Splicing 12 ga wire to 18 ga

Just about done installing my new battery charger. The battery leads required 12 ga wire so that’s all I bought. I also ran it to extend the input ac as well but when I went to splice it I find the plug wire from the charger is 18ga. Seems odd but that’s what the mfg used. I can’t find step down butt splices in those sizes for joining the two wires. Is there an acceptable way to splice them or shhould I buy and rerun the power cord extension? Not sure I should use 18 ga to extend the power cord another 5 feet? I suppose I could use wire nuts and tape it real good but that’s generally not acceptable in a marine installation. Advice appreciated.

Just strip the 18 awg back twice the length and fold on top of it self that will take up the extra room. It is never a problem using a larger wire to connect to a smaller one when it is down stream.

supercat wrote:

Just strip the 18 awg back twice the length and fold on top of it self that will take up the extra room. It is never a problem using a larger wire to connect to a smaller one when it is down stream.

that would work or you could also solder them together

supercat wrote:

Just strip the 18 awg back twice the length and fold on top of it self that will take up the extra room. It is never a problem using a larger wire to connect to a smaller one when it is down stream.

^^^^^^^ This!

HRG

I would use a soldered Western Union splice with shrink tube over the splices. And then a shrink tube cover.

How-To: Splice Wire to NASA Standards

Definitely agree with djshannon, shrink tube is required.

Brad Dimond wrote:

Definitely agree with djshannon, shrink tube is required.

I use the heat-shrink butt splices with solder inside the splices and then also cover that with the shrink tube. Probably overkill but it’s not expensive and has served me well.

I read where solder is not good in vibrating environments like marine applications? I ended up doubling it over in a shrink tube butt splice with an additional sleeve of shrink wrap over the whole thing then taped at each end.

suzuki wrote:

I read where solder is not good in vibrating environments like marine applications? I ended up doubling it over in a shrink tube butt splice with an additional sleeve of shrink wrap over the whole thing then taped at each end.

That does make sense and sounds like you’ll be solid — although I’ve never had an issue with mine and I do take the trailer down some washboard dirt backroads up in shield country. I might just be lucky.

I almost broke down and used wire nuts! LOL

They make crimp on end spliced (like wire nut) that after you crimp it, heat it with a heat gun. It has silicone inside that will ooze out and waterproof the connection. Also has built in shrink tube if my brain is working. Did my sno-mo trailer. Worked great. I could go the the workshop and get you more info if you want.