Say, can I just set the module to 14.4V and the current limit to something high-ish and then monitor if the current it draws is dropping, or is there another way (if there is even a way)?
Yes, it's possible, but you must:
- put a series diode in series with the battery (a high current diode, I put a double diode in parallel). This is a must, because if there is a power outage, then the battery will start pumping current back into the PSU. Depending on the PSU model, pumping current into the PSU might be dangerous or not, but better safe than sorry. Put a series diode.
- limit the current, e.g. for the first few hours put a car light bulb in series with the battery. After the battery voltage is 12-13V, the light bulb can be removed, but keep the protection diode in series with the battery.
- the 14.4V top charging voltage (measured on the battery) depends with battery temperature, I am using this table:
Lead Acid generic specs
-----------------------
At a comfortable temperature of 20°C (68°F), gassing starts at charge voltage of 2.415V/cell. When going to –20°C (0°F), the gassing threshold rises to 2.97V/cell.
Battery status -40°C (-40°F) -20°C (-4°F) 0°C (32°F) 25°C (77°F) 40°C (104°F)
Voltage limit on recharge 17.1 16.2 15.3 14.7 14.1
Float voltage at full charge 15.3 14.7 14.1 13.8 13.5
or lower or lower or lower or lower or lower
gasing at 20*C for V >= 14.4V
nominal, no load = 12.6V
floating charge = 13.5...13.8V
- do not let it unsupervised, and be careful with wiring, because a car battery can easily melt very thick wires and start a fire when short-circuited.
Later edit:
https://www.eevblog.com/forum/chat/charging-my-car-battery/