Hoomya Metal Detector Extended Capacity Battery Pack

thingiverse

This is an extended capacity battery case for my Hoomya MD-840 metal detector. It conveniently replaces the small PP3 9v batteries with the larger lantern style PP9 9v batteries. It simply clamps round the forearm rest and hangs nicely under your arm. Furthermore, should you want to remove it, you need only unscrew it and disconnect the battery clips from the metal detector itself -- it does not alter or damage your detector in any way. I was getting tired of forking out for expensive 9v batteries (small type) and so decided to design a bolt-on case that carries two large lantern batteries (PP9), each one being the equivalent of 6 of the smaller ones. This means that I can now be out for a hundred hours without having to worry about swapping or buying expensive batteries. - You will need to connect the existing PP3 battery connectors in the battery compartment to a second pair of PP3 connectors. They will just click together - but remember that you now have the opposite colours for -ve and +ve. - Connect the large lantern style battery to two PP9 connectors and thread both sets of leads through the hole. - The ends of the leads form each type of connector will then need to be soldered together. There will be two pairs (four wires) - Remember that polarity has been switched because of the connectors in the battery compartment. - Tidy your wiring and you're done! :)