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Scenario

A boondocking weekend in a travel trailer on 200 Ah of lithium and 400 W of solar

Works, tight. 2 × LiTime 12V 100Ah LiFePO4 gives 2,048 Wh usable at a 20% reserve; these loads use 1,080 Wh a day and charging adds 2,256 Wh, so it lasts charging covers daily use against a 2-day target calculated. Data updated .

Open this setup in the planner to change any part, load or hour.

Two days off-grid in June near Denver, panels flat on the roof. The converter only matters back on shore power.

The setup

  • Battery: LiTime 12V 100Ah LiFePO4 × 2
  • Converter: WFCO WF-8955LiS (lithium switch)
  • Solar controller: Victron Energy SmartSolar MPPT 100/30
  • Inverter: Victron Energy Phoenix Inverter 12/1200 VE.Direct 120V
  • Solar: 400 W, flat on the roof
  • Place and month: Denver, CO, June: 7.52 peak sun hours on a flat surface; coldest mean daily low 11.7 °C calculated
  • Inverter on 5 h a day (as long as the longest-running AC load), efficiency 91% (maker's peak figure)

Daily loads

LoadRunning WQty × hoursBattery-side Wh/day
LED light (per bulb) (AC)11.5 Wrange 8–15 W6 × 5 h379 Wh calculated
Shurflo 4008 3.0 GPM water pump (12 V DC)61.2 Wrange 26.4–81.6 W1 × 0.5 h31 Wh calculated
Phone/laptop charger (AC)60 Wrange 20–100 W2 × 3 h396 Wh calculated
TV (portable) (AC)100 Wrange 50–150 W1 × 2 h220 Wh calculated

Every appliance figure we list: appliance wattage.

Typical running watts are the midpoint of the published range calculated; a load with no published duty cycle is counted at its running watts for every hour listed. Inverter idle draw: 11 W maker spec × 5 h.

Charging per day

Solar 2,256 Wh (panel W, capped by the controller, × peak sun hours × 0.75), alternator 0 Wh, shore 0 Wh calculated.

Compatibility checks

  • 12 V parts: works. Every part chosen is a 12 V part.
  • Batteries in parallel: works. Within the battery maker's stated parallel count.
  • Converter lithium mode: works, tight. The converter has a lithium mode, but a voltage to compare is not published by one of the makers.
  • Converter current: works. The converter's rated output is within the bank's published max charge current.
  • Inverter vs BMS (continuous): works. At full rated power the inverter draw is under 80% of the bank's BMS continuous rating.
  • Inverter vs BMS (surge): works. The inverter's rated surge draw is within the bank's published BMS peak current.
  • Solar controller current: works. The solar controller's rated output is within the bank's published max charge current.
  • Cold-weather charging: works. The coldest expected temperature is at or above the battery maker's minimum charging temperature.

Smallest banks that pass every check

None of the batteries we list passes every check with these chargers and inverter, at up to its maker's stated parallel count. The checks above show which limit is hit; changing a charger or the inverter in the planner changes the result.

How each check works: compatibility checks. Every formula: methodology.

Sources