turn the motor, do not keep trying it - just stop.
A small lesson on batteries etc:
Nicad battery packs consist of 1 or more cells. each cell is 1.2 volts. So 6 cells X 1.2 = 7.2v. This is what the cheap stock 540 motors are rated for.
Lipo packs can also be made up of several cells. They are typically 2,3 or 4 cells. Each cell here is 3.7volts. Your brushless motor can handle the 11.1volt Lipo and probably will need 11.1v to push enough current to start it turning.
Your brushless motor can deliver more torque and power (circular power) but also requires more current to start it turning.
So, in short, if you go to Lipo packs use 11.1v. However, Lipo packs require a special charger made for Lipo batteries. You can't charge a Lipo pack using a nicad Charger.
As for the current ratings, such as 5000mah, this is a rating of how much current a battery can supply for one hour. So, your 5000mah means that that pack can supply 5amps or 5000 milli-amps for one hour. This is a fairly large capacity battery and the larger the capacity, usually the more expensive the packs become.
So, I took some measurements of current draw from my setup and found that it draws about 10-12amps of current. So for simple math purposes lets say the motor draws 10amps (full throttle).
10amps / 5.0amps/h = 2
Convert hours to minutes:
So there are 60 minutes in 1 hour and 60 / 2 = 30 minutes. Your battery should provide 10 amps for 30 minutes.
For the 3000mah pack: 10/3.3 = .33 or 3 so 60 / 3 = 20 minutes.
BTW: your ESC should work great. Like I said, the motor does not draw a lot of current so a huge ESC is not needed. What is more important is that these devices get no air so they tend to get hot so it is more important that they keep cool. The larger ESC tend to have larger heat sinks to they can handle more heat. With water cooling, you should have no problems.