18F4550 Solar battery charger / regulator & inverter system

[DavidK]

Rytech
You might consider using the Allegro ACS712 in the battery leg of your system. It is a Hall Effect-Based Linear Current Sensor that is isolated from your current source. The fact that it is a bi-directional current sensor would allow you to monitor which direction the current is flowing; into the battery or out of the battery. On an A to D scale 2.5 VDC equals zero current and 2.5 to 5 VDC (well almost 5 VDC) is current in one direction and 0 to 2.5 VDC (almost) is current in the opposite direction. Even though I have not tried it, it is supposed to work in the AC leg of your project to monitor AC current flow. Even though it is a SOIC chip, it will handle 5 amps. There is another chip that handles over 20 amps.

[RYTECH]

Thanks for your suggestion, I'm always interested in other IC's / sensors that do current monitoring / reporting as my experience in current metering started and ended with using maxim 4172's...

As for their use in my posted "theoretical circuit" diagram, I've used diodes to "direct traffic" (possibly stupidly) at various points in the circuit... flow should at any any given point should be unidirectional. But perhaps there is a more reasonable "topology" that I should consider.

Nice information.. lets keep the ideas rolling folks hopefully by chatting we can come up with some kind of ideal way to layout this circuit.

(please note, just in case you were wondering, I do not intend to profit from or otherwise abuse any contribution made by fellow members towards this discussion, and if there is anything I can help others with (4172's, 18F4550 hardware etc) I will try to do so)

My vision here is to create a "open source" green power battery system that many people can cheaply use, enjoy, and almost more importantly understand.

[RYTECH]

Rytech
it is supposed to work in the AC leg of your project to monitor AC current flow.

David, I'm more interested in keeping track of the DC elements of the circuit > monitoring the power coming in from the solar array and the power out of the battery banks

[RYTECH]

I dug up my notes for some of the stuff I'd been researching last summer for charging batteries and came across notes for the texas instruments UC3906/2906, i think it would be better than the linear regulator/resistor combo for charging so I'm posting the data sheet in case anyone wants to look at it with me... actually the data sheet won't upload but I did post another document I found on the 2906/3906

The data sheet is pretty straight-forward... although I'm having some difficulty determining the resistor values necessary to indicate to the charger ic the bulk charge rate and for how many cells it's charging... maybe someone can make sense of it...

[Acetronics2]

May be you should have a look to AN U104 ... ( U for UNITRODE )

where it is clearly explained ... with the scheme ( ! )

Alain

[RYTECH]

Thanks I've posted that document in case others wish to review it.

[jcdillin]

Are you still working on this?


Right now i'm working on getting the parts together to start a small solar power system for my shed. At least give me lighting and some ventilation fans. I already have a few of the high power chips from allergo for reading amperage from the batteries and the panels. I am starting to work on the schematics and deciding which pic I want to go with. I would be interested in working more on this.

Jerry

[sayzer]

RYTECH,

Do you need the solar panels ONLY for charging?
I did not get it clear enough with the posts above.


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[RYTECH]

Hi people... sorry for the delayed response, i've gotten somewhat sidetracked designing a perpetual motion machine...lol...

as for the power system.. I would like it to a) recharge the batteries and b) supply the load with any additional unused power from various input sources...