In our previous LD FL and now in our "new" '05 RB, I've had to maintain a constant vigil over the batteries, using a Pro-Fill system to keep the batteries' water levels at the optimum level. On our 5-6 month winter trek, we are mostly using campground hookups, so the old Parallax/Magnetek 7345 single-stage charger/converter tends to over-charge the batteries. The PDI PD4655 upgrade kit is essentially a drop-in replacement.
There are three parts to the converter/charger, and one has to access each of them. At the upper left is the AC panel - this is where the power from the surge protector is fed in. On the right is the 12V distribution panel. The PDI kit includes a replacement 12V panel, with three additional circuit connections. Here I'm in the process of transfering each wire, one by one, moving its fuse and writing down what each circuit is. At the bottom, in the wide compartment, is the old converter/charger. It merely slides out and the new one slides in, with 5 wires to connect. PDI's instructions are quite clear.
A close-up of the 12V distribution panel, showing the additional circuit connections. On the right side is the Charge Wizard green indicator light, which tells you which of the three charging phases is in use.
Here is the completed installation, with the new converter/charger in place in the bottom compartment. All that remains is to re-mount the brown panel cover.