How Long Does the Anker F3800 Run a Well Pump, Fridge, and Freezer?
Bottom Line Up Front
Running a 3/4 HP well pump, full-size refrigerator, and chest freezer simultaneously, the F3800's 3,264Wh of usable stored energy lasts approximately 22–31 hours before exhaustion. Add a 2,400W solar array on a clear day and the system sustains indefinitely — daily solar potential (12,000Wh) vastly exceeds the 2,470–3,550Wh daily load. Add expansion batteries for no-sun buffer: each BP3800 adds roughly one additional day of autonomous runtime.
Jeff M. evaluates products based on technical specifications, manufacturer data, and aggregated owner feedback rather than direct long-term personal use.
When the grid fails, calculating a solar generator's actual runtime requires looking past the capacity number on the label and working through the real power draw of each appliance. Running a 240V well pump, a full-size refrigerator, and a chest freezer off a single F3800, the answer is one day from stored energy alone — 22 to 31 hours depending on your specific appliances. With solar, indefinitely. With expansion batteries, up to a week without any sun.
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The Load Calculation
The F3800 carries 3,840Wh of rated capacity. At 85% conversion efficiency (the standard loss from DC battery to AC output), usable stored energy is:
3,840Wh × 0.85 = 3,264Wh available for your appliances.
Daily energy draw per appliance:
Well pump (3/4 HP, 240V): ~1,100W running. In normal household use, the pump cycles intermittently to fill the pressure tank — approximately 30 minutes of total daily runtime. Daily consumption: ~550Wh/day.
Full-size refrigerator: Compressor runs 30–40% of the time at 50–75W average draw. Daily consumption: ~1,200–1,800Wh/day.
Chest freezer: More efficient than upright units due to top-loading design — cold air doesn't spill when opened. Average draw 30–50W. Daily consumption: ~720–1,200Wh/day.
Combined daily load: approximately 2,470–3,550Wh/day.
Without Solar: The 24-Hour Reality
Your 3,264Wh of usable stored energy covers roughly one full day — 22 to 31 hours — against the 2,470–3,550Wh daily combined load. At the higher consumption end, the system shuts down before completing a full 24-hour cycle.
This is the no-solar, no-expansion baseline. A single F3800 buys you one day of full home water, refrigeration, and freezer operation with zero sun.
Load shedding protocol when solar is unavailable:
- Cut the chest freezer first. A quality chest freezer holds safe temperatures for 24–48 hours without power if kept closed. Cutting it saves up to 1,200Wh immediately.
- Reduce well pump cycles. Limit water use to drinking and critical sanitation. Avoid unnecessary flushes and multi-appliance use that forces frequent pump cycling.
- Protect the refrigerator. Keep it online for food safety and medication. Keep the door closed to minimize compressor cycling.
With the freezer cut and pump cycles reduced, the remaining load drops to ~1,400–2,100Wh/day — stretching the base F3800 to 36–55 hours before exhaustion.
With Solar: Indefinite Runtime
The F3800 accepts up to 2,400W of solar input via dual XT-60 ports. Under 5 peak sun hours with a 2,400W array:
2,400W × 5 hours = 12,000Wh potential daily solar harvest
That 12,000Wh ceiling far exceeds the 2,470–3,550Wh daily combined load. During peak daylight hours, incoming solar drives the appliances directly while simultaneously recharging the F3800's cells back toward 100% before dark. The system sustains indefinitely under reasonable solar conditions.
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The Expansion Option
Each BP3800 expansion battery adds 3,840Wh of capacity, scaling no-solar runtime proportionally:
| Configuration | Total Capacity | Usable (×0.85) | Days (no solar) |
|---|---|---|---|
| F3800 base only | 3,840Wh | 3,264Wh | ~1 day |
| + 1 expansion | 7,680Wh | 6,528Wh | ~2 days |
| + 2 expansions | 11,520Wh | 9,792Wh | ~3 days |
| + 3 expansions | 15,360Wh | 13,056Wh | ~4 days |
| + 6 expansions (max) | 26,880Wh | 22,848Wh | ~7 days |
Fully expanded, the F3800 system runs well pump, refrigerator, and chest freezer for approximately 7 days with zero solar input.
What This Doesn't Cover
Consecutive overcast days: Dense cloud cover can drop solar input to under 15% of rated output, breaking the indefinite-run cycle and forcing load shedding.
Additional loads: The calculations above assume the F3800 is dedicated to these three appliances. Adding a coffee maker (1,000–1,200W), lighting (575Wh/day), or device charging accelerates depletion proportionally.
Battery aging: LFP cells naturally degrade to roughly 80% capacity over 8–10 years of cycling. Factor this into long-term planning — a 10-year-old F3800 provides approximately 2,611Wh usable at base, not 3,264Wh.
For the no-sun extended outage planning guide, see How Many Expansion Batteries Does the F3800 Need for a Week-Long Winter Storm?
For the full home power planning framework, see the Grid-Down Home Power Guide.
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