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Scenario

Winter boondocking: will heated lithium run the furnace fan?

Works. 2 × Epoch 12V 105Ah Heated Bluetooth (Essential) gives 2,150 Wh usable at a 20% reserve; these loads use 1,208 Wh a day and charging adds 1,029 Wh, so it lasts 12.0 days against a 3-day target calculated. Data updated .

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

January near Flagstaff. The furnace blower is counted for 8 hours of run time a day; how long it actually runs depends on your rig and the weather. The battery heater's own draw is not published, so it is not added.

The setup

  • Battery: Epoch 12V 105Ah Heated Bluetooth (Essential) × 2
  • Solar controller: Victron Energy SmartSolar MPPT 100/30
  • Solar: 400 W, flat on the roof
  • Place and month: Flagstaff, AZ, January: 3.43 peak sun hours on a flat surface; coldest mean daily low -8 °C calculated

Daily loads

LoadRunning WQty × hoursBattery-side Wh/day
Suburban SF-42Q furnace blower (12 V) (12 V DC)108 W1 × 8 h864 Wh calculated
LED light (per bulb) (AC)11.5 Wrange 8–15 W4 × 6 h314 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

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.

Charging per day

Solar 1,029 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.
  • 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

Same chargers, inverter and loads, trying each battery we list at up to its maker's stated parallel count (one battery where no count is stated). Ranked by bank size, smallest first; we don't rank by price or quality.

  1. Epoch 12V 105Ah Heated Bluetooth (Essential) × 1: 1,344 Wh rated, lasts 6.0 days
  2. SOK SK12V206H 206Ah 12V (heated, Bluetooth) × 1: 2,637 Wh rated, lasts 11.8 days
  3. Epoch 12V 300Ah Heated Bluetooth Group 31 × 1: 3,840 Wh rated, lasts 17.1 days

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

Sources