Partly checked

Ruixu RX-12K + Fortress Power eVault Max 18.5

Voltage matches: the 51.2 V battery suits this 48 V inverter.
Can't check battery communication yet: the inverter's communication links aren't on file.

Checked automatically against spec sheets. Not yet confirmed in a real install. Last checked 2026-10-28. We don't track firmware versions.

Size the battery cable and fuse for this pair in the build tool, from your run length.

Published limits, side by side

Spec	Ruixu RX-12K	Fortress Power eVault Max 18.5
Voltage	48 V accepts 40–60 V	51.2 V
Current	Max battery current 228 A	Max charge 180 A Max output 180 A Peak output 230 A
Communication	None listed	Sol-Ark closed loopOpen loop (no comms)
Cable connection	Stud size M10	Terminal M10

Values come from each maker's documents. "Not published" means the maker doesn't state it.

Confirm with the makers before you buy

Whether one battery can take the inverter's full current. The inverter's max battery current is 228 A. This battery is rated for 180 A charging and 180 A output. Ask how many batteries to run in parallel.
Which firmware versions support this pairing. We don't track firmware.
That your cable lugs fit the inverter's battery studs (M10) and the battery's terminals (M10).
How to install both safely, from each maker's manual and your local code.

This result checks two things: the battery's voltage suits the inverter, and the inverter maker lists this battery for closed-loop communication (the battery tells the inverter how to charge it). It doesn't check current limits, charge settings, firmware, cable sizes, or safe installation. Confirm those with both makers before you buy.

Sources

This result comes from the documents below. We haven't yet found an outside source that confirms it, such as a forum report or a video of a real install.

Where to buy

Ruixu RX-12K

Fortress Power eVault Max 18.5

No store links yet. The maker's site is below.
Fortress Power (maker)

Other batteries for the Ruixu RX-12K

Battery	Result
EG4 LifePower4 48V V2	Partly checked : Ruixu RX-12K with EG4 LifePower4 48V V2
EG4 WallMount All Weather 280Ah	Partly checked : Ruixu RX-12K with EG4 WallMount All Weather 280Ah
BigBattery 48V Husky 2 100Ah High Power Version	Partly checked : Ruixu RX-12K with BigBattery 48V Husky 2 100Ah High Power Version
SimpliPhi Power AmpliPHI 3.8	Partly checked : Ruixu RX-12K with SimpliPhi Power AmpliPHI 3.8
LiTime 48V 100Ah Smart ComFlex	Partly checked : Ruixu RX-12K with LiTime 48V 100Ah Smart ComFlex
SimpliPhi Power PHI-3.8-48-60	Partly checked : Ruixu RX-12K with SimpliPhi Power PHI-3.8-48-60
PYTES V5	Partly checked : Ruixu RX-12K with PYTES V5
Discover Energy Systems HELIOS ESS 52-48-16000	Partly checked : Ruixu RX-12K with Discover Energy Systems HELIOS ESS 52-48-16000
Endur ESP-5100	Partly checked : Ruixu RX-12K with Endur ESP-5100
Pecron EP3800-48V	Partly checked : Ruixu RX-12K with Pecron EP3800-48V

Other inverters for the Fortress Power eVault Max 18.5

Inverter	Result
SOL-ARK 18K-2P-LV	Specs match : SOL-ARK 18K-2P-LV with Fortress Power eVault Max 18.5
SOL-ARK 12K-2P-N	Specs match : SOL-ARK 12K-2P-N with Fortress Power eVault Max 18.5
SOL-ARK 5K-1P-N	Specs match : SOL-ARK 5K-1P-N with Fortress Power eVault Max 18.5
SOL-ARK 12K-2P-LL	Specs match : SOL-ARK 12K-2P-LL with Fortress Power eVault Max 18.5
SOL-ARK 15K-2P-LV	Specs match : SOL-ARK 15K-2P-LV with Fortress Power eVault Max 18.5
EG4 FlexBOSS18	Needs manual setup : EG4 FlexBOSS18 with Fortress Power eVault Max 18.5
Growatt SPF 6000T DVM-MPV	Needs manual setup : Growatt SPF 6000T DVM-MPV with Fortress Power eVault Max 18.5
Victron Energy MultiPlus-II 48/5000/70-50	Needs manual setup : Victron Energy MultiPlus-II 48/5000/70-50 with Fortress Power eVault Max 18.5
POWMR FU10-248P	Needs manual setup : POWMR FU10-248P with Fortress Power eVault Max 18.5
OutBack Power FXR3048A	Needs manual setup : OutBack Power FXR3048A with Fortress Power eVault Max 18.5

Spot a mistake? Email errata@offgridstacks.com with this page's link.