2026-09-01

Replacing VRLA with LiFePO4: A Site Retrofit Checklist

Battery ESS48V Telecom BatteryRetrofit

Most lithium retrofits go wrong in the details rather than in the battery. This checklist covers what to verify before the swap, what to change on site, and the tests that catch the problems while they are still cheap to fix.

Start with why

Sites usually move to LiFePO4 for one of three reasons: the VRLA strings are dying faster than expected, the site needs longer runtime in the same space, or the operator wants remote visibility into battery health. Your reason determines what matters most in the retrofit — sizing, footprint, or monitoring.

Before you order

Pre-order checks for a VRLA to LiFePO4 telecom retrofit
Check	Why it matters
Site DC load and required backup hours	Sets capacity. Work from usable energy, not nameplate — see the runtime guide
Existing rectifier or UPS make, model and charge settings	Lithium needs a different charge profile; confirm the unit can be configured
Cabinet or shelter space and floor loading	Lithium is lighter, but rack format and depth still have to fit
Ambient temperature range at the site	Drives sizing and expected service life
Monitoring system and protocol	RS485, CAN or SNMP — decide before installation, not after

Electrical checks on site

Voltage window — confirm the replacement pack's nominal and operating range sit inside what the rectifier or UPS expects.
Charge profile — update charge voltage and, where applicable, temperature compensation. Leaving VRLA settings in place is the most common commissioning error.
Protection devices — check breaker ratings and cable sizing against the new pack's short-circuit capability, which differs from lead-acid.
Earthing and bonding — verify continuity before energising.
Terminations — torque to specification and re-check after the first thermal cycle.

Mechanical and environmental

Confirm the rack or cabinet can take the module format, and that airflow around the pack is not blocked.
Check the pack is not sited where it will collect solar gain or sit next to a heat source.
Verify lifting and handling access — lithium modules are lighter, but they still need a safe route in.

Commissioning tests worth doing

Insulation resistance check before energising.
Communication test — confirm the monitoring system actually receives SOC, SOH and cell data, not just that the cable is plugged in.
Alarm test — trigger each configured alarm and confirm it arrives where someone will see it.
Controlled discharge test — verify delivered capacity against the calculated runtime rather than trusting the nameplate.
Recharge observation — confirm the pack returns to full and that charge current behaves as expected at the site's temperature.

The four mistakes that cause most retrofit pain

Leaving VRLA charge settings in place — the pack either undercharges or is stressed.
Treating communication as optional — the battery works, but nobody can see it, so health checks revert to site visits.
Sizing on nameplate energy — the bank meets spec at commissioning and falls short two years later.
Not updating the monitoring template — the NMS polls the old OIDs, or thresholds tuned for lead-acid fire constantly.

Our 48V LiFePO4 telecom series is built as a drop-in replacement for VRLA strings, and we supply the charge settings and protocol configuration with the pack. For the commercial argument, see LiFePO4 vs lead-acid: the total cost math, and for a worked multi-site retrofit, the VRLA to LiFePO4 telecom retrofit case study.

FAQ

Do I have to replace my rectifier or UPS?

Usually not. If the nominal voltage band matches and the charge profile can be configured for lithium, the existing equipment stays. Replace it only if it cannot accept lithium settings or cannot communicate with the BMS.

How long does a site retrofit take?

It depends on the site, but the swap itself is usually quick — the time goes into the pre-checks and commissioning tests above. Rushing those is what produces call-backs.

Can I mix lithium with the existing VRLA string?

No. Different chemistries have different charge and discharge characteristics, and paralleling them leads to poor performance and shortened life. Replace the string as a whole.

What should I do with the old VRLA batteries?

Lead-acid is a well-established recycling stream. Arrange disposal through a licensed recycler and keep the documentation — many jurisdictions require it.