Lumia 730 / Lumia 640 battery compatible?

[Ideasondesign]

Does anyone know if the batteries of these two models "640" and 730" share the same size?
I was thinking weather the 640 battery would work on a 730 since it'd provide more autonomy.

Anyone willing to test it?

 

[Warren_2185]

I have a 735 and a 640 and the battery sizes are different. They don't fit each other. I guess you could use a spacer of some kind.

 

[Ideasondesign]

Is the 640 bigger or smaller?

 

[TranquilKnight]

Is the 640 bigger or smaller?

640's battery is bigger.