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Old 12-02-2006, 06:53 AM   #16
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How come the negative side of the battery always is harder to heat up? I just built 2 3300 practice packs and the neg side took almost 2x as long to heat up enough to liquefy the solder as the pos.
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Old 12-03-2006, 06:36 PM   #17
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Quote:
Originally Posted by andsetinn
I disagree with you there. You should use as much solder as it needs to get a strong solid joint. And it should be between the joint and fill it up. Solder is bad conductor but it's immeasurably better conductor than nothing. You should pre solder the cell with quality rosin core solder and then push the bar against the cell as you heat the bar with good powerful soldering iron. The solder should be shiny when you've soldered it, if it isn't shiny you've overheated the solder resulting in higher resistance and weaker soldering job.

Stuff to keep in mind is:
Some solder is better than other, the one I recommend for beginners is 60/40 rosin core. Immediately throw away (you should recycle it, it contains lead) the solder that came with the cheap soldering iron.
Lot of soldering irons are not as powerful as they're rated, especially the cheap ones.
Never use soldering guns.
In the ideal world mating surfaces of battery bars and cells would be finished to a perfect match. This would allow a surface-to-surface fit that maximizes electrical conductivity between the bar ends and cells. This fit would be so tight as to not allow solder to wick between the bar ends and the cells during the soldering process. At that point the only purpose for solder would be to create a bar to cell bond around the circumference of the bar ends.
In the real world cells and stamped battery bars do not mate well. Most of the time a very small (non-conductive) air gap exists between the bar ends and the cells. So, what is a person to do?
Without question the best soldering procedure is one that fills in these non-conductive air gaps or voids while simultaneously minimizing the thickness of that same solder between the bar ends and cells. This is best done by NOT tinning the cell or the battery bars. Even without tinning a thin solder layer will inevitably wick between the bar ends and the cells during the soldering process. Holding a battery bar tightly to the cell while soldering will minimize this solder layer to the point of just enough to fill air gaps while providing an efficient yet incredibly strong joint. How strong? I've personally witnessed 6-cell packs that where broken into two pieces during violent crashes. In each case the soldered joints were still intact but the battery bars had snapped cleanly.
Assemblies as duckman996 described can be done using a $30.00, 80-watt iron with a 3/8" chisel tip. With a good quality solder and flux I've assembled thousands of quality battery packs like this.
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Old 12-03-2006, 09:55 PM   #18
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i just came back into 1/10 after a decade+ hiatus and i too was wondering about braid when i first ordered my cells this time around hehe

i had another issue because the 4200's coupled with the tight confines of the xxx-t mf2 made for almost zero room for battery bars. I tried a few and the only ones that worked were Trinity gold, flattened dead flat between two pieces of wood hit with a hammer. I used a 80w Weller with big chisel tip that cost me 13$ from Lowes. I did not tin anything, i simply scored the ends of the cells with some 150 grit and used minimal solder. They have held up great!

Here are the packs when i was finished.




Oh, i didn't use a jig either, i used a priority mail box with a slot cutout and stuffed with foam, cutout to support the bottom of the pack and then i had a rubber band keeping the cells close.

This is the type of thing that happens when you don't have a worthwhile LHS.
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Old 12-03-2006, 11:29 PM   #19
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Quote:
Originally Posted by MikeXray
How come the negative side of the battery always is harder to heat up? I just built 2 3300 practice packs and the neg side took almost 2x as long to heat up enough to liquefy the solder as the pos.
I agree with you that it is a bit harder on the negative end.

Check out a picture of the construction of a battery cell on the Internet. I believe that the broader cell casing material at the negative end acts as more of a "heat sink" than the positive end...And therefore requires a bit more heat to accept soldering.

Good one!

But, why are you still getting 3300s in this day and age?
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Old 12-04-2006, 05:05 AM   #20
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This is what I do when putting together packs.

1. Always grind/rough up both ends of the cell.
2. Apply a small amount of flux and lightly tin each end of the cell
3. Apply another small amount of flux and install the bar using a small amount of solder.
4. Use lighter fluid and a tooth brush to remove and left over flux.

On my 4200's I use the EA/SMC Silver Intelect bars for assembly and 2 Trinity silver bars for the hook up leads. When I put a pack together I use Pure Silver Solder as well. Voltage does not travel "through" the bars/solder but around the outside. So going from one cell to another, you use Silver Solder, Silver bar, and Silver Solder your voltage travels across only Silver.

Another important tip is to use a very hot iron. Best result is to assemble the pack in the least amount of time. The longer you let your iron sit on the cell the better chance you have to damage your cells.

This pic is an old school 3300's.

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Old 12-04-2006, 07:50 AM   #21
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Quote:
Originally Posted by Still Bill
But, why are you still getting 3300s in this day and age?
Stormer had them for dirt cheap, I have 6 packs of 4200's just wanted some more practice packs.
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Old 12-04-2006, 09:36 AM   #22
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Default Battery Bars..

Thanks for all the info guys and the tips....

Just picked up 40 muchmore bars and 20 bar ends, for dirt cheap on the bay... looks sweet..

Thanks..
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