Compatible replacement battery kits for Best Power Unity series UPS systems (UT3K, UT4K, UT5K, UT8K). Match your unit by exact model number and the product grid shows each kit's voltage and amp-hour rating. Shipped from our Canadian warehouse.
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In stockThe Best Power Unity series (UT3K, UT4K, UT5K and UT8K) is a line of line-interactive and online UPS systems originally built by Best Power, a brand now part of Eaton's power quality portfolio. Like every UPS, these units depend on sealed lead-acid batteries that wear out and need periodic replacement to keep runtime and protection intact. The kits in this collection are compatible aftermarket replacements built to the same form factor and electrical specification as the original packs.
Each cell in these kits is a 12-volt sealed lead-acid (SLA/VRLA) battery. UPS systems reach their required DC bus voltage by wiring several 12V batteries in series, and they increase runtime by using higher-capacity cells or additional strings. That is why the per-battery amp-hour (Ah) rating varies across the Unity range — a larger UPS needs more stored energy. Because capacity differs from model to model, confirm the exact rating on the product page rather than assuming one figure fits the whole series. The product grid above lists the voltage and amp-hour rating for each kit.
The single most reliable way to order the correct kit is to match by exact UPS model number (for example, Unity UT3K, UT4K, UT5K or UT8K) and, where present, the original battery part number printed on the pack or on the UPS label. Match-by-model avoids the common mistake of ordering a kit with the wrong voltage or amp-hour rating. Each product in this collection is mapped to a specific Unity model so you can confirm fit before you buy.
Genuine OEM battery packs are sold under the manufacturer's own label and command a premium. Aftermarket replacement batteries use the same standardized SLA cell sizes and the same voltage and amp-hour ratings, so a correctly matched aftermarket kit delivers equivalent runtime and protection at a lower cost. The kits here are compatible replacements — they are not sold as factory-original parts, but they meet the same electrical specification required by the UPS.
Sealed lead-acid UPS batteries typically last 3 to 5 years under normal conditions. Heat is the biggest enemy of battery life: as a rule of thumb, every roughly 8°C of sustained temperature above 25°C can cut expected battery life by about half. Keeping the UPS in a cool, ventilated location and replacing batteries on schedule prevents surprise failures during an outage.
Before starting, confirm you have the correct kit for your exact model. General steps:
If you are unsure whether your unit supports hot-swap, treat it as a power-down replacement.
How do I know which kit fits my UPS? Match by your exact Unity model number (UT3K, UT4K, UT5K or UT8K) and the original battery part number if shown. The product grid lists each kit's voltage and amp-hour rating.
What voltage and amp-hour rating do these use? Each cell is 12V sealed lead-acid; the amp-hour rating varies by model, so check the spec on the product page for your unit rather than assuming a single number for the whole series.
How long will the new batteries last? Typically 3 to 5 years, shorter in hot environments.
Can I replace the batteries without shutting down? Only on rack-mount, Smart-UPS-style and online units designed for hot-swap. Desktop and non-hot-swap units must be powered down first.
Are these genuine OEM batteries? No — they are compatible aftermarket replacements built to the same electrical specification.
Best Power, Unity, and Powerware are trademarks of their respective owner, Eaton Corporation. UPSPLUSBATTERY.ca is not affiliated with, endorsed by, or authorized by the manufacturer; aftermarket batteries are compatible replacements.
Replacement batteries for Best Power Unity / Unity-UT Series UPS — the line-interactive and online double-conversion lineup deployed in lab environments, broadcast facilities, and small server rooms. Models supported include Unity UT3K (3kVA), Unity UT4K (4kVA), Unity UT5K (5kVA), Unity UT8K (8kVA), Unity UT10K (10kVA), and Unity Fortress LI series (UT3K Fortress LI 460, plus matching BAT-006x cartridge codes).
Unity UPS systems are paired with Best Power's BAT-006x cartridge series (BAT-0061, BAT-0062, BAT-0063, BAT-0064 etc.) — each cartridge holds 4 to 12 SLA cells (12V 7-9Ah) depending on capacity. Always confirm the cartridge BAT-XXXX code and the UT model number before ordering. Hot-swap on most Unity models lets you replace cartridges without dropping the load.
Recommended swap interval: 3-5 years per IEEE 1188 in normal operating conditions. Best Power's Unity line was largely succeeded by Eaton 9PX and 9SX after the 2007 Eaton acquisition — if you're modernizing, contact Eaton Service Canada. For Unity battery commissioning across Canada contact GDF Technologies.
Our Canadian team has specified APC, Eaton, Tripp Lite, Vertiv, Mitsubishi, Toshiba, CyberPower, XPC, and Delta UPS for healthcare, data centres, and government. Enquiries answered in business hours.