I just finished installing my new converter board (for lithium) and my new lithium batteries. See my comment #36 in this post for the actual parts. I thought that I would provide an update on the issues that I found and tests that I did.
Before removing anything I tested the charging current to the lead acid batteries at an initial 12.0V charge level (about 50%). The charging current was 42A so I know that the resistance of the batteries is limiting the charging current since the alternator is a 225A alternator.
Installing the new converter went well. However since the large DC cables have to go around back I needed to remove the DC fuse board (upper right in img_9792). I broke the plastic tab which provides pressure on the bottom to lock it in place. I am still searching for a fix so if anyone has done this (I am probably the only one) and has a good solution please let me know. I am thinking that I will build a small plastic "spreader" (opposite of a clamp) to put pressure between the tab that I broke and the bottom of the DC board. Since I also bent a couple of the fuses I installed the new DC fuse board (which has a switch for selecting between lithium and lead batteries). I was just going to jumper the cable that goes between the converter and the DC fuse board in the new setup.
In order to connect the DC cables to the new DC fuse board, I had to open the strain reliefs to allow the DC cables to move. Unfortunately these are cheap plastic units which are almost impossible to get to open (img_9794). They have a one way clamp that uses a gentle slope to push the clamp in but a perpendicular face to pull the clamp out. I finally got them off and replaced them with screw tightened strain reliefs (img_9795 bottom red and white cable). You can see the amount of construction debris left under the bed/behind the power center) by Thor manufacturing. I vacuumed it all out.
I then labeled all the battery wires and made a sketch of the connections. The sketch was useful because all the labels fell off. The batteries installed easily. I had to buy one longer M8 bolt because three cables were connected to one post and I couldn't get them all to fit. For some reason the new bolt has a bolt flat size 1mm smaller than the batter bolts (I think because the battery bolts have rounded corners and a phillips screw fitting in the hex head).
I plugged the RV into shore power and the converter worked fine. It charged the batteries at 45A with a 55% state of charge of the batteries. There were no other loads so the batteries limit themselves. The recommended charge rate is 20A per battery so the battery BMS must limit charging. I removed the shore power and started the engine. The generator charged the batteries at 45A. So I am not going to change my IRD (after removing my reservoir coolant tank I found that I have an IRD, not a BIRD) or trombetta and I won't install a DC to DC charger. I didn't even check the alternator temperature due to the low charging current. I will recheck the charge current when the charge level goes down to below 25%. I also checked my starting current of my RV engine starter. It was over 600A. How much over I do not know since my Hall Effect CT has a max range of 600A. I started the Onan generator off the coach batteries and the Onan generator drew 80A for starting current. I checked the ripple in the DC converter and it was 0.015V which is fine.
When I installed the LFP batteries, I downloaded the Li App. It gives the charging current and system voltage both by individual battery and as a paralleled system. The voltage and current matched my measurements until the batteries reached 100% state of charge. Then the battery app stated that the voltage was 13.5V but my measurements were 14.6V out of the converter. I assume that the battery BMS must just disconnect the incoming power (or prevent any further current flow) once 100% charged. From the app one can actually shut off the battery. The batteries were shipped that way. To wake them up you just need to connect it to a voltage (I am not certain what the minimum required voltage is) but they woke up as soon as I turned on the converter with shore power.
I plan to test these batteries by dry camping soon.