I built a basic SLA charger circuit using a laptop charger and a buck module that has an adjustable maximum voltage and current. I also added a diode so the circuit can just be left attached to the battery when it isn't charging. I detached the battery (diode still attached) to set the maximum voltage and current and set them to 14.5 volts and 0.2 amps respectively. When I attached the charger to the battery and tested it it worked fine until it stopped at 14.2 volts. I left it on for a while to be sure it wasn't actually still charging and the voltage didn't increase any more. I detached it and increased the voltage (without the battery) to 14.8 volts. When I reattached it and tested it again, the battery charged to 14.5 volts and then stopped. Is this ok, or should I set the voltage without the battery to 14.5 volts? I will add a link to the module if I can find it. Thanks in advance for help. I included a basic diagram of the circuit as it is now.
Edit: Here is the buck module
https://www.aliexpress.com/item/325...f9-1550466771573-09540-ctuNxGq4&terminal_id=c

 

The voltage drop across the diode increases when there is a load on the output. You should be fine the way you have it set.

 

Why dont you just modify the Laptop charger to give out 13.8V to 14.6V.....easier to do for me....

 

Do you have a schematic of the buck converter?
If so you could connect the voltage feedback point to the output of the diode.
That would eliminate the effects of the diode drop.

It should be a Schottky diode to minimize the voltage drop.

 

The diode is a schottky. I probably should have mentioned that. I used the adjustable buck module since I wanted to be able to charge 6 volt batteries with minimal modifications and the module seemed like the simplest way to do that.

 

Set the charge voltage with the diode connected and a resistor load of about 0.15A.