I use LM350 to charge lead-acid batteries up to 3A. To this end, I added a 0.22R shunt in the feedback. The values of R1 and R2 ensure that the output voltage is exactly 13.8 V. I also measured the voltage when the circuit was not loaded. However, once I connected the battery, the output voltage of the LM350 dropped to around 13.4 volts. How is it possible? I think the return should keep it at 13.8 volts.
What am I doing wrong?