How to Calculate Battery Capacity

Everyone wants a battery that is small and light, but there are compromises, especially if the margin for failure is narrow for critical missions. When calculating battery size, the fleet user should consider two factors: [1] allowing for spare capacity to provide for unforeseen activities, and [2] anticipating capacity fade that occurs naturally with the age of the battery. Equipment manufacturers tend to ignore the fading aspect when calculating the required capacity and base the service on a new battery with full capacity.

The acceptable capacity performance range of a well-managed battery fleet is 80 to 100 percent, meaning that packs that fall below the 80 percent threshold are replaced. Allocating 20 percent fade in addition to a 20 percent emergency reserve would reduce the usable battery capacity to 60 percent. Such a large reserve for a worst-case scenario may not be practical and battery users go for more leniency. A battery analyzer plays an important role in battery management in that the batteries are checked every one to thee months to ensure they all fall within the anticipated performance bandwidth. 

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Comments

On April 23, 2011 at 3:07am
S.M. TAHIR HUSSAIN wrote:

I AM WORKING ATLAS BATTERY LIMITED (PAKISTAN) AS A OFFICER IN QUALITY DEPARTMENT, THIS WEB SIDE IS GOOD FOR EVERY PERSON WHO INTREST AND RELATED BATTERY. AND BATTERY COMPONENT.

On July 4, 2011 at 4:30am
Adrian Smit wrote:

We are trying to locate the best battery for a vehicle tracking device, the battery needs to be a small as possible, have no charge source once it has been full charged our devices are not hot wired into the vehicle the device needs to live on its own battery for as long as possible. Our devices don’t have any LED lights or battery drawing components other that the GPS and GSM modules. Can you suggest the right battery for us.

Regards Adrian Smit.

On September 25, 2011 at 11:46am
satyendra wrote:

hi every one…
ageing of batteries matters for calculating the capacity. like when cells are new, it has 100% capacity but as time passes and usage cells goes on capacity decreases…so how to know exactly what is the fraction of capacity reduced while using.

On October 14, 2011 at 8:38am
mahmood wrote:

hello SM TAHIR HUSSAIN! im MBA student of PAF-KIET doing my finance elective course of financial modeling & forcasting for this i have selected atlas battery to work so i need a company contact person to have a quality output so please allow me to contact with you, your support will be a great addition to my study report!

looking forward for your kind support!

im available at email: mahmoodsofur@gmail.com

On December 13, 2011 at 8:26pm
chris king wrote:

We are trying to figure out the best size and type rechargeable battery to use in our solar light.  It currently is set up with 4 aaa’s.  it is trickle charges with a 5-6V solar panel.  Any thoughts?  Some say low mA ni-cads, others nmhi.

On March 16, 2012 at 6:35pm
Michael Mc Cann wrote:

I am designing an off-grid solar electric system for domestic use.  Based on 16.6 KW/day use, 5hours of direct sun/day and a 3.8KW PV array located 100’/30m from the battery pack. Any ideas on battery size/quantity/volts?

Thanks.
Michael

On March 26, 2012 at 4:04am
Deepak chaudhary wrote:

i am interested in designing battery for electric vehicle can oyu let me know design formulas?

On March 28, 2012 at 1:04am
ssempijja michael wrote:

I Thank you for the great job you’re doing in availing such credible information,are there non
lead acid batteries to a tune of 180 amp hrs that can effectively be used in MBT(Tanks).
Best regards:

On April 29, 2012 at 12:35pm
Syed Muhammad Tahir Hussain wrote:

Dear Satyendra,

I am Tahir Hussain from Karachi, Pakistan and i am working Atlas Battery Limited.
I read you comment about “aging of battery matters for calculating the capacity”.
Battery Aging and Capacity are the two different things and we can not calculate battery life from its own capacity.
(1) Battery aging mean , battery life. We always calculate battery life in cycles. One discharge plus one recharge equals one cycle . Battery cycles depend on battery size , capacity, electrolyte volume , plate surface area and etc. Some small batteries have short life (less cycles) example 800 cycle. Some batteries have large cycles 5000 cycles( its also depend on vehicle running).( You can see JIS standard )
(2) Battery capacity means the ability of a fully charged battery to deliver a specified of electricity (Amp-Hrs) at a given rate (A) and period of time (H). When both numbers multiply each other its called battery capacity and its symbol AH.  Example a battery which delivers 10 amps for 10 hrs that means 100 AH.

Best wishes,
Tahir
(syedhussain123456@hotmail.com)