VB-E3 · Server BBU Module

Server BBU module for GPU-dense nodes.

The VB-E3 is a 1U BBU battery backup unit that lives inside the node: 1.5 kWh of 21700 LFP on a 48V/54V bus, bridging in under 1 ms — fast enough that the GPUs never see the dip.

VB-E3 DATASHEET

Bus voltage	48V / 54V DC
Capacity	1.5 kWh
Bridge	<1 ms
Full load	≥5 min
1/4 load	≥20 min
Telemetry	PMBus
Cooling	Cold-plate compatible
Cells	21700 LFP

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VB-E3 server BBU module front panel — 1U, 48V/54V bus

VB-E3 module seated inside a liquid-cooled AI compute node

FIG.02 — VB-E3 inside an AI compute node · 1024x1536

In the node

Backup where the load actually is

GB300-class racks concentrate kilowatts per node, and the publicly announced 33kW server BBUs shown at GTC 2025 define the reference for this class: per-node backup, liquid-cooling compatibility, 1U packaging. VB-E3 is VoltBridge's entry in the class of publicly announced 33kW server BBUs — a bridge that keeps the node alive while facility power sorts itself out.

Per-node bridge in under 1 ms — no rail-collapse reboot
Cold-plate compatible for liquid-cooled AI nodes
≥5 min at full load, ≥20 min at quarter load — enough for safe migration
PMBus telemetry into the node's own management plane

VB-E3 datasheet

Full specifications

Parameter	VB-E3
Form factor	1U server BBU module
DC bus	48V / 54V
Capacity	1.5 kWh
Bridge transfer	<1 ms
Runtime, full load	≥5 min
Runtime, 1/4 load	≥20 min
Cell platform	21700 LFP
Operating temperature	-5~45°C
Cooling	Cold-plate liquid-cooling compatible
Telemetry	PMBus
Dimensions	190 W × 43.6 H × 260 D mm (1U-wide blade)
Weight	2.9 kg
Compliance	UN 38.3 tested · IEC 62619 designed & tested · CE (DoC)
Warranty	5 years

Runtime figures at 25°C, new cells; bridge time measured at the module DC terminals

Module details

Under the handle

Cold plate

Cold-plate thermal path

A liquid-cooled baseplate holds cell temperature flat during high-rate bridge discharge — no fan noise inside the node, no hot spots after transfer.

VB-E3 interface panel with PMBus and power connectors

Telemetry

PMBus interface panel

Voltage, current, temperature and state-of-health on PMBus, so the node BMC treats the BBU as a first-class component, not a black box.

VB-E3 module being slid into a 1U server slot

Integration

Slot-in installation

1U packaging with standard server mounting points. Our engineers review bus, firmware and mechanical fit with your team before samples ship.

FAQ

VB-E3 questions engineers ask first

Q1How is a server BBU different from a rack BBU shelf?▾

Scope of protection. The rack shelf backs up the whole rack's DC bus; the VB-E3 backs up one node from inside the chassis. High-value GPU nodes often get both — the node-level bridge reacts first, rack-level runtime sits behind it.

Q2What does a sub-1 ms bridge actually protect?▾

The VB-E3 closes onto the bus in under a millisecond — before downstream converters register an input outage — so a training run continues instead of rebooting mid-checkpoint.

Q3Does it fit liquid-cooled GB300-class nodes?▾

Yes — the thermal design is cold-plate compatible, matching the direction of the publicly announced 33kW-class server BBUs. We review mechanical, thermal and firmware integration per platform before sampling.

Protect the node, not just the room.

Send us the node architecture and your bridge-time target — we reply within 48 hours with a fit review and a sample plan for the VB-E3.

Need rack-level instead?