Hi Eddie,
The battery connections are straight forward and simple. 4/0 from battery cabinet to bus bar, 2/0 from buss bar to each 6500, equal length cables, chargeverter output to busbar. 2-48V-LL-v2 2-48V-LL-v2S
6500EX-1 is the main unit, the other 6500 is only used for an additional charge control at this time, we do not have enough load to justify the additional power consumption (draw) of that unit.
6500EX-1 - PV input - 9 SolarEver 410W 6500EX-1 - AC out to panel - panel out to manual transfer switches 6500EX-1 - AC input 10A - Utility - only used if batteries get to below 20%
6500EX-2 - No AC input or output 6500EX-2 - PV input 10 Canadian Solar 390W 6500EX-2 - PV input 03 Canadian Solar 390W
The system has been running practically flawlessly since previous RMA on defective unit.
Friday morning we lost power, on checking the system:
6500EX-2 was off (black screen, non responsive) 6500EX-1 Fault code 02: Internal temperature to high (Ambient air temperature 68 deg F. Batteries in protect mode
I fully shutdown the system, disconnected the PV input from both units, shut down all breakers and turned off all BMS's.
I started each battery one at a time from top to bottom waiting for each to boot, then turned on all the breakers on the batteries.
I turned on the wall breaker (nader) for 6500EX-1 and the batteries immediately go into protect mode.
I shutdown the system again and restarted the batteries as above, this time I turned on the breaker (nader) for 6500EX-2, same batteries went into protect mode.
I shutdown the system and disconnected both 6500EX units from the bus bar and turned on the breakers, no issue's power to bus bar. I then connected unit 1 and tested - protect mode, started over connected unit 2 only, same, protect mode.
I reconnected the cables to the bus bar both naders off, started the generator and ran the chargeverter, the batteries began to charge as normal.
I shutdown the chargeverter and connected PV to unit 1, unit 1 recognized the PV and starter inverting, have 120v at subpanel, but error bP - battery disconnected as expected as breaker has to stay in off position.
Turned on PV for 6500EX-2 - The unit did not respond, disconnected inside PV disconnect, checked breakers and power at outside box, all okay. Came in and checked power at input of inside disconnect, all okay, turned on inside disconnect, no response on unit, pv input on both side of disconnect read 0. I cut the female end off an an extension cord, used this to supply AC to unit 2. The unit powered on and would show inverting, as nothing was connected to AC output did not test, turned PV power on and the unit did not recognize any PV input as before.
I shut the unit down, removed the test ac cord, shut down the batteries and all breakers / disconnects then called for support.
Eddie, I am hoping this meets the information you requested and we can find a way to get back up and running quickly.
Thank you
All has been well since last fall until now 
