# Best answer: How long can a car battery run a 12v fan?

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## How long will a 12V fan run on battery?

If you use the upper 500ma (1/2 amp) draw for your calculation, the fan will use 1 AH (amp hour) of power every 2 hours. If you have a typical single battery that came with the camper it is more than likely about 80-90 AH, of which 40-45 AH is usable before you need to re-charge the battery.

## How long can radiator fan run on battery?

some cars are configured this way, but it shouldn’t run for more than about 5~10 minutes, if it is supposed to run after shutdown.

## Will running fan drain car battery?

The problem is although the current draw over 45 minutes might be “low”, your battery might be weak, meaning it could have a bad cell and a low reserve capacity. It doesn’t take much to “drain” a weak battery.

## How long will a 100Ah battery run an appliance that requires 400W?

A 100Ah 12 volt deep-cycle lead-acid battery can run a 400W continuous DC load for 1.5 hours with the recommended 50% Depth of Discharge. A 100Ah 12 volt deep-cycle lead-acid battery can run a 400W rated AC fridge for 15 hours at a rate of 40 watts per hour.

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## How many amps does a 12 volt battery have?

Car batteries will typically have a capacity of 48 amp hours. What this means is a fully-charged 12-volt car battery rated at 48 amp hours can deliver 1 amp for 48 hours or 2 amps for 24 hours. This also means the battery can supply 8 amps for 6 hours under ideal operating conditions.

## How many Watts does a small 12V fan use?

For instance, a 12v fan that has a 0.25A current will draw 3 watts of power. Amp draw will compound linearly as you add more devices into a system (think adding a new water pipe with a consistent pressure); voltage will not change unless the power supply is changed.

## Should radiator fan turn on when AC is on?

Both radiator fans should always run when the AC compressor is engaged. To check the temperature at which the fan comes on, turn the A/C off and keep the engine running until it reaches normal operating temperature. Most fans should come on when the coolant reaches about 200 to 230 degrees.

## Is it normal for radiator fan to stay on?

This is normal in many vehicles, such as BMW or Mercedes-Benz. The radiator fan may run up to five minutes and sometimes longer. Unless there is an electrical issue, it may stay on all the time until it drains the battery. … Running cooling fans help cool down the engine even after you turn off the car.

## What temp should my electric fan turn on?

Your radiator fan should kick in at about 200 degrees Fahrenheit. If you notice your vehicle is overheating or at the very least running hotter than it normally does, listen for the fan to see if you can hear it.

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## Can a bad fan relay cause battery drain?

3. Cooling fans stay on at all times. … If the relay shorts internally, it may cause power to be permanently switched on, which will cause the fans to run at all times. Depending on the wiring setup of the vehicle, this may cause them to stay on even when the vehicle is off, which will drain the battery.

## What are the signs of a bad alternator?

7 Signs of a Failing Alternator

• Dim or Overly Bright Lights. …