There are versions of the common 7805 that can supply up to 3A. If your main battery got a nominal voltage higher then 24V you should make the regulation in two steps. A normal ELFA73-095-60 should do the work. It can supply 2A.

There are drawbacks with common BECs. The most noticeable is the radio interference. At 1A and 24V input the loss is about 20W. It will require a rather large heatsink. Hopefully the average current is much lower then 1A.

Have Fun
STB