Fire hazard?

[joshludden]

Good evening arrma fam! Need a parallel wiring harness for some batteries & didn't want to wait for the ones I bought so I thought I'd try to make one out of stuff that I have on hand. Really testing my skill level here & I couldn't really find pics or videos that really helped. I just need to know if this is safe to use or am I risking a call to the fire department. Bear in mind that I will of course wrap both pos & neg separately before heat shrinking them together. Please be kind (but honest!), this is my 1st attempt @ anything like this

 

[Diem Turner]

Good evening arrma fam! Need a parallel wiring harness for some batteries & didn't want to wait for the ones I bought so I thought I'd try to make one out of stuff that I have on hand. Really testing my skill level here & I couldn't really find pics or videos that really helped. I just need to know if this is safe to use or am I risking a call to the fire department. Bear in mind that I will of course wrap both pos & neg separately before heat shrinking them together. Please be kind (but honest!), this is my 1st attempt @ anything like this

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They're not the prettiest, but it looks like you got good enough penetration with the solder. Here's a quick soldering tutorial on thicker guage wires. The one thing that is worth noting here is how he applies the solder to the wire and not the soldering iron (the only exception here being at the very beginning - you want to put a blob of solder on the front of the tip as this will increase the surface contact between iron and wire by many orders of magnitude which will, in turn, aid massively in heat transfer). You don't neccessarily need to wrap wire around it (though it can help), the application of the solder was the point I was getting at here. But to answer your question, I think you'll be fine using those. No worries about a fireball (assuming the positive and negative wires don't touch ).

Here's a more in depth soldering tutorial of do's and don'ts. Don't let the "stupid" in the thumbnail throw you off...I'm not saying you're stupid I just found this to explain a lot of the ins and outs rather well despite having no voice over, it's all just onscreen text. One thing I would highly reccommend is getting leaded solder (preferably of the 63/37 variety).
63/37 solder is made of 63% tin and 37% lead. It has a melting point of 183°C, slightly lower than the more common 60/40 blend. The primary advantage of this solder is not the lower melting point, but its eutectic property. What that means is, after you remove heat from the solder joint, moving the parts will not result in a cold solder joint (which can happen with 60/40 solder).
It makes soldering sooo much easier. If you get a chance to compare solder with and without head to head, you'll quickly understand what I'm on about. And, as will all manual tasks, there is only one way to mastery (or, at least, jackery...lol)...practice, practice, practice.

 

[Engineer]

I concur - looks like it should work.

 

[joshludden]

They're not the prettiest, but it looks like you got good enough penetration with the solder. Here's a quick soldering tutorial on thicker guage wires. The one thing that is worth noting here is how he applies the solder to the wire and not the soldering iron (the only exception here being at the very beginning - you want to put a blob of solder on the front of the tip as this will increase the surface contact between iron and wire by many orders of magnitude which will, in turn, aid massively in heat transfer). You don't neccessarily need to wrap wire around it (though it can help), the application of the solder was the point I was getting at here. But to answer your question, I think you'll be fine using those. No worries about a fireball (assuming the positive and negative wires don't touch ).

I agree, they're not pretty but hopefully they'll be adequate. Thanks for the link, I was struggling to find something like that. My soldering iron is 80w & I had it set on 400°c which is about 750°f. From the info that I'd gathered that is recommended? It did seem to cool down quite quickly so I had to take my time tho. Thanks again for all your help- hopefully those 3s speed trials are coming soon!!

 

[Diem Turner]

I agree, they're not pretty but hopefully they'll be adequate. Thanks for the link, I was struggling to find something like that. My soldering iron is 80w & I had it set on 400°c which is about 750°f. From the info that I'd gathered that is recommended? It did seem to cool down quite quickly so I had to take my time tho. Thanks again for all your help- hopefully those 3s speed trials are coming soon!!

For 8AWG wire (particularly in conjunction with QS8 connectors) I always set my iron for maximum, 500°C. There are limits to this rule, particularly with really thin wires, but on thicker stuff like 12 or 10AWG upwards, you want to get as much heat as possible into the joint as fast as you can. If you set the temperature lower, all this does is give the heat time to travel down the wire, sucking the heat away from the solder joint and you just wind up having to keep the soldering iron on the joint that much longer which can result in some ugly melted connectors. One other tip, always put the opposite connector on the other side when soldering near the connector. This will keep the pins from moving in the plastic should it become softened from the heat. Happy to help and can't wait to see those 3S passes!!

 

[Tex Koder]

Looks okay..
But how are you planning to get the heatshrink tubing on now that they're all soldered up?

 

[joshludden]

Looks okay..
But how are you planning to get the heatshrink tubing on now that they're all soldered up?

Just a big fat one to cover up the electrical tape that I used to separate the pos & neg

 

[Rcproponent]

Just a big fat one to cover up the electrical tape that I used to separate the pos & neg

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That’s what I’d be scared of… I’d wrap the red leads in electrical tape prior to heat shrink. If those wires flex enough to tough kiss your batteries and possibly your car bye Bye

 

[rcastello755]

looks ok I don’t like electrical tape,
unless is absolutely needed like on the field if a connector looks funny that’s it. To me if I forget to heat shrink it I take it apart and re-do them you’ll get more practice and won’t have to worry about tape loosing grip under heat stress imho.

 

[AIan]

You could use some rubber tube split down the edge to wrap the expo red and black wires first then tape then big shrink wrap.

 

[Engineer]

I wouldn’t have used the shrink wrap as it pulls the wires together. If there are any sharp edges or points on the solder connection they can abrade through the electrical tape from the vibrations of the car and then cause a short.

My two cents - just insulate the wires individually and call it good.

 

[Cereal_killer]

Just a big fat one to cover up the electrical tape that I used to separate the pos & neg

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No sir... you need to wrap them separately underneath. With electrical tape or shrink. That isn't safe.


Edit. Misread. My bad

 

[AIan]

Also it’s good to stagger when soldiering two wires next to each other. I know sometimes aesthetics call for simitry but sometimes we need to sacrifice beauty for functionality.

 

[jkflow]

Agree with the individual heat shrink. You do not want to squeeze the wires together. Electrical tape is OK for static wiring but you will have constant movement.
Will work for a couple sessions but will fail at the worst possible time.
Overall your approach is correct and nice job soldering.

 

[joshludden]

Also it’s good to stagger when soldiering two wires next to each other. I know sometimes aesthetics call for simitry but sometimes we need to sacrifice beauty for functionality.

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Purpose? To keep the joints further away from each other?

 

[Engineer]

Purpose? To keep the joints further away from each other?

Enough physical separation so that there is no way they can make electrical contact and short out.

 

[joshludden]

Enough physical separation so that there is no way they can make electrical contact and short out.

Gotcha. There is definitely a learning curve here. I really appreciate all of the input & concerns. I did wrap both the pos & neg w/ about 10 wraps of electrical tape before the big heatshrink & there weren't any sharp edges or wires poking through, but to be safe I'll just cut that heatshrink off & wrap them in some rubber tubing, then electrical tape. Keep in mind that I was just being impatient & wanted to run while waiting for the ones that I ordered so it should be good for a couple of days.
And...woke up to thunderstorms w/ chances of rain all day ☹

 

[jkflow]

Made the same mistake i. e. solder and forgetting the heatshrink many times. Couple curse words later I typically resolder, everything else is a band aid.

 

[Tex Koder]

Just a big fat one to cover up the electrical tape that I used to separate the pos & neg

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Sir, you are asking for some major heartache later..
As other members have stated, using electrical tape to cover those solder joints is basically a temporary fix ,especially on our types of RCs that's going to be put under a lot of vibrations/Stress - from bashing, jumps, tumbles, slamming into trees/curbs.

As soon as the stress exceeds adhesive strength of the tape or rubs through the thin tape themselves, your rig and batteries will have a seriously Bad day.

Best to completely redo these connectors and stagger the soldering connections as recommended by others. use heatshrink tubing on those cables separately AND DO NOT tape or heatshrink the two positive & negative joints together. Because you never know when your soldered joints may fail and come apart, also.

(at least not until you have enough soldering experience to reliably & confidently solder cables of that size/gauge...)

Just a courtesy Heads Up.