Hi,
I also keep in mind this is a topic in the beginners section of this forum.
Safety has many faces, also with Power Supply's.
I develop Power Supply's and try to think about what can go wrong if the user has a moment of not thinking before doing.
A beginner usually does not have a professional Power Supply from KeySight which I have shown some info from.
The average hobbyist does not have a thick Thyristor across the output of his Power Supply and does not have all those safety measures that the fancy Power Supply's from Harrison, HP, KeySight and some others, usually all have.
If you are going to charge with e.g. a current of say 4-Ampere then you are not going to take a diode just that can handle 4-Ampere, then you choose something that can handle say 20-Ampere or more
and again think about the reverse voltage of the diode.
It is often beneficial to use a dual Schottky diode to keep the voltage drop low across the diode.
Also consider cooling of the diode at higher currents.
Again, so also keep in mind the reverse voltage of your diode!
The series diode is primarily intended to ensure that you do not send energy back into the Power Supply to do damage.
If you still want to use your power supply to charge batteries, then including a good fuse in series is an extra layer of safety.
ExampleBelow is a not complete description of how to connect and charge a car battery for charging.
The point is to give you a direction on how to carry it out, additions I would love to hear.
Measure the voltage of the battery you want to charge e.g. a car battery.
This measures e.g. 11.3V, you use a thick Schottky diode(heatsink?) and you use a fuse suitable for your application.
Turn on your Power Supply and set it to e.g. 12V for this car battery and also set the maximum current you want to charge it with, then connect the plus pole in the Power Supply last.
This way is to keep the difference between the battery voltage and the Power Supply Voltage as small as possible so that large surge currents do not flow,
if your Power Supply has a large capacitor across its output terminals, this is common with smps power supplies.
Slowly increase the voltage of the Power Supply until it charges with the current you want, but also measure the voltage at the battery terminals.
Be sure not to exceed the maximum voltage for the battery you want to charge.
Make sure you can quickly disconnect the battery or Power Supply if calamities occur.
If your battery is charging, don't hang out with the neighbors for dinner.
Check the temperature, charge current and the battery voltage regularly.
Battery voltage is different from de Power Supply voltage if using a diode and fuse!
Kind regards,
Bram