Battery capacity decreases as the rate of discharge increases. Batteries (say 100ah battery) have been tested at a given discharge rate of 20 hours. That means a constant use of 5 amps an hour for 20 hours (5 x 20 =100).

## How long will a battery last with a 1 Amp draw?

It depends on the power demand of your system. 3 Ah means that if you pull 3 Amperes from the battery for 1 hour, it will be discharged completely after 1 hour. So if you pull 1 Amps, it will last **3 hours**.

## 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 should a car battery draw when off?

Most vehicles draw some battery current when the key is off, thanks to the clock and the internal memory of engine computers, body-control modules, and radio presets. Altogether, they draw a very small amount of current. **Fifty milliamps** would be a safe upper limit for this, though many vehicles will draw less.

## 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.

## How long will a 100Ah battery run an appliance that requires 1000w?

Table: Running times for various AC loads

100Ah deep-cycle lead-acid battery with AC loads with inverter – 50% recommended discharge | |
---|---|

Load (watts) | Run time (hours) |

800 |
0.65 |

900 |
0.57 |

1000 |
0.52 |

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

A 12V 100ah battery can run a 100W appliance for **20 hours** at a draw of 5 amps/hour. Due to inverter inefficiency and energy losses, drawing more than 5 amps an hour reduces the ah capacity rapidly, but drawing less slows the discharge rate.

## How long will a 100 Ah battery last?

A 100 ah battery should give you (100/10=10) **10 hours** of usage. If you use it for 5 mins a day, it could last 120 days.

## How long will a 200Ah battery last?

Depending on how many amps your appliances are drawing, a 200Ah battery will likely last you **between two and eight hours**. At 25 amps, you can expect the 200Ah battery to last eight hours.

## How long does a 4.0 Ah battery last?

So by that logic, a 4.0Ah battery should last for **2 hours** in the same electric mower.

## How much should car battery voltage drop overnight?

Shouldn’t go much below **~12.6v** and can go up to 13 to 14+volt while running/charging. Any decent car battery will only lose at most 0.01V maximum, the security of the car will draw some current but it should only be low.