# ThunderSky owners: Check your connections



## CroDriver (Jan 8, 2009)

Every time I was accelerating hard (and pulling high currents) I heard some noise from my batteries. I thought that the currents where too much for the cells and they are venting a little bit.

A few days ago I took my whole car apart for a new paint job. I noticed a copper link on the cells was black - like it was burning. 

It turns out that the screw hole on that terminal is shorter than on others. The screw and washer where tightened but there was no pressure to compress the separate copper layers. Because of the bad connection the copper bar heated up.

It's not enough just to check if all screws are tighten, we have to check if the copper bars are well compressed.

I was using screws, washers and copper bars that came with my TS cells

P.S. I forgot to take a photo, sorry


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## etischer (Jun 16, 2008)

The threaded holes on my TS cells are also different depth. I hadn't thought to check if the bolts have bottomed out. Thanks for the heads up. 




CroDriver said:


> Every time I was accelerating hard (and pulling high currents) I heard some noise from my batteries. I thought that the currents where too much for the cells and they are venting a little bit.
> 
> A few days ago I took my whole car apart for a new paint job. I noticed a copper link on the cells was black - like it was burning.
> 
> ...


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## azdeltawye (Dec 30, 2008)

CroDriver said:


> ....
> It turns out that the screw hole on that terminal is shorter than on others. The screw and washer where tightened but there was no pressure to compress the separate copper layers. Because of the bad connection the copper bar heated up.
> ....


 
This is why I am using stainless steel studs instead of the cap screws supplied by the mfgr. It adds more cost but is good insurance of making sound connections to the battery terminals...


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## CroDriver (Jan 8, 2009)

azdeltawye said:


> This is why I am using stainless steel studs instead of the cap screws supplied by the mfgr. It adds more cost but is good insurance of making sound connections to the battery terminals...


I have found copper bolts so I'll use them now in my pack


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## major (Apr 4, 2008)

CroDriver said:


> I have found copper bolts so I'll use them now in my pack


Hi Cro,

I'd think copper would be a poor choice. I doubt you can get sufficient clamping force without ripping the copper threads off. That is why you rarely see copper threaded fasteners. Brass or maybe copper plated steel.

The bolt should not conduct current in a proper installation. It just clamps the busbar to the battery terminal. Personally I don't like stainless steel bolts. I use good quality plated steel fasteners with the proper lock and flat washers, torqued to spec and rechecked the next day.

Regards,

major


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## JRP3 (Mar 7, 2008)

Major, why don't you like SS bolts?


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## MN Driver (Sep 29, 2009)

major said:


> The bolt should not conduct current in a proper installation. It just clamps the busbar to the battery terminal. Personally I don't like stainless steel bolts. I use good quality plated steel fasteners with the proper lock and flat washers, torqued to spec and rechecked the next day.


When you check the torque on something, do you just torque it down a second time to make sure its tight or do you try to back it off with a little pressure to see if it holds?

I've always just torqued down bolts and just torqued them again if I thought that they might get loose over time.

If they aren't supporsed to be the current conductor, can a thread locking compound be used, or is this a bad idea? I thought that we weren't using thread locker because of the conductivity issues in the first place, now you've got me wondering.


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## major (Apr 4, 2008)

JRP3 said:


> Major, why don't you like SS bolts?


Hi JR,

Mainly bad experience with larger nuts and bolts where the threads gulled and seized. I just don't like 'em. And if you drop one, can't retrieve it with a magnet.

major


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## major (Apr 4, 2008)

MN Driver said:


> When you check the torque on something, do you just torque it down a second time to make sure its tight or do you try to back it off with a little pressure to see if it holds?


Hi MN,

With the torque wrench again. Just a habit. Especially when clamping material like lead, aluminum and copper. I don't bother when clamping steel.



> If they aren't supporsed to be the current conductor, can a thread locking compound be used, or is this a bad idea?


I suppose. I don't use it on batteries because I always seem to have to take the connection off at some time. Like I said, the proper fastener with lock and flat washer assembled to the proper torque should work fine. If that loosens, you have other problems.

Regards,

major


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## JRP3 (Mar 7, 2008)

major said:


> Hi JR,
> 
> Mainly bad experience with larger nuts and bolts where the threads gulled and seized. I just don't like 'em. And if you drop one, can't retrieve it with a magnet.
> 
> major


I'm using this stuff on all connections, including the threads, should prevent galling: NO-OX-ID A-Special Electrical Grade
http://www.sanchem.com/aSpecialE.html


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## major (Apr 4, 2008)

JRP3 said:


> I'm using this stuff on all connections, including the threads, should prevent galling: NO-OX-ID A-Special Electrical Grade
> http://www.sanchem.com/aSpecialE.html


Hi JR,

Thanks for the link. What I'm talking about is thread deformation, not oxidation. Once you send 2 or 3 hours under a bus trying to get one 1/2" bolt loose, you know what I mean . I've had trouble with 1/4-20 SS bolts elsewhere on non-electrical applications. I hate the suckers. Use if you want 

Regards,

major


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## JRP3 (Mar 7, 2008)

I too have dealt with seized SS fasteners, usually in aluminum. My understanding of galling is material interference between the two metals during assembly, exacerbated by corrosion and oxidation. The NO-OX should provide lubrication during assembly to prevent the surfaces from digging into each other and provide protection from corrosion and oxidation. At least I hope it works that way. I've had plenty of battles with rusted standard fasteners as well and am a firm believer in some sort of thread goop no matter what the material.


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## GizmoEV (Nov 28, 2009)

etischer said:


> The threaded holes on my TS cells are also different depth. I hadn't thought to check if the bolts have bottomed out. Thanks for the heads up.


I ran a bottom tap down each of the posts on my TS pack. Based on feel, not all of the holes were tapped the same. Some had more metal come out with the tap than others. I also noticed that not all of the holes were tapped to the bottom but only varied by about one turn.

I'm using brass bolts with bronze split washers. My BMS boards mount with a small screw down the center of the brass bolts.

See my blog at http://2003gizmo.blogspot.com/. If you click on a picture you will see a larger version.


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