Building Your Own HHO Generator: Complete DIY Guide

Materials List

• 316L stainless steel sheet (1.0–1.5mm thick)
• Neoprene or EPDM gasket material (3mm thick)
• Acrylic or HDPE end plates
• M6 stainless steel bolts, nuts, and washers
• Epoxy or silicone sealant
• 6mm silicone tubing
• Barbed fittings (gas outlet, electrolyte fill)

Cutting the Plates

Cut your 316L stainless to your desired plate size — 4×6 inches is a common standard for automotive cells. Use an angle grinder or plasma cutter. Sand all edges smooth to prevent current concentration. Drill a center hole (12–20mm) for gas escape and two corner holes for electrolyte flow.

Making the Gaskets

Cut neoprene gaskets the same external dimensions as the plates, with the center section removed to leave only a border seal. Gasket thickness (3mm) sets the inter-plate gap. The gasket must seal between each plate while leaving the center active area exposed to electrolyte.

Assembly

Stack plates and gaskets alternately. Secure with stainless bolts through corner holes. Connect positive leads to every other plate group and negative to the remaining plates. The neutral plates in between need no electrical connection — just good gasket sealing.

Making the Casing

House the dry cell in a secondary reservoir/casing made from HDPE or acrylic. This allows the cell to be partially submerged in electrolyte from the sides while keeping the plate faces relatively dry (hence "dry cell"). Add a fill port and gas outlet at the top.

Testing

Start with plain distilled water (no electrolyte) to test for leaks. Once sealed, add KOH incrementally while monitoring current with an ammeter. A successful first build should produce visible HHO bubbles at the outlet within minutes of power application.