# loctite LiFePO4 battery term bolts?



## DIYguy (Sep 18, 2008)

I wouldn't use loctite or petroleum on battery terminal threads.. Use the appropriate spring washer (belleville or lock) and the correct torque,...what ever that happens to be. Then check them after one week, then one month...three months...etc...


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## coryrc (Aug 5, 2008)

dtbaker said:


> yes, or no on LiFePO4 terminal bolts?
> 
> I hate the thought of one coming loose, but not sure if loctite would mess us the conductivity between terminal bolt/terminal. Otherwise I'll just use a little petroleum jelly and trust the spring washers I guess.


Stainless steel resistivity is about 700 nano-Ohm-meters
Copper resistivity is about 17 nano-Ohm-meters
Aluminum is about 50% more than copper
So if the surface area of the bolt and the copper pad were equal (which it isn't, the copper pad is much bigger than the bolt), only about 17/700 (2.4%) of the current would be going through the bolt. So I wouldn't worry about the bolt's conductivity.

I haven't had any loosen on me yet, but loctite wouldn't hurt anything.



dtbaker said:


> Also, I am not finding any torque specs on tightening the terminal bolts, which makes me a little vervous going into AL and CU posts.... Anyone have safe specs on this?


For 8mm bolts, I use 100in-lbs. At 120in-lbs, some threads started to show damage after a couple cycles.


Cory
http://www.pacificev.com


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## azdeltawye (Dec 30, 2008)

I scrapped the bolts that came with the batteries altogether and used stainless steel M8 - 1.25 X 35mm studs. 

This method ensures that you use all the available female threads in battery posts since they are the weakest link...


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## dtbaker (Jan 5, 2008)

azdeltawye said:


> I scrapped the bolts that came with the batteries altogether and used stainless steel M8 - 1.25 X 35mm studs.
> 
> This method ensures that you use all the available female threads in battery posts since they are the weakest link...


not a bad solution since I have heard the depth of the threads is not consistant and sometimes causes loose connections if you THINK you are tight, and you're not.

Did you get set screws and drive them down first ?, or cut all-thread to length, or ? and I am assuming you used SS to avoid galvanic reaction with either copper or al and as well as being non-rusting? Would you go with 35mm length again, or will 30mm leave enough length for the thicker stack of stuff when putting on the standard 2/0 lug on the last terminals?

ya know, this reminds me to ask, are the bolts that come with the Thunderskys SS, or not? I am unfamiliar with the markings on the head of metric stuff. Hhhmm, I guess I can go check with a magnet.... just checked, not stainless.


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## CroDriver (Jan 8, 2009)

Yes, watch out for the issue that dtbaker is mentioning, I had that problem with my old TS pack...



dtbaker said:


> not a bad solution since I have heard the depth of the threads is not consistant and sometimes causes loose connections if you THINK you are tight, and you're not.


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## azdeltawye (Dec 30, 2008)

dtbaker said:


> ...
> Did you get set screws and drive them down first ?, or cut all-thread to length, or ? and I am assuming you used SS to avoid galvanic reaction with either copper or al and as well as being non-rusting? Would you go with 35mm length again, or will 30mm leave enough length for the thicker stack of stuff when putting on the standard 2/0 lug on the last terminals?
> 
> ya know, this reminds me to ask, are the bolts that come with the Thunderskys SS, or not? I am unfamiliar with the markings on the head of metric stuff. Hhhmm, I guess I can go check with a magnet.... just checked, not stainless.


I used stainless steel studs because I wanted to duplicate what I had received with my Thundersky cells (grade A4 stainless cap screws). Also I figured it would be best to use stainless a precaution to avoid any galvanic reaction between the dis-similar metals. 

I used all-thread and cut it up myself because it was much less expensive than buying the studs outright. However cutting, chamfering and thread-chasing 90 studs was a time consuming PITA. Next time I will pony up the extra change and buy them pre-cut.
http://www.mcmaster.com/#studs/=9ukadi
http://www.mcmaster.com/#washers/=9ukm18

I used 35mm length to allow for the worst case terminal configuration: two flat washers (one extra-thick and one regular), a split washer, the cable lug and BMS lug. All hardware (washers, nuts and studs) were 18-8 stainless.

All this stainless hardware was quite expensive but I figured it was worth it at ~ 1% of the cost of the pack…


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## dtbaker (Jan 5, 2008)

hhhmmm, my TS came with bolts, flat, and lock washers, but NOT stainless since the magnet stuck to them....

I priced ss set screws, toothed washers and nuts totalling about $55 for SS at boltdepot.com . I guess it would be not a bad investment since there have been stories of inconsistant depth tapping, and I'd like to make sure I grab all available thread in the soft terminals! I kinda wonder why TS ships with bolts instead of studs?


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## EVfun (Mar 14, 2010)

This is what I chose for the terminal bolts. I covered my allen wrench with heat shrink so only a 1/4 tip was exposed. It would have been nearly impossible to short anything out while tightening the interconnects down. My washers and lockwashers from Thundersky where stainless steel so I used them. Instead of using the TS interconnects I replaced them with braided interconnects shown here. It is a very pretty package, here is a progress picture from earlier this year.


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## tomofreno (Mar 3, 2009)

> my TS came with bolts, flat, and lock washers, but NOT stainless since the magnet stuck to them


All stainless steels except the austenitic group (300 series) are magnetic.


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## DIYguy (Sep 18, 2008)

tomofreno said:


> All stainless steels except the austenitic group (300 series) are magnetic.


Oops... I think it is actually the ferritic SS that are magnetic. The austenitic are typically not magnetic.... (ferritic = ferrite = iron = magnetic)...  ... that's how I try and remember it. The autenitic has more nickel

Sorry...that's actually what you said Tom. I miss read that...


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## DIYguy (Sep 18, 2008)

I like the stud idea... very good. Allows use of all the threads without worrying about bottoming out or using too few... nice.


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## JRP3 (Mar 7, 2008)

I used this http://www.sanchem.com/aSpecialE.html on the bolt threads and all mating surfaces with the stock hardware and have had no issues so far.


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