battery

Start by googling Peukerts law.

Are you asking here "how can we know to what degree a rechargeable battery is charged?"

Take a look at this website, especially at the links toward the bottom of the page. Also keep in mind that different battery technologies (lithium ion, rechargeable alkaline, NiCd, NiMH, lead-acid, etc.) vary in their charging requirements and methodologies.

nice link

Today I picked up one of those new hand cranked flashlights. To my surprise it also contained a radio in the handle. NICE!! Product was made for Duracell and sold by Costco.

During weather induced power outages this is a real good idea so people can tune to local broadcast stations for news updates, civil Defence and Emergency Measures instructions, etc.

The package said 1 minute of cranking equals 30 minutes of run time for the light or 12 minutes for radio. I assume this means a full charge. However I do not know what constitutes a full charge or even what technology the battery uses. No mention is made of expected shelf life or if the battery requires periodic maintenance cycling for optimum service life. One really good feature of this product is the charging port and included USB cable. You can actually use this product to charge your cell phone or recharge the battery from your computer USB port.

Most cell towers have gensets and UPS power supplies for maintaining service during power outages. This little product is another step in the right direction. It also diverts more batteries from the ever increasing garbage disposal pile.

Maybe the energy crunch will be solved by many little steps like this, instead of one giant and wonderous invention.

You give so little valid information (do you have any idea how many different battery types there are in this world??)that it is impossible to give you an exact answer, but I will do my best.

All batteries have a voltage gradient from full to empty, with lead acid this is well known and easy to measure.

Other cell types usually need either a specialist voltmeter that is exceedingly accurate over say 1 volt range or even less (individual cells)and you need to have the graph pf the voltage to capacity in your hand at the same time.....or some specialist chip to do the job.

You will also need to know the temperature of the battery as this affects the readings....

Usually thats enough.

my mobile battery is Li-lon 3.7 v, whenever i charged it after 10-15 min it showing full charge but when i switched off charger and again switched on, it start charging again, surprise

Sounds like a faulty charger or battery. Either borrow another known good battery or charger and try again, that way you will find out which is defective.....

A common cause of battery problems is that many people charge them before fully empty and as a lot of the modern batteries have a limited number of charges, they get used up quicker than they should. OEM batteries are usually better than all the other cheap ones as are original chargers....cheap chargers kill batteries too with too much current.....

On really old Mobiles, you might still have a Nicad battery, these suffer from "Memory effect"......then you must drain the battery completely each time for the best capacity.

A better method is to have two batteries (or more) and only recharge when really empty, not before. I have an old Nokia cellphone and the batteries (NIMH) are equally old.....must be 5 or 6 years now and the batteries are all perfect!!! I actually have 3 as there were times when I could not get to a mains connection for some days.....3 is generally overdoing it for a private person I feel due to cost considerations.....