Description
APC Back-UPS 400 VA UPS Battery Backup BK400 120V 60Hz Uninterruptible Power
The APC Back-UPS 400 (model BK400) is a compact tower-form uninterruptible power supply designed to protect desktop computers and peripherals from power outages, surges, and voltage fluctuations. Operating on 120V AC at 60Hz, it delivers up to 400VA/250W of battery-backed output through two NEMA 5-15R receptacles. Note: internal batteries are not included with this unit.
Specifications & What's Included
- Model: APC Back-UPS 400, BK400 (BD variant)
- VA Rating: 400 VA
- Output: 120V AC, 60Hz — 250W, 3.3A (BK400)
- Input: 120V AC, 60Hz — 5A (BK400)
- Output Receptacles: 2 × NEMA 5-15R (battery-backed)
- Serial Interface: DB9 port for PC communication
- DIP Switches: configurable Low Battery Signal voltage, Transfer Voltage, Delay Alarm, and Reduce Transfer Voltage
- Site Wiring Fault Indicator: yes
- Overload Protector: push-to-reset button on rear panel
- Certifications: CSA LR63938; UL Listed 42C2, E95463
- Country of Manufacture: Philippines
- Form Factor: desktop tower
- Batteries: not included
- Unit only — no cables or mounting accessories
Applications
The APC Back-UPS 400 was introduced in the mid-to-late 1990s as an entry-level UPS for desktop PCs, monitors, and small network equipment. It provides enough battery runtime to save work and perform a controlled shutdown during a power outage, and its surge/spike protection guards sensitive electronics from line disturbances. The DB9 serial interface allowed connection to a host PC running APC's PowerChute software for automated, graceful shutdowns — a common setup in offices and small businesses of that era. Units like this remain in use today for protecting legacy equipment, point-of-sale terminals, older workstations, and lab instruments that require clean, uninterrupted AC power. Because the internal lead-acid batteries are not included, a buyer will need to source and install compatible replacement batteries before the unit is operational as a full UPS.
This APC Back-UPS 400 (BK400) uninterruptible power supply has been inspected and appears to be in good used condition. It was pulled from a working environment where it was previously in service. The housing shows light yellowing and minor surface wear typical of older equipment of this type. Note: batteries are not included — the unit ships without internal batteries. Please review our photos and contact us with any questions.
Warranty Information
Additional Information
Brand: |
APC |
Model: |
Back-UPS 400 |
MPN: |
BK400 |
SKU: |
13963 |
Type: |
Uninterruptible Power Supply (UPS) |
VA Rating: |
400 VA |
Output Power: |
250W (BK400) |
Output Voltage: |
120V AC, 60Hz |
Output Current: |
3.3A (BK400) |
Input Voltage: |
120V AC, 60Hz |
Input Current: |
5A (BK400) |
Output Receptacles: |
2 x NEMA 5-15R |
Interface/Signaling: |
DB9 serial port, DIP switch (Low Batt/Transfer/Delay/Alarm) |
Site Wiring Fault Indicator: |
Yes |
Overload Protector: |
Push-to-reset button |
Certifications: |
CSA LR63938, UL Listed 42C2 E95463 |
Country/Region of Manufacture: |
Philippines |
Form Factor: |
Tower |
Batteries Included: |
No |
Seller Notes: |
Unit only — batteries not included. |
Condition Notes: |
This APC Back-UPS 400 (BK400) UPS has been inspected and is in good used condition, pulled from a working environment. Batteries are not included. Minor cosmetic wear typical for age. Please contact us with any questions. |
California Prop 65 Warning: |
WARNING: This product can expose you to chemicals including lead and lead compounds, and DEHP (a phthalate), which are known to the State of California to cause cancer and birth defects or other reproductive harm. Go to P65Warnings.ca.gov |