8.what happens when power limit (520w) is exceeded? e.g. if 600w (rarely) in to a 12 volt battery bank through this controller ,,,fry or limit?
If are using 600W charging a 12v battery, the charging voltage may probably be higher than 40A if you 've got a good sunlight, and it will damage the controller. We limit the input power is also a way to protect the controller.
9.What does it mean if battery light is blinking and what should I do about it？
If it's green, and slow blinking, it indicates battery is full, green light fast blinking indicates overvoltage, charging will be stopped.
10.Can I monitor and control multiple charge controllers with one MT-50?
The MT50 can only monitor its own charge controller, you cannot monitor multiple mppt charge controllers with one MT50.
11.Can this controller equalize a 24v battery bank？
Yes it will work with both 12v and 24v battery bank. If it detects that the battery is being over discharged, the solar controller will automatically turn the battery to equalization charging stage, and the equalization charging will be 120mins. Equalizing charge and boost charge are not carried out constantly in a full charge process to avoid too much gas precipitation or overheating of battery.
12.I have 7 100watt renogy panels and 6 125amh batteries 12volt system ,will this charger support this big of a system ?
For 12v battery system, this 40A unit can only handle max 520W solar panel. You can add another 40A charger or a 20A (if you are not adding more panels in the future), and parallel the two controller connect to the same battery bank.
13.Does anyone have the specification for the serial port？
The manual have listed that, RS-485 ports via the open standard Modbus protocol are supported to meet different occasion of demand.
14.Is this a positive ground or negative ground controller?
15.With 8 12v/100w panels, which is best: two 48v arrays or one 96v arrays?
Two 48V arrays will be better. 4 in series and parallel the two strings. You will get 88V open circuit. This MPPT charge controller can handle max 6x12v panels connected in series.
16.What’s the width length and depth of the controller itself？
The LxWxH: 302.5 x 182.7 x 63.5 mm
17.Can one set this so that there is no float charge for LiFePo4 batteries? (so that the charge current is totally disconnected once the battery is full)？
You can set the cut off voltage close to the float, but if you don't want complex setting, another resolution is use a DC to DC relay , once battery reach a certain voltage, use relay to cut the panel's input .
18.How is it that the "recommended power input" is 600w, but the "max pv input power" is 520w for a 12v system?
Considering solar panel's efficiency. The rated 520W is technical value, but generally for a 520W solar panel, it will not generate a actual 520W power, so we have this recommendation. 600W panel, with it's conversion rate, it may have 500W power output even at a full sun. Plus, our controller has this protection, even PV output greater than 520W, still not damage the controller.
19.What is the minimum input voltage from pv arrays in order to charge a 24v battery bank?
Minimum voltage should be at least 44V (Voc), if you are using 12v panel, it should be at least 2 in series. a 60cells 24v panel wouldn't be working charging a 24v battery bank. 72cells panel will be fine.
20.Can this be programmed to shutdown inverter at a certain voltage?
We can achieve this feature, but it require another device called "solid state relay", you can refer to this itemhttps://www.amazon.com/dp/B07429RK43 , there is a schematic on the product description.
The theory is, connect the relay to the controller's load, and set the LVD at 11.1V, when battery voltage drop to 11.1V, the controller will turn the "load " terminals off, and this terminal connect the solid state relay, when there is no voltage on the relay, it will turn off the inverter at the same time.