People come to CH for answers.
Sometimes the best answer is to tell the OP not to do what he wants to do.
However, it is helpful if both the OP and anybody reading a post get the sense of why one method is better than another.
He asked about the 7805 regulator, and he got some answers.
He said he wanted to use a 12 volt motorcycle battery.
He said he wanted to power his smartphone. He did say which phone. Most often a smartphone uses a small lithium-ion battery, about 4 volts, which should not be overcharged.
Overcharging a small cell-phone battery is a mistake.He was told to use a fuse close to the battery. Good advice.
Or else, just don't try to make a DIY external battery thing for a cell phone. You can get them already made.
This is information people need to know. This risk is more that just loss of property. Bodily harm can come from a DIY project that involves a lithium-ion battery. Even some commercial designs have under estimated the volatility of this type of battery.
This is a serious subject and should not be trivialized.
This is from a government agency.
http://www.nfpa.org/news-and-research/fire-statistics-and-reports/research-reports/hazardous-materials/lithium-ion-batteries-hazard-and-use-assessmentThere is a video to watch.
Yes the video is about storage problems. From that one can see that these batteries have some issues. Using the battery improperly may cause the batter overheat and catch fire. If a battery does catch fire, you can try to stop it with water.
The OP did not make it clear if he was going to leave the battery inside the cellphone. Some cell phones do not work without the battery in place and a changer connected. And some cell phones have a battery that is wired internally and you can not remove it.
