newbie questions

[Grinder]

Battery Perfomance Tip:

60/40 solder is about 11% as conductive as copper whereas 1% silver solder is about 14% as conductive.  The idea is to make a conductive joint from your battery bar to the battery.  Since the material you are soldering with is a poor conductor compared to copper your main objective is to make that connection as thin as possible.  When you solder (aside from all the typical stuff you need to know about soldering, eg cleaning, flux, tip size, etc) you will want to keep the bar pressed down on the tab firmly to keep the gap that the solder fills between the bar and the tab as thin as possible giving you the least amount of solder for the electrons to flow through.

There are a few tricks to getting the most out of you soldering and just like any other form of welding the quality of the joint makes a big difference as to the final outcome (strength and conduction)

A couple more tips:

Solder will oxidize and become a very poor conductor.  Excessive heat will cause this.  If your solder joint is not shinny you are loosing perfomance by poor conduction.  Every now and then clean the blob of solder that accumulates on your wires (or trim them) and solder tabs.  Using flux will keep the solder from oxidizing as well - just remember to clean it up afterwords with a little alcohol (you have to rub it on, not drink it Rob...) and give you excellent solder joints.

If you decide to take the plunge and do your own batteries check with someone who knows how to do it properly first.  There are a few tricks that will help you get the most out of your batteries.  Don't forget to stay on the battery for no more than five seconds esp on the positive side.  With a proper iron and some practice you can do a tab in 1 to 2 seconds.

Oh and silver solder is highly recomended not only for its better conductivity but it is also a much stronger physical connection.

[gearhead]

I do happen to have silver solder, so I would like to try it. I am wondering if my hobby sized oxy torch would work better/faster. If not, then what wattage iron do I need?

[Tom]

As described in a previous post, the most important thing about the soldering iron you use for this task is the heat capacity, not the wattage.

You want a soldering iron with a big tip, the bigger the better.

Again, you shouldn't care much about the temperature, or the wattage; you should care most about the size of the tip.

I could repeat the above once again, but I won't bother.

You need to be careful about your silver solder.  Often times, silver solder is sold for repairing jewlery, since it is mechanically fairly strong.  Since it is often sold intended to be used for something other than electrical work, it will often have an acid flux core.

You should never use acid flux when soldering electronics.

And Grinder, soldering is quite different than welding.  Soldering is quite similar to brazing, the only difference being the temperature.  However, welding is a different process entirely, which involves melting the pieces to be joined, rather than flowing a metal onto both surfaces to be joined.

[haddow]

And if this is something you can see yourself doing often in the future spend 20 bucks and get a Deans battery building jig it is worth its weight in Gold and makes the job very easy especially if you have a nice fat solding tip. Canadain Tire had one for 40 bucks that works awesome.

good luck

[Grinder]

Yes the Canadian Tire is perfect for building batteries and soldering your wires to your motor can, etc.....  a worth while investment.  I've got two variable temp soldering irons and a few decent pencil irons but nothing that works like the CND Tire iron because of the massive tip on it...

And yes silver solder does come in a "jewlery" grade which does contain acid core flux which is bad for electronics.  Mainly because it needs to be removed by water rather than alcohol or flux remover...

Chemically soldering/brazing may be different than welding - I guess my point is that a lot of the techniques are similar....  cleanliness, flow, etc...  definately don't be using a flame for soldering temperature sensitive items like batteries - you will run into the problem of heat capacity versus temperature....  get the iron with the big tip....