The Redmi Turbo 4 Pro is being tested with a 7500 mAh battery, while some of the company's other models will be tested with 8000 mAh batteries

Recently, rumours surfaced that the new Redmi Turbo 4 Pro smartphone will feature a 7,500mAh battery. Initially, it was speculated that the battery capacity would be around 7000 mAh, but the latest data confirms a higher capacity.
Here's What We Know
It is reported that the 7500 mAh battery was successfully tested during the Redmi Turbo 4 Pro prototype tests. In addition, it has been reported that Redmi is testing an 8000 mAh battery for future models, probably from the K90 series.
Chinese smartphone makers, including Redmi, are looking to increase the battery capacity of their devices by utilising new silicon-carbon anode technology that packs more power in the same battery volume.
The new direction from increasing charging power to increasing battery capacity has become a prominent trend in the market. Once the race for battery capacity stabilises, manufacturers are expected to return to improving charging times, which have recently taken a minimum of 35-40 minutes.
Source: Digital Chat Station, GSMArena