Help! Can I solder 12awg too a 8awg or 10awg wire?

[Chriso518]

I've recently purchased a 52v ebike battery that has a 12awg power cable but my 1500w controller only has a 8 or 10awg power cable (it's doesn't specify what size it is on the controller power cable casing) and I was wondering if I could solder the cables together or what would be the best way too connect the 12awg wire from the battery too the 8/10awg wire from my controller?

 

[MontyPAS]

I've recently purchased a 52v ebike battery that has a 12awg power cable but my 1500w controller only has a 8 or 10awg power cable (it's doesn't specify what size it is on the controller power cable casing) and I was wondering if I could solder the cables together or what would be the best way too connect the 12awg wire from the battery too the 8/10awg wire from my controller?View attachment 39027

Get a matching plug and socket.... Xt60. Xt90. Anderson Power pole. Solder and sleeve or crimp join.... The choice is yours

 

[Nealh]

If you wish yes you can solder the wires direct, don't forget to slide on some heat shrink out of the way first. I use two pieces of shrink per each joint, the second piece slightly longer then the first.

 

[MontyPAS]

Also....
When making a soldered joint, it is good practice to make a good mechanical joint by twisting the wires together before soldering. Do not just butt together and rely on the strength of the solder.
A lot of the lead free solders require a slightly hotter iron as well!

 

[Ocsid]

On my car I have wiped the soldered up joint with an antirust fluid before heat shrinking the sleeve over it, so there is no room for moisture to ever wick into it. I use Supertrol which I have to hand, though I feel Waxoyl would be nearly as effective. Moisture and traces of residual fluxes are sometimes quite damaging, doing as I have seems to keep that issue at bay.

 

[MontyPAS]

On my car I have wiped the soldered up joint with an antirust fluid before heat shrinking the sleeve over it, so there is no room for moisture to ever wick into it. I use Supertrol which I have to hand, though I feel Waxoyl would be nearly as effective. Moisture and traces of residual fluxes are sometimes quite damaging, doing as I have seems to keep that issue at bay.

Copper oxidizes when heated, and soldering uses heat to melt the solder.
As VFR said the solder will stop the oxidization on the soldered area! But not the surrounding copper.
Correctly fitted and shrunk, heat shrink tubing should not need additional waterproofing.
If water does get onto any exposed copper wiring you will eventually suffer from Verdigris. This is a green oxide patina, which is notorious for causing high resistance problems in wiring!

 

[Fordulike]

+1 on the heat shrink. I use the adhesive lined tubing, which gives additional protection against water ingression.

 

[vfr400]

Copper oxidizes when heated, and soldering uses heat to melt the solder.
As VFR said the solder will stop the oxidization on the soldered area! But not the surrounding copper.

Oxidation on the wire away from the terminal is not such a problem for an ebike in normal use though definitely an issue for marine use. The oxidation happens on the surface and would take ages to eat through the wire. The problem is when it happens on a DIY crimped connector, where the surface oxidation breaks down the contact area between the wire and the terminal, which then makes the terminal heat up when the current goes through it. I'm sure you've seen all those recent photos of melted sleeves around the bullet connectors. It seems to be a pandemic at the moment. That's the issue that has to be avoided.