What AWG cable is suitable for a LiFePO4 12V 100Ah battery

Lithium battery 12 V, DC up to 50 A:

AWG 6 → suitable, with a margin

diameter ≈ 4.1 mm

cross-section ≈ 16 mm²

If the cable length is up to 1–1.5 m — AWG 6 is ideal

If the cable is longer (2–3 m and more) — it is better to take AWG 4 to reduce voltage drop

Practical advice

Take a soft copper (OFC) cable

Crimping tips + heat shrink are a must

For batteries, it is advisable to have a 10–20% current margin

Let's analyze it in detail and step by step, without unnecessary confusion 

I will explain in simple words, but technically correct.

1. What is AWG

AWG (American Wire Gauge) is an American system for designating wire thickness.

 Important:

The SMALLER the AWG number — the THICKER the cable

AWG ≠ mm², but there is an exact match between them

Current for 12 V — why is it critical?

In 12 V systems, currents are very large.

Formula: P = U × I

For example:

600 W ÷ 12 V = 50 A

1000 W ÷ 12 V = 83 A

❗ Therefore, the cable is always taken with a margin, otherwise:

- heating

- voltage drop

- power loss

- fire hazard

Is AWG 6 enough for 50 A?

✅ YES, if:

- copper cable

- length up to 1–1.5 m

- normal ventilation

AWG 6 parameters:

- cross-section: 16 mm²

- safe current: 55–75 A

- withstands more for a short time

❌ NOT recommended if:

- length over 2 m

- inverter >800 W

- surge current >60–70 A

 In these cases, AWG 4 (21 mm²) is better

Voltage drop (very important)

For 12 V, allowable drop:

≤3% — ideal

≤5% — acceptable

Example (50 A, 2 m round trip):

AWG 6 → drop ≈ 0.35–0.4 V

AWG 4 → ≈ 0.2–0.25 V

Less drop =

✔ stable inverter operation

✔ less heating

✔ longer battery life

Cable type — no less important

I recommend:

OFC copper (100%)

multi-core, flexible

marking: Battery cable, Welding cable

❌ Do not take:

CCA (aluminum + copper coating)

rigid single-core

Fuse (required!)

Between the battery and the load:

for 50 A → 60–70 A

type: ANL / MIDI

put a maximum of 20–30 cm from the battery

Brief summary

50 A, up to 1.5 m → AWG 6 (16 mm²)

50 A, 2–3 m → AWG 4 (21 mm²)

 inverter ≥800 W → immediately AWG 4