Port side Batteries dry much faster than Starboard side



HI, I just finished my 2.8 ROV. Yesterday I tested in the poll and it work fine for a couple of minutes. like 3 to 4 minutes, then suddenly everything shut off. So I disconnected the usb cable in order to prevent any short circuit in the case that the electronics cylinder was making water. It was not.
So I re connect the ethernet cable and the usb cable to my Mac Pro. I saw the main board starting to flash the blue leds, a minute or so later the camera LEDS flashed for a couple of times and then the cockpit re-stablished connection with the ROV.
So I tried once more, It went into the pool at about 5 ft down it work well, camera, camera LEDS, lasers, all three motors, etc, etc,… and 4 minutes later… again it suddenly shutdown!!!
I repeat the entire process three times, and the same thing kept happening!

Today I decided to test the ROV controls, connections and everything I could imagine out of the water. everything worked perfect… I even discover a couple of tricks to maneuver and let the motors running with out pushing the forward arrow! any way all was good.
Then I noticed that the battery voltage was shifting from 5.6 to 8.3 or 9 volts very fast. I thought it was because I was trying everything, lights intensity, lasers on and of, vertical motor on an of, changing the speed of the motors etc, etc…
So decided to take the batteries out, mark them by side and sequence 1,2,3. and then measure the voltage in each battery.
To my surprise, The port side 3 batteries were 50% lower that stboard ones!!!
I put the batteries back to both the tubes battery and I just couldn´t connect to the cockpit. everything started normal, but about two minutes later, the camera LEDS started to blink non stop. untill I disconnected the USB cable.
I am now recharging the port side batteries, to try it again.

Does this happen to anyone else??? any comments that may help understand what may be happening?

Your comments will be much appreciated!
V. Manuel


Hi Manuel.
I have the same problem as you, but I use LIPO batteries for my ROV 2.6.
I decided to change de batteries because I had troubles with LIFE in the past.
However I still with the same problem. Port lipo batteries are discharged faster than starboard LIPO batteries. I don’t know why.
I think port batteries controls the motors (a big cuantity of currents), and the starboard batteries controls the electronics, but I am not sure.
The advantage to have lipo batteries with XT-60 conectors is that I can replace them really quickly and I have more than 2 to use each time.


Hi dankybas,

Thanks for your comments. I had a tought that like you said, it might have something with the motors and with the rest of the electronics. Same as in boats. Normally one bank of batteries are for engines and other for the house. other for gennys etc, etc… But wanted to make sure I hadn´t a short circuit.

My OROV came with the blue batteries, I think they are NiMH or something like that. I did not got the LIFE ones. But being in the RC airplane hobby, I have many LIPO batteries. from 3 cells and 2200 Mah, for the foamies, up to 7 cells and 7500Mah, for the larger helis. What kind are you using? and how are you managing the heat of the batteries? Did you made new tubes with the shape of the batteries?

I like your idea. hope you can share a bit more.
Regards from Guadalajara, Mexico.



Hi Manuel:

Are you still having this issue? It sounds to me like you might not be drawing any power at all out of your starboard battery pack.

I would try opening up the ROV main tube, disconnecting the controller board, and probing the battery voltages as they appear at the DB-25 connector on the endcap. You might find that there is no voltage coming from the starboard battery pack.

If this is the case, I would review all the wiring, and make sure that the individual cells in the starboard pack are making solid contact with one another. I would go back and review the instructions to see how to prepare the individual cells to make sure they make proper contact with each other when inserted into the battery tubes.

Let us know what you find.



Hi Walt,

Thank you very much for your advice. I will check on your suggestions.
will let you know the result soon.

Best Regards!


I’ve had this problem before too… never figured out why it was happening.

This means that you don’t need both battery tubes to run the rov? i.e you could run the rov with an empty battery tube?


Hi Guilleaume,

I think you are right. If ROV´s are like the RC helis and planes, that you use sometimes 2 or 4 batteries, is mainly because to have more voltage. current is the same. therefore the flying time is longer.
Probably here with the ROV is the same.
But since I updated the firmware of the BBB the batteries are consuming the same voltage.
One thing I just noticed is that the stbd tube is making a little water.
I have been only testing my tt/OBLIVION (its her name, after my boat. :slight_smile: ) in the pool, that the depth is to shallow 5ft.
Another problem I have is that the port motor runs faster than the stbd one, so tt/OBLIVION dives in circles! I need to keep correcting heading. and in my Mac pro when push ctrl and right arrow, the google chrome hides!!! So I have now two new problems. Need to equal the speed of the two forward & revese motors, and the water liking on the port tube!!!
Any suggestions???


btw there’s a heading hold function on the cockpit
for leaking you should inspect as to where the leak was coming from front or rear, caps/ oring fail also check that enough epoxy/glues is use to cover the tiny hole on both battery tube end-caps. there are extra oring include inside the kit if oring is the prblm…


Hi kyril_acap

Thank you for the tips. I have tried already the heading hold button on the cockpit. But because of the issue of the motors, that the stbd runs faster than the port one, the ROV does not hold its heading!
Any idea on how to balance the rpms on the motors?
Also I will re seal the back of the two battery tubes with 5 min epoxy. See if it work. if not. it is easier to remove than the 30min.

Thans again, and best Regards!


i think its due to coding that the stbd run faster than port… if i wasnt mistaken, it was 50% higher since the difference in pitch angle of both propeller.though im not sure why they make it 50%…might be after several testing, they found that to be ‘sweet point’ on their set up…

but the heading hold should be able to do this… well i haven’t tried yet since my ROV is customized in different setup.:smile:


hi kyril,

Thanks for your answer. So did you modify your ROV? Would you share your changes??? :blush:


discussion link. nut my rov still isnt properly working yet. and for now i only use thrusters,camera and sensors.no light/laser attached yet