conflict (seemingly at least) in diagrams/illustrations

bill

I'm assembling a MNDC 250. In one instance I read, "...use nothing smaller than #2 wire for the C.C. Bat +, anything smaller may damage C.C.". In MNDC 250 I read, "tie battery bank (+) lead thru # 6 wire at the inverter DC breaker to the C.C. Looking at the photos I see what appears to be # 6 lead (top photo page 6) coming from the bottom of the 250 breaker. In all pictures of the C.C. the lead tied to the B+ has to be at least 0/1. Why would I use a #6 lead when Outback tells me that anything smaller than #2 may damage the unit? Or is there a change of wire size we don't see?

zoneblue

The key there is to minimize voltage drop, if you can keep that under 0.1V between battery and controller, then that ensures setpoint accuracy. This is complicated by the fact that the midnite and outback controllers screw terminals only take 4 awg. However, Usually this distance is real short, eg the controller is bolted to the side of the mndc. (assuming you battery cables are much bigger 0 to 4/0). In this case 4 guage for the cotnroller is fine. When in doubt check the voltage drop, and ampacity using http://www.calculator.net/voltage-drop-calculator.html

And yes the controller pos connects to the battery side of the inverter breaker. Dont try to connnect it to the plus bus bar... it isnt rated for 100 amps.

vtmaps

bill wrote: »

I'm assembling a MNDC 250. In one instance I read, "...use nothing smaller than #2 wire for the C.C. Bat +, anything smaller may damage C.C.". In MNDC 250 I read, "tie battery bank (+) lead thru # 6 wire at the inverter DC breaker to the C.C. Looking at the photos I see what appears to be # 6 lead (top photo page 6) coming from the bottom of the 250 breaker. In all pictures of the C.C. the lead tied to the B+ has to be at least 0/1. Why would I use a #6 lead when Outback tells me that anything smaller than #2 may damage the unit? Or is there a change of wire size we don't see?

In your ePanel there is a battery bus that is connected by very heavy cable to the battery terminals. Probably the Outback instructions assume that you are connecting the controller (through a circuit breaker) to the battery terminals with several feet of cable, rather than just a very short cable to the battery bus.

--vtMaps