Short answer: About 10 to 15 hours. Medium answer: If your battery is an 80 Ah battery (that is a smallish car battery) it will be 80% drained after 12.8 hours (after 15.2 hours the battery is 90% used up).
What is an acceptable amount of draw on a car battery?
A normal amount of parasitic draw for newer cars is between 50-milliamp to 85-milliamp current draw. A normal amount of parasitic draw for older cars is a reading less than 50-milliamp. Anything past these amounts indicates an electrical issue and should be addressed by a mechanic.
How do you calculate how long a battery will last?
To determine how long your battery will last, calculate the battery’s total capacity and divide it by your circuit’s power. Multiply the battery’s reserve capacity by 60. With a reserve capacity, for instance, of 120: 120 x 60 = 7,200.
How many amps does a dead battery draw?
Generally, a car battery pulls approximately 400 amps for small vehicles to start and more than 1000 amps for the large ones. That is why the car manufacturers provide bigger amps in the car battery than it needs to start.
How many amp hours does it take to start a car?
On average a 4 or 6 cylinder car will draw about 250 amps for 3 seconds to start. That works out to be 0.21 Amp-Hrs. The alternator on a car can easily restore that amount of energy in 30 seconds at about 40% efficiency. Which means about 0.52 Amp-Hrs are needed from the alternator to recover the battery.
What can drain a car battery when the car is off?
Even while your car is off, your battery provides power to things like the clock, the radio, and the alarm system. These things shouldn’t have a major impact on your battery. What may drain a car battery when it’s off are things such as interior lights, door lights, or even bad relays.
How many amps does a car use at idle?
Typical Current Loads for Automotive Systems, Lighting and Accessories: Engine Idling (no lights or accessories on) – 35 to 50 amps.
How long does a 5 Ah battery last?
The difference is how long they can last. A 2.5 AH (amp hour) battery could theoretically deliver one ampere of current for 2.5 hours before it is out. A 5 AH battery can do that for 5 hours, etc.
How long will 2ah battery last?
A compact 2ah battery should last about 6-8 hours, so you get about 3-4 hours per ah.
How long will a 7Ah battery last?
Look for the energy rating listed in units of Ah, that is Ampere-hours. For example, a 12V 7Ah battery will last for 7Ah/10A = 0.7 h = 42 minutes while supplying 10A.
How much amp draw is too much?
In fact, we suggest a 25-milliamp draw is acceptable and anything that exceeds 100-milliamps indicates an electrical issue that needs to be addressed.
How do I check for a battery draw?
Pull the negative off the battery. Put the test light between the post and the ground wire. If the light illuminates, you have a draw. Use the fuse pull method to find the draw; when the light goes out, you found the draw.
Does revving engine charge battery faster?
But when your engine turns faster, the engine’s alternator also turns faster. … That way, all of the alternator’s power can be directed to recharging the battery. Once the car starts, you can rev it up to charge the battery faster, but the best way to do that is to just drive it.
What draws the most power from a car battery?
The starter motor is the most energy-hungry consumer in the car, but without it nothing works. Multiple starting attempts drain the battery, especially if it is old and has been poorly maintained. The radiator fan starts when the engine gets too hot, for example in traffic queues in summer when there is no airflow.
How many amp hours is the average car battery?
Typical automotive battery: 70 amp-hours @ 3.5 A (secondary cell) D-size carbon-zinc battery: 4.5 amp-hours @ 100 mA (primary cell)