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ebarker 09-07-2009 12:32

Re: Solar Battery Plant Question
 
Quote:

Originally Posted by Al Skierkiewicz (Post 866156)
One application that used batteries in series/parallel operation was electric submarines.

Hopefully this machine will not convert itself into a submarine.. haha..

We are starting to think at this phase of the project to simplify it and use a single deep cycle marine battery. One battery, no or'ing....

One panel about 200 watts or a couple at 125 watts, and some variety of charge controller, not sure what kind. We are not looking to generate 500 watts but at most half that. So now we need to pick panels and charge controllers.

The craft is large, just over 9 feet long and about 6 feet wide but we would like to not cover more than 2/3 of the top.

MrForbes 09-07-2009 12:45

Re: Solar Battery Plant Question
 
You really need to figure out how much current the thing draws....then you can actually design a power system for it.

Al Skierkiewicz 09-07-2009 17:24

Re: Solar Battery Plant Question
 
Ed,
That sounds like a better solution. There are many places where you can pick up PV cast offs, surplus and smaller sizes which can be rewired (series/parallel) to fit your needs for power and size. There are also many suppliers of charge controllers designed for RV and agricultural use that would be perfect as well.

EricVanWyk 09-07-2009 17:38

Re: Solar Battery Plant Question
 
Our battery expert had the following to add:

Quote:

You can put Pb-acid batteries in parallel. You can do this with other chemistries that are charged in the same way (current limit to voltage limit to taper current cutoff), such as Li-ion and Ni-Zn. All you need to do is charge them fully before connecting. Ni-Cd and Ni-MH are very difficult.



Two important issues with putting cells and/or batteries in parallel are:

Safety. If one cell or battery is shorted internally, the energy from the other flows to the shorted one, thus increasing fire safety hazard significantly. Thermal fuses may be required.
Balance. If the parallel group is exposed to frequent thermal cycles or large temperature gradients, such as under the hood of a car, then charge will be transferred between the components in parallel. Under favorable conditions, such as indoors, this is not significant. A symmetrical layout can help reduce thermal gradients caused by self-heating.

ebarker 09-07-2009 21:56

Re: Solar Battery Plant Question
 
Thanks for the comments.

I just got in at 9:30 pm. This is as bad as build season. 4 and 5 days a week.

We are thinking about building a simulation in Labview to model the power management to help get a feel for how this is gonna roll. We have to get on the lake in a few days. We can do a bollard test and profile the power consumption at various throttle settings.

Any recommendations on charge controllers - simple type - manage the battery without disconnecting the load.

Thanks again.

Ed

MrForbes 09-07-2009 22:51

Re: Solar Battery Plant Question
 
We used one of these

http://www.affordable-solar.com/morn...controller.htm

on our underwater ROV power system.

What kind of motors/props are you using? trolling motors or something else?

Al Skierkiewicz 10-07-2009 08:00

Re: Solar Battery Plant Question
 
Ed,
When I was checking I found this site...
http://www.solarpanelstore.com/solar...ntrollers.html and this site...
http://www.absak.com/catalog/index.php/cPath/27_137

Both have a variety of controllers, some of which have load sensing and cutoff for battery protection. Both sites have the Morningstar product Jim recommends which looks pretty good if it fits your load requirements.

ebarker 10-07-2009 19:47

Re: Solar Battery Plant Question
 
Quote:

Originally Posted by squirrel (Post 866251)
We used one of these

http://www.affordable-solar.com/morn...controller.htmWhat kind of motors/props are you using? trolling motors or something else?


Minn-Kota Endura 30 - 30 lb thrust, 12 VDC, factory props. IFI Control System - 2005 model if I remember correctly. Victor 884 speed controllers. Electronics are contained in a Pentair NEMA fixture.

The motors are 4 wire circuits. A call to their tech support reveals that we cut and cap two wires and connect the other two to the victor.

8020 automation framing attached to lightweight fiberglass, foam, aluminum pontoons.

The pontoons are closed cell polystyrene foam topped with an 0.030" aluminum cap that is shaped in a 2" tall, 10" wide beam.

The cap acts as a beam and binds the automation frame to the pontoons.
The pontoons have a fiberglass skin that is essentially in tension.

If you look at the side of the craft it looks like a bridge structure, the aluminum cap is in tension as the downward force on the legs try to spread. The cap disperses the load across the foam.

The trick was to figure out how to disperse the stress and keep the weight very low. One days we need to make some drawings and explain how the stress work.

Each pontoon is only about 25 or 30 lbs each. A design goal was to be able to carry the machine to a lake that doesn't not have a landing. So the basic machine needs to weight something like a heavy FRC robot. That is asking a lot considering this is 9+ feet long.

We have been working on this for two years now. Construction pictures are here The pictures haven't been updated in a year.


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