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Overview of Phase 2: Wiring Panel, Inverters, Worktable
This page gives an overview of Phase 2.
Phase 2 by early Feb 2018:
- Add a 2nd Lithionics 5 kW 400 amp battery in parallel with the existing battery for a total of 800 amps / 10 kW for extended runtime, thus increasing the odds that charging can occur while necessary driving is done. Also yields power for some hours of 1.5 kW electric heating, thus saving fuel.
- Add 2nd Xantrex Freedom XC 2000W inverter charger for total charging power of 160 amps when on shore power, plus redundancy, plus ability to run a space heater on one inverter and gear on another.
- Rewire shore power outlet from 12 AWG (insufficient) to 8 AWG terminating in two standard household outlets in wall.
- Install custom butcher block table for workstation surface.
- Bolt both inverters onto rear underside of table, thus freeing up floor space occupied by existing inverter, and also shortening power cable runs to maintain higher voltage in the 130+ amp range.
Phase 2 Benefits:
- More than double the runtime: twice the amp-hours means twice as much stored power but also means 1/2 the draw from each battery will reduce voltage losses at high draw, leading to more efficient power inversion.
- Twice the shore power charging rate (80 amps X 2) via 30 amp shore power, thus keeping total charge time the same since the battery storage is 2X.
- Double inverters with the option to use 0 (direct shore power) or 1 or 2 inverters. This matters because some places might not have 30 amp shore power, so one inverter must be unplugged so it won’t overlod an 18 amp circuit.
- Inverters hard-wired for AC input on the inverter end, but terminate in regular 120V household plugs, each of which can be plugged into shore power outlets in wall.
- Dual shore power outlets also allow direct use of shore power, bypassing batteries and inverters and thus eliminating annoying fan noise from inverter when on shore power.
Proposed wiring schematic
All wiring from batteries to inverters is to be 4/0.
Wiring from alternator to solenoids is dual 1/0 to dual solenoids (one wire each). Two wires to ensure solenoid not near its limit. Convert to 4/0 if testing shows that it encourages alternator to send more amps (how to test without actually making cables?!)
Background: Phase 1 wiring as of Jan 2018
This panel installed under time pressure. It serves a single 400 amp Lithionics battery and one inverter/charger.
There is significant volatage drop when drawing 130 amps all the way to 200 amps. A redesign for shorter cable lengths using 4/0 cabling is in order to cut voltage losses by 2/3. This matters a lot becuase at 200 amps draw, the voltage from the battery can go as low as 11.7V, so further drops make the inverter bitch and moan as well as being inefficient.
Xantrex XC inverter/charger
The Xantrex XC inverter/charger which is bolted to the driver seat box. The wiring panel is to the left on the wall. Phase 2 contemplates bolting on both inverters under a 48 X 29 X 1.5 inch butcher block table surface. That will free up some valuable floor area under the desk.
Double cables from alternator to battery
Double 1/0 cables were run from the auxiliary battery (the Mercedes Sprinter is wired from alternator to starter battery to auxiliary battery). Net result: a drop of only 0.05 volts from the auxiliary battery to the terminals of the Lithionics battery. That’s about 12 feet of cabling running to the two solenoids on the wiring panel, then running to the battery.
TBD is testing whether two cable encourages the alternator to ouput more amperage or less—the assumption had been that two cables is better, but this should be proven by testing (disconnecting one cable).