# Ah (Amp-hour)

> Electrical capacity: 60 Ah delivers 60 A for 1 hour, or 1 A for 60 hours. Indicates how much energy the battery stores.

**Categoría**: Technical specifications
**URL canónica**: https://baterias.com/gb/battery-glossary/ah
**Idioma**: en-GB

## Definition

Ah (amp-hour) is the unit of electrical capacity of a battery: it indicates how much current it can deliver for how long. The standard measure is **C20**: a 60 Ah battery discharged at the C20 rate delivers 3 A (60 ÷ 20) for 20 hours. For automotive use typical Ah ranges from 40 (city cars) to 110 (SUV/large diesel); in marine and deep-cycle applications it can reach 200-300 Ah. Important: **Ah decreases at higher discharge rates** (Peukert effect) — a 100 Ah battery at C20 may only deliver 70-80 Ah if discharged in 1 hour. For pure starting the relevant figure is CCA (instantaneous current), but Ah determines how long consumers (lights, radio, parking heating) can run with the engine off. Replacing a battery with one of HIGHER Ah than the original generally causes no problems (the alternator still charges it); going LOWER may leave you short on auxiliary power.

## See also

- [CCA (Cold Cranking Amps)](https://baterias.com/gb/battery-glossary/cca)
- [RC (Reserve Capacity)](https://baterias.com/gb/battery-glossary/rc)
- [C20 / C5 / C100 (discharge rate)](https://baterias.com/gb/battery-glossary/c20)

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