A lot of reading indeed. I've been at it for 2 weeks and am just scratching the surface. My panels are Canadian Solar CS5P-255Ms. They have a VMP of 49v an IMP of 5.21a and a VOC of 59.8v. When I disconnect the panels from the batteries and test the panel volts I get 55v on a sunny day. The SOC voltage of the batteries without a load hangs around 55v and with a load, 52v. I am aware that the C-40 is not an MPPT and am looking into getting one. I have my system set up so the current from the panels can go directly to the inverter/loads when needed so that's why my amps rise under load. (C-40 acting as load control basically.) As I understand XeonPony my panels will never get the batteries to the bulk voltage of 57.6v without an MMPT charger right? Would wiring my panels in series solve this? (Be patient with the new guy .) Many thanks for the help. More reading (a lot) for me.
No worries on being patient, some got it, some don't. You need answers now and I understand as while you are reading, your batteries are taking some abuse.
I'm afraid you will be needing to series the two panels and go MPPT via the best controller you can afford. If you do series without MPPT, you may find you only get ~275 watt/hr but you will be able to charge the batteries indeed although at a substantial panel loss and I don't know what kind of voltages the c-40 is capable of controlling. I can preach Midnite Solar but unless you are going to continue to add the same panels of the same type to your array, there are other controllers out there that may better suit your need with just these two panels at nominal 510w. I say this because at 48 nominal volts float will need just over 52 volts as you mentioned. Bulk and absorb are even higher than that, not to mention equalizing stage. So far, you don't have near the voltage needed to do anything more than what you have discovered. At this stage, you may have enough voltage to keep your batteries from ruining so long as you have another source to completely charge your batteries. I'd suggest that you do just that and put the system on hold until you can better configure your panels for actual battery charging or do the above scheme for a substantial loss. At best, you have a grid tie set of panels if you have an inverter which can track that voltage and current into the grid.
As far as what you will get from your panels, right now you may actually only get ~300 watt/hr from your set, while with mppt you could get over panel ratings of course depending on your complete system layout. What is the amp/hr rating of your battery set? If your group is too large, your available power ( as configured at the moment ) may only be enough to maintain your battery group. So, at the moment, this advice is nothing more than a guess.
Glad you asked now instead of waiting and wondering why your batteries will no longer produce voltage as label rated. Good luck.