Sizing a battery is arithmetic once you have the load list — EGbatt shares the exact method we use so your quote and your real need line up.

Overview

To size a LiFePO4 battery you need four numbers: daily energy use (kWh), allowable depth of discharge (use 80–90% for LFP), days of autonomy (off-grid), and the peak power (kW) the inverter must supply. The capacity formula is daily kWh ÷ DoD = usable bank kWh; for autonomy multiply by days. The power side is peak load (plus motor surges) ÷ inverter efficiency, and it sets the C-rate the cells must support. EGbatt applies this to every proposal; do it yourself first and your RFQ will come back faster and closer.

Key specifications

SpecificationValueWhy it matters Step 1Load list → daily kWhSum device Wh ÷ 1000. Step 2Capacity = daily kWh ÷ DoD (0.8–0.9)Usable bank size. Step 3× autonomy days (off-grid)Reserve for clouds. Step 4Peak kW + surges → inverter & C-rateSets power, not just energy. Step 5Match voltage (12/24/48V)Cable and loss trade-off.

Typical applications

  • Home storage: Daily use + backup.
  • Off-grid: Add autonomy days.
  • C&I peak shaving: Peak kW drives power.
  • PV sizing: Refill the bank.

How to specify & buying guide

  • Build the load list in watts × hours before anything else — guesses blow up the design.
  • Use 80–90% DoD for LFP; lead-acid's 50% will undersize a replacement.
  • Do not forget motor-start surges when setting inverter kW.
  • Pick voltage by power: 12V small, 24V mid, 48V above a few kW.

Engineering & manufacturing at EGbatt

Our guides are written by the same engineering team that grades the cells and builds the packs. They are meant to help importers, installers and procurement specifiers make defensible decisions — not to rank for a keyword.

Certifications & compliance

  • UN38.3 — Mandatory lithium battery transport test (altitude, thermal, vibration, shock, external short). Required for any cross-border shipment.
  • IEC62619 — International safety standard for industrial Li-ion cells and batteries; expected by EU and most APAC buyers.
  • CE — EU declaration of conformity for the applicable directives.

Frequently asked questions

What formula do I use?

Capacity (kWh) = daily kWh ÷ DoD; for off-grid multiply by autonomy days. Power sets the inverter and C-rate.

What DoD do I use for LFP?

80–90% usable; far deeper than lead-acid's 50%.

How do I size the inverter?

Peak load plus motor-start surges, divided by inverter efficiency.

Why does voltage matter?

Higher voltage carries power at lower current — smaller cables, fewer losses above a few kW.

Related products & resources

  • Cost per kWh
  • 48V LiFePO4
  • LFP vs Lead-Acid

Request a quote

Send us your voltage, capacity, dimensions, certification target and annual volume. Our engineering team returns a proposal within three working days. Start your RFQ or review our custom pack capabilities.

Request a LiFePO4 quote

Tell us your product, volume and specs — our engineering team returns a proposal within three working days.

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