“Typical” is not enough information. Our “typical” robot is tuned to pull ~180A consistently because of our drivetrain sizing choices.
You can use a tool like the jvn calculator to ballpark the electrical loads your mechanism will generate. Plug your mechanical loads, motors, gearboxes in and out pops a ballpark electrical load.
You can use a tool like the Driver station data logger to find the average load in your system if you’re using a modern PDP. Run your mechanism on a battery for ten-fifteen minutes and then pull the “match log” from the driver station, and use the traces to find your max & average load.
You could consider keeping a battery in the circuit as normal and then bolting a 6A-10A fast charger to it directly. (A lot of off-grid PV systems will do something like that, where the PV DC is fed into a mppt battery charger, and then an inverter pulls power off the battery.)
If you have more than 120W (12v*10a) average power consumption, I’d set up a second (and third…) battery and fast charger in parallel rather than attach a second charger to a single battery, for heat management reasons. Lead-acid batteries are pretty stable and happy to get banked together, not like fussy lithium chemistries.
Alternatively you can go to a single much larger car battery and get closer to 100-150Ah, if you have something like a “daytime hours only” runtime requirement and can just let the battery run down all day and then charge overnight.