Are the local batteries not good for cellphones.

Cheap are often low of quality..i will not gamble on them because they might damage your precious phones. better buy the original specified battery for the said model just to be safe.

I think they are cheap because the production line is not as seriously treated as those expensive counterparts. The materials they have used are probably not the best one and may even be below some standards. And then they probably deploy little to no quality assurance to their products. So, are they not good? Yes, there are various problems reports of these batteries and yet, there are plenty of people using them.

Buying Original Equipment Manufactured (OEM) batteries are always better because they're made to fit with your cell phone perfectly - they come off the same assembly lines as the one that came with your phone. Aftermarket batteries are made to specification to your cell phone, but only to certain tolerances; therefore, they're not a perfect match to your cell phone. However, it's up to you to decide if it's worth it - in this case you could buy 5 aftermarket batteries instead of one OEM cell phone battery.

Local battery are cheap imitation of the original ones. These Batteries are not recommended for long use. There are instances, based upon my experience, that it easily gets bloated and at times explode. I only used this type of batteries as an emergency backup when I'm traveling.