Thread: Battery bars
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Old 01-07-2006, 11:21 PM
  #42  
BigDogRacing
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Well, I'll take a second out of my busy schedule to post a little information here for those that want to learn something, and also to entertain BATT_MAN too!

The idea that elctricity, or more accurately the flow of electrons, only happens on the surface of a conductor is old school. The truth is that flow begins at the surface, but as the volume (amperage) increases, the amount of material conducting the flow increases and begins to move closer to the center of the material. If your conductor were round, then under relatively low amperage the material allowing the flow would look like a thin walled tube, but as the volume (amperage) increases, the wall of the tube gets thicker and thicker.

So how is this relative to our battery bars? Well, BATT_MAN is correct that the plating is so thin that the only time you might actually be able to tell a measurable difference is super low current. In our case, we use a lot of current so the actual bar material is doing most of the work. The vast majority of the bars out there are copper based material with a very thin plating.

What concerns me the most about this thread is that the persons I expected to give useful information haven't done so! Shame on you guys!!

For those of you who don't know this, you should take heed and don't let this good advice go in one eye and out the other!!

While the bar or manufacturer might not be very important, and the soldering technique and solder IS very important, the way you prepare your bar and cells is also very important!! First you should lightly sand or scuff the center of the cell's button and case (negative end) to assure there is no coatings and most importantly to give the solder a rough surface to make good adhesion. Next you should do the same to the surface of the bar where it contacts the cell, but on the bar you absolutely positively need to sandthrough the plating!! If you don't, there a very good chance the bar can pop loose and leave the plating attatched to the solder- it happens all the time!! But what's worse, is that this can happen but not detatch fully- then you have a situation where the bar is barely making contact, but it looks fine to the naked eye. This is very bad, cause now you will spend days on a wild goose chase looking for the reason of your loss in performance.

Personally I use the flat side of a cut-off wheel on my dremel to keep my surface flat. I also use goos rosin flux and clean the flux off after assembly. Here's another tip- if you use some motor spray and clean the solder joints right after assembly, the flux will come off very easily. Use an old toothbrush with the motor spray on those stubborn spots.

Also, if you're worried about overheating the cells during soldering, and you have a very good iron, just put them in the fridge for a few hours after you prep everything for assembly but before you do the soldering. With a good iron you won't even be able to tell they are cold, but instead of potentially boiling the electrolyte, you will just warm the cells up to normal temperature. No problem!!!
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