Sir I'm a complete newbie about circuitry. I just want to use a cellphone battery BL-5C to a fetal Doppler that is using a 9 volts battery. Do you think it's possible?

 

"need help!!!" is not a helpful topic message. The fact that you need input is obvious just by posting here.

What do you mean by "a cellphone battery BL-5C to a fetal Doppler that is using a 9 volts battery"

Is a fetal Doppler a very, very young Doppler?

Please write in plain and clear English.

 

According to Google, a "fetal doppler" is a gizmo for monitoring the heartbeat of a fetus.

I very very strongly suggest any medical equipment NOT be modified in any way. If there is a problem with the gizmo, contact your medial provider immediately!!

 

Nokia recently recalled 46 million of their BL-5C batteries. Seems that they like to overheat.

It only supplies 3.7v.

It would not only not work, but could be very dangerous to try it.

I suggest you stick to the recommended batteries for the device.