[mindfulness]

Let's say someone is selling you what is supposed to be a new battery but it's really an old battery that's just been fully charged. If you are allowed to install it before buying, is there any quick test you can run on the spot before you buy it to test it's a new, fresh battery versus just an old fully recharged one? Or is that impossible and you need to use the battery over the course of a day to determine whether its good or not?

[Haptik]

A Multimeter can be used to check the authenticity of the battery. It can be bought at any electronics/electrical store. If the battery voltage and the multimeter reading are the same or nearly equal, the battery is new.

[srkmagnus]

If you are purchasing a battery that is not in original packaging then considering staying away. If you must purchase it then place it on a flat surface, such as a table. Give it a quick spin and if it rotates for a few seconds it's likely a bad battery showing signs of "swelling". The battery should not spin like a top if its in good condition.

Also, consider sticking with a reputable company or reseller so you at least have a warranty on the battery if you must return it for any reason.

[Eclipse2K]

If you are purchasing a battery that is not in original packaging then considering staying away. If you must purchase it then place it on a flat surface, such as a table. Give it a quick spin and if it rotates for a few seconds it's likely a bad battery showing signs of "swelling". The battery should not spin like a top if its in good condition.

Also, consider sticking with a reputable company or reseller so you at least have a warranty on the battery if you must return it for any reason.

I didn't even think of spinning a battery. Nice tip even though I always buy new from reputable sellers.

Samsung Galaxy Note 3 using Tapatalk

[Sizzers]

Let's say someone is selling you what is supposed to be a new battery but it's really an old battery that's just been fully charged.

If it's fully charged then it's not a new battery.