Is it possible to control the charging voltage?
The battery voltage is controlled at a hardware level, not natively controllable via any Android APIs. Depending on your device &amp; firmware, there may be apps that can control the manufacturer specific features, but that's very unlikely.

Try looking into Voltage Control on the Play Store, it can under-clock the CPU, maybe even the voltage - Voltage Control


  Voltage Control Extreme (developer name sulph8), features include: 
  - Support more than one profile
  - CPU history display
  - overvolting support (+50mV and 1500mV limit) 
  - undervolting up to -250mV (lite version limited to -200mV)