I'm not an expert, but when one of my customers returned a battery with this connector on it, I thought I might be able to help a few people learn how to solder. This isn't the first connector I've seen like this.
CAUTION! When soldering
connectors on a battery. Do one wire at a time. Never expose
both wires at the same time. You could let the smoke out of the battery. That's
BAD.
A soldering iron that will get up to about 700 degrees. That means something at least 40 watts. Personally, I like a soldering "station", which lets you control the tip temperature a little better. The Weller brand is good. You want something with a tip about 1/8 inch wide.
Solder. I buy solder at Radio Shack in big rolls. You want to get the right size. Too big and you'll have trouble melting it. Too small and it just won't flow fast enough. The right size is .050. You'll probably want a 60/40 rosin core. It works for me.
Never buy acid core solder unless you are doing some plumbing. It's NOT for electronics.
A third hand, a vise or a friend. You can't have too many hands. A pair of pliers with a rubber band around the grips works too.
I show how I hold the connector in my vise with a spare set of connectors. Some welding gloves really help too.
A heat gun. Not a hair dryer, a heat gun. Use this to shrink your shrink wrap.
Shrink wrap. 1/4 inch works well on larger wire. NEVER use electrical tape. It doesn't hold up.
Flux paste. This stuff is great. I like the non-corrosive stuff, but it isn't a requirement. Our connectors are made of material that doesn't corrode and, if you tin your wire properly, it won't corrode either. Just put a little on the areas that you'll be soldering and then solder normally. This stuff makes the solder flow better and stick better.
Tin the wire.A picture is worth a thousand words. Click on the pictures
Slide the shrink wrap over the joint and shrink it with the heat gun.
This is what you're looking
for
There you have it.