Replace a cellphone battery with a Capacitor for always plugged in use?

 I've been using old cellphones as ip cameras for a home security network. The problem they are constantly charging and this causes the batteries to eventually bloat. Naturally this is a safety issue. I would run without the battery but the phone refuses to boot when there is no battery. How would I design a circuit in place of the battery to fool the phone into a thinking it has a battery? I was thinking a simple capacitor based circuit would be enough. 
Phones in question Nexus 4, Samsung Galaxy S3

If you would read other forums, it would tell you that it might be a bit hard to trick the phone to think that there is still battery installed. Also, I learned that there is a chip that reads out the presences of the battery. You could go for dummy batteries. There are also other suggestions in using resistors to compensate for the resistance of the battery but I believe they are still no use to the circuitry of the phone.