TELECOM DC POWER ENGINEERING TOOL

-48V Telecom Battery Runtime Calculator

Estimate battery runtime, required capacity, parallel strings and discharge-current rise for OLT, BBU, transport, core and access telecom sites.

2 V cells × 24Constant power/currentTemperature & ageingReverse sizing
48

Battery bank and load parameters

Select an engineering preset, then replace it with actual battery and equipment data.

All defaults are editable engineering presets, not universal standards. Final sizing must use manufacturer discharge curves, end voltage and measured site load.
Battery-bank structure
V
V
V
V
cells
strings
Ah
h
Telecom equipment load

Equipment current list

EquipmentQtyUnit currentTotal current
Total0 A
Design and capacity corrections
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%
%
%
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h
RT

Runtime and capacity results

Current runtime and reverse sizing for the target duration.

Estimated runtime

Model:
Nominal voltage
Reference float voltage
End voltage
Design load
Average battery current
Current at end voltage
Nameplate energy
Estimated delivered energy
Target runtime coverage
Effective usable capacity
Average C-rate/string
Total cells/modules
Combined usable factor

Model comparison

Simple model
Peukert estimate

Reverse sizing for target runtime

Required total capacity
Capacity/string at current count
Parallel strings at current Ah
Current minus target

Calculation breakdown

Engineering judgement

    METHODOLOGY

    Methodology and engineering boundaries

    DC load and power factor

    Equipment supplied from a -48 V DC bus does not use AC power factor. Enter an equipment DC-current list or the total DC current; power is derived from nominal bus voltage.

    Simplified energy model

    The model uses average discharge voltage and adjusts Ah capacity for usable depth, ageing, temperature and manufacturer-curve calibration.

    Peukert estimate

    The rate effect is estimated from rated duration, per-string current and an editable Peukert exponent. Constant-power loads use average-current approximation.

    Reverse sizing

    The calculator derives total Ah, Ah/string and parallel-string count for the target runtime. Final design must also satisfy vendor parallel, protection, current-sharing and end-voltage limits.

    Engineering references: IEEE 485-2020 · IEC 60896-22 · ETSI EN 300 132-2

    FAQ

    Frequently asked questions

    Why is there no power-factor input?

    Power factor applies to AC systems. During an outage, the battery supplies the DC bus, so use DC watts or amperes.

    Why not use only 48 V × Ah ÷ watts?

    Runtime also depends on end voltage, discharge rate, ageing, temperature, usable depth, DC losses and the manufacturer's discharge curve.

    Why does the preset use 24 two-volt cells?

    Twenty-four 2 V cells form a nominal 48 V string. It is a common telecom arrangement, but the actual site and vendor configuration governs.

    What Peukert exponent should be used?

    Use manufacturer data whenever possible. Presets are editable engineering references; lithium and high-rate systems particularly require vendor curves or BMS data.

    Can the result be used directly for procurement?

    No. It is for comparison and preliminary sizing. Procurement requires measured load, manufacturer tables, site temperature, end voltage and redundancy review.

    PROJECT RECORDS

    Project history

    ENGINEERING WORKFLOW

    Continue the engineering workflow

    Current workflowPoE & Rack Power Design Workflow

    Verify PoE source capacity, cable voltage delivery, rack power and cooling, then estimate telecom battery backup runtime.

    Step 4 of 4
    PreviousNetwork Rack Power & Cooling CalculatorCalculate rack power, current, cooling load, energy and cost.
    NextWorkflow complete

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    Also used inTelecom Power & Energy Workflow
    Telecom DC system note

    -48 V describes telecom DC polarity; calculations use voltage magnitude. A DC load has no AC power-factor input.