Heat shrink solder connectors are the thing to use in this case: https://www.amazon.co.uk/-/dp/B073RMRCC3 https://www.amazon.co.uk/-/dp/B073RMRCC3 Waterproof,

Heat shrink solder connectors are the thing to use in this case: https://www.amazon.co.uk/-/dp/B073RMRCC3 https://www.amazon.co.uk/-/dp/B073RMRCC3 Waterproof, tension proof, will handle more current than the wire itself, hard to install wrong, and very reliable (ie. No fires)