# Battery FAQs

• Q. What is battery?
• A battery is an electro-chemical device used to produce the electrical energy through the chemical reactions.
Basically a battery is a combination of cells. Mostly a battery is of 12V(six cells).
• Q. What is AH, mentioned on a battery?
• AH (Ampere-Hour) is defined as the capacity of a battery. The AH defines how much energy a battery can deliver.Technically it is defined as the backup time provided by the battery according the amount of the current drawn.

Eg. If a battery has the rating of 12V/100AH, then if 100 Ampere amount of current is drawn from the battery it will provide backup time of one hour. If the current drawn is reduced to 50 A, then it will provide backup for 2 hours.
• Q. What is meant by internal battery and external battery?
• In the internal battery system, a small sized battery (of capacity 7.2 Ah) is mounted in the entire cabinet itself. You cannot apply any external battery in these systems to increase the back-up time.

In the external battery system, no internal battery is used. The batteries should be connected externally. If external battery is connected, then minimum capacity should be of 18 AH and maximum capacity should be of 200 AH.
• Q. What is the relation between charging current and AH in battery?
• There is a very wide relation, but in short the charging current is to be set according to the AH of battery. Commonly it is said that the charging current should be approx AH/10.

Eg.: - For a battery of 100 AH is used, then the charging current would range as Thus 10 A changing current is proper for 100 AH battery.
• Q. How to calculate the backup time?
• To calculate the backup time, multiply the battery bank used with Ah and divide it by the load applied. The answer is multiplied with 0.7 (efficiency) to get the value towards more practical value. Eg. A system of 1000VA/24V having battery connected of 100 AH runs on full load, then 