How Long Will A 100Ah Battery Last? + Calculator

A 12v 100ah lithium battery with a 100% DoD limit will last between 22 hours (running a 50-watt AC appliance) to 36 minutes (running a 2000-watt AC appliance).

In this post, you’ll learn how long will a 100ah battery last running a different size AC or DC load (with examples).

Need an easy solution? use our battery runtime calculator ( given below ) and ” Enter the battery specs and the total load in watts ” to find out how long will a 100ah battery last

Also, I’ll share the manual calculation method and some other important points to keep in mind that the other websites aren’t talking about.

How Long Will 100ah Battery Last – Calculator​

Battery Capacity
Ah
Battery Volts
V
Select Battery Type
Load Connected with inverter?
Total Load (watts)
Wh

Note: use my solar panel size calculator for a battery 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): in this case, it’ll be 100
  • Enter the battery voltage: is this a 12, 24, or 48-volt battery?
  • 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?: Are you using an inverter to run the load or is the load connected directly through the battery?
  • Enter total load in watts: Enter the total load in watts (e.g 500 for 500 watts of output load)

After entering the information, click “Calculate” button to find out how long will a 100ah battery last

if you’ve got some time keep reading… I’ll share a manual calculation method that you can use in the future to calculate any size battery runtime on any load and also some additional information about batteries that will affect the battery last time.

Example 1: How Long Will A 100ah Battery Run An Appliance That Requires 1000 Watt

how long will a 100ah battery run an appliance that requires 1000 watt

12v 100ah battery will last anywhere from 32 minutes (with lead-acid battery) to 60 minutes (with lithium battery) while running an appliance that requires 1000 watts

Example 2: How Long Will A 100ah Battery Run An Appliance That Requires 400 Watt

how long will a 100ah battery run an appliance that requires 400 watt

12v 100ah battery will last anywhere from 1 hour and 22 minutes (with lead-acid battery) to 2 hours and 42 minutes (with lithium battery) while running an appliance that requires 400 watts

Video – All About Battery Basics (Must Watch!)

This guys has explained in detail the battery basics, MUST watch to understand how batteries work (charge and discharged) 

Steps To Calculate 100ah Battery Runtime

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 100ah battery

100ah battery in watts = 100 * 12 = 1200 watt-hours 

2- Multiply the battery watt-hours to 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 = 1200 * 50% = 600wh

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 = 600 * 90% = 540 AC watt-hours 

4- Divide the battery AC watt-hours by the total load connected. Let’s say 100-watt appliance is connected with your 100ah battery

100ah battery runtime on 100w appliance = 540 / 100 = 5.4 hours

How long will a 100ah battery run an appliance that requires 100w? 12v 100ah lead-acid battery with a 50% DoD limit will last about 5.4 hours while running a 100-watt appliance.

How Long Will A 100ah Battery Last? – Chart

Here’s a chart on how long will a 12v 100ah lithium (LiFePO4) battery will last while running a different watt load.

How Long Will 100ah Lead-Acid Battery Last?

Appliance Power Required100ah Battery Runtime
20 watt27 hours
40 watt13.6 hours
50 watt10.9 hours
60 watt9 hours
100 watt5.5 hours
150 watt3.6 hours
200 watt2.7 hours
300 watt1.8 hours
400 watt1.3 hours
500 watt1 hour
600 watt54 minutes
800 watt40 minutes
1000 watt33 minutes
1200 watt27 minutes
1500 watt21 minutes
2000 watt12 minutes
3000 watt10 minutes

Summary

  • 12v 100ah lead-acid battery will last about 11 hours running a 50-watt appliance
  • 12v 100ah lead-acid battery will last about 2 hours and 42 minutes running a 200-watt appliance
  • 12v 100ah lead-acid battery will last 21 minutes running a 1500-watt appliance
  • 12v 100ah lead-acid battery will last about 10 minutes running a 3000-watt appliance

How Long Will 100ah Lithium (LiFePO4) Battery Last?

Appliance Power Required100ah Battery Runtime
20 watt54 hours
40 watt27 hours
50 watt22 hours
60 watt18 hours
100 watt11 hours
150 watt7 hours
200 watt5.4 hours
300 watt3.6 hours
400 watt2.7 hours
500 watt2.1 hours
600 watt1.8 hours
800 watt1.3 hours
1000 watt1 hour
1200 watt54 minutes
1500 watt43 minutes
2000 watt33 minutes
3000 watt21 minutes

Summary

  • 12v 100ah lithium battery will last 27 hours running a 40-watt appliance
  • 12v 100ah lithium battery will last 1 hour and 48 minutes running a 600-watt appliance
  • 12v 100ah lithium battery will last 1 hour and 18 minutes running an 800-watt appliance
  • 12v 100ah lithium battery will last 54 minutes running a 1200-watt appliance

Note! The values are based on AC output load with a 90% efficient inverter.

Assumptions & Shortcomings Of All These Methods

Here are some extra yet important points to keep in mind when figuring out how long will your 100ah battery will last running a 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 (1h → 1C, 2h → 0.5C, 5h → 0.2C, etc.)

Related FAQ’s

How long will a fridge run on a 100Ah battery?

a 12v 100Ah lead-acid battery with 50% depth of discharge will run a small size camping fridge (2-5 cu. ft.) for about 18-24 hours and a large-sized kitchen fridge (20-25 cu. ft.) for about 6-8 hours

How long will a 100Ah battery run a TV?

a 100ah battery will run a Tv for about 10-50 hours. The exact value will depend on the size and type of television, and also the battery depth of discharge limit

How many watts can a 100Ah battery run?

You can safely run 600 watts on a 100ah lithium battery at a time and 120 watts on 100ah lead-acid battery

How long will a 100Ah battery run a light?

100ah lead-acid battery can run a 100 watt of lights for about 6 hours

What can I run off a 100Ah battery?

100ah battery is equal to 1200 watt-hours and you can run almost any all kind of home appliances with it, like fridge, tv, charging phone, laptop, lights, etc…

Is 100Ah enough for camping?

100ah battery would be enough for camping to run most of the basic appliances like lights, charging phones and laptops, etc…

how long will a 100ah lithium battery last

100ah lithium battery will last 1 hour (running a 1200 watts DC of load) and 120 hours (running a 12 watts of DC load)

100Ah means how many watts

12v 100ah means 1200 watts, 24v 100ah means 2400 watts, 48v 100ah means 4800 watts. To calculate the watts in a battery use this formula ( battery watts = battery amp-hours * battery volts )

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I'm an experienced Sales Consultant with a demonstrated history of working in the renewables and environment industry. Skilled in Photography, Customer Service, and Sales.