EG4 Electronics makes its WallMount battery in two versions for different spaces. The WallMount 314Ah Indoor stores about 16kWh in an IP20 cabinet with active balancing and over-the-air firmware updates, according to EG4’s spec sheet. The WallMount 280Ah All Weather stores 14.3kWh in an IP65 enclosure with built-in self-heating, an LCD touchscreen and 600A busbars, according to EG4’s All Weather spec sheet. Both are 51.2V LiFePO4 packs with 10-year warranties. Below I compare them spec by spec, work through real sizing examples and explain which one fits your install.
All figures come from EG4’s WallMount 314Ah Indoor spec sheet (v1.0.4) and WallMount All Weather spec sheet (v1.2.1), plus EG4’s All Weather product page. Runtime and heater-energy examples are my own estimates, and I’ve shown the math.
The Short Answer
- Choose the WallMount 314Ah Indoor if the battery will live in a conditioned or protected space (garage, utility room or basement) and you want the most energy per cabinet, 200A continuous discharge, active balancing and a 10,000-cycle rating.
- Choose the WallMount All Weather if the battery has to go outside next to the inverter on an exterior wall, or in an unheated space where IP65 sealing and self-heating matter.
Spec Comparison
| Spec | WallMount 314Ah Indoor | WallMount 280Ah All Weather |
|---|---|---|
| Model | WM-48-314-IN-XX | WP-16/280-1AWLL |
| Nominal energy | 16kWh | 14.3kWh |
| Usable at 80% DoD | 12.86kWh | About 11.4kWh (my calculation) |
| Voltage / capacity | 51.2V / 314Ah | 51.2V / 280Ah |
| Max continuous charge | 157A | 140A |
| Max continuous discharge | 200A (157A recommended) | 140A; 200A for 30 min |
| Continuous power | 8kW charge / 10.2kW discharge | About 7.2kW at 140A (my calculation) |
| Peak power | 12.8kW (3 s) | Not listed |
| Round-trip efficiency | 95% | Not listed (lifetime math uses 90%) |
| Cell balancing | Active, 2-3A | Passive, 120mA |
| Battery heater | 448W; on ≤32°F, off ≥37°F | 224W; on ≤32°F, off ≥41°F |
| Charge temp range | 32-122°F | 32-122°F |
| Discharge temp range | -4-131°F | -4-131°F |
| Enclosure rating | IP20 | IP65 |
| Dimensions (H x W x D) | 34.1 x 18.1 x 9.6 in | 36.1 x 22.3 x 9.1 in (with side panels) |
| Weight | 293.2 lb (133 kg) | 308.6 lb (140 kg) |
| Display | LED status + EG4 monitoring app | On-board LCD touchscreen |
| Connections | Degson quick connector / screw terminal; 250A breaker | Weather-tight quick connects; built-in 600A busbars (4+/4-) |
| Communication | RS485, CAN; auto-configuration, OTA updates | RS485, CAN; selectable closed-loop protocols |
| Max parallel | 32 units | Not listed on spec sheet |
| Cycle life | 10,000 @ 0.5C, 80% DoD (70% EOL) | 8,000+ @ 0.5C, 80% DoD |
| Lifetime production | 122.2MWh | 82.6MWh |
| Design life | 10 years | 15+ years |
| Warranty | 10 years or 10,000 cycles | 10 years |
| Certifications | UL 1973, UL 9540A; UL 9540 in listed configurations | UL 1973, UL 9540A; UL 9540 with FlexBOSS21, 18kPV and 12kPV (EG4 product page) |
The Big Difference: Where It Can Live
The enclosure ratings tell most of the story. IP20 on the Indoor model means protection against fingers and larger objects, but none against water. It’s made for a dry, protected room. IP65 on the All Weather model means dust-tight and protected against water jets, which is what you want on an exterior wall exposed to rain and dust.
EG4 also built outdoor-specific hardware into the All Weather: weather-tight quick-connect battery cables, an optional conduit box that mates directly to the EG4 18kPV’s connection ports, and an emergency stop that can shut down all batteries and inverters equipped with rapid shutdown in one touch. If your inverter is already mounted outside, the All Weather keeps the whole system on one wall without running heavy DC cable indoors.
Clearances differ too. EG4’s All Weather spec sheet lists 3 inches side-to-side and 0.75 inch front-to-back between stacked units for outdoor installs, and 6 inches and 2 inches for indoor installs. Always confirm against your local code and the current EG4 manual.
Cold Weather: How the Heaters Compare
Both batteries share the same LiFePO4 limits: charging from 32°F to 122°F and discharging from -4°F to 131°F. Both have built-in heaters that switch on when the internal battery temperature drops to 32°F, so they can keep accepting charge in the cold.
- Indoor: 448W heater, off at 37°F.
- All Weather: 224W heater, off at 41°F.
Heater energy example: on a cold night, if the All Weather’s 224W heater runs for 4 hours in total, it uses about 0.9kWh (224W x 4h), roughly 8% of the battery’s usable 11.4kWh. The Indoor model’s larger heater warms faster, but in a heated space it may rarely need to run. In an unheated garage in a cold climate, budget for heater energy with either model.
Worked Examples: Sizing for Your Home
Example 1: Overnight backup for essentials
A fridge, internet, lights, a furnace blower and a few outlets might average about 800W overnight. For 12 hours, that’s 9.6kWh.
- One Indoor (12.86kWh usable) covers it with about 3.3kWh to spare.
- One All Weather (about 11.4kWh usable) covers it with about 1.8kWh to spare.
Example 2: Running a large load
A 5-ton heat pump starting alongside household loads might need 8-10kW for short periods.
- One Indoor: 200A x 51.2V ≈ 10.2kW continuous, with a 12.8kW 3-second peak.
- One All Weather: 140A x 51.2V ≈ 7.2kW continuous, or 200A (about 10.2kW) for up to 30 minutes.
For sustained heavy loads, two All Weather units in parallel double the available current. Check your inverter’s battery-current limit too.
Example 3: Daily solar cycling
Cycling 80% of capacity every day for 10 years is about 3,650 cycles, well within both ratings (8,000+ and 10,000). Lifetime production, which EG4 calculates as the energy delivered over the rated cycles, is 122.2MWh for the Indoor and 82.6MWh for the All Weather. Per cabinet, the Indoor model delivers more energy over its life.
BMS, Balancing and Monitoring
The newer 314Ah Indoor uses active balancing at 2-3A, which EG4 says speeds up cell equalization for longer life. It also auto-configures without DIP switches, receives over-the-air firmware updates, connects to the EG4 battery monitoring app, and has configurable NO/NC + 12V outputs for generator start or alarms.
The All Weather uses passive balancing at 120mA and an on-board LCD touchscreen. From the screen you can select closed-loop communication with EG4, Schneider, Sol-Ark, Victron, Growatt, Megarevo, Luxpower and Deye inverters. Its built-in 600A busbars (four positive and four negative terminals) mean you can parallel batteries and inverters without an external busbar.
Already looking at EG4 inverters? Compare options in our EG4 18kPV review and Victron vs EG4 guide. For a full look at the indoor model, see our EG4 WallMount 314Ah Indoor review.
Size and Weight
The Indoor model is narrower (18.1 in vs 22.3 in) and a little lighter (293.2 lb vs 308.6 lb), which makes it easier to fit between studs or beside a water heater. Either way, plan for a two-person (or more) lift and a wall or floor rated for about 300 pounds per unit.
Installation Planning Checklist
- Pick the location first. Inside a dry, protected room means the Indoor model. Exposed to weather means the All Weather.
- Check the wall or floor. Each unit weighs about 300 lb. EG4 lists floor mount/wall attached for the Indoor model.
- Plan clearances. Use EG4’s current spacing figures for your install type, and confirm them with your local authority having jurisdiction (AHJ).
- Match the inverter. Confirm closed-loop communication support and the battery-current limit on your inverter.
- Size the DC wiring and protection for the battery’s continuous current: 200A for the Indoor, 140A continuous (200A for 30 minutes) for the All Weather.
- Use a UL 9540 listed combination where your jurisdiction requires it. EG4 publishes the supported configurations.
Which Should You Buy?
| Your situation | Better fit |
|---|---|
| Conditioned utility room or basement | Indoor 314Ah |
| Inverter mounted outside on an exterior wall | All Weather |
| Unheated garage in a freezing climate | Either; All Weather for dust and moisture, Indoor for more kWh |
| Most kWh and power per cabinet | Indoor 314Ah |
| Want an E-stop and integrated busbars | All Weather |
| Mixed-brand inverter with closed-loop comms | All Weather (long protocol list); check the Indoor’s compatibility list for your inverter |
FAQ
Can I install the EG4 WallMount Indoor outside?
No. It’s rated IP20 and designed for protected indoor spaces. For outdoor installs, EG4 makes the IP65 All Weather version.
Does the All Weather battery have a heater?
Yes. It has a 224W, 56V heater that turns on at an internal temperature of 32°F or below and off at 41°F or above.
Which one stores more energy?
The Indoor 314Ah stores 16kWh (12.86kWh usable at 80% DoD). The All Weather stores 14.3kWh.
Can I mix Indoor and All Weather batteries?
EG4’s spec sheets don’t cover mixing models. Check with EG4 before combining different batteries in one bank, since capacity and BMS behavior differ.
What’s the warranty?
Both carry 10-year warranties. The Indoor lists 10 years or 10,000 cycles. Register through EG4’s warranty page.
What inverters work with them?
EG4 lists its 18kPV, 12kPV, 12000XP and 6000XP for the All Weather, plus closed-loop support for several other brands. The Indoor’s BMS automatically detects and communicates with EG4 inverters.
Bottom Line
Both WallMount batteries use the same 51.2V LiFePO4 platform, but they’re built for different places. The 314Ah Indoor gives you the most energy, power and cycle life per cabinet for protected spaces. The All Weather trades a little capacity for IP65 sealing, outdoor-rated connectors, an E-stop and integrated busbars, so it can go next to an outdoor inverter. Choose based on where the battery will live, then size the bank using the examples above.