petrol engines

[Guest]

ok did a test today .i had the batterys fully charged and set a stop watch on the boat .its only lasted 8min then the boat power drops and hardly get anything ,if i take it out the water it workds fine just noth neough power is i put it in the water as getting resistance

Doing a load test on the battery first might show the battery is the problem, how old is the battery? and do you allow the battery to run right out before re-charging, is the wiring getting hot while the load is on the motor, chuck it in the bath and allow it to push against the end of the bath and check the wiring while running.

[Guest]

the batterys are only a month old .

i am getting told the motor is a big problem of a guy on a fishing forum as it runs at 18000rpm and i really only need arounf 800-900 also the prop is to big at 50mm needs to be around 30mm

[Guest]

the batterys are only a month old .i am getting told the motor is a big problem of a guy on a fishing forum as it runs at 18000rpm and i really only need arounf 800-900 also the prop is to big at 50mm needs to be around 30mm

The larger the prop the greater the current draw and load on the motor sometime no extra speed or power, if you reduce the rpm of the prop but increase the pitch you will find for adaptation you are wanting a slower turning prop with a longer pitch will give you what you want, again the greater the pitch the more load on the battery.

[Guest]

Looks to me like a cell burn out. Have you tried another battery pack. The binding on the prop would have caused a high drive resistance and the battery would have overheated and probably cooked a cell. Putting this accidental resistance on the battery would have the same effect as using a higher load motor on an inadequate source. The result would be that after short use the pack will give up the gohst. Rapid discharge would certainly damage the pack. try to borrow one of a mate and see how it goes.

Andy