I've habitually applied some 'liquid tape' then some spray-on silicone grease after connecting battery terminals. This seems to work within a flooded-leaded batteries life cycle providing you can keep the batteries out of inclimate weather.

Short story; I'll be making new connection and revisiting old ones.

Should I spray silicone grease on the affected connection after the soldered lugs have cooled down and before moving the shrink tubing up to position it and apply heat? Will this finalize the connection or is this redundant? It doesn't seem like its that much overcompensation or overspray even is it doesn't help but I don't want to do it if it hurts a waterproof connection. In addition, I want to see a corrosion problem; I don't just want to hide it.

I've got the ¼" shrink tubing, the 8ga lugs, the electrical grade solder and torch, the 8ga copper cable and a few can of silicon grade spray grease. FWIW, I also have some Lithium grease spray but I don't know if that is appropriate.

FWIW, this is an auxiliary battery connection. Truck battery positive through 70A isolator to 100AH battery via 3 metres of 8ga positive cable and short 8ga to a frame ground.

How should I proceed?

  • 1
    Be mindful of hot fluid when heat shrinking - that stuff is somewhat like napalm, sticking to your skin and burning if it squirts out.
    – Criggie
    Mar 9, 2020 at 20:18
  • 1
    @Criggie, thanks for the warning but I'll probably use the same propane torch at 6-8 in to circumcise the connections. I lent my hot air gun to a furniture restorer a while back and it was never returned
    – user16128
    Mar 10, 2020 at 2:13

2 Answers 2


Using silicone grease before you shrink the tube is not a problem,except the shrink tube might slide off easier.

A better solution than using grease is probably to get shrink tube that has glue on the inside,i know it cost a bit more but after you have shrinked it on it will not go anywhere.

It is this type https://www.amazon.com/Ancor-Marine-Electrical-Activated-Adhesive/dp/B000QCPKE8

  • I've never seen shrink tubing with glue inside. I just have a standard 3 ft length of quarter inch tube that I got from the electrical connections aisle of the auto parts store. However, I will look into the availability of this.
    – user16128
    Mar 9, 2020 at 19:55
  • 5
    Heat shrink tubing with glue on the inside is frequently labeled as marine or water-proof heat shrink tubing.
    – Draw3D
    Mar 9, 2020 at 20:01
  • 1
    i have added a link in my answer,you can get connectors too with glue inside for use in water exposed areas. Mar 10, 2020 at 5:49

You use grease on terminals to protect them from corrosion due to oxygen exposure, the shrink tubing will do the same job so there's no point putting grease inside. In fact, the grease is more likely to get squeezed into the wrong place and prevent a good seal, so my advice is not to use it.

  • FWIW, I plan to 1) Slip unheated shrink tubing onto uncoupled connection. 2) Insert stripped wire into lug. 3) Crimp lug. 4) Heat lug until solder runs into it.5) After cooling everything down, slip shrink tubing over connection and reheat, My question is whether there is any benefit to adding 4.5) Spray connection liberally with silicone grease before slipping the shrink tube collar up to cover the connection.
    – user16128
    Mar 10, 2020 at 2:28

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