How Long Will A 12V 12ah Battery Last?

in short, a 12v 12ah battery will last between 12 hours (running a 12-watt DC appliance) to 1 hour (running a 140-watt appliance)

12ah battery is a small-sized battery compared to other 12v batteries like 100ah or 200Ah.

Due to lower Amp-hours capacity, you can’t run heavy appliances on it but the question comes what devices can you run on it, and for how long?

So in this blog, I’m gonna share with you what you can run with a 12v 12ah battery and its estimated run time before the battery gets fully drained

Need an easy solution? Use the our battery runtime calculator (given below) to find out how long will a 12v 12ah battery will last

Battery Runtime Calculator

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

Note! use my solar panel size calculator for a battery to recharge your battery in desired hours with solar panels.


  • 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 12
  • Enter the battery voltage: in this case, it’ll be 12
  • 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 12ah battery last

What Does a 12v 12ah Battery Mean?

The battery capacity is measured in Ah but the appliances are measured in watts. So to converter Ah into watts (watts = Ah x volts)

12 * 12 = 144 watts

12V 12Ah battery means 144 watts of capacity which you can use to run your small devices like LED bulbs, charging phones, etc…

These small batteries are designed in a way to so they can draw a small amount of power slowly for a longer period of time or in simple words 12ah battery will last 1 hour if you’re running a 1A capacity device with it

Video – Explaining Battery Capacity

12ah Battery Backup Time

How long will a 12v 12ah battery last depends on the total output load or what capacity of the electronic device you’re running on it?

For example, a 12ah battery is equal to 144 watts which means you can run a 10w capacity appliance on it for 14 hours or a 140W appliance for 1 hour if the battery is a lithium battery

if you have a lead-acid small 12ah battery it means you’ll be only able to use only 72 watts because of it discharge limit (50%). 144/2 = 72 watts. The same goes for AGM battery type

But most of the small batteries you’ll get will be the lithium-ion battery which means you can fully discharge the battery to 0%

here’s a list of appliances connected with a 12ah battery and how long your battery will last while running those appliances

ApplianceWatts required Estimated Running time with 12v 12ah battery
22 Inch LED TV17W8.4 hours
32 Inch LED TV20W7.2 hours
42 Inch LED TV58W2.4 hours
55 Inch LED TV116W1.2 hours
Air Purifier25W5.7 hours
Aquarium Pump20W7.2 hours
Ceiling Fan60W2.4 hours
DVD Player30W4.8 hours
Electric Shaver15W9.6 hours
LED Light Bulb10W14 hours
Phone Charger7W20 hours
Tablet Computer10W14 hours
Wall Fan60W2.4 hours
WiFi Router10W14 hours
How long will a 12ah battery last?

Simply divide the Watt capacity of your battery by the appliance wattage required to calculate how many hours will your battery last

Video – Unboxing & Testing 12ah battery

What is Needed To Run Appliances with a 12ah Battery?

As we know that batteries store power in DC (Direct Current) so if You are running DC appliances with your 12ah battery then yes you can directly connect them to the battery but for devices that require AC (alternating current), you’ll need a UPS or the inverter.

UPS comes in a builtin inverter but you can separately use an inverter that will convert the DC power into AC

I would recommend using a 12v 150W inverter with a 12ah battery

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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.