Describe those going slightly more accurately
Power is
either AC 16V => DC 17V
or
switching power supply DC 13.8V max 2.5A
device is 7/24
If the power fails I want to add a backup battery 12V 4-30 Ah
I like taking the battery attached so as not to constantly recharged, because it costs money and, second, shorter battery life.
Therefore, we need either a controllable current source 0-1A
or switched current source, for example, 0, 100 mA, 700 mA (not charging, slow and fast charging)