View Full Version : Motors for driving propellers in water!

11-29-2009, 07:50 PM
Hi guys... I will be glad if some one can help me out here...

I want to make a solar boat. It also has to cross a dark tunnel.. and the light sources are 500 watt halogen bulbs. now.. i figured out the circuit n all. will be using the solar engine... but i am confused with the motors... what kind of motors should i use voltage rating? rpm? current??

The size of the solar cell must not exceed 150 sq cm... another doubt is should i use gears ... i have never used gears before...

waiting for your expert replies...

11-29-2009, 10:37 PM
all depends on your solar panel and the battery. If you have already purchased the solar cells, post their spec.

11-30-2009, 01:19 PM
1. The Motor should be a high efficiency type.
2. The RPM depends upon the propeller and is proportional to the number of blades.
3. It is obvious that the voltage must be less than the solar panel output voltage. Solar cell Voltages vary with the incident light. Measure the loaded voltage output ( a few LEDs connected to the solarcell, ) in bright and low light ...
4. The 'Dark' crossing will not be difficult, as the boat will move by inertia even when the motor has stopped. Moreover, all solar projects will use a 'burst storage' capacitor which will charge and discharge intermittently into the load/Motor.
5. The use of gears is subject to (2.) above. Any load or propeller will be efficient with the use of gears.

11-30-2009, 08:10 PM
thanks a lot for the help... i have not bought the solar cells yet... but for estimates i think the output i can get from the solar cells will be around 6 volts.. not more than that...
so based on this voltage which motor do you guys suggest..

i was also thinking of using a noctunal solar engine which can charge itself during light and discharge in the dark..

so what do u think should i use? both d circuits.. a normal zener based solar engine and nocturnal one together or just the normal one depending upon the inertia...?

will the motors work properly if i use both d circuits on them??

:D :D

11-30-2009, 10:33 PM
IF the solar cell size(or boat size) is not a restriction kindly use 2W solar ccell from CEL (1W+1W) they will give u 400mA current at 4.5V good enugh to run most motors.........


11-30-2009, 10:56 PM
the low voltage motors with an smps fan(you can get it easily from some computer shop) like the motors offered by tri/robokits/robosoft.
cut the smps fan siza a little by some blade and see the results...

12-01-2009, 11:59 AM
these is a size restriction.. The size of the solar cell must not exceed 150 sq cm, (excluding the casing). and the size limit of d boat is 250 mm X 200 mm X 200 mm....

12-02-2009, 11:04 AM
can anyone give some ideas abt the shaft i could use.. coz i cant inser the motors under water...

12-08-2009, 01:04 AM
:idea: ball-point pen refill..... :!: