I want to know that does charging a mobile phone in car can cause any issue with the battery. I am having a Micromax Canvas phone. I am using a portable car charger here. And it works well. But I am finding the battery output is getting lower day by day.

At first I use to get an entire day usage but now the battery is getting depleted and now the output is limited to 5 hours only. I am looking for some help here through which I can improve the charging.