Active product line

48V LiFePO4 lithium batteries for telecom

This is the second product line and it behaves nothing like the rectifier business. Here the buyer usually has a healthy plant and a dying VRLA string, and the decision is not a part number — it is an architecture. There are two, they are marked with voltages that look like near neighbours, and they are not interchangeable.

How it sits in the shelf

The part number is printed on the module front. That number, or a phone photo of it, is all we need to start.

Illustrative schematic drawn by VOLT48 — not to scale, and not a manufacturer drawing.

Availability & lifecycle

Active, competitive and well supplied. The differentiator is not sourcing, it is choosing the right architecture, sizing the bank correctly and confirming the charge profile before anyone ships anything.

Two architectures. Read this before you compare prices.

LiFePO4 cells are nominally 3.2 V, so the nominal voltage on the label tells you the cell count — and the cell count decides whether the pack fits a −48 V telecom plant. Telecom equipment is specified to a normal service range of −40.5 V to −57.0 V (ETSI EN 300 132-2), and that upper limit is what separates the two.

Telecom retrofit · 15S

48.0 V nominal · 15 cells

Charge 52.5–54.0 V · end of discharge 40.5 V

At 3.60 V per cell a 15S pack asks for 54.0 V, which sits inside the window the equipment guarantees.

Admitted use: VRLA replacement in a −48 V plant: base station, fiber node or PoP, repeater, transmission room, private network.

Use exclusions: Not suitable as a rack BBU for AI servers. Not suitable for a discharge rate above the declared figure. Requires prior validation of the rectifier and the controller.

Rack energy storage · 16S

51.2 V nominal · 16 cells

Charge 56.0–57.6 V · end of discharge 43.2 V

At 3.60 V per cell a 16S pack asks for 57.6 V — above the −57.0 V limit. Dropped into a plant left at the common 53.5 V factory default it sees about 3.34 V per cell, below the constant-voltage knee, and never reaches full charge.

Admitted use: Rack storage behind an inverter or a wide-range converter: technical room backup, off-grid solar support.

Use exclusions: Not suitable for retrofit in a −48 V plant without prior validation, because its full-charge voltage can exceed the range the telecom equipment guarantees.

Per-cell figures are calculated from the declared cell counts; the window limits are the equipment manufacturer's published values. Confirm both against the datasheet of the specific model before ordering.

Models we are asked for

Part number	Model	Indicative specification
—	48 V LiFePO4 50Ah · 15S	19" rack · integrated BMS · RS485/CAN · telecom retrofit architecture
—	48 V LiFePO4 100Ah · 15S	19" rack 3U · integrated BMS · RS485/CAN · telecom retrofit architecture
—	48 V LiFePO4 150Ah / 200Ah · 15S	19" rack 4U · integrated BMS · parallel capable · telecom retrofit architecture
—	51.2 V LiFePO4 100Ah · 16S	19" rack · integrated BMS · rack storage architecture — NOT a −48 V retrofit without validation

Specifications are indicative and published by the manufacturer. Availability, exact revision and lead time are confirmed in the written quotation.

Where it is used

VRLA replacement in existing −48 V plants (15S)
Cellular tower and repeater backup
Fiber node and ISP cabinet autonomy
Sites with weight, footprint or temperature constraints
Rack storage behind an inverter or wide-range converter (16S)

Battery bank wired into a DC backup power system — Site photography. Illustrative of the environment — not of a specific model.

What to send us

The site load in amps or kW, the autonomy you actually need in hours, the rectifier or plant model that will charge the bank, and the ambient temperature range. Those four things determine the answer; the part number does not. If you already have a quotation from someone else, send it — the first thing worth checking is whether it is 15S or 16S, and whether it states the charge voltage setpoint at all.

Not sure what the number on your label is? Look it up in the part number index →

Compatibility notes

Lithium is not always the right call. If a site is cool, rarely cycles and has space, a like-for-like VRLA replacement can be the cheaper answer over the asset life — and we will tell you when that is the case. What we will not do is sell you a 51.2 V rack battery as a drop-in for a −48 V string.

Certification & transport

Transport and safety documentation matters on every lithium shipment: a UN 38.3 test summary for the exact model, IEC 62619 for industrial stationary cells and batteries, plus the safety data sheet. We confirm which documents come with a given product, for that model number, before you order — a family certificate or a logo printed in a catalogue is not evidence. Shipping is UN3480, Class 9. One consequence people discover late: a damaged or defective battery cannot be transported without prior approval from the national competent authority, which is why returns are handled by remote diagnosis and on-site replacement rather than by courier.

Common questions about this family

Can I put a 51.2 V rack battery in my −48 V plant?

Probably not without validating it first, and the reason is arithmetic rather than commercial preference. A 51.2 V pack is 16 cells; at a full-charge target of 3.60 V per cell it asks for 57.6 V, above the −57.0 V upper limit telecom equipment is specified for. A 48 V pack is 15 cells and asks for 54.0 V, which fits. The two are marked as if they were near neighbours and they are not interchangeable.

Can my existing rectifier charge a LiFePO4 bank correctly?

That is the question to answer before buying anything. Lithium needs a charge profile and a voltage window that not every legacy 48 V plant can deliver, temperature compensation has to be switched off, the charge current has to be limited, and the controller has to be able to talk to the BMS or at least not fight it. Send the rectifier or plant model along with the load and the controller firmware version, and we will tell you whether it works as-is.

How much autonomy do I actually need?

It is set by four things: the site load in amps or kW, the hours of autonomy the site genuinely requires, the charging capability of the plant, and the ambient temperature range. Send those four and you get a useful answer; send the part number of your old VRLA and you get a guess.