Stationary VRLA batteries: AGM and GEL

A stationary battery stays in one place, sits on charge and supplies power the moment the mains drops or the system calls for it. This section groups VRLA AGM and GEL blocks in 2, 6 and 12 V built for fixed duty, either on float or in light cycling.

Narrow the list by voltage, Ah rating, dimensions and terminal style to find the exact replacement for your equipment.

What makes a battery stationary

Most of its life is spent on float charge: the charger holds it full at a steady voltage (roughly 2.25–2.30 V per cell at 20 °C, depending on the maker) and it only discharges during an outage or a short peak. It is therefore designed to last years in standby, with low self-discharge and no electrolyte maintenance. VRLA blocks are sealed and recombine nearly all internal gas, so they can go into cabinets and equipment rooms.

AGM or GEL for your application

• AGM: low internal resistance and strong high-current delivery, which is why most uninterruptible power supplies use it.
• GEL: copes better with repeated deep discharges and moderate heat, making it a good fit for daily cycling.

The design life printed on datasheets (5, 10 or 12 years on float) is measured in the lab at 20 °C. Heat is what shortens it in the real world: every 10 °C above that reference can roughly halve it.

Picking the right replacement

Read four values off the battery you are removing: nominal voltage, Ah capacity (a 20-hour rating and a 10-hour rating are not directly comparable), outside dimensions and terminal type (F1/F2 faston, M5/M6 bolt, front terminal…). Where several blocks are wired in series, replace the whole string at once with units from the same batch; mixing old and new ones unbalances charging.

Jump straight to UPS batteries, front-terminal telecom batteries or small batteries for alarms and emergency lighting.

Stationary battery FAQ

Can a stationary battery start an engine?

That is not what it is built for. It supplies current over minutes or hours, not a burst of hundreds of amps for a few seconds. A vehicle needs a starter battery.

How long can it sit on a shelf uncharged?

VRLA blocks self-discharge slowly, yet stored units should be recharged every few months, sooner in a warm storeroom. A battery left flat for long sulphates and loses capacity.

Does mounting orientation matter?

Many AGM models accept side mounting, though not all do. Check the datasheet of the specific model before laying it on its side.