Ok well then the limiting factor now is the 50vdc Max drive limit. For safety you really need to leave a 10% safety margin for back Emf when the mootrs are slowing down and effectively turn into dynamos and send voltage back to the drives etc.

So 45Vdc is the Max you can run these motors at safely. If you try to push more then you risk the chance of blowing the drives up.

What machine is this going on.?