Hikoki Hitachi 18V Battery Power Adapter DIY

Turn your Hikoki / Hitachi 18V tool batteries into a compact portable power source.

This 2-part adapter slides directly onto compatible Hikoki/Hitachi 18V batteries and provides simple access to the battery terminals using two small aluminum contact plates. The top cover screws onto the base to protect the wiring and create a clean, flat backside.

Originally designed to power a small water pump for transferring fresh water from a barrel into a camper, but it is also perfect for many other portable DIY power projects.

 

Metal connectors:

General dimension see picture.Thickness between1 and1.5mm.
Chamfer 1edge so it slides into  the contact more easily.

Features

• Fits Hikoki / Hitachi 18V batteries
• Simple 2-part design
• Uses aluminum contact strips for battery terminals
• Screw-on cover for cable protection
• Flat backside for easy mounting
• Compact and easy to print
• Ideal for portable off-grid setups

Possible Use Cases

• Camper fresh water transfer pump
• Portable camping shower pump
• LED lighting projects
• Small ventilation fans
• Portable soldering station
• RC battery charging setups
• DIY bench power source
• Fishing or boating accessories
• Emergency power adapter
• Small air pumps
• Electronics testing
• Arduino / ESP32 projects
• Portable USB converter projects
• Field repairs and service kits

Notes

• Designed for low-power DIY applications
• Always double-check polarity before connecting devices
• Use appropriate wire thickness and fuse protection for safety
• Use small 4mm screws (20mm) to mount the 2 parts

If you build something useful with it, upload a review and photo — I would love to see different applications!