What external battery would you recommend for a Zoom F4 recorder?

Hello. I recently purchased a used F4 and it seems to be in a pretty good shape. The problem is that the battery pack on the back of the device for the nimh and lithium batteries is missing and so the best solution would probably be to buy an external battery with a hirose connector. Are there any good batteries that you would recommend? I would probably run at least 2 channels with phantom power on and that would probably require a decent battery life.

Thanks in advance