Paula 3 brushless question

Motor:
A brushless no smaller than 540-size should work fine on Paula 3. In-runner should have a proper reduction gearbox for higher torque output and power efficiency.

Battery & ESC:
You can use NiCd, NiHM or lead-acid battery to power brushless motor. Li-po is not the best choice for heavy duty application because its discharge rate is usually lower than NiHM or lead-acid. For instance, 4400mah implies the battery can discharge at the rate of 4.4A for an hour. If it is a 15C battery, the maximum discharge rate would be 4.4 x 15 = 66A for 4 minutes (60/15=4). 20C would be 4.4 x 20 = 88A for 3 minutes. If your motor (brush or brushless) drains more current than the Li-po can handle, the battery would be cooked. In the worst case, it would burst into fire and toast your boat. Therefore, the choice of Li-po and ESC is highly dependent to your choice of motor.

Besides, Li-po would be permanently damaged once they're shorted (the risk is high in case of boating). Since Paula 3 is not such a tiny boat, it should not have weight problem that requires the use of Li-po.

Although I'm a Li-po supporter, I must admit that the use of Li-po requires extra caution.

Better believe in brother jpmontoya2

By the way, you can check the current rate at stall of the Speed motor series at Graupner's web site. Here is the link:
https://shop.graupner.de/webuerp/servlet/AA?wgr=821

Take the 7.2V Speed 500 for instance, it drains 59A when its output shaft is fully stopped by means of external force, which implies the motor drains less than 59A as long as it is revolving. The exact current drainage, just as brother jpmontoya2 said, depends on the pitch and size of the prop.

[ 本帖最後由 夜遊神 於 2008-5-24 23:18 編輯 ]