The prototypes are ready - 3 of them, in their glossy black heatshrink covers - all looking good.
Now what’s needed is a small self-adhesive vinyl label which I can stick on the front to give the charge controller a really professional look. Fortunately, I know a bloke who’s got a machine that can both print [...]
I’m making up a small number of pre-production prototypes so I can test various configurations of multiple charge controllers. These will be:
One solar panel, two charge controllers, two batteries - this was suggested by a boat enthusiast who wants to use a single solar panel to keep two batteries (used for different purposes) topped up.
Two [...]
Here is the MOSFET circuit including protection and EMC related components.
Firstly that innocuous looking 10k resistor connected to the gate of the IRFZ44N MOSFET. This component makes a huge difference to the amount of RFI (Radio Frequency Interference) that the charge controller generates. Together with the FETs own gate capacitance, it slightly increases the rise and fall [...]
Printed Circuit Board
Microcontroller PIC 12F683
MOSFET IRFZ44N
LED blue 5mm
Voltage Regulator 5v TSC2950-50
Transistor 2N3904
Transistor 2N3906 (x2)
Diode 1N4007
Diode 1N4148 (x4)
Schottky Diode TSR845
Transient suppression diode 1.5KE36CA
Zener Diode 9.1v (selected for 0.5% accuracy)
Resistor 220k 0.4W (x3)
Resistor 10k 0.4W
Resistor 220R
Resistor 200k 1%
Resistor 56k 1%
Capacitor 1uF tantalum (x3)
Capacitor 100nF
Capacitor 47nF (x2)
Capacitor 6.8nF
Cable 14A red (250mm)
Cable 14A yellow (250mm)
Cable 14A black (250mm x2)
Heat [...]
Continue reading about PWM5 Solar Charge Controller Parts List
While I was looking for a solution to the EMC issue, I thought about turning the regular 122Hz PWM frequency into something more like white noise. The idea was to spread the spectrum of the emmited radiation so that at any one frequency, the signal would be weaker.
It didn’t work. The intended effect was minimal, [...]
Electromagnetic Compatibility. This one has kept me busy recently.
At some point I’m going to have to address the issue of CE marking. That’s the little logo that electronic devices must have if they’re to be sold in the EEC. Two of the directives are of interest; the Low Voltage Directive and the EMC Directive.
Fortunately the [...]
What happens when you connect a 20 watt solar panel to a 21 watt bulb? I tried this last summer and the most I could get was 8.5 watts. The bulb glowed a dim orange. When I used a 15 watt bulb (three 5W bulbs in parallel), I was able to get 18.2 watts. The bulbs lit up [...]
The holy grail of solar charge controllers is the maximum power point tracker (MPPT). How easy would it be to design one that’s both cheap and efficient?
The PWM controller is pretty much finished now, so we’ll use it as a building block and add on MPPT functionality. The sketch shows a few components added to the PWM controller block diagram; [...]
There’s an inherent danger when using a MOSFET as a series switch, the body diode. While we can stop current flowing from drain to source by switching the FET off, we can’t prevent current flowing from source to drain.
In the charge controller circuit, source is connected to the battery’s positive terminal and drain to the [...]