charging Lead acid batteries

I have a large robot that has a 12 volt 36 amp an hour battery. I also have a small robot that will drive inside the large robot. The small robot will have a 12 volt 1 amp an hour lead acid battery. My goal is to charge the small robot with the larger robot. could I possibly just connect the small battery in parallel with the large battery? would that work if there is a load on the large battery?

thank you for your assistance.

It won't work very well. 12V lead acid batteries need about 13.6V to charge properly, but produce much less than that (i.e. about 12V) when under load. You'll need a DC-DC converter or home-made boost converter to charge one 12V battery from another.