Motor questions



Hi, I’m building my own rov but using the open rov electronics, why do the motors have three wires? Most dc motors I’ve seen have two… as do the bilge pumps I’ve been planning on using… how should I connect them…?


The OROV DST-700 motors are not brushed dc motors. They are brushless motors and require a brushless ESC to control them.
The ESCs on the OROV 2.8 Controller Board are brushess ESCs and are not designed to drive a brushed dc motor such as the two wire bilge pump motors that you are trying to use.


Is there a wiring fix I could use to sort that? Obviously current is current… so should it not work the same?


You will have to replace the three brushless ESCs on the OROV Controller Board with brushed dc motor ESCs to be able to control the dc bilge pump motors. Did you not refer to the links that I provided in my first post?
IMHO I believe that the DST-700 brushless motors are far superior to the dc bilge pump motors even though they require a fair amount of maintenance after each dive. The rubber seal on the bilge pump motor shaft will tighten and wear more at depths of more than a few feet below the surface. They are really not designed to be used at extreme depths (33 meters).


I did, however import tax would put the set up over £100 and I can’t afford that…

So I am looking for a low cost solution


The DST-700 can be purchased from Hobby King in HK. Wouldn’t that be cheaper import tax wise?


Thanks I’ll give that a look


It was thank you, will I have to modify the motor in any way?


The OROV 2.8 Controller Board can drive the brushless DST-700 directly though the wire harness cables.
The OROV ROV assembly guide here will show you how the motors are attached to the wire harness.


Thanks for all the help

I was referring to preparing the motors for immersion… do they need a silicon coating or can I just rinse Them after every dive?


I would follow OROV’s recommendation for pre and post dive motor maintenance:

Step 36 — Motor Protection
Before each dive lubricate and protect each of the motors.
Silicon spray lubricant works very well for this.
Other types of lubrication are available and should be used according to their ability to resist exposure in seawater.
Step 37 — Motor Protection (cont.)
Apply spray lubrication generously through the holes in the motor bells. Make sure that all the surfaces are coated.
Rotate the motors several times to work the lubricant into the upper bearing.
Step 38 — Motor Protection (cont.)
Now apply spray lubricant to the lower bearings in each of the motors.
These are accessible through the holes in the acrylic structure as shown on the port and starboard motors.
The vertical motor’s lower bearing is more difficult to reach and requires you move around the wire bundle.
Allow the lubricant to settle and/or dry (about 1 minute for the silicone lubricant).

tep 44 — Motor Maintenance
The most important part of post-dive maintenance is cleaning the motors. The exposed magnets tend to corrode easily. The bearings also need to be lubricated and protected from rust.
First, rinse the motors with fresh water (see previous step)
Then thoroughly dry the motors with compressed air (if available).
Immediately afterwards, re-apply spray silicon lubrication. Move the motors with you hands for a few rotations to ensure that the bearings are well lubricated. Review the previous steps on proper lubrication. This should be done before and after each and every dive.
WD-40 is great to keep the motors from corroding as it displaces any water. It is not as great as a waterproof lubricant, however and should be used in conjunction with another, more water-resistant lubrication.