HiOPs circuit.Your system gnd needs to be on the battery/load side of the MOSFET not the PV side.Forget about measuring the PV voltage, use a shottky blocking diode in series with the positive PV terminal.That is if it isn't already fitted.Then switch the MOSFET ON when the battery needs charge, if the PV voltage is high enough it will provide current.If the PV voltage is too low then NO current will flow.What are you PV specs.What are you battery specs?Tom..
Won't work, the Arduino pin will drag the gate down towards zero volts when the Arduino ispowered down. You simulation lacks the Arduino pin circuitry so wouldn't show that.You must arrange a LOW output to turn on the load and a HIGH output to turn it off. HoweverHIGH = 5V, not 8V, so an extra level shifting transistor is probably the best way. Drive an NPNthat shorts the gate to ground in that circuit.
Use a NPN as a buffer between Arduino and MOSFET gate. Then use pullup or pulldown on the gate to hold whatever default level you want when the Arduino is off and the NPN collector is floating.
Hi,Move the earth like i advised earlier.
Hi,Move the earth like i advised earlier.Tom....
No, definitely don't move the ground there!
I only partially agree with that Tom. The circuit definitely has problems with ground placement, but making that change alone (battery negative and Arduino ground at the mosfet drain) creates more problems than it solves.Jaun: You need to move the ground to the battery negative as Tom suggests (because that is where you want the ground for the Arduino to be) AND you need to flip the mosfet around (exchange source and drain) so that you are switching the solar cell and not the battery.Your circuit is confusing, however from what you previously said I'm taking your "load" as the battery and your voltage source "V5" as the solar cell. This is a FAR from realistic simulation though.BTW. Your simulation probably wont work properly when you make the suggested changes, but frankly that is just because your simulation is such a poor model.
Mark. I know that the ops circuit is poorly drawn, but previously he said ...-------------------------------------------------NOTES:- Switch (key=space) is arduino pin,- Load is battery.-------------------------------------------------So yes, he really does want the ground (common reference node) at the negative of the battery, not at the negative of the solar cell as it currently is shown.Refer to my previous post. He has to move both the ground and the mosfet (so that it switches the solar cell rather than the battery).
Clever pv controllers use a maximum power transfer algorithm.the pv panel has both a voltage ( which increases ) and an internal resistance - (which decreases) as the illumination level increases. Given the battery isn't fully charged : - the controller acts as a boost convertor at low illumination levels.- it acts as a buck convertor at higher levels.As the internal resistance of the pv is unknown , a hunting algorithm is used to find the highest power transfer point.Allan
I think it is not necessary to have a PV and battery model in the simulation.