Adhesive Lined Heat Shrink 3:1
Adhesive lined heat shrink, 3:1 shrink ratio. Dual wall tubing with a hot melt adhesive liner that flows as it recovers and seals the joint against water. This is what belongs over a crimped battery lug, and non-adhesive tubing is not a substitute.
Size it to the lug, not the cable
This is the mistake everyone makes. The tube has to pass over the crimped barrel of the lug, which is meaningfully fatter than the cable, and then recover down onto the cable behind it. That is why you want a 3:1 ratio and why our sizing chart is written against lug barrels.
| Cable | Cable OD | Approx. lug barrel OD | Heat shrink size |
|---|---|---|---|
| 6mm² | 4.3mm | ~7mm | 9.5mm |
| 10mm² | 6.0mm | ~9mm | 12.7mm |
| 16mm² | 8.3mm | ~11mm | 19mm |
| 25mm² | 10.1mm | ~13mm | 19mm |
| 35mm² | 11.8mm | ~15mm | 25.4mm |
| 50mm² | 13.3mm | ~17mm | 25.4mm |
| 70mm² | 15.5mm | ~20mm | 39mm |
| 95mm² | 17.9mm | ~23mm | 39mm |
Applying it
Slide the tube on before you crimp. Use a hot air gun at about 180°C, not a naked flame and not a paint stripper on full. Work from the middle outward so the air escapes, and stop when a small bead of adhesive appears at each end. Scorched tubing has lost its seal even if it looks fine.