* Need an easy solution? *Enter the battery specs and the load connected with the inverter into our battery runtime calculator (given below) to find out how long will a 12v battery run a 400-watt inverter.

*Easy!* right?* *

Also, I’ll share some other factors which can affect the battery runtime

## Battery Runtime Calculator

Note!use my solar panel size calculator to find out what size solar panel you need to recharge your battery in desired hours with solar panels.

### Assumptions:

**Inverter Efficiency:**90%**Lead-acid battery:**50% depth of discharge limit**Lithium (LiFePO4):**100% depth of discharge limit

**Battery Depth of discharge DoD:** is the percentage of the battery that has been discharged relative to the total battery capacity. The recommended depth of discharge limit for lead-acid, AGM, and gel batteries is about 50%. Only lithium (LiFePO4) batteries can be fully discharged to 100%.

### How To Use The Calculator

**Enter the battery capacity in amp-hours (Ah):**Enter the battery capacity in amp-hours. for 100ah enter 100.**Enter the battery voltage:**in this it’ll be 12v**Select the battery type:**Select “Lead-acid” if you’re using a flooded or sealed (AGM or gel) lead acid battery. Select “Lithium (LiFePO4)” if you use a lithium-iron phosphate battery.**load Connected with inverter?:**in this scenario, select yes.**Enter total load in watts:**if you’re running your 400-watt inverter at its full capacity then enter 400 otherwise if the output load is below 400 watts enter the value accordingly.

After entering the information, click** “Calculate” **button to find out how long will a 12v battery run a 400 watt inverter

**Important! **it’s not recommended to run your inverter at its full capacity always leave 20% of the capacity.

### Example 1: how long will a car battery run a 400-watt inverter

A car battery will run a 400-watt inverter for about **50 minutes **

## Video – All about battery basics (Must watch!)

## Steps to calculate 12v battery runtime on 400 watt inverter

Follow these steps to calculate the battery life/runtime while running a load.

### Steps

**1- Converter battery ah into watt-hours (Wh)**. to calculate the battery capacity in watt-hours use this formula

**Battery capacity in watt-hours **= Battery amp-hours (Ah) * Battery Volts

let’s say you have a 12v 50ah battery

`50ah battery in watts = 50 * 12 = 600 watt-hours `

**2- Multiply the battery watt-hours by the battery depth of discharge limit**. **( Default battery depth of discharge limit, Lead-acid battery: 50% DoD limit; Lithium: 100% DoD limit )**. Let’s say you have a lead-acid type battery

`Battery capacity in wh after DoD limit = 600 * 50% = 300wh`

**3- Multiply the battery capacity after the DoD limit with the inverter efficiency rate to calculate the AC watt-hours ( Most of the inverters are about 90% efficient)**

`Battery AC watts = 300 * 90% = 270 AC watt-hours `

**4- Divide the battery AC watt-hours by the total load connected. **Let’s say 400-watt appliance is connected to your 50ah battery

`50ah battery runtime on 500w appliance = 270 / 400 = 0.6 hours or 40 minutes (hours to minutes = 0.6 * 60)`

Note:There are some shortcomings of these methods which i’ll discuss at the end

**How long will a 12v battery last with a 400-watt inverter?**

here’s a chart on how long your 400W inverter will last on a 12v battery

12v Battery Capacity | Battery Type | Est. Runtime |
---|---|---|

50ah | Lead-acid | 40 minutes |

60ah | Lead-acid | 48 minutes |

70ah | Lead-acid | 1 hour |

100ah | Lead-acid | 1.3 hours |

150ah | Lead-acid | 2 hours |

200ah | Lead-acid | 2.7 hours |

50ah | Lithium (LiFePO4) | 1.3 hours |

60ah | Lithium (LiFePO4) | 1.6 hours |

70ah | Lithium (LiFePO4) | 1.9 hours |

100ah | Lithium (LiFePO4) | 2.7 hours |

150ah | Lithium (LiFePO4) | 4 hours |

200ah | Lithium (LiFePO4) | 5.4 |

### Summary

- 12v lead-acid battery will last anywhere from
**40 minutes**(on 50ah battery)**to 2.7 hours**(on 200ah battery) - 12v Lithium (LiFePO4) battery will last anywhere from
**1.3 hours**(on 50ah battery)**to 5.4 hours**(on 200ah battery)

## Assumptions & Shortcomings of All These Methods

Here are some extra yet important points to keep in mind when figuring out how long will your 12v battery will last running a 400 watt inverter load

### Battery life cycle count:

- The storage capacity of the battery will decrease with every cycle ( a cycle is when you charge and discharge the battery to its DoD limit ).
- if you have used your battery for a few hundred cycles then the result will be different. ( this factor isn’t included in my above-given methods )

### Batteries are rated for 5 amps over 20 hours of time:

- Especially lead-acid type batteries are designed to be discharged at 20 hours. ( means 100ah
**lead-acid batteries are recommended to be discharged @ 5 amps**in order to maintain the battery health and reduce the discharge efficiency ). - on the other hand,
**AGM and lithium (LiFePO4)**can be**discharged at 50% of their capacity**. - Discharging your battery at a higher rate will increase heat in the battery’s internal cells which will cause power loss. (this factor isn’t included in my above-given methods).
**For example**, if you discharge your lead-acid battery with 100 amps then it’s will not last 30 minutes ( keep in mind the 50% DoD limit ). but it may last about 10-15 minutes.- Check the battery discharge rate on the specs sheet of your battery or it’ll be mentioned on the battery

**Related FAQ’s**

**How long will a battery run a 400-watt inverter?**

12v 100Ah battery will run a 400W inverter for 2.6 hours which will fully discharge the battery from 0-100% so which 100Ah lead-acid or AGM battery with 50% DOD limit it will run for 75 minutes

**How many batteries do I need for a 400-watt inverter?**

you’ll need 2 x 12v 100Ah lithium batteries in order to run your 400w inverter for 5 hours or 4 x 12v 100ah lead-acid or AGM batteries

**Related Posts**

- How Long Will A 12v Battery Last With 500w Inverter?
- Solar Battery Charge Time Calculator
- Solar DC Watts To AC Watts Calculator & Formula
- Amps To Watts Calculator: How Many Watts In A 12-Volt Battery?

*I hope this guide was helpful to you if you have any queries Contact Us Thank You! *