Needs manual setup
EG4 FlexBOSS21 + Victron Energy Lithium NG 51,2/100
- Voltage matches: the 51.2 V battery suits this 48 V inverter.
- The inverter maker doesn't list this battery for closed-loop communication. The battery maker doesn't say it can run without communication. Ask them before you set it up by hand.
Checked automatically against spec sheets. Not yet confirmed in a real install. Last checked 2026-10-12. We don't track firmware versions.
Size the battery cable and fuse for this pair in the build tool, from your run length.
What you'll set up yourself
- Ask Victron Energy whether this battery can run without communication. Their documents don't say.
-
Enter the battery's charge settings on the inverter by hand, in the battery
settings described in the inverter's manual.
- Max charge current: no more than 100 A per battery, from the battery's spec sheet.
- Charge voltage, float voltage, and low-voltage cutoff: from the Victron Energy Lithium NG 51,2/100 manual.
- Closed-loop communication needs an extra part: Victron VE.Bus BMS NG or Lynx Smart BMS NG.
Published limits, side by side
| Spec | EG4 FlexBOSS21 | Victron Energy Lithium NG 51,2/100 |
|---|---|---|
| Voltage | 48 V accepts 40–60 V | 51.2 V |
| Current | Max battery current 250 A | Max charge 100 A Max output 100 A Peak output 200 A |
| Communication | EG4 hybrid closed loop | Victron VE.Bus BMSVictron Lynx Smart BMS |
| Cable connection | Stud size Not published | Terminal M8 threaded inserts and bolts |
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 250 A. This battery is rated for 100 A charging and 100 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 (Not published) and the battery's terminals (M8 threaded inserts and bolts).
- 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
EG4 FlexBOSS21
- Current Connected
- EG4 (maker)
Victron Energy Lithium NG 51,2/100
- No store links yet. The maker's site is below.
- Victron Energy (maker)
Spot a mistake? Email errata@offgridstacks.com with this page's link.