Uniweld P4KD9S Aluminum Soft Solder Kit with Metal Tip Flux Applicator

I used this product to make connections to the aluminum tabs on a Tesla 3 battery pack.The product worked, but left pinholes like others have observed. I had some other good aluminum solder that was flux core and worked ok, but when I paired this flux with the good solder, it worked great.

so whilst the kit didn't work for me, I am not sure I can fully blame the product. I was trying to fill a pinhole in my A/c condenser and just couldn't get it to seal. It would seemingly flow with the flux only to find that under pressure the 'freon' would leak (I could hear and feel it). I bought a butane torch with needle flame, that seemed to hot, added the soldering tip to the torch and that was about the right temp.Bottom line you HAVE to get the oil out of the condenser to properly fix it.Probably works great on a radiator.

As others have reviewed, doesn't work quite as advertised. I was able to make a joint between copper and aluminum, but no matter how clean and how many attempts with different approaches, the joint was always porous. Simply could not make a complete joint. The solder does not flow unless there is liquid flux on it. The flux gets in the joint and bubbles, leading to holes. The joint is also very shallow because of this. I took the joints apart and the depth of the joint didn't make it 1/8" down the pipe. It will stick, but it is neither structural nor gas tight.I have been in HVAC for 6 years and can braze no problem. Tried my oxy, then toned it down with mapp. No method of approach got advertised results.

Got a instant hot water heater with a blow out in the line. Had an AC guy weld it. It blow out instantly. Bought this stuff and used as directed. Have had no problems with it. Good as new. Amazing stuff.

A little tricky to use.. and it's expensive.. but it works