Lance TC - lithium - DC-DC charger question

Lithium changes the parameters of TC battery charging. An old lead acid or newer agm work just fine with simple truck and TC battery separation devices. I kept the battery types the same in everything. All lead acid 12.6 volts or agm 12.8 volts so one system wouldn't discharge into the other even if fully charged. I used to use a constant duty solenoid switch to connect and separate the two systems with a 4 gauge +/- wires to the TC. My old agm batteries could take a higher charge current than the lead acid but nothing compared to what the lithium batteries will accept. The lead and AGM internal resistance was high enough, no extra current limiting was needed. With lithium, a large battery bank can look like a near short drawing a lot of current causing a need for a current limiting device. I have seen the solar panels pouring 60 amps current into the life batteries and more with the engine running and the Victron dc dc 30 amp charger contributing to the mix. The lithium batteries look much much more like a dead short when they are significantly discharged. Your alternators could handle the load an agm could accept. The alternator needs to be spinning fast in hope of being able to handle the load demand. Victron has a couple videos explaining and demonstrating this and it becomes very clear very fast why you need a dc to dc charge controller if you want to charge your life batteries off your alternator. I'm a proponent of Victron products and they have served me well. When you do setup a dc to dc charge controller, be sure there is no connection to your TC system by the old 12 volt charge wire. It is of no use to you anymore excepting that you can use it for the key on trigger to activate the dc to dc charger turning it on and off automatically when you run the truck. You can also run a separate dedicated wire to do that. I did it to avoid possible conflict with the chance I might be towing something with electric brakes or other system. So remember, the more lithium batteries you have, the more you will need a dc dc controller. For large requirements, I believe you can wire multiple units in parallel to increase current if your electrical system can handle it. I currently have 675 watts solar on the roof and 404 amp hours lithium batteries. I am generally fully charged within 4 hours of sun up. After full charge, I switch my fridge from gas to 120 volt AC and run it off solar till low afternoon sun. The new system was pricey but it sure makes a difference camping. A favorite feature about lithium is it is always at 13.2 or more volts. The lights are always bright, the water pump always runs fast and hard, the FF fans work at full speed, everything electrical in the camper runs great and there is never a slowing down or brownout condition like AGM and lead acid have. After having made the jump to lithium and all it's particulars, I highly recommend it. It's not a necessity and if you're happy with the old tech, by all means save the money and keep doing what you're doing.