AI servers are shifting their power distribution from 12 V toward 48 V – and up to 800 V for rack-level distribution – to cut losses and copper. That shift puts a heavier demand on the aluminum electrolytic capacitors that smooth and store energy along the power chain.
AI-optimized servers are forecast to consume 175 TWh in 2026, up 84% in a year. More power at higher voltage changes what the bulk capacitors in every stage have to do.
Why Data Center Power Is Moving to 48 V and 800 V
Lower voltage means higher current and thicker copper. Raising the bus voltage reduces current for the same power, which cuts conduction loss and copper cost across a dense rack:
- 48 V is now the standard intermediate bus inside AI servers and accelerators, replacing 12 V for the high-current stages.
- 800 V (and intermediate DC distribution) is used at the rack or power-shelf level to move power more efficiently before it steps down.
Both changes ripple through every capacitor in the chain.
Where Aluminum Electrolytic Capacitors Fit
Aluminum electrolytic capacitors are the bulk-energy workhorse of these power stages:
- Bulk input capacitance on the AC-DC front end and after the rectifier.
- Bus hold-up and holdup energy – storing enough energy to ride through a brief grid or transfer interruption.
- Output filtering on intermediate and point-of-load rails.
Our aluminum electrolytic capacitor guide covers the types and how they work.
How the Capacitor Changes Across the Power Chain
The same AI server uses different capacitor types at each voltage level, and the role shifts as the voltage rises:
| Power stage | Voltage | Typical capacitor | Role |
|---|---|---|---|
| AC-DC front end | 400-800 V | Film + electrolytic | Bulk + DC-link |
| Intermediate bus | 48 V | Aluminum electrolytic | Bulk + hold-up |
| Point-of-load | 12 V / 1 V | Polymer + MLCC | Decoupling |
Film capacitors handle the DC-link ripple at the highest voltages, and MLCCs handle the smallest high-frequency decoupling – but the bulk energy that keeps the bus alive through a grid glitch is where aluminum electrolytic capacitors earn their place, offering the highest capacitance for their size and cost.
What to Specify at 48 V and 800 V
- Voltage rating – match the bus: low-voltage rails use lower-rated parts, while higher-voltage stages need snap-in or screw-terminal parts with adequate rating.
- Ripple current – higher current density raises ripple, so low ESR and high ripple rating matter.
- Lifetime at temperature – denser racks run warmer, so long-life series (5000 h and above) are often the right call.
- Form factor – Xuansn snap-in and screw-terminal electrolytic capacitors for the higher-power stages.
In practice, the deciding factors at 48 V and 800 V are ripple current and lifetime. A capacitor that meets the capacitance but cannot handle the ripple current will overheat and fail early; a part rated for 2000 h at 105 °C may not last in a rack that runs near that temperature continuously. That is why long-life series with a wide operating temperature range are worth the small extra cost at the front of the design.
Common Questions About Data Center Power and Electrolytic Capacitors
Why is 48 V replacing 12 V in AI servers?
At the same power, 48 V carries a quarter of the current of 12 V, so conduction losses and copper weight drop. This makes it the preferred intermediate bus for high-power AI accelerators.
What capacitors are used in an 800 V data center power stage?
The bulk bus typically uses aluminum electrolytic capacitors for energy storage and hold-up, with film capacitors for DC-link and ripple-heavy positions, and ceramic capacitors for high-frequency decoupling.
What lifetime should AI server capacitors have?
AI racks run warm and dense, so long-life aluminum electrolytic series – commonly 5000 h and above at rated temperature – are usually specified to avoid premature field failures.
More on AI Server Power
AI server power demand is reshaping power design here.
Need aluminum electrolytic capacitors for 48 V or 800 V data center power? Xuansn Capacitor manufactures aluminum electrolytic capacitors for power supplies – our engineers will reply within 24 hours with feasibility and a quote.
✉ sales1@xuanxcapacitors.com | ☎ +86-769-8166 8821 | Send your specification
Sources: Gartner data center electricity forecast, June 2026 (AI-optimized servers 175 TWh, up 84%).
