Lumenier RB2205C-12 2400KV SKITZO Ceramic Bearing Motor
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Old Jan 24, 2003, 07:46 PM
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Question

End-to-End Packs with an Odd Cell


Hoping to appeal to your technical generosity:

Please advise on good ways to add that last cell at the end of an end-to-end soldered battery pack. I want to make a nine-cell pack out of an 8-cell one. Are there special bars that make this easier?

Thanks
Freezing in NJ
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Old Jan 25, 2003, 04:55 AM
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Use wire?
Old Jan 25, 2003, 05:20 AM
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I use copper bars, about 1mm x 5mm x 20mm for sub C cells. You could fasion these from a piece of copper water pipe if you can't get hold of a strip of copper the right shape.

Pre-tin both ends of the copper bar. Solder the bar to the ends of each 'stick' of 4 cells so the bars point out away from each other. Use the loose cell as a guide to bend the bars with a right angle. Remove the loose cell and bend the bars a little more so that the cell is now gripped by the bars. It's now very easy to solder the end cell and get it all lined up perfectly.

Mike
Old Jan 25, 2003, 06:20 AM
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If you are trying to do this config: ====|
where "|" is the last cell then The easiest is to do this:

Get some Desoldering Braid (Battery braid) from your local Electronics store for about $2.. If you need more thickness simply bend in two or 3 etc.

Cut strips to length. Pre-tin the battery ends. Put one strip on the end of each battery first. Put last cell between the two ends. Glue in place with a thick CA. Hit it with some booster. When dry. Bend braid into place and solder.

Anyway that's the easiest I know of and braid is cheap. Wire works too. But the braid is soo flat it will bend to any shape..

If you need more info let me know. I build a lot of packs this way and have some pics etc.

Mike
Old Jan 25, 2003, 09:24 AM
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One way to do this is to remove the bar or braid that is connecting the two sticks together and put the odd cell on the end. This might not be the prettiest pack but it should give you the general idea.
Old Jan 25, 2003, 09:48 AM
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I use a couple of battery bars - both bent at right-angles. I've soldered the button of one cell to the side case of another, but the contact area is low, and you have to use too much solder to get a good physical connection. I like to use bars, and not braid, because the braid has a little mechanical give to it, which will eventually wear the braid or the connection. This is all personal preference, of course. Do what you're most comfortable with - for me, it's bars. Solder the bars to the ends of the stick first, as close to perfect alignment as possible, then tune with a pair of pliers to get it so the end cell is a push-tight fit. Then solder in place.
..a
Old Jan 25, 2003, 10:13 AM
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Here is my first attempt at the "odd" cell. I use these in my Kwik-e. These CP2400 cells were some of my first cells I tried to solder together and I was trying to learn to solder at the time hence the excess solder.
Last edited by kelvin; Jan 25, 2003 at 12:16 PM.
Old Jan 25, 2003, 10:14 AM
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Another. I use braid with some heat shrink.
Old Jan 25, 2003, 11:27 AM
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Nicely done!
..a
Old Jan 26, 2003, 09:00 AM
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Nice pack. Only thing is that solder joint between the wire and cell looks like it could have used a hotter iron. The solder should flow freely around all the contact points. When it cools it should be uniform in shape and shiney.

-Ben
Old Jan 26, 2003, 10:26 AM
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Quote:
Originally posted by Ben Diss
Nice pack. Only thing is that solder joint between the wire and cell looks like it could have used a hotter iron. The solder should flow freely around all the contact points. When it cools it should be uniform in shape and shiney.

-Ben
My iron is a 60 watt Hobbico. I'm always afraid to get things too hot on the cells. My procedure is to tin the cell and braid. Then I hold the braid down with a screw driver. Then I apply the iron and release the screw driver, wait a few seconds, the solder melts and then I apply to screw driver tip onto the braid to hold it and remove the iron. The screwdriver tip seems to absorb some of the heat.

I'll check my connections. Thanks

Kelvin
Old Jan 26, 2003, 11:01 AM
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Last (odd#) Cell - Thanks


Thanks for all your ideas and recommendations. I'll post with my results.
Old Jan 26, 2003, 01:16 PM
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Hmm... Flying W in New Jersey? Does that refer to a little airport east of Philly with an airplane shaped swimming pool (that hasn't been used in 20 years).

I did my primary flight training there in '90.

-Ben
Old Jan 29, 2003, 09:27 PM
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Here you go.. had to make a 7xCP1300 tonite..
..a
Old Jan 29, 2003, 09:27 PM
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