Electrical Upgrade - Distribution Panel and DC - DC 50A Charger, January 2024

Distribution Panel - To power everything in the Serenity that is AC from the inverter, it requires some modification of the distribution panel. 

The existing wiring only powers some AC circuits directly from the inverter. This keeps the inverter and house phases separate since they are never on at the same time in the panel. The panel is setup for 240 so has two separate power buses. Since 30A is only 120V it only needs one side of the panel. I will power one leg with the shore/Gen power and the other with the inverter. To do this, I need to move all loads to the inverter side and cut the neutral bus so that the Shore/Gen power and the Inverter can have their own phases. 

This is the existing panel before modification. All AC circuits are on one leg, including AC power to the inverter, which passes this onto the single inverter AC circuit in the RV. 

I was lucky that when I pulled the old inverted circuit wire back from the old inverter, it was long enough to reach the panel.  I did have to run a new Inverter AC IN wire because it needed to support 30A and EEE only ran 12AWG wire, so I ran two 10AWG wires from the panel to the inverter for the Inverter AC IN and AC OUT (back to the panel). 

This is the panel after modification. I have cut the neutral bus to separate the Shore/Gen side (right) from the inverter side (left). 

On the left, all house circuits (sans the 3Way fridge) will be on the Inverter circuit and be fed from the inverter via pass through of Shore/Gen power or inverted power from the batteries. 

The right is the Main Shore 30A breaker, a 30A feed breaker to the Inverter and a 15A breaker for the 3W Fridge. 

This is the finished panel.

Alternator Charging -  One of the good/bad things about Lithium batteries is their ability to deliver and receive large currents (Amps). Unlike a lead-acid battery, the internal resistance and corresponding voltage of a lithium battery does not rise until it is nearly 95% fully charged. This will result in a heavy load being drawn from the alternator for a long time causing over heating and burnout. The solution is to limit the amount of current the lithium batteries can draw from the Alternator. 

To address this, I am removing the existing isolation solenoid/charger from the LTV and replacing it with a Kisae 50A DC to DC charger. This will limit the charge current to 50A while driving. The Sprinter has a 220A alternator of which 80A can be used for auxiliary devices per the Mercedes specifications. 

In addition, I am adding isolation breakers (60A) and a relay switch to turn off (sleep) the charger when the vehicle is not running. The Relay basically uses the ignition wire to determine if the engine is running and not connect the chassis battery/alternator to the Kisae until it sees 12V from the ignition. The Kisae is powered by the house batteries and thinks the engine is running when it sees more than 12.8V sustained from the Chassis/Alt battery. This is a problem if you attach a charger (like a trickle charger) to the chassis battery, the Kisae will power up and could discharge the house batteries as well as the chassis battery.  This is also an issue for the Trik-L-Start charger I had previously installed in the LTV.  Lithium batteries have a higher float voltage so the Trik-L-Start thinks the RV is plugged in and will try to to charge the chassis batteries even when not connected to shore power. I had to remove this device and may add a device that is compatible with Li voltages later. 

I put the charger, breakers etc. under the dinette seat. I moved some of the self resetting breakers and a few other things to make room, but there was plenty of space. 

I am still waiting for my batteries, when they arrive, the next phase will be wiring up the batteries and the lynx distribution bus.