OP - I understand your frustration. I was quite content in my thinking the data I was seeing on my ARC-50, with a MS2812/Temp Sensor/BMK-Meter all going thru a BMK-Meter Kit Shunt - was keeping me accurately informed on teh contain of my house bank... Well, not quite -was the real truth!
On the info line's where you are seeing on Line One 'Bulk Charging, and line 2 'DC 13.9V + 24A' - here is my understanding after a recent call to Magnum Tech Support:
Line 1: Is pretty basic, showing that the Inverter/Charger is in Charge mode, and it's in the Bulk stage.
Line 2: Shows the DV value is 13.9V. And that the 'Amps are at 24A. Now, her is where it gets less then easy to understand what that '24A' might represent. In charge mode, one would hope it would reflect what the Charge In Amp's are being fed into the battery. So that Tapered Down 'Amps' could be determined. But from my recent call with Magnum Tech Support, I was informed it's really a combo of the 'Amp's draw to the coach + the Amp's Charge to the battery.'. So say the coach is drawing 10Amps, that would mean the Charge Amps would be 14Amps = 24A displayed'.
And while Magnum's manuals have lots of info. I agree, that between my MS2812, BMK-Meter and ARC-50 Control Panel - NO WHERE DID I READ WHAT THE 'Line 2 Display of Volts and or Amps represent.
Unfortunately, I interpreted the '24A' of Line 2 to represent the 'Tapered Down' charge amps value - so important to monitoring the actually charge status of a battery bank... This miss interpretation by me, resulted me 'hammering my suspect battery bank', with multiple charges and equalize charges - in the quest to obtaining 'Full Charge' amp values for my specific size Battery Bank. ( 4 Amps, was the value that Lifeline indicated as Full Charge for my 800AH Bank. My coach idle/parasitic draw of between 9-12 Amps. And the 'Line 2' Amps reflected never dropped below 12-12Amps displayed. (Usually between 13-15Amps was displayed.) ---- Well, that made me feel think, wrongly, that my battery bank was not fully charged (4Amps recommend by Lifeline).
So, I learned quite a bit - sadly after the fact, on what was, or was not, displayed by the Magnum ARC-50 panel. And yes, I've pointed out how misleading this value is, as well as if this info is 'documented' in any of their documentation - it was buried where I missed it(:!
Don't get me wrong. I like Magnum products. I like their tech support. But, the deeper I dive into things, the more I learn about both documentation confusion, as well as frankly IMO 'Holes in their the Charging Programing Logic'. And that's OK, as they evolve, and I continue to learn.
I as an owner. Have sole responsibility for the care and feeding my House and Chassis battery - I sort of 'Burn as I learn!'. Expensive lesson's, at time...
Best to you,
Smitty