Single Battery


#1

I know the batteries on the ROV are connected in parallel through the controller. I have 2 questions:

  1. Is it possible to use just a single 12 V battery with more amper hours?
  2. On the DB25 pin 4 and 7 are the GND. Pin 5 is for the positive of one of the batteries and pin 6 for the other. If i use a single battery where do i connect it?

Thank you


#2

Hello Giorgos,

You can turn on and use the ROV with batteries in just one tube for not as long but two gives a nicer balance and duration. If I was using just one bigger battery I'd join the two power and ground pins going to the battery pack. Walt made the board and would probably chime in if this would be a problem. If there was some current supply problem with the kind of battery you are using then you can always switch to the lower thrust settings but have it going. A power problem will show up with the ROV rebooting itself(like a salt water motor short) or just shutting down(like what happens when you drive it with the batteries too low) and should be easy to spot and correct.

-Matt


#3

Hi Giorgos

If you are using just 1 battery then Use both 4&7 for Ground and 5&6 for +12v.

These can be tied together and you should use both pins because the max current on 1 pin of a DB25 connector is 5 Amps so using 2 pins increases the current capacity to 10A.

I use 2 11.1V 5000ma LiPo packs tied together and then they connect to both pins mentioned above.


#4

Hi Matt and thanks for your quich answer and help.

I have two more questions based on your answer:

1. How can i switch to the lower thrust settings? We are using OpenROV 2.5B

2. What are the current requirements in order not to have current supply problems?

Thanks

Giorgos


#5

Thanks David.

Your answer sounds good. What are the characteristics of the packs that you are using? do you have any problems with the LiPo packs?


#6

After reading your answer i came up with another idea so i have one more question for you David. If you know of course, can you charge the LiPo batteries as they are connected to the ROV? Meaning, can I pass power from the surface in order to charge these batteries? This will give the ROV longer dive time.


#7

The answer to your question on charging is yes, but do you need to, is another question.

If charging from the surface then you would need the proper charger used for LiPo Batteries in the ROV and because the tether will have a significant voltage drop before it gets to the ROV then the voltage at the surface will have to be something much higher. This brings into play other safety issues and there have been many discussions on both in this form on that very topic.

The OpenROV team have been testing different batteries and have found some that out perform the LiPo batteries but I have not seen or tested them myself. Because I am not using the OpenROV housing and I have lots of Boyancy, my ROV has the batteries mounted inside the ROV. Using this last summer I was able to get Hours of Dive time on one charge, and that was using bigger motors than what is used on the OpenROV today. This winter I have switched to the same motors as those used by OpenROV and I expect to get even longer battery life.

If you decide to try the charging battery from the surface scenario please share with us your results but play safe when working with higher voltages. You can also search this site for discussions by others who have been playing with this.

As for the batteries that I use: http://www.hobbyking.com/hobbyking/store/__9184__Turnigy_5000mAh_3S_20C_Lipo_Pack.html


#8

Thank you David for your response.

I also thought about the safety issues when supplying power from the surface. So for now I will forget this and work only with batteries on board the ROV. I am also designing my own housing and not using the OpenROV housing and as a result i also have a lot of buoyancy so the weight is not an issue.

What concerns me is safety and whether the LiPo batteries are safe underwater with all the pressures. At what depths have you managed to dive to?


#9

With the Batteries inside the ROV pressure is not an issue as it will be at atmospheric pressure, I have had mine only down to 65' or so but will be testing it down to close to 300' this summer. The majority of my dives will be under 130'. I would love to see you post some pictures of your build, it's always good to see different ideas of how people do things.I will get one of my latest build and post it for you.


#10

I will send you one as soon as we finalize it. now we are the "prototype" level. just testing things

would love to see one of yours as well.

thanks for all your help!