An MPPT solar charge controller using Arduino as well as a homemade Li-Ion battery. Also an 18650 battery tester. So 3 projects simultaneously because they’re closely related.
I’m using a CC CV boost converter to convert solar energy to the voltage for a 7s Li-Ion battery. The arduino reads voltage and current and will try to adjust the CC value to obtain an optimal wattage. I have removed the CC potentiometer and replaced that with an Arduino PWM pin with voltage divider that sets the corresponding current limit. This way a relation between CC pwm duty cycle and solar output can be set.
DIY Li-Ion battery goes hand in hand with the solar project. I’m making a home battery out of salvaged laptop batteries. That requires a battery tester as well which I’m also making myself. The battery tester works by charging a battery with a TP4056 module and discharging as soon as it’s fully charged over a resistor while monitoring voltage/current over time. This happens 16x in parallel using multiplexers so 16 batteries can be tested simultaneously.
I’m also taking safety very seriously so all batteries are equipped with both thermal fuses and current fuses. That involves 3D modelling battery holders, printing them, spot welding/soldering etc. As well as an additional monitoring system on top of a commercial BMS so that the battery status can be monitored remotely. I intend to have a smoke detector, thermostats and an emergency cutoff switch controlled by that second BMS.
Once everything works to a somewhat satisfying degree I intend to post the projects in more detail.
Every project tends to explode in scope in terms of what it all requires so I’m not making as much progress as I want but it has been very educational.
Those wet solder sponges cause a thermal shock every time you wipe the tip. I recommend using brass windings instead. They also won’t completely wipe the solder off the tip either.
You always want a small layer of solder on your tip at all times to prevent it from oxidising. Oxidation means bad heat transfer causing soldering to be much more difficult. Also store it with a small blob of solder on it.
You should avoid scraping or sanding the oxidation of the tip. There is a small layer of silver that won’t oxidise so quickly but below that is normal iron. Not sure if that applied to cheaper Chinese irons but it’s better not to learn bad habits. Once you remove the silver layer you’ll get oxidation much more quickly and you’ll have to keep scraping until the tip is gone.
You can remove oxidation with the brass windings much more easily than with a sponge. When you apply solder with flux the rest of the oxidation should come off fairly quickly.
Buying a cheap model to practice is a great idea, when you are used to that you can look into a better iron. I’ve been very happy with the TS100 but the Pinecil is the newer model apparently.
Wattage does not mean how hot it gets, it means how fast it gets to the desired temperature. Also Chinese vendors tend to exaggerate greatly with specifications, especially with cheap products.
With soldering you want to maximize heat transfer at all times so flat surfaces (chisel tip for example) are usually ideal. If you want to remove solder from a hole in a PCB you’re better off with a round tip as that has the most contact area then. It will make it easier to use a solder sucker in that case for example. Personally I have the chisel tip on 90% of the time and might be willing to switch to the large flat one.
Seems your linked website as a very believable conclusion attached to it. I have a similar issue where the relay module would behave erratically. In my case it was when the relay module/595 chips received power before the Arduino was fully powered up. It’s unlikely that a load affects your relay module as they should never be connected to the main circuit.
I guess something like a pulldown resistor on the SER, CLK and RCLK pins would solve the issue since that would kill any noise. The noise is probably the kind of voltage that BARELY registers as HIGH but highly random.
That or making the relay module only turn on after the microcontroller has finished starting up using a mosfet or something.