I've never gotten a dynamo that powerful so you may be trying to run more steam than bronze pipes can carry. Also don't forget you lose a few EU going down wires. A battery box means you can charge it up more slowly with a less powerful dynamo, then burst out the power to run the machine for a while. Or you can charge the battery box with multiple smaller dynamos.
my issue thus far with the battery box is, let's say i'm trying to run a MV electrolyzer with a MV battery box. how many batteries should/can i use? does using more than one battery at a time make a difference? how much power does it put out when attached to a machine of the same tier? how do i change the power output to better suite my needs? currently i've tried using multiple batteries and after the number of batteries exceeds the amperage limit on the wires they ignite. with any number of setups i've tried they have all failed to run properly. most recently i tried running a MV electrolyzer with a MV battery box trying to process magnetite. i tried 1-15 batteries in the large battery box and none of them processed the magnetite.