FRPS-100 Issues

[BroadAspect]

We have a FG200D cluster with an FRPS-100 in a facility with two power feeds A and B. We have the FG200Ds split across the two feeds. Then per the FRPS-100 documentation we connected the 1-2 and 1-1, and the 2-1 and 2-2 DC outputs connected to the other PDU. The other day data center is having a de-energized (thanks new OHSA rules!) power panel maintenance window.  We lost one of our firewalls in the cluster. So we are left scratching our heads. Is the FRPS unit as dump as the old Cisco backup power units for the 35-- and 37-- series gear? Does the DC outputs not have a shared rail that will keep both FG200 units going when we lose A or B PDU? My tech tonight found that we have Firewall-A of the cluster on FRPS 1-2 and 1-2 which also went to the A PDU and the FRPS power supply 1 also goes to PDU A. therefore when A went down, we lost our A firewall.  I had my tech swap the AC power input cables to the FRPS. So now I assume that if the PDU A goes down, our firewall A will get power from PDU B.  Thinking about crossing the DC-Output cables to the FGs, but worried that may cause an issue there. The documentation certainly doesn't mention to do it that way!

Is it just me or does the Fortinet documentation seriously lack? What have you done to maintain power redundancy to a FortiGate with only single AC power input? At our other facility we have used a rack power Trip-lite Auto transfer switch and never have problem like this. Man I hate single corded devices!