Self-Heating LiFePO4 Batteries

Charging LiFePO4 below freezing damages the cell — CMX Battery's self-heating packs solve it with an internal film that warms the cells before they take a charge.

Overview

Standard LiFePO4 must not be charged below 0°C; doing so plates lithium metal and permanently hurts the cell. CMX Battery self-heating batteries embed a heating film that draws a small current to warm the cells above the charge threshold before the BMS allows charging. The result is a pack that safely charges in a cold shed, RV or off-grid cabin through winter — at the cost of a little energy to run the heater. We build self-heating variants at 12V/24V/48V for exactly these climates.

Key specifications

Specification	Value	Why it matters
Feature	Internal self-heating film	Enables sub-0°C charging.
Trigger	Heats above charge threshold before charge	Protects the cell.
Voltage	12.8 / 25.6 / 51.2V	Per application.
Chemistry	LiFePO4	Safe when warm.
Trade-off	Small energy to run heater	Worth it in cold climates.

Typical applications

Cold-climate RVs: Winter charging.
Off-grid cabins: Below-freezing charge.
Solar in winter: Low-temperature banks.
Outdoor telecom: Unattended sites.

How to specify & buying guide

Choose self-heating only if the pack will actually be charged below 0°C; otherwise a standard LFP is cheaper.
Confirm the heater draws from the pack (slight loss) and that the BMS gates charge on temperature.
Size capacity with the heater overhead in mind for cold periods.
Keep the pack within the inverter's LFP voltage window.

Engineering & manufacturing at CMX Battery

Our modules pair matched LiFePO4 cells with a purpose-built BMS, busbars and mechanical enclosure. We design for the thermal and vibration profile of the application — stationary rack, wall mount or mobile pack — and validate the assembly on capacity, IR balance and thermal runaway margin before it ships.

Certifications & compliance

UN38.3 — Mandatory lithium battery transport test (altitude, thermal, vibration, shock, external short). Required for any cross-border shipment.
IEC62619 — International safety standard for industrial Li-ion cells and batteries; expected by EU and most APAC buyers.
CE — EU declaration of conformity for the applicable directives.
RoHS — Restriction of hazardous substances in the battery and BMS.
IP65 — Dust-tight and low-pressure water-jet resistant — suitable for outdoor enclosures.

Frequently asked questions

Can it charge below freezing?

Yes — the internal heater warms the cells above the threshold before the BMS allows charge.

Does heating use my stored energy?

A small amount, drawn from the pack to run the film.

Is discharge also limited in cold?

Discharge is fine to lower temperatures; it is charging that needs the heater.

When do I need this vs low-temp cells?

If you charge below 0°C, self-heating; if only discharge is cold, low-temperature cells may suffice.

Request a quote

Send us your voltage, capacity, dimensions, certification target and annual volume. Our engineering team returns a proposal within three working days. Start your RFQ or review our custom pack capabilities.