Battery backup for a pellet stove

People buy pellet stoves partly as insurance against losing heat, which makes the discovery in the first hour of a winter outage particularly unwelcome: the stove is an electrical appliance that happens to burn wood. Take away house current and the auger stops feeding, the blowers stop turning, and the appliance stops being a heat source. Unusually for this site, the numbers you need are published clearly, on the same page of every owner's manual, and so is the manufacturer's own view of what to do about it. We have not tested any of these products, and the Amazon links above are affiliate links, disclosed at the top of this page.

What the manuals publish, and where

Pellet stove makers put the electrical rating in the listing and code approvals section at the front of the owner's manual, usually alongside the glass specification. Three manuals, all published by Hearth & Home Technologies and read on August 19, 2026:

• Harman XXV Pellet Stove. The appliance certification table lists an ELECTRICAL RATING of 115 VAC, 60 Hz, Start 4.2 Amps, Run 2.8 Amps, tested by OMNI Test Laboratories to ASTM E 1509-04 among other standards.
• Quadra-Fire Classic Bay 1200. Section E, Electrical Rating: 115 VAC, 60 Hz, Start 3.75 Amps, Run 1.88 Amps.
• Quadra-Fire Santa Fe. Section E, Electrical Rating: 115 VAC, 60 Hz, Start 4.1 Amps, Run 1.1 Amps.

Multiply the running amps by 115 V and you get the ceiling on the apparent power the stove asks for while it burns:

| Model | Published start | Published run | Start, at 115 V | Run, at 115 V |

|---|---|---|---|---|

| Quadra-Fire Santa Fe | 4.1 A | 1.1 A | about 472 VA | about 127 VA |

| Quadra-Fire Classic Bay 1200 | 3.75 A | 1.88 A | about 431 VA | about 216 VA |

| Harman XXV | 4.2 A | 2.8 A | about 483 VA | about 322 VA |

Two honest caveats attach to that table. Volt-amps are not watts. The auger and the two blowers are motors with a power factor below one, so the real watt draw is lower than the volt-amp figure, and none of the three manuals publishes a power factor or a watt number, so we cannot convert precisely. We print the volt-amp figure because it is derived from what is published and it is the conservative direction to plan in. And the run figure is a rating, not a live reading: these stoves modulate feed rate and blower speed, so actual consumption moves with the heat setting.

The spread is the finding. Three models from the same corporate family differ by 2.5 times on the running figure, from 1.1 A to 2.8 A. There is no such thing as the wattage of a pellet stove. There is only the number on the certification page of your manual, and the label on the back of your appliance.

The start figure, and why it does not decide the answer

Every one of those manuals publishes a start rating higher than its run rating, by a factor of 1.3 to 3.7. The igniter is the main reason: it is a resistive hot-surface element that draws hard while the pellets catch, alongside the auger and the combustion blower running to establish the fire.

That phase is short. Harman's starting instructions say to let the appliance burn for approximately 7 to 10 minutes after ignition before it settles into its control settings, and Quadra-Fire's Classic Bay instructions say approximately 15 minutes. So the start figure sets the output requirement, once per ignition cycle, and the run figure sets the capacity requirement, for the whole outage.

Against the largest published start figure here, about 483 VA, every unit in the picks above publishes at least 3,840 W of continuous output. The surge question that dominates our well pump and air conditioner guides simply does not arise for a pellet stove. This is a small load with a large runtime requirement, which is the opposite shape.

One detail worth knowing from the Harman manual, because it affects what a marginal power supply does to the stove: the low draft pressure switch monitors negative pressure in the firebox, and if draft becomes too low for proper combustion the switch opens, "cutting power to the feed motor and the igniter circuits." The stove is designed to protect itself when the exhaust path is not working, which is a good reason to prefer a clean sine wave supply and not to improvise.

What the makers say about battery backup

This is the part that distinguishes a pellet stove from every other appliance on this site, and it deserves quoting rather than summarizing.

Harman's owner's manual devotes a section titled "Loss of Power" to it and opens with a recommendation, in bold in the original: "Harman strongly recommends installing battery back-up to minimize entry of smoke into the room in the event of power loss." The reason follows immediately: "Your pellet/biomass burning appliance relies on a combustion blower to remove exhaust. A power failure will cause the combustion blower to stop. This may lead to exhaust seeping into the room. Vertical rise in the venting may provide natural draft. It is, however, no guarantee against leakage."

Harman then names two approved options, and the distinction between them is the whole design decision:

• An uninterruptible power supply. Harman states that appliances with Rev E or later software, available beginning in November 2010, may be plugged directly into a Harman approved UPS, and names two: "The APC (American Power Conversion) model #BE750G and the TrippLite model INTERNET750U are tested and approved. Other brands or models may not be compatible." What it buys is limited, and Harman says so: "When power is lost, a fully charged UPS will power a safe, combustion blower only shut-down. Your appliance will pulse the blower every few seconds to clear exhaust until the fire is out. NOTE: The UPS provides safe shut-down only. It is not intended for continued operation."
• A dedicated 12 V system. "The Surefire 512 connects to a 12 volt deep cycle battery that will run your appliance for up to eight (8) hours. It includes a trickle charge feature that keeps your battery charged when power is available." Harman adds the caveat: "If the power is out for longer than battery life, smoke leakage may still occur unless your stove has been safely shut down."

Read that carefully before buying anything, because it sets a standard the rest of this page has to live under. A portable power station is not on Harman's approved list. Harman tested and approved two specific UPS models and one dedicated 12 V controller, and explicitly warns that other brands or models may not be compatible. If you are considering a power station for this job, that is a question for your stove's dealer and your stove's manual, not one this page can settle. What the arithmetic below does is tell you what capacity the job would take, so that conversation starts with real numbers.

The runtime arithmetic

Rated capacity divided by the published running figure, treating volt-amps as watts, which overstates the load and therefore understates the runtime. These use rated rather than usable capacity and ignore inverter losses, the low voltage cutoff and the station's own standby draw, so treat them as ceilings with a conservative load assumption pulling the other way.

| Unit | Rated capacity | At 127 VA (Santa Fe) | At 216 VA (Classic Bay 1200) | At 322 VA (Harman XXV) |

|---|---|---|---|---|

| BLUETTI Apex 300 | 2,764.8 Wh | 21.8 h | 12.8 h | 8.6 h |

| Anker SOLIX F3800 Plus | 3,840 Wh | 30.2 h | 17.8 h | 11.9 h |

| EcoFlow DELTA Pro 3 | 4,096 Wh | 32.3 h | 19.0 h | 12.7 h |

| Jackery Explorer 5000 Plus | 5,040 Wh | 39.7 h | 23.3 h | 15.7 h |

| EcoFlow DELTA Pro Ultra | 6,144 Wh | 48.4 h | 28.4 h | 19.1 h |

The shape is the useful part. On a low-draw model, a single large power station covers one to two days of continuous burning. On a high-draw model, the same unit covers most of a day and no more. A pellet stove burns continuously to hold a room temperature, unlike a furnace that cycles, so there is no duty cycle discount to apply here the way there is for a gas furnace in our winter outage guide.

That also means a multi-day cold snap is not a single-battery problem. It is an expansion battery problem, a second unit problem, or a recharge problem, and the recharge route is covered in our generator pairing guide.

The practical checklist

• Read your own certification page. Section E of the owner's manual, or the safety label on the back of the appliance. The number varies by 2.5 times across three models from one manufacturer.
• Ask the dealer what your maker approves. Harman names specific tested products and warns that others may not be compatible. Other makers may say something different. This is not a place to assume.
• Understand what you are buying: a shutdown or a run. Harman's own framing separates the two. A small UPS buys a safe, blower-only shutdown that clears the exhaust. Running the stove through the outage is a larger and different purchase.
• Check the transfer time if the stove stays plugged in. A stove that reboots on transfer is a stove whose ignition cycle restarts. Published switchover figures for the units above are collected in our transfer times guide.
• Check what the cold does to the battery. If the unit lives in an unheated space, every maker publishes a charging temperature range narrower than its discharging range, and those figures are in home batteries in cold weather.
• Keep carbon monoxide detectors working. Harman's stated failure mode in an outage is exhaust entering the room, and Ready.gov instructs installing working carbon monoxide detectors on every level of the home.

Choosing between the picks

• One long winter night on a low-draw stove: the BLUETTI Apex 300 at 2,764.8 Wh, with the longest published cycle rating of the plug-in units on this page at 6,000 or more cycles to 80 percent.
• A full day at the higher published draws, with room to grow: the EcoFlow DELTA Pro 3 at 4,096 Wh, expandable to 12 kWh on one unit.
• The stove plus the fridge, the router and the lights: the Jackery Explorer 5000 Plus at 5,040 Wh, whose bundled Smart Transfer Switch is the route to circuits if the stove is on a dedicated one.
• A multi-day cold snap: the EcoFlow DELTA Pro Ultra at 6,144 Wh per battery, expandable to 30 kWh on one inverter.

Every figure above is a manufacturer publication recorded with its stated basis: electrical ratings and power-failure guidance from the Harman XXV, Quadra-Fire Classic Bay 1200 and Quadra-Fire Santa Fe owner's manuals published by Hearth & Home Technologies, and power station capacities and output ratings from each maker's own spec table. The runtime numbers are arithmetic on those claims under the assumptions stated, not measurements we made, and not an endorsement of running any specific stove from any specific power station. Your stove's manual and your dealer govern that.