How many amp hours in a car battery

When is your car battery too old? Is your speedometer as accurate as you think? November 11, Timing belt check: an expert guide. November 10, Cars, vans and tools on YouTube: highlights from Haynes. For example if you draw at 1C on a lead acid battery you will only get half of the capacity that you would have if you had drawn at 0. For lead acid batteries the rated capacity i.

If you are discharging at a slow rate you will get the rated number of amp-hours out of them. However, at high discharge rates the capacity falls steeply. A rule of thumb is that for a 1 hour discharge rate i. Charts that detail this effect for different discharge rate can be used for greater accuracy.

For example, if your portable guitar amplifier is drawing a steady 20 amps and you want it to last 1 hour you would start out with Step Thus you would need a 50 amp hour sealed lead acid battery to run the amplifier for 1 hour at 20 amps average draw. Step 4. The obvious thing to do is the thing to do. Figure out an average power drawn. Consider a repetitive cycle where each cycle is 1 hour.

In highway conditions, you can fully-charge a healthy battery in about 30 minutes — much faster than it charges using a battery tender. Eventually, yes. The stated CCA of a battery tells you its amp capacity when the battery is new. Damage from heat and vibration — along with standard wear and tear — will reduce its total capacity, and in turn, its amp hours and amp rating.

Deep discharges prevent the battery from charging fully and allow it to lose its charge more easily. Even in ideal circumstances, most batteries die after about years and will become gradually weaker until they lose power.

Then, you will need to change them. Bonus: Check out our guide on charging a connected battery! Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Contents 1 What are the ampere ratings? Discharge period used for Ah rating. Credit: tuningenmedellin. Related Posts. About The Author. Tim Miller.