Soldering E-Bike Battery Leads ... your favorite method?

LI-ghtcycle

LI-ghtcycle

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I've forgotten more than I can remember of my high-school electrical shop class, and I know I had to learn some very specific splices like the "western union" and pig tails, but I have been looking up more of a "T" connection, and the best I have found so far is this:
http://www.tpub.com/content/construction/14027/css/14027_123.htm
14027_123_1.jpg


I have to do this kind of connection for 10 leads (5 pos, 5 neg) and if there is a better way to solder five 14G leads to a 12G main, please share! :wink:

I did this (with strand, not solid core wire) wrapping 3 times on the main 12G wire, but it was very time consuming, difficult to strip the 12G in the middle of the wire, and wanted you-all's thoughts. I'm not really wanting to solder all 5 leads to the same connection, my iron might not be up to it, and it would be near impossible to untangle if I ever needed to separate them. :roll:

Thanks in advanced! 8)
 
LI-ghtcycle said:
I have to do this kind of connection for 10 leads (5 pos, 5 neg) and if there is a better way to solder five 14G leads to a 12G main, please share! :wink:

I did this (with strand, not solid core wire) wrapping 3 times on the main 12G wire, but it was very time consuming, difficult to strip the 12G in the middle of the wire, and wanted you-all's thoughts. I'm not really wanting to solder all 5 leads to the same connection, my iron might not be up to it, and it would be near impossible to untangle if I ever needed to separate them. :roll:

Thanks in advanced! 8)
Click to expand...

5 leads to 1, I wouldn't Solder that. I would crimp on ring terminals to all 5 leads, and the main lead, then put a bolt through them. (I would solder the ring terminals to each wire though. better connection than just crimping)

But if it just has to be soldered. I would start by pre tinning each lead, stripped back 1 inch. Use the least amount of solder possable. I would then arange the ends so 3 approached from one side, 3 from the other over lapping each other. Then wrap the 6 leads with a thin strand of copper wire tightly but space between the windings for the solder to flow. I'd then use a pen torch to heat it up to solder, as an iron wouldn't get the heat in deep enough quick enough.
 
Drunkskunk said:
I'd then use a pen torch to heat it up to solder, as an iron wouldn't get the heat in deep enough quick enough.
Click to expand...

EXCELLENT idea! Wish I'd thought of that earlier.

BTW, keep in mind that a solder connection, once the bike is up and running, can carry LESS current than a straight wire that's never been soldered. Current flows down the OUTSIDE of each wire strand. A wire with lots of strands, can carry more current than, say, a solid wire of the same weight of copper.

That is, a stranded (unsoldered) wire carrying current, will heat up less than a same-weight solid wire... or a tinned stranded wire.

Take your ebike for a long, vigorous run, with lots of accelerations, uphill runs, etc. Then feel the high-current drive wires, either the two going to the battery, or the three going to the (brushless) motor. Most of the wire length will be cool... but the connections, or any point where the wire has been thoroughly tinned, will be warmer.

Drunkskunk, where do you get such a pen torch?
 
Little-Acorn said:
Drunkskunk said:
I'd then use a pen torch to heat it up to solder, as an iron wouldn't get the heat in deep enough quick enough.
Click to expand...

EXCELLENT idea! Wish I'd thought of that earlier.

BTW, keep in mind that a solder connection, once the bike is up and running, can carry LESS current than a straight wire that's never been soldered. Current flows down the OUTSIDE of each wire strand. A wire with lots of strands, can carry more current than, say, a solid wire of the same weight of copper.

That is, a stranded (unsoldered) wire carrying current, will heat up less than a same-weight solid wire... or a tinned stranded wire.

Take your ebike for a long, vigorous run, with lots of accelerations, uphill runs, etc. Then feel the high-current drive wires, either the two going to the battery, or the three going to the (brushless) motor. Most of the wire length will be cool... but the connections, or any point where the wire has been thoroughly tinned, will be warmer.

Drunkskunk, where do you get such a pen torch?
Click to expand...


This isn't correct at all. This is a common misconception. Very commonly people make poor solder connections (aka, lead-free solder making cold un-wetted joints that visually appear fine), and this is why they get hot at the soldered connections.

Solder being over a wire only lower the resistance in that area by a bit, and reduces the localized heating.

If I had to join a series of wires to a larger wire, I would make the connection all at one point, and try to keep the wire lengths roughly equal (though it doesn't matter much for low power applications).

This picture was taken to show the cell, but if you look inside the pack it's sitting on, you can see 8 places where groups of 4x 10awg wires being connected together to a 4awg wire.

pc220396.jpg


I did this with a handheld 15-150w burst button soldering iron. I use torches for soldering plumbing, and 0-0000awg cables, but if I try to always avoid them when possible with electrical work due to oxidizing the surface of the copper and vaporizing the flux before it can clean properly.

These are small wires, so get the right solder, and it should be cake to solder with an iron. Get the wrong solder, and it may be impossible, or turn out poorly at best. Also, do NOT wick the wire beyond the point you are connecting it, or you make a stiff place just waiting to crack and fail from vibration. Proper temp control and flux placement are critical to avoid wicking, which is the way soldering newbs often fail if they manage to get past doing cold solder joints.

Just cut some little 6" pieces of wire and practice and play with it until you get a good process. Remember, never add the solder to the iron, always add the solder to the work, and poke it frequently with the solder as a temp indiactor. Tin both parts seperately without wicking more than just the area of the joint, then lay them against the iron tip together. Unless they are identical wires with identical pressure against the tip, one will melt first. Take this one away from the heat heat the moment it melts and wait for the other one to melt before re-applying it. Once they both melt together, pull the heat away instantly and keep them completely still until the surface dulls.
 
Great info thanks! I have another question about soldering irons in general. I have a 60 Watt iron, just a plug-in, no burst switch or anything, and I believe I didn't remember to properly tin the first tip and it burnt it's self up pretty quickly with a hot-spot developing on the tip, and the tip it's self seemed to liquify and fall apart as if made of solder! :shock:

I got out the spare tip it came with, was very careful to tin it and clean it, and yet after what I would have thought to be normal use, not excessive, just building 2 sets of E-Bike wiring, it too has melted it's tip off. I am wondering if it's regulator is shot, I clean it with both a brass hand brush and wipe it off with a damp rag after every use, and tin it as it is cooling (after it's unplugged) and clean it again with the brass brush and finish with the rag so it's always put away with a nice shinny tip.

What am I doing wrong? Or maybe I just bought too low-end of a iron? It's the same one that the local hobby shop uses to put together their customer's battery packs, and yes it was just $9, but I spent probably $15 on the ultra fine high-end solder (large spool but really high-end stuff from Radio Shack ... well, the best they had anyway :lol: )

Any ideas?
 
LI-ghtcycle said:
Great info thanks! I have another question about soldering irons in general. I have a 60 Watt iron, just a plug-in, no burst switch or anything, and I believe I didn't remember to properly tin the first tip and it burnt it's self up pretty quickly with a hot-spot developing on the tip, and the tip it's self seemed to liquify and fall apart as if made of solder! :shock:

I got out the spare tip it came with, was very careful to tin it and clean it, and yet after what I would have thought to be normal use, not excessive, just building 2 sets of E-Bike wiring, it too has melted it's tip off. I am wondering if it's regulator is shot, I clean it with both a brass hand brush and wipe it off with a damp rag after every use, and tin it as it is cooling (after it's unplugged) and clean it again with the brass brush and finish with the rag so it's always put away with a nice shinny tip.

What am I doing wrong? Or maybe I just bought too low-end of a iron? It's the same one that the local hobby shop uses to put together their customer's battery packs, and yes it was just $9, but I spent probably $15 on the ultra fine high-end solder (large spool but really high-end stuff from Radio Shack ... well, the best they had anyway :lol: )

Any ideas?
Click to expand...

I was taught to use soldering iron when I was 14 when I was in a tech/high school. You simply get a 45W soldering iron for 10 to 14 gauge. Anything below that should use a 15W iron. Also, you should buy some solder wax or some people call them solder resin. Heat up the iron, dip the tip into the resin, tap on the wire, and apply the solder. BTW, I bought my soldering stuff from Radio Shack & highly recommended them since they still have soldering iron tips replacement for some of my 15 years old irons. Just my 2 cents. :)
 
High wattage irons can't hold a tinning when they sit idle. This is because when they reach temp equilibrium (watts in = watts out in heating the air around them), they are beyond a temp that the metals in solder rapidly oxidize. This is why a 60w iron is always burning tips, and they also have an excessively hot idle temp for most work, which causes flux to vaporize before cleaning the surfaces and makes for poor joint quality.

I've got a $500 soldering station, and it's sat collecting dust since discovering a booster iron, burst iron, button iron, thermal recovery iron, whatever you want to call them.

I use a 15w/150w, but here is one I found for $7.99 that is almost as good.

http://www.mcmelectronics.com/product/21-8145&CAWELAID=220244247

At idle, the iron is only using 20w, so the thermal equilibrium temp is below the rapid oxidation point of the metals in solder, so it holds a tin perfectly, and this tinning protects the tip from taking any damage. When you want to solder big cables, hit the button and apply firm contact, and you've got the power of a soldering gun in the form factor of an iron, and you've got the ability to actively control the desired temp of the soldering as you're working by simply working the button as needed. This way the iron never gets excessively hot, yet you can still pump serious power into big cables. It's been 3 years now of almost daily work, and because I never let the tinning oxidize on the tip, it still looks and works like new. I do surface mount stuff the size of a pin head with it, as well as 4awg cables. Pretty versatile.

IMO- Every iron I've ever got from RadioSnatch sucked. The tips there suck as well and seem to be designed around frequent replacement... Resin/flux isn't going to extend the life of the tip, it's a temperature activated acid to clean the surface of a metal, leaving it in a more venerable and damage prone condition.

My $0.02
 
liveforphysics said:
High wattage irons can't hold a tinning when they sit idle. This is because when they reach temp equilibrium (watts in = watts out in heating the air around them), they are beyond a temp that the metals in solder rapidly oxidize. This is why a 60w iron is always burning tips, and they also have an excessively hot idle temp for most work, which causes flux to vaporize before cleaning the surfaces and makes for poor joint quality.

I've got a $500 soldering station, and it's sat collecting dust since discovering a booster iron, burst iron, button iron, thermal recovery iron, whatever you want to call them.

I use a 15w/150w, but here is one I found for $7.99 that is almost as good.

http://www.mcmelectronics.com/product/21-8145&CAWELAID=220244247

At idle, the iron is only using 20w, so the thermal equilibrium temp is below the rapid oxidation point of the metals in solder, so it holds a tin perfectly, and this tinning protects the tip from taking any damage. When you want to solder big cables, hit the button and apply firm contact, and you've got the power of a soldering gun in the form factor of an iron, and you've got the ability to actively control the desired temp of the soldering as you're working by simply working the button as needed. This way the iron never gets excessively hot, yet you can still pump serious power into big cables. It's been 3 years now of almost daily work, and because I never let the tinning oxidize on the tip, it still looks and works like new. I do surface mount stuff the size of a pin head with it, as well as 4awg cables. Pretty versatile.

IMO- Every iron I've ever got from RadioSnatch sucked. The tips there suck as well and seem to be designed around frequent replacement... Resin/flux isn't going to extend the life of the tip, it's a temperature activated acid to clean the surface of a metal, leaving it in a more venerable and damage prone condition.

My $0.02
Click to expand...

Thanks much for that link! I think I will get one of those Irons asap. I was wondering if my iron was just malfunctioning since it was burning it's self up so much, what your saying makes a lot of sense! :shock:
 
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