Electronic device and battery holder

A battery unit housed in an electronic device in use, comprising:

• a positive terminal and a negative terminal arranged side by side on one end side of the battery unit in use;
• a battery holder configured for holding one of a first battery and a second battery in use, the first battery and the second battery having different shapes;
• a spacer configured for defining a position of the first battery or the second battery,
• wherein the spacer is constituted in use by a first spacer designed for the first battery or a second spacer designed for the second battery,
• the second spacer holds the second battery in use and has a positive terminal and a negative terminal which are electrically connected to a positive terminal and a negative terminal of the second battery in use,
• the battery holder has an upright wall portion formed at one end of the battery holder and configured to come into contact with and support the first battery or the second spacer so as to expose the positive terminal and the negative terminal of the battery unit,
• the positive terminal and the negative terminal of the battery unit is the positive terminal and the negative terminal of the first battery when the first battery and the first spacer are held by the battery holder, and
• the positive terminal and the negative terminal of the battery unit is the positive terminal and the negative terminal of the second spacer when the second battery and the second spacer is held by the battery holder.