The Home Battery ReportIndependent · No installer money

Fortress Power eVault Max 18.5 vs EG4 PowerPro WallMount

A straight, side by side read on specs and warranties, with the honest caveats. Every figure is from the manufacturer datasheet; sources are at the bottom.

Figure - Specs to scalebars vs the largest in our database
Fortress Power eVault Max 18.5 versus EG4 PowerPro WallMount: specs to scaleHorizontal bars comparing usable capacity, continuous power, peak power, warranty for Fortress Power eVault Max 18.5 and EG4 PowerPro WallMount, each scaled against the largest value in the home battery database.Fortress Power eVault Max 18.5EG4 PowerPro WallMountUsable capacity18.43 kWh14.3 kWhContinuous power9.2 kW10.2 kWPeak power12 kWNot publishedWarranty10 yr10 yr
SpecFortress Power eVault Max 18.5EG4 PowerPro WallMount
ChemistryLFPLFP
Usable capacity18.43 kWh14.3 kWh
Continuous power9.2 kW10.2 kW
Peak power12 kWNot published
Round-trip efficiency98%Not published
Warranty10 year warranty, rated for 8,000 cycles at 80 percent depth of discharge10 year warranty, over 8000 cycles at 80 percent depth of discharge, 82.6 MWh rated lifetime production
Backup scopeWhole-home capableWhole-home capable
InverterSeparateSeparate

What actually differs

  • More usable capacity: the Fortress Power eVault Max 18.5 offers 18.43 kWh vs 14.3 kWh, so at that size it carries more of your home for longer per charge.
  • More continuous power: the EG4 PowerPro WallMount sustains 10.2 kW vs 9.2 kW, which matters for running big loads like an AC at once.

Which one pays off is a numbers question.

Neither spec sheet tells you the payback in your home. That comes from your rate plan and incentives.

Run the Worth It calculator →

eVault Max 18.5 vs PowerPro WallMount FAQ

Is the Fortress Power eVault Max 18.5 or the EG4 PowerPro WallMount better?

Neither is universally better. The Fortress Power eVault Max 18.5 carries more usable capacity (18.43 kWh vs 14.3 kWh), while the smaller unit can cost less and fit tighter spaces. The right pick depends on your home's loads, backup needs, and budget, not the brand on the box.

What is the difference in usable capacity between the Fortress Power eVault Max 18.5 and the EG4 PowerPro WallMount?

The Fortress Power eVault Max 18.5 offers 18.43 kWh and the EG4 PowerPro WallMount offers 14.3 kWh of usable capacity.

Which has more continuous power, the Fortress Power eVault Max 18.5 or the EG4 PowerPro WallMount?

The EG4 PowerPro WallMount sustains 10.2 kW continuous vs 9.2 kW, which matters for running big loads like an air conditioner at once.

Is the Fortress Power eVault Max 18.5 or the EG4 PowerPro WallMount cheaper?

Neither spec sheet tells you the installed cost or the payback in your home. That depends on your electricity rate plan and local incentives, so run the numbers for your address rather than comparing sticker prices.

Sources

Source: Fortress Power eVault Max 18.5 Technical Datasheet. Specs verified 2026-07-01. Figures are per single unit at beginning of life; confirm the current datasheet with your installer.

Source: EG4 14.3kWh PowerPro WallMount All Weather Battery Specification Sheet Ver. 1.0.1. Specs verified 2026-07-01. Figures are per single unit at beginning of life; confirm the current datasheet with your installer.