Aboutcleggsan Expertise All technical areas of Electronics Engineering.
Experience BSEE, MBA, Design, R&D, University Research.
Senior Life Member of IEEE. Life Fellow of AES.
Organizations IEEE, Consumer Electronics Society, Audio Engineering Society.
Broad teaching experience; work experience mostly in consumer electronics and conversion from analog to digital technologies. Pioneer in digital audio at all levels.
we have been designing a solar powered charger. the board is composed of three modules. (1) a converter from solar panel to a fixed voltage (5V); (2) powerpath charger for battery and (3) a 5V to 12V converter.
previously, we've made the board with these three modules but become of unknown event, module 1 stopped working. so we designed another circuit for this module. After constructing the circuit, i connected the output of module 1 to the input to module 2 (which is what in our design).
however, as i have seen during my test, there is a significant loss of current delivered from our source (dc power supply) to the current delivered by the module 1. there would be an 85mA loss. that amount of current is very much significant for us since we are using batteries.
would the big loss be attributed to the fact that i used two separate boards? should their ground planes be a single plane to minimize loss? hope i have clearly explained my problem and that you would have a good suggestion regarding this problem.
thank you very much.
ANSWER: I would need much more information about the circuitry and interface you are using between the panels and the boards to the battery pack.
But, I suspect you are not losing current; but not getting enough voltage out to produce sufficient charging current. You may need another solar panel, you may need higher voltage from your power supply feeding the circuits or you may have an impedance mismatch from one board to another.
You can check these things out easily. With your vom measure the voltage coming from the solar panel with input to board disconnected. Then connect it and see if there is a drop in voltage; if so, the input impedance to the current amplifier is too low. And so forth, you can go from stage to stage testing and making sure you have the expected voltages or current flow.
Then, let me know more after testing as suggested above. If you can send a schematic drawing or URL reference for the design you are using that would help me to know what you are doing!
C
PS: you can attach an image on your return question if you have schematic or block diagram, etc.
---------- FOLLOW-UP ----------
QUESTION: hi cleggsan, good day!
remember my question above? been doing the tests and still the same scenario is occurring. i have attached the images for the first and second modules.module 1 will be the solar converter then to the charger. been doing some changes in the values of inductance but still same result occurred.
i would also like to add that you are right, there is no current lost but rather the voltage in the solar panel drops. i am afraid we cant change the panels because of financial constraints so we're thinking of finding solutions on the power circuit.
can you recommend any solution to this?
thanks a lot.
xavier
ANSWER: Sorry, you did not send the images.
Based on what you have told me the power supply (solar panel or battery) is not putting out enough power to keep the voltage up. It is pumping out maximum current but needs more and the result is drooping voltage!
Seems to me the solar panel is not putting out enough current; or if it is, then the charger or battery is not supplying enough to power the boards.
Here is a scenario for you to consider: If the solar panel is charging up a battery and the boards are being powered by the battery then when the battery is fully charged and can supply enough power to the boards it will be okey until the battery begins to run down. At that point the solar panel must supply the charging power if it can. So, if you put a voltmeter on the solar panel and another voltmeter on the output of the battery and watch it you should find the voltage remains full up for some time - until the battery becomes discharged, then it will begin to droop.
Does that make sense to you?
Let me know more.
C
---------- FOLLOW-UP ----------
QUESTION: hi cleggsan!
sorry for the images. as i have sent my previous question, the site says there was a server error so i thought i wasnt able to send the message. by the way. here is the image (i hope it will be attached).
the problem that has been bothering us right now is, our solar panel is delivering 300mA (max) but the charger delivers only ~60mA to the battery. this system is supposed to power another system of around 500mA. so there is a great probability that the battery will be drained right?
i am hoping that we can still come up with a solution to this.
by the way, thanks for your immediate replies.
Answer Got the schematic images this time. Thanks.
Look, this whole thing is a matter of ohm's law. Voltage = current times resistance. With a few voltage measurements and current calculations you can easily determine how much current, voltaage and power are necessary versus what you are getting.
First, when you say the solar panel is delivering 300ma is that an actual measured current or just the specification from the data sheet. You can measure it very easily by putting the ammeter in series with the output lead. When you say the charger is delivering only ~60ma is that an estimation or a measurement? And it is supposed to deliver much more, right? So, is it because the charger is defective OR because its output voltage is too low and can't get any more out because of the too low volage?
So, I think you have some circuit analysis work to do. Have you scoped the converter and charger for waveforms to assure yourself they are working as they should?
If you do not understand how to diagnose the circuit topology and troubleshoot the system you should get someone who can. It can be done mostly by use of a simiple vom, but if the converter, for example, is not running optimumly it could be you will need an oscilloscope to check out the running frequency and operational levels. An electronics engineer should be able to do it easily - if there is one around that you can call on to help.
You can get a second opinion from my colleauge on allexperts electrical engineering section.
)