I do not think one could think of this as a circuit but I think it is fine to call it that. Anyway onto the topic. I want to build a basic motor powered off a solar panel. It is small and have not worked out any of the components so I am not going to get techinical since it is only getting started. My only real question is adding in some Batteries. This is low voltage at about 6 volts. amps is .3. I want the solar panels to go to the batteries. And then the motor to the batteries as well. I plan on having more charge going in that what is going out. Or at least in terms of current. I was thinking to aim for about .6 amp charge at 8v. So there is a total of 2v and .3 amps (in theory) charging the battery. So by the time it is night the batteries can be running the motor for some time. Which in mind, I do not plan on having the motor go all night. So basically my question for the time is, can I charge and discharge at the same rate, but have more charge then discharge (unless it is cloudy...). Thanks!

Added: Forgot to say. What battery chem. would be the best. Ni-Cd, Ni-Mh, Li-ion, LI-po are my preferred ones. Otherwise anything on that would be nice.

 

Your plan will work fine except for the run time after dark. You'll need a big battery and a larger panel to charge it, in order to run more than just a little while. How long do you want it to go without solar?

NiCads are the easiest to work with in these sort of applications because they can accept a larger trickle current without as much concern to overcharging.

 

Well I do plan on using a larger battery. Maybe 3 sets in parallel. Having about 2-3 per set. For now it is just the basic idea and will work into finer detail later. I also plan on using either a bigger panel or a few in series/parallel and stuff. As for run time. Was looking for a good 2-3 hours. Maybe more. Work on that once I know what I will get for sure. And I shall defiantly consider to go with Ni-Cd then, thanks for the recommendation. Thank you for the reply.

 

You should be able to calculate the energy required to run your motor for 3 hours, in watt-hours. That will define the bare minimum battery capacity. That's usually quoted in amp-hours or milliamp-hours. Multiply by the nominal voltage to get watt-hours.

Then figure that your panel will have to produce, in the time it's lit, about double that (to allow for all efficiency losses) over and above the energy to run the motor at the same time.

Before you commit to a battery chemistry, plan your system on paper. It may be that you will not be able to use even nicads without a charge controller to avoid over charging. I suspect this will be the case because your panel will be powerful enough to run the motor. Once you are forced into using a controller, any battery chemistry may be ok.

 

Okay, sounds like a plan. I will take everything into my plan. Thank you