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Ultracell 12V 18Ah Rechargeable VRLA Battery - UL18-12

£4999
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Description

The Ultracell UL18-12 is a 12V 18Ah sealed lead-acid battery in a valve-regulated design, delivering 18Ah capacity at a 20-hour discharge rate. The battery uses absorbed glass mat (AGM) technology, where the electrolyte is held in a fibreglass mat between the plates rather than free-flowing, making it spill-proof and maintenance-free.

Designed as backup power for fire alarm panels, uninterruptible power supplies, emergency lighting systems and security equipment, the UL18-12 provides standby power when mains supply is interrupted. The battery measures 180mm length by 80mm width by 170mm height and weighs 5.7kg, fitting standard battery compartments in fire alarm control panels including the ESP MAG816. Terminal posts at the top accept M5 or M6 ring terminals for connection to charging circuits and load.

The VRLA construction means the battery does not require topping up with water during its service life, and the sealed case prevents acid leakage even if the battery is mounted on its side. Constant voltage charging is recommended at 14.4-15.0V for cycle use or 13.6-13.8V for standby applications. The battery carries CE certification and is manufactured to ISO standards, with a typical service life of 3-5 years in float standby applications at 20°C ambient temperature.

Specification
Product Net Weight (KG) 0
Product Gross Weight (KG) 5.7
Outer Length (mm) 180
Outer Width (mm) 80
Outer Height (mm) 170
Downloads

Product Specification Sheet

Frequently Asked

What is the difference between 18Ah and 20HR capacity?

The 18Ah rating is measured at a 20-hour discharge rate (20HR), meaning the battery can deliver 0.9A continuously for 20 hours before reaching its end-of-discharge voltage. Faster discharge rates will yield lower total capacity, while slower rates may yield slightly higher capacity.

What charging voltage should be used?

For standby float charging (fire alarm panels, UPS), use 13.6-13.8V. For cycle use where the battery is regularly discharged and recharged, use 14.4-15.0V. See the specification sheet for detailed charging parameters and temperature compensation.

Is this battery compatible with the ESP MAG816 fire alarm panel?

Yes. The UL18-12 is the replacement battery for the ESP MAG816 control panel, fitting the battery compartment dimensions and matching the panel's charging circuit specifications.

How long does the battery last?

In float standby applications at 20°C ambient temperature, the typical service life is 3-5 years. Higher temperatures reduce service life significantly — every 10°C above 20°C approximately halves the expected lifespan. The battery should be replaced when it can no longer deliver the required backup runtime during mains failure testing.

Shipping & Returns

Free worldwide delivery

Free worldwide delivery on all orders over £99. International orders for third-party brand products may be subject to an additional courier surcharge based on volumetric weight, particularly on larger lighting fixtures — if a surcharge applies, our team will email you with the amount before dispatch and you can proceed or cancel for a full refund. See full delivery terms.

Returns

30-day returns window from delivery. As all our products are electrical or lighting goods, returned items must be inspected and recertified by a qualified electrician before resale — the cost of this inspection (25–40% of the item value) is deducted from your refund. Customers pay return shipping. Made-to-order, special-order and clearance items cannot be returned. See full returns policy.

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    Description

    The Ultracell UL18-12 is a 12V 18Ah sealed lead-acid battery in a valve-regulated design, delivering 18Ah capacity at a 20-hour discharge rate. The battery uses absorbed glass mat (AGM) technology, where the electrolyte is held in a fibreglass mat between the plates rather than free-flowing, making it spill-proof and maintenance-free.

    Designed as backup power for fire alarm panels, uninterruptible power supplies, emergency lighting systems and security equipment, the UL18-12 provides standby power when mains supply is interrupted. The battery measures 180mm length by 80mm width by 170mm height and weighs 5.7kg, fitting standard battery compartments in fire alarm control panels including the ESP MAG816. Terminal posts at the top accept M5 or M6 ring terminals for connection to charging circuits and load.

    The VRLA construction means the battery does not require topping up with water during its service life, and the sealed case prevents acid leakage even if the battery is mounted on its side. Constant voltage charging is recommended at 14.4-15.0V for cycle use or 13.6-13.8V for standby applications. The battery carries CE certification and is manufactured to ISO standards, with a typical service life of 3-5 years in float standby applications at 20°C ambient temperature.

    Specification
    Product Net Weight (KG) 0
    Product Gross Weight (KG) 5.7
    Outer Length (mm) 180
    Outer Width (mm) 80
    Outer Height (mm) 170
    Downloads

    Product Specification Sheet

    Frequently Asked

    What is the difference between 18Ah and 20HR capacity?

    The 18Ah rating is measured at a 20-hour discharge rate (20HR), meaning the battery can deliver 0.9A continuously for 20 hours before reaching its end-of-discharge voltage. Faster discharge rates will yield lower total capacity, while slower rates may yield slightly higher capacity.

    What charging voltage should be used?

    For standby float charging (fire alarm panels, UPS), use 13.6-13.8V. For cycle use where the battery is regularly discharged and recharged, use 14.4-15.0V. See the specification sheet for detailed charging parameters and temperature compensation.

    Is this battery compatible with the ESP MAG816 fire alarm panel?

    Yes. The UL18-12 is the replacement battery for the ESP MAG816 control panel, fitting the battery compartment dimensions and matching the panel's charging circuit specifications.

    How long does the battery last?

    In float standby applications at 20°C ambient temperature, the typical service life is 3-5 years. Higher temperatures reduce service life significantly — every 10°C above 20°C approximately halves the expected lifespan. The battery should be replaced when it can no longer deliver the required backup runtime during mains failure testing.

    Shipping & Returns

    Free worldwide delivery

    Free worldwide delivery on all orders over £99. International orders for third-party brand products may be subject to an additional courier surcharge based on volumetric weight, particularly on larger lighting fixtures — if a surcharge applies, our team will email you with the amount before dispatch and you can proceed or cancel for a full refund. See full delivery terms.

    Returns

    30-day returns window from delivery. As all our products are electrical or lighting goods, returned items must be inspected and recertified by a qualified electrician before resale — the cost of this inspection (25–40% of the item value) is deducted from your refund. Customers pay return shipping. Made-to-order, special-order and clearance items cannot be returned. See full returns policy.