How long will 150ah battery last while running a load will depend on various factors, such as output load, battery discharge efficiency, speed of discharge, and temperature.

Most answers out there will give you a ‘theoretical’ number. However, the actual runtime of a battery is influenced by many real-world factors, including the battery’s discharge chemistry, how quickly it is used, and the temperature of the surroundings.

** Looking for a quick answer?** Try using

**our battery runtime calculator**to calculate your battery’s runtime.

## Amp-hours, Watt-hours, and Battery discharge Efficiency

Power is measured in watts. Here are some formulas to remember:

- Watts = Volts × Amps
- Amps = Watts ÷ Volts
- Volts = Watts ÷ Amps

**Amp-hours (Ah) **is a way of measuring how much electrical charge a battery can provide over time, measured in amps. If a battery has 150ah capacity, it means it can supply 150 amp of current for one hour “theoretically”.

**Watt-hours (Wh) **is a unit of measurement that tells us how much energy an electrical device consumes over time. It’s like the energy consumed by a 1-watt device for one hour.

**Lead acid vs Lithium battery discharge limit (DoD):** Lead acid, AGM, and gel batteries are suggested to only be discharged 50% while lithium batteries can be completely discharged. This means that from a 150ah lead acid battery, you can only use 75 amps.

**Battery discharge efficiency:** Unfortunately, batteries are not 100% efficient when discharging. The efficiency rate will depend on the battery type.

Based on directscience.com data:

- Lead-acid batteries discharge efficiency ≈ 80 − 85%
- Lithium-ion batteries discharge efficiency ≈ 90 − 95%

Here’s a table on 150ah battery usable amp-hours after considering discharge efficiency (Lead acid: 85%, and Lithium: 95%).

Battery type | 150ah battery usable capacity (in ah) |
---|---|

Lead acid | 127ah |

Lithium (LiFePO4) | 142ah |

## 150ah battery how many watts?

150ah or 150 amp-hours battery means it can provide 1 amp for 150 hours or 150 amps for 1 hour.

In order to determine how much power a battery can actually hold, we typically measure its capacity in watt-hours.

Formula:Battery capacity Wh = Ah × Volts

12v 150ah battery capacity in watt-hours:

150 × 12 = 1800 watt-hours

24v 150ah battery capacity in watt-hours:

150 × 24 = 3600 watt-hours

12v 150ah battery is equal to **1800 watt-hours** and 24v 150ah battery is equal to **3600 watt-hours**. This means 150 amp-hour 24v battery stores double the power of a 12v 150 amp-hour battery.

Now, let’s crunch some numbers, and after this, I’ll explain why it’s not possible to achieve a 100% accurate runtime.

**Related post: Battery Amp Hours To Watts (Ah To Watts) Calculator**

## 5 steps To Calculate 150ah Battery Runtime

Let’s figure out your 150ah battery backup time, follow these steps.

### Steps

**1. Converter battery amp-hours (Ah) into watt-hours (Wh)**. Let’s say you have a 12v 150ah battery.

150ah battery in watts = 150 × 12 = 1800 watt-hours

**2. If you are using a lead-acid battery, make sure to multiply its watt-hour capacity by 0.5, which takes into account the depth of discharge limit.** For example, if you have a 150ah lead-acid battery.

`Battery capacity in wh after DoD limit = 1800 × 50% = 900wh`

**3. To adjust battery discharge efficiency, multiply the battery’s capacity by a certain factor. For lead-acid batteries, multiply by 0.85, and for lithium-ion batteries, multiply by 0.95.**

`Battery usable watt-hours: 900 × 0.85 = 765wh`

**4. To adjust for the inverter’s efficiency, multiply the battery’s usable capacity by 0.9, **which is a typical efficiency rate for inverters.

`Battery AC watts = 765 × 90% = 688 AC watt-hours `

**5. Divide the battery’s AC watt-hours by the sum of all the devices that are connected to it.** Let’s say you’re running a 100-watt appliance with a 12v 150ah battery.

150ah battery runtime on 100 watt appliance = 688 ÷ 100 = 6.8 hours

Turns out, a 12v 150ah lead acid battery will run 100-watt appliance for about **7 hours**.

## effect of discharging rate on your battery’s performance

A battery will not provide the same amount of energy as its label if used quickly, known as Peukert’s law. This is because more energy is wasted as heat when a battery discharges quickly instead of being used to power devices.

But this only applies to lead-acid batteries. On the other hand, lithium batteries can be safely discharged at 50% of their capacity without any power loss.

This means you can discharge your lithium battery in 2 hours without causing any power losses. However, lead-acid batteries are made to be discharged over a longer period of 20 hours, and if you discharge them too quickly, their efficiency will go down.

**Related post: Battery Charge And Discharge Rate Calculator: C-Rating To Amps**

This table displays the usable capacity of a 150ah lead-acid battery in amp-hours based on the rate of discharge.

Usable 150ah lead acid battery capacity | Hours of discharge |
---|---|

150ah | 20 hours |

135ah | 10 hours |

130ah | 8 hours |

123ah | 6 hours |

120ah | 5 hours |

105ah | 3 hours |

90ah | 2 hours |

75ah | 1 hour |

**Note:**This table doesn’t take into account lead acid’s 50% DoD limit.

## How Temperature Affects Battery Performance

Batteries are sensitive to temperature changes, and extreme temperatures can affect their discharge efficiency.

**When the temperature is too high**, the battery’s internal resistance increases, causing it to lose capacity and discharge efficiency.**When the temperature is too low**, the battery’s chemical reactions slow down, reducing its ability to produce the required power.

Therefore, it’s crucial to keep your batteries in the right temperature range, which is typically between **68°F and 77°F (20°C to 25°C)**. *Ask your manufacturer* for a *more accurate number or look at your battery specs sheet data.*

As a general rule, a temperature increase to 77ºF or 25º C can cut battery performance by 50%.

## How long does a 150ah battery last? – chart

Here are charts on how long will 12v 150ah lead acid and lithium batteries will last running different small household appliances.

### 12v 150ah lead acid battery

Appliance power required | 12v 150ah lead acid battery runtime |
---|---|

50 watts | 14 hours |

100 watts | 7 hours |

200 watts | 3.5 hours |

300 watts | 2 hours |

400 watts | 1.7 hours |

500 watts | 1.3 hours |

600 watts | 1 hour |

^{Note: This table doesn’t take into account Peukert’s law and temperature}

#### summary

- 12v 150ah lead acid battery will last between
**14 hours**(running a 50w load)**to 1 hour**(running a 600-watt load) while running different appliances.

### 12v 150ah Lithium battery

Appliance power required | 12v 150ah lead acid battery runtime |
---|---|

50 watts | 31 hours |

100 watts | 16 hours |

200 watts | 8 hours |

300 watts | 5 hours |

400 watts | 4 hours |

500 watts | 3 hours |

600 watts | 2.5 hours |

#### summary

- 12v 150ah lithium battery will last between
**30 hours**(running 50w load**) to 2 hours**(running 600-watt load)