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30Ah to Wh — 360 Wh at 12V

30Ah stores 360 Wh at 12V, 720 Wh at 24V, and 1,440 Wh at 48V. Below: usable energy per chemistry, what it runs, and how the same energy is built from standard modules.

30Ah at 12V is 360 Wh — that is 0.36 kWh of nameplate energy.

Formula: Wh = Ah × V. The voltage is the nominal battery voltage, not the charging voltage.

A real LiFePO4 module of 30Ah is usually labelled 384 Wh, because its nominal voltage is 12.8V rather than a round 12V. Both 360 Wh and 384 Wh describe the same battery.

V
1V60V
Ah
0Ah1000Ah

Result

Stored Energy
360 Wh
@ 12V
In Kilowatt-Hours
0.36 kWh
Wh = Ah × V = 30 × 12 = 360 Wh

Energy in Wh equals capacity in Ah multiplied by battery voltage. 1000 Wh equals 1 kWh.

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V
12V
Input
30Ah
Output
360Wh
kWh
0.36kWh

At every system voltage

The same capacity stores four times the energy at 48V that it does at 12V, and draws a quarter of the current for the same load.

System voltageCapacityEnergykWh
12 V30 Ah360 Wh0.36
24 V30 Ah720 Wh0.72
48 V30 Ah1,440 Wh1.44

How much of it you can actually use

Nameplate energy is not usable energy. Depth of discharge caps what you may take out before you damage the battery, and it differs by chemistry.

ChemistryDepth of dischargeUsable energyUsable capacityCycles at that DoD
LiFePO480 %288 Wh24 Ah~3,500
AGM50 %180 Wh15 Ah~600
Gel50 %180 Wh15 Ah~800
Flooded lead-acid50 %180 Wh15 Ah~400

What that runs

Runtime from the usable LiFePO4 energy at 12V (80% depth of discharge), one load at a time, no inverter losses on the DC rows.

LoadPowerRuntime
LED lighting15 W19.2 h
12V compressor fridge (average)45 W6.4 h
Diesel heater (fan and glow plug average)30 W9.6 h
Water pump (while running)65 W4.4 h
Laptop plus router75 W3.8 h
Kettle through an inverter1200 W0.2 h

What this size is in practice

30Ah sits between a power bank and a house battery. Typical uses: a portable compressor cool box for a weekend, a 12V camera or radio setup, or a starter pack for a small boat with no house bank at all.

Building the same energy from standard modules

How many standard 100Ah 12V modules add up to this energy, and what capacity that becomes at each system voltage.

System voltageCapacityStandard modules
12 V30 Ah1 x 100Ah / 12V
24 V15 Ah1 x 100Ah / 12V
48 V7.5 Ah1 x 100Ah / 12V

Other capacities (Ah)

Other energy values (Wh)

FAQ

How many Wh is 30Ah?

30Ah is 360 Wh at 12V, 720 Wh at 24V, and 1,440 Wh at 48V. Multiply the amp-hours by the nominal battery voltage: Wh = Ah × V.

How much of that 360 Wh can I use?

On LiFePO4 at 80% depth of discharge you get 288 Wh (24 Ah at 12V). On AGM or gel at 50% you get 180 Wh (15 Ah). Same nameplate, very different usable energy.

How long does that run a 12V fridge?

A compressor fridge averaging 45 W runs about 6.4 hours on the usable LiFePO4 energy at 12V. Cycling depends on ambient temperature, so treat this as the upper bound for a well-insulated unit.

Why does the datasheet say 384 Wh instead of 360 Wh?

Because LiFePO4 has a nominal voltage of 12.8V per 12V module, not exactly 12V. 30Ah × 12.8V = 384 Wh. The 12V figure of 360 Wh is the conservative system-voltage calculation. Both describe the same battery.

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