How much current can a car/truck battery supply?

Question

In my area, electricity faliure is great problem. i want to design cheap UPS for my home. i want to use normal car/truck battery.
Plz tell me electrical specifications of such batteries.
Also give any other suggestion about this if u can

Answer 1

There is a specification for automotive batteries, called, "Cold Cranking Amps" (CCA). This is the available current for a starter motor. Under CCA conditions (for short times) the terminal voltage drops from the nominal down to about 9 volts. CCA's can range from 500 all the way up to 1000 Amps for larger sized car batteries.

Normally, these 12V batteries are rated for normal operating current less around the 100 Amp range.

Deep cycle marine batteries (similar to car batteries) are generally what you would want to have for a UPS, as they are designed for cycling (charge - discharge).

Fresh and fully charged, a 12V lead secondary cell battery (car battery) has a terminal voltage of about 14.5 volts. Nominally the terminal voltage is 12.6 volts.

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Answer 2

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YES. But you have to consider the powers supply (PSU). This needs to be a stabilized voltage/current source of 13.8 Volts and capable of drawing a minimum of 12 Amps. The reason I say 12 Amps is because under full load, a small PSU rated at say 5 Amps will soon die if its load is 5 Amps... It is all a matter of duty cycle. A PSU rated at 12 Amps will run 5 Amps all day with no over heating problems. Now, to the antenna (areal actually). At 27.8 Mhz you will need an antenna (full wave is 10.257 meters with the Velocity Factor of .95% taken into account). A quarter wave would be 2.562 meters in length., but a counterpoise will need to be used, and that is, of course, ground. A half wave dipole with a two and a half turn coil, tapped at a 1/4 turn from the base will be resonant and be 50 Ohms at the antenna base. The cable will need to be cut to length, too, but this will, by virtue of coax being coax, then the velocity factor will be .66. So the (50 ohm) coax will be 18.348 meters. This will give you a VSWR of about 1.5 to 1 into an 50 Ohm load (the CB). You could make a SLIM-JIM antenna, and this would drop the main lobe to something like 15 degrees, rather then the normal 45 degrees that sends most of your transmitted signal to the moon. Look up SLIM-JIM on the web, and the might even have a calculated one ready to build, too. I made one twenty years ago for 28 Mhz, and boy did it perform well. I hope that helps Kind regards Dr Antony

Answer 3

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RE:
How much current can a car/truck battery supply?
In my area, electricity faliure is great problem. i want to design cheap UPS for my home. i want to use normal car/truck battery.
Plz tell me electrical specifications of such batteries.
Also give any other suggestion about this if u can

Answer 4

Your question is not complete. Batteries can give immense current for short duration.
But you are having power cuts of what duration, what will be your load (Voltage x Current X power factor), what kind of devices you have to run. All these are required for any calculation on duration of the battery.
The battery AH is the main thing to bother with. The higher the AH,the more time the battery can support the load.
But again you cannot take large loads out of the battery since if you exceed the charge-discharge cycle of the battery, the battery will get damaged.
Again the battery has to be charged back. If you discharge fast, it will take longer time to charge.
All the above have to be considered when you make an UPS.

Answer 5

My search indicates that the range for cars and light trucks is about 450 to 870 cold cranking amps. Cold Cranking amps is defined as the minimum electric current (in amps) that a charged 12-volt battery can deliver for 30 seconds at 0 degrees F (brrrrr) without falling below 7.2 volts.

Answer 6

many different types of batteries so this would be difficult

Answer 7

Ask the guys at the auto supply store.