Hello everybody. I want to have other batteries. When i seach for that i find that the battery model of GQ EMF-390v2 is 18650. The battery has it wrotten like SW18650, with 3.6/3.7V, like the manual says.
But i can't find the mAh (milliampere-hour), the power that i think could broke the meter.
The battery is 2500mAh (2.5Ah). Any 18650 battery 2000-2500mAh will work fine. If you are buying a battery new, I would go with a decent brand such as Samsung or LG, or Panasonic, or some other decent manufacturer. These batteries store a large amount of energy for their size so I would always go with a reputable manufacturer for safety reasons. And also quality. The cheaper batteries generally don't live up to their capacity specification and I would avoid any battery >2500mAh as the numbers are generally fake on the cheaper batteries.
In a nutshell, any 18650 battery will work. Stay around the original capacity of 2500mAh (2000-2500 is fine), and use a decent manufacturer battery and you will be good.