A standard small car battery is about 45 amp/hours. That means that it will supply over two amps for 20 hours. A battery should not be discharged at a higher current draw, or asked to deliver more amps than its amp/hour rating divided by 10 in order to get maximum capacity out of it.
How much power does a car battery put out?
Your battery energy capacity is 12 volts x 40 amp-hours, for a total of 480 watt-hours. Divide this by 50 watts, and you get 9.6 hours. BUT. This is a car battery, not a deep-discharge marine battery.
An average car battery has a capacity of around 48 amp hours which means that, fully charged, it delivers 1 amp for 48 hours, 2 amps for 24 hours, 8 amps for 6 hours and so on.
The key is to use the watts you know to calculate the amps at the battery voltage . For example, say you want to run a 250 watt 110VAC light bulb from an inverter for 5 hours. Amp-hours (at 12 volts) = watt-hours / 12 volts = 1470 / 12 = 122.5 amp-hours.
This means that a battery has a 100 A.H. capacity if it is discharged over 20 hours, or at about 5 Amps-per-hour (100 A.H. / 20 hours = 5 Amps DC). However, this same battery would last only one hour if the discharge rate was 50 Amps-per-hour (50 Amps DC x 1 hour = 50 A.H.) because of the high rate of discharge.
The actual resting voltage, or the voltage a battery will settle at 12-24 hours after being removed from the charger, is closer to 2.1 volts per cell, or about 6.4 volts for a 6v battery, and 12.7 volts for a 12v battery. These numbers assume 100% healthy cells, and may vary a bit lower for older batteries.
Fully charged automotive batteries should measure at 12.6 volts or above. When the engine is running, this measurement should be 13.7 to 14.7 volts. If you don't have a multimeter to tell you the voltage of your battery, you can do a test of your electrical system by starting the car and turning on the headlights.
While a battery that allows a car start at the first turn of the key is a joyful thing, it doesn't last forever. In fact, depending on where you live and how you drive, the condition of your charging system, and a number of other factors, a battery lasts about four years on average.
An amp hour (AH) is a rating usually found on deep cycle batteries. The standard rating is an amp rating taken for 20 hours. What this means for a 100 AH rated battery is this: Draw from the battery for 20 hours, and it will provide a total of 100 amp hours. That translates to about 5 amps an hour.
Ah means Ampere Hours. All batteries are rated according to their power output. Virtually all car batteries run at 12 volts for but the car battery Ah and CCA ratings vary. The average car battery will have an Ah rating somewhere around 50Ah.
Power in Watts = Current in Amps x Voltage. A battery rated for 100 amp hours will provide 5 amps for 20 hours. If we have a 12 volt battery, we multiply 100 by 12 and determine that the battery will provide 1200 watt hours.
Convert mAh to Watt hours. Insert milliamp hour (mAh) and voltage (V) and click on Calculate to obtain Watt hours (Wh). Formula is (mAh)*(V)/1000 = (Wh). For example, if you have a 300mAh battery rated at 5V, the power is 300mAh * 5V / 1000 = 1.5Wh.
Use only distilled water to fill the cells. Distilled water can be purchased at most grocery stores. If the electrolyte levels in the cells are low (plates are exposed), fill each cell to just cover the plates. Then use a battery charger to recharge the battery, or just drive the car for a few days in normal service.
The charging of lead-acid batteries can be hazardous. However, many workers may not see it that way since it is such a common activity in many workplaces. The two primary risks are from hydrogen gas formed when the battery is being charged and the sulfuric acid in the battery fluid.
A standard 12-volt, lead-acid battery is made up of six cells connected in series. Each cell produces approximately two volts. The cells are filled with an electrolyte.
The most common battery rating is the AMP-HOUR RATING. This is a unit of measurement for battery capacity, obtained by multiplying a current flow in amperes by the time in hours of discharge. (Example: A battery which delivers 5 amperes for 20 hours delivers 5 amperes times 20 hours, or 100 ampere-hours.)
The real capacity of a battery is measured in Watt-Hours. (Wh). This takes into account the variation in voltage as the battery discharges. Apmere Hour (Ah) is often used as a proxy for capacity when voltage is assumed to be within usable range and exact voltage at which current is delivered over time is not important.
This deep-cycle marine/RV battery is rated for 500 MCA (marine cranking amps) and 80 amp-hours. The 140-minute reserve capacity indicates the number of minutes a battery can deliver 25 amps of current without dropping below 10.5 volts.
An ampere hour (abbreviated Ah, or sometimes amp hour) is the amount of energy charge in a battery that will allow one ampere of current to flow for one hour. An ampere is a unit of measure of the rate of electron flow or current in an electrical conductor.
Reserve Capacity (RC) is the number of minutes a fully charged battery at 80 o F (26.7 o C) is discharged at 25 amps before the voltage falls below 10.5 volts. To convert Reserve Capacity (RC) to Ampere-Hours at the 25 amp rate, multiple RC by .4167.
All deep cycle batteries are rated in amp-hours. An amp-hour is one amp for one hour, or 10 amps for 1/10 of an hour and so forth. It is amps x hours. If you have something that pulls 20 amps, and you use it for 20 minutes, then the amp-hours used would be 20 (amps) x .333 (hours), or 6.67 AH.
Whether a car battery is flooded or dry, they're both both typically lead-acid batteries, with plates of lead and lead dioxide and electrolyte inside a polypropylene case. In an AGM battery, the electrolyte is absorbed in a glass mat separator (hence the AGM moniker).