ET1 series LiFePO4 online UPS

Swap a shelf of lead-acid blocks for one light, compact, long-lived lithium pack — built into the UPS rather than bolted on.

THTAK ET1 series product photo — Appearance for reference only; actual specification and accessories follow the quotation.

Brand: THTAK (our own line)
Type: Online double-conversion (LiFePO4 battery)
Typical use: Machine rooms, vehicles, space-limited sites
Models covered: ET1-3KR rack-mount lithium online UPS, ET1-3KVA tower with built-in lithium, ET1-6KRS rack-mount with external lithium pack
Category: UPS systems / THTAK — our own product line

Product details Specifications

Designed as a lithium UPS, not converted to one

Lithium retrofits into lead-acid UPS frames are where most lithium projects go wrong — the charge profile is different and the BMS has to fight the charger. The ET1 is designed around LiFePO4 from the start: charger, BMS and pack are engineered together and shipped as one tested unit.

Where it earns its keep

The ET1 suits the jobs where lead-acid is most awkward: a cabinet with no spare U, a vehicle where every kilogram counts, or a warm room where lead-acid ages twice as fast as the datasheet promises.

Key features

LiFePO4 chemistry — cycle life far beyond lead-acid
Smaller and lighter at the same backup capacity — for space- and weight-limited sites
Online double-conversion, output isolated from the mains
Matched BMS with over-charge, over-discharge, over-temperature and short-circuit protection
Rack and tower models for different install environments
No watering or topping up — day-to-day, just watch the alarms

Where it fits

Tight rooms and cabinets

Lithium's size and weight fit where a battery room cannot be built or the cabinet is near its load limit.

Vehicles and mobile equipment

Less vehicle weight, tolerant of vibration and temperature swings — comms vehicles and conversions.

Hot environments

In warm equipment rooms, lithium tolerates heat and outlives lead-acid clearly.

Frequently asked questions

Why lithium in a UPS, rather than lead-acid?

Three reasons that matter in practice: half the volume and weight for the same runtime; two to three times the cycle life; and flat discharge behaviour, so runtime estimates hold. The purchase price is higher — the total cost over 8–10 years usually is not, especially where the room runs warm.

Is the battery replaceable?

Yes — the packs are modular with a matched BMS. But at LiFePO4 lifetimes, the realistic plan is that the batteries outlast the first replacement cycle of an equivalent lead-acid unit.

Related models & accessories

THTAK LT500–1500 series

Lithium batteries inside a line-interactive body — compact, maintenance-free, and no separate battery box to find room for.

View details

EATON 9PX series

The mainstream choice for server rooms: online double-conversion keeps the output fully isolated from the mains, with efficiency and serviceability at practical levels.

View details

DT1 / DT2 / DT3K series

Low-voltage output with lithium iron phosphate cells — for non-220 V environments where installation space and weight are constrained.

View details

Specifications

Capacity	3–6 kVA (by model)
Architecture	Online double-conversion
Battery type	LiFePO4 with BMS
Form factor	Rack (3KR / 6KRS) or tower (3KVA)
Output waveform	Pure sine wave
Runtime	By model and load — sized against the actual load
Charging	External battery pack supported on some models
Typical sites	Machine rooms, vehicles, tight equipment spaces, unmanned sites

Specifications follow the manufacturer's latest data. Actual configuration must be sized against the site load, required runtime and distribution environment — this table is for selection reference only.

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