What are the side effects of using apps that trickle charge battery. App like "Battery Doctor". It charges around 30-50 (varies with device) mins after battery is fully charged, which results in a bit longer battery backup as I found out. But is that harmful for battery health? Like damaging the battery? Or should I charge normally up to the device says "Fully Charged"?
especially on a rapid-charger, this is normal charging behavior to achieve complete 'depth' of charge. I wish they wouldn't report it as "charged/100%" if it was still trickling.
Here is a graph of the charge curve. note the voltage on the battery tops out but the current is still drawn.
It's somewhat an EE question, but higher voltage is provided to the battery until the charge rate (current draw) drops to 5-2% of C, with C being the total storage. IE, on a 3000mAh battery this would be a charge rate of 60mA. Lower cutoffs (1%) are detrimental to battery health (IE, over 3-500 charges degrades capacity by, oh, 5-10%), but given OEM replacement batteries are $10-15 FOB from China, it is wiser to consider them sacrificial and not concern yourself with their health.
I know it's a shift in thinking but it's much easier to convert to Qi charging (just get a TPU case too to help hold it on) and just drop it on the pad whenever you are at work or at home. Once you have a phone with Qi you won't be interested in one without. plugging in twice a day (once to top up) is hard.