Battery Life Calculation

id actually be more concerned with the materials the battery was made of and the number of times it was charged, example...a lithium ion battery should retain near full power for 2000 charging cycles, a lead acid would be less than half that number

Be a pretty useless battery if it had a 5 hour shelf life.

Well said.

GA

Particularly your comment:-

Most people, even some electronics design consultants have very little understanding of batteries.

Is SO true!!

Basically, a good design of equipment, that uses as much of the energy available as possible from say Alkaline batteries, will quickly damage most rechargeable cells....so such electronic devices need to "know" what type of battery they have pushed into them by the owner....or rechargeable batteries need to be made clever enough to handle it better.....e.g. more expensive, which is probably just a waste of money....

A simple Alkaline/Rechargeable "switch" on/in the device might help matters.....

Also, some cheap AA, AAA and 9 volt Block battery chargers do more harm than good I feel.....I like one with a bit of intelligence! But they cost more. Its also difficult to "know" how well they are designed....

Some of the other comments here simply do not reflect any current knowledge on even (very old design) LA batteries....

The 5 hour battery life number is how long the battery will operate without requiring a recharge.

In order for the calculations to be reasonably accurate, all of the pertinent DATA on the battery use such as; type of device the battery is installed in, the device duty cycle (Quantity of minutes per hour as a percentage) and ambient temperature must be factored in.

If your calculator does not allow entry of pertinent device application DATA then it cannot be accurate and most likely is a WAG based on "normal" usage.

Your calculator just takes the capacity of the battery in milliamp hours and divides by the load in milliamps. You could probably do that in your head.

What is the battery for?

• Your car?
• R/C car?
• Cell phone?
• Hair dryer?
• Large Hadron Collider?

Throw us a bone here!

It's classic GIGO (garbage in garbage out)

One of our competitors claimed a battery life of over a year for a once a day timed pump. He'd done a similar "battery life" calculation based on the power consumed by the pump when it ran for 5minutes each day.
He forgot the 10mA or so consumed continuously for the 1,440 minutes of the entire day by his low tech electronics.
The product was hopeless.

Del

You have various variables that will effect the battery life(usage between charges)....Foremost among these would be the AH or mAh capacity of the battery, and the load imposed mA or wattage or amperage, rarely a steady usage rate for any device, so this is just an estimate....That's why phone manufacturers have stand-by time and usage time stats on their products....

Example...

....iPhone 6's battery lasted 35 hours of low mixed usage (including standby) and 14 hours of heavy usage, with the brightness set to 50%. The iPhone 6 is powered by an 1,810mAh battery...

http://www.trustedreviews.com/iphone-6-review-battery-life-and-verdict-page-6#mHbRcZ2khwykUp5b.99

Extreme temperatures will also effect your battery and charging methodology will play a role in battery lifespan(how long the battery is good), these guidelines are usually listed on the manufacturers website or sold with the product....

Recharging? Rechargeable?

Who said rechargeable?

Hurry, I'm unplugged!

Battery life calculators just give you a general idea. But battery life involves many different factors such as: voltage, what charge standard they use (i.e. 20ah,) capacity, manufacturer, charge rate, discharge rate and materials.

The BEST way to determine your battery's capacity or life expectancy is use the manufacturer's data sheet. In my experience, if you just ask, they will provide one. A good data sheet will include all the specs in easy to read charts outlining the charge and discharge capabilities and different rates, as well as EOL and storage information.

If the manufacturer does not provide a good data sheet, use another battery.

Look at this......

http://professional.duracell.com/en/product-datasheets

An example extract from the D size Alkaline MN1300 (LR20) data.

The importance of Del the Cat's comment on the minimum working

voltage of the load is clear.

At 1000 mA and 1.25V the cell still has ~85% capacity left and could

be transferred to a torch or radio for almost full use.

67model

Building on 67model's comment these profiles were taken from a NIMH battery. Notice how the alkaline battery voltage sort of drifts slowly toward it's cutoff voltage where the NIMH drops some voltage right away, maintains a slow drift then drops off faster as it approaches cutoff voltage. (see blue line) This is an example of how different materials affect charge and discharge and battery life.

I also provided comparison charts to show in real time the difference between load. This was a NIMH 6VDC 4.5Ah discharging at 25C (25% capacity) and 50C(50% capacity) At 25C (1.125amps) it discharged in 3 hours 40 minutes (calculated dicharge time was 4 hours.) At 50C (2.25 amps) it discharged in 1 hour 40 minutes (calculated discharge time was 2 hours.)
This battery passed our testing however because the manufacturer's discharge characteristics indicate a lower discharge capacity at higher discharge rates indicated in their data sheet.