12v 50Ah lead-acid battery with 50% depth of discharge will run a small-size camping fridge (2-5 cu. ft.) for about 9-12 hours and a large-sized kitchen fridge (20-25 cu. ft.) for about 3-4 hours.
in this short guide, I’ll explain it with the help of charts and the factors which will affect the 50Ah battery runtime on the refrigerator.
Hate calculations? use the calculator given below to find out the 50Ah battery runtime on a fridge
Battery Runtime Calculator
- Lead-acid battery: 50% DoD (depth of discharge) limit
- Lithium (LiFePO4): 100% DoD (depth of discharge) limit
- Inverter efficiency: 90% efficient
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
- Battery Capacity: Enter battery capacity in Amp-hours (Ah) in this case it’ll be 50
- Battery Volts: Enter battery voltage, is it 12, 24, or 48v?
- Load Connected with inverter? is your fridge running through the inverter or is it running directly from the battery (which is possible if you have a 12v fridge and a 12v battery but in this case also you would have to install a DC-DC voltage regulator to protect the refrigerator from voltage fluctuations)
- Total Load: Will be the average total power consumption of the fridge (Per hour) including duty cycles, keep reading to figure out the power consumption of your fridge
After Entering the values click “ CALCULATE “ to find out the estimated runtime of your 50Ah battery on the refrigerator.
Suppose you have a 12v mini camping fridge (4.5 cu. ft.), which consumes about 700Wh of power in 24 hours and 30w per hour, and a 12v 50Ah lead-acid battery
Note: in order to recharge your batteries you’d need the right size solar panel. use my free online solar panel calculator for battery
Related Post: Solar Panel Calculator For Battery
How Much Power Does a Refrigerator Use?
On average latest technology, refrigerators consume about 60-350 watts of power when running and 0.5-2.5kWh per day. but on the other hand, an old technology fridge (manufactured before 2010) consumes about 400- 700 watts of power and 3.2-5.6kW per day.
To calculate the accurate power consumption of your fridge read the product description sheet on your fridge to find out.
if you have a new model fridge there will be an estimated “yearly power consumption” by the company but if it doesn’t then calculate the wattage consumption of your fridge with this formula (watts = amps*volts)
let’s take my medium size RV fridge as an example (mentioned above)
115 * 1.1 = 126.5
This fridge will consume 126 watts of power when the compressor is running.
Duty Cycle: new technology fridge runs about 8-10 hours per day in total (depending on external or internal factors).
On the other hand, if you have an old technology fridge I’ll have a duty cycle of about 12-15 hours.
126 * 8 = 1000Wh or 1kWh
Medium size RV fridge consumes about 1kWh of power per day with 8 hours of duty cycle.
Note! To get started, the fridge requires a surge wattage (burst of power which will last for a few seconds) which is usually about 2-3 times higher than the continuous wattage consumption of the fridge.
Why am i telling you this? because you’d need the right size inverter to handle this surge wattage. which i have explained in detailed
Must Read: What Size Inverter To Run A Fridge?
Need an easy and accurate solution? use this watt meter to find out the total power consumption of any appliance, place this meter between the outlet and the fridge cable plug and leave it for 24 hours. after 24 hours it’ll show you the total power consumption during this period of time.
- Choose from the Kill-a-Watt's four settings to monitor your electrical usage
- Monitor your electrical usage by day, week, month, or year
- Features easy-to-read screen
- Electricity usage monitor connects to appliances and assesses efficiency
- Large LCD display counts consumption by the kilowatt-hour
- Calculates electricity expenses by the day, week, month, or year
- Displays volts, amps, and wattage within 0.2 - 2.0percent accuracy
- Compatible with inverters; designed for use with AC 115-volt appliances
Watch this short and quick video to save electricity usage of your fridge/refrigerator.
How Long Will a 50Ah Battery Run A Fridge? – Chart
Here are some charts on how long will a 50Ah battery will last on a different size fridge.
|Fridge Type||Est. Runtime on 50ah lead-acid battery||Est. Runtime on 50ah lithium battery|
|12v mini fridge (2 cu. ft.)||12||24|
|camping fridge (4.5 cu. ft.)||8||17|
|kitchen fridge (10 cu. ft.)||6||12|
|kitchen fridge (15 cu. ft.)||5||10|
|kitchen fridge (20 cu. ft.)||4||8|
|kitchen fridge (25 cu. ft.)||3||6|
|kitchen fridge (30 cu. ft.)||2||4|
- 12v 50ah lead-acid battery with a 50% depth of discharge limit will a kitchen size fridge (20 cu. ft.) for about 4 hours.
How To Calculate How Long Will a 50ah Battery Run a Refrigerator
Follow these steps to calculate the 50ah battery life/runtime while running a fridge.
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. I’ll take a medium size RV fridge as an example which consumes about 40 watts per hour
50ah battery runtime on a fridge = 270 / 40 = 6.7 hours
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