EcoFlow Delta Pro 3 Review — 92% Delivered, 240 V Verified, and a Well Pump on Battery

From full to shutdown on a constant 300 W load, with a meter at the AC outlet, it ran for 12 hours 40 minutes and delivered 3,772 watt-hours from a rated 4,096 Wh — 92.1%.

That's the highest usable percentage of all eleven units I tested, and within 18 Wh of the 3,790 Wh OutdoorGearLab published.[1]

Some of that is physics rather than engineering: an inverter's fixed overhead is a much smaller share of a 4 kWh pack than of a 288 Wh one. But the Anker SOLIX F3800 Plus, at a similar size, delivered 89.8% on the same test.

The outage drill. My electrician fitted a transfer switch, I cut the mains, and I let the Delta Pro 3 carry real household circuits. The fridge, freezer and router ran for 31 hours. The switchover took 10 ms, so nothing reset. I also ran the well pump on 240 V, which is the reason this class of unit exists.

This is the Delta Pro 3's real differentiator. It provides native 120 V and 240 V split-phase output, including an L14-30 outlet, and I verified it on my well pump.[2] Of the eleven units I tested, only it and the Anker SOLIX F3800 Plus do this.

That matters for a specific, short list of appliances: a well pump, an electric dryer, most central air handlers, an electric range. Everything on a normal household circuit is 120 V and doesn't care.

Calculated from my measured capacity — assumptions here.

My observed fridge-only runtime of 80 hours beat the calculation, because my fridge drew a little less than the assumed average.

2 hours 32 minutes from empty to full on the wall, with input peaking at 1,820 W — slightly above EcoFlow's 1,800 W figure.[2] That's quick on a 240 V circuit; on a standard 120 V outlet it's noticeably slower, which is the main reason I rated charging 4 rather than 5.

Solar is the standout: 2,600 W across two MPPT ports — a high-voltage port up to 1,600 W and a low-voltage port up to 1,000 W.[2] My 2,400 W roof array peaked at 2,480 W into it. That's enough to refill the pack in a single good day.

113.2 lb on my scale. It has wheels and a pull handle, which work well on smooth, flat floors and much less well on anything else. Plan where it lives before you buy it. I rated handling 3 out of 5.

Everything else is premium. The build is excellent, with rugged port covers. The big screen and menus are the easiest I used. The 240 V and RV outlets are where you'd want them. And EcoFlow's app is the best I tested for home-backup scheduling.

It was quieter than I expected for 4 kW: 41 dBA at about 500 W, 58 dBA at maximum output. In a garage that's nothing.

One thing to know: its idle draw with the inverter on was 34 W — about the same as a CPAP. Over a day that's 800 Wh, so switch AC off when you don't need it.

LiFePO4 rated for 4,000 cycles to 80%, five-year warranty.[2] 4,000 W continuous, which I held for ten minutes, and expansion to 12 kWh on a single unit or 48 kWh as a paired system.[2]

• $3,699 before add-ons, and about $0.98 per usable watt-hour — worse value per watt-hour than several units a tenth of the price.
• 113 lb. Easy on flat floors only.
• Needs an electrician for panel connection. Whole-home use is a project, not a purchase.
• Slow on a 120 V wall outlet.
• 34 W idle draw.

The obvious rival is the Anker SOLIX F3800 Plus, which I also tested. It out-muscles the Delta Pro 3 — I held 6,000 W through it, against 4,000 W here — accepted more solar (3,050 W against 2,480 W), and costs $1,300 less.

The Delta Pro 3 delivered 324 Wh more usable energy, switched over in 10 ms rather than 20, weighed 23 lb less, has a better app and a longer cycle rating, and ran my fridge, freezer and router three hours longer. For home backup I'd buy the EcoFlow; for off-grid solar, the Anker. The full comparison is here.

After 44 days, including a real outage drill through a transfer switch, the Delta Pro 3 is the best power station I've tested, and it's my pick for home backup. It delivered 92% of its rating, ran my well pump on 240 V, kept the fridge, freezer and router going for 31 hours, and switched over without a flicker. I'd buy it again.

The reservations are practical rather than technical. It costs over $3,000 before add-ons. It weighs 113 lb. Using it as home backup properly means a transfer switch and an electrician. And it's slower to recharge from a standard 120 V outlet.

If you're replacing a gas generator, this is the one. If you want more raw power and solar for less money, the Anker SOLIX F3800 Plus is the alternative — at 136 lb and with louder fans.