The HM-5 uses an EVE ER 14250 3.6V battery which is a 1/2 AA lithium battery.
See the attached datasheet for the EVE ER 14250.
You may Google "ER 14250" and find several manufacturers that produce this type of battery. Besides EVE, we believe that the following are compatible (though not tested by Solutionbee):
- SAFT LS 14250
- Ultralife 14250
- Tadiran TLL-5902
The cost of this battery varies between $2.00 and $5.00 USD.
Replacing the Battery
- Peel back the corners of the label on the HM-5's electronic module. This will reveal four screws.
- Loosen the four screws with a few turns carefully without stripping the screws until the module cover is loose. It is not necessary to loosen and remove the screws completely... a few turns alone will do.
- Carefully open the top cover. Wires connect the to halves of the electronic module so do not separate the two halves completely.
- Note the battery holder. Remove the battery and replace it with a new one. Note that the existing battery is held in place with glue from a glue gun in order to keep it in place during transportation.
- Close the cover and tighten the screws.