# Bolts or screws for LIFEPO4 Cells



## pedm (May 2, 2011)

Hi everyone,

Witch bolts are better for connecting LIFEPO4 Cells. My Hi-power baterries came with aluminium ones (looks like aluminium). But it easily beaks:









And gets rust:









Is it best to use Stainless Steel? The constructor says that this should not be used:



> YOu cannot use the stainless steel screw, since the material is not
> the same as our original ones.


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## dougingraham (Jul 26, 2011)

pedm said:


> Is it best to use Stainless Steel? The constructor says that this should not be used:


I think everybody uses stainless these days. The bolt does not (should not actually) carry current and the only worry would be galvanic corrosion which is minimal between aluminum and stainless. I am using Noalox on the threads more as an anti seize compound to prevent galled threads.

You can probably buy better quality aluminum than the provided ones if you are really concerned about it.


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## pedm (May 2, 2011)

dougingraham said:


> I think everybody uses stainless these days. The bolt does not (should not actually) carry current and the only worry would be galvanic corrosion which is minimal between aluminum and stainless. I am using Noalox on the threads more as an anti seize compound to prevent galled threads.
> 
> You can probably buy better quality aluminum than the provided ones if you are really concerned about it.


Great! Thanks for your precious reply. I really read on the internet that the two metals together can get galvanic corrosion, but if it is minimal I prefer to have more strong bolts than the aluminium provided by them. And maybe replacing for stainless steel and applying Noalox on the terminals will solve the corrosion problem.


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## mharvey (Oct 30, 2009)

pedm said:


> Great! Thanks for your precious reply. I really read on the internet that the two metals together can get galvanic corrosion, but if it is minimal I prefer to have more strong bolts than the aluminium provided by them. And maybe replacing for stainless steel and applying Noalox on the terminals will solve the corrosion problem.


Just a friendly caution not to overtighten whatever bolt you use. Follow the mfg torque specs (if you don't have 10-15 ft.lb with a lock washer should be more than adequate). Otherwise you can damage the cell internals - any decent grade decent quality bolt should do. 

I prefer stainless bellville washers & bolts with noalox. This way I get positive locking, no galvanic corrosion. I really don't like having to troubleshoot pack string connections . This setup is pretty much _"Set it and forget it"_ from my experience.


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## Zak650 (Sep 20, 2008)

Hi,
You might look into NORD-LOCK® washers available from Mcmaster-Carr. You use 2 washers/bolt. They lock against each other using a wedge system and actually have to see more compression in order to be removed or loosened. I think the zinc coated might actually be the best for this application. They come in two different OD sizes. Also braided straps, stainless bolts, & nord-lock washers are available as a kit from EVTV.me site/store. I really feel this is the best way to connect these brick type cells.


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## onegreenev (May 18, 2012)

I have a combination of stainless and zinc coated bolts and washers and they seem to be doing just fine. I would never use aluminum bolts.


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## pedm (May 2, 2011)

onegreenev said:


> I have a combination of stainless and zinc coated bolts and washers and they seem to be doing just fine. I would never use aluminum bolts.


I replaced the aluminium bolt with a M10 stainless steel. I was not enable to fix the battery terminal, so it had to be transformed into a threaded hole of M10 1.5. I remained the other bolts, the aluminium ones. When I turned the system on. The circuit breaker tripped. But on the terminal I could not find any problem. So after turning the circuit breaker back on and connecting the contractor. The Kelly HSE after working with green light for a wile it gives an error when pressing the throttle: 

Internal Reset: Reset caused by over current, high battery voltage or low supply voltage. It is  normal if occurs occasionally. 

Can you help me out. I can't get this car to road it is giving me too much problems. 

Should I really replace all the bolts even if the factory says not to do it so?
Should I use an aluminium M10 Bolt instead of a stainless steel? 
Using a different bolt material for one terminal can origin in this kind of problems?


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## EVfun (Mar 14, 2010)

onegreenev said:


> I have a combination of stainless and zinc coated bolts and washers and they seem to be doing just fine. I would never use aluminum bolts.


+1 on the aluminum bolts. It just never ends well!

Most people will find some zinc coated steel in their fastening system. I use split lock washers and those are almost always zinc coated steel. The only reason I can see against stainless steel is that Aluminum is sacrificial SS in a galvanic reaction. Zinc is sacrificial to Aluminum so it could be used if that is a concern.


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## onegreenev (May 18, 2012)

Zinc is also cheaper. So far no issues with galvanic corrosion. Good quality Zinc coated bolts and washers will do you fine on aluminum.


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## Roy Von Rogers (Mar 21, 2009)

http://evtvshop.projectooc.com/products.php?cat=7


Roy


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## mharvey (Oct 30, 2009)

Zak650 said:


> Hi,
> You might look into NORD-LOCK® washers available from Mcmaster-Carr. You use 2 washers/bolt. They lock against each other using a wedge system and actually have to see more compression in order to be removed or loosened. I think the zinc coated might actually be the best for this application. They come in two different OD sizes. Also braided straps, stainless bolts, & nord-lock washers are available as a kit from EVTV.me site/store. I really feel this is the best way to connect these brick type cells.


 
Agreed on all points, except the minimal advantage of the nord-lock over the bellville washers doesn't justify the cost of those nord-locks. Of course I only looked at McMaster and Fastenal. About a buck per pair...crazy talk. I dont have issues at all with loosening bolts so it would be like thowing money away. As for SS v zinc, I'll stick with my SS b/c I'm a neat freak and hate stains .


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## TigerNut (Dec 18, 2009)

Roy Von Rogers said:


> http://evtvshop.projectooc.com/products.php?cat=7
> 
> 
> Roy


So those braided strap lugs are tinned copper, then we have aluminum terminals with stainless fasteners and zinc-plated Nordlocks... obviously it works so long as everything is tight, but has anyone actually done an analysis of what the various half-cell potentials are if you do get moisture in the connections? Would it be a good idea to clearcoat the connections after doing initial testing, just to ensure that there is minimal moisture ingress?

Second thing - the straps have some ability to flex and accommodate variation in cell spacing, and you can get them in 60 and 70mm widths. So why are the lug holes ovalized? You're giving up about 1/3 of the contact area on the battery terminal...


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## Roy Von Rogers (Mar 21, 2009)

TigerNut said:


> So those braided strap lugs are tinned copper, then we have aluminum terminals with stainless fasteners and zinc-plated Nordlocks... obviously it works so long as everything is tight, but has anyone actually done an analysis of what the various half-cell potentials are if you do get moisture in the connections? Would it be a good idea to clearcoat the connections after doing initial testing, just to ensure that there is minimal moisture ingress?
> 
> Second thing - the straps have some ability to flex and accommodate variation in cell spacing, and you can get them in 60 and 70mm widths. So why are the lug holes ovalized? You're giving up about 1/3 of the contact area on the battery terminal...


Discerning smokers, smoke Camel dung...lol

Geez man, buy some and see, and btw they are not oversize holes, they are elongated, and you should be able to figure out why.

Btw, I have no association with the seller exept watching his videos, just in case your wondering why I posted the link.

Roy


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## PStechPaul (May 1, 2012)

Those copper braided straps look pretty good and the prices are reasonable. We use such straps for grounding on our high current circuit breaker test sets, and as flexible connections to breakers where we have pulsed several thousand amps. But we have always used copper for high current connections, and silver plating makes the connection even more reliable. Silver oxide is much more conductive than copper oxide. Here is a link to a company that specializes in copper products, and they have laminated copper bus bars that may be useful:
http://store.electrical-insulators-and-copper-ground-bars.com/flexible-insulated-busbar.html

At one time I made a high current transformer using aluminum bus bar, and it worked, but even when I wire brushed the mating surfaces before assembly, there was always significant voltage drop, and after a while they deteriorated. When I replaced the bus with copper I got almost twice as much current. There is a lot of information about connection of bus bars, and it requires a clean, flat surface, and sometimes brushing the mating surfaces at right angles creates thousands of small point contacts which make good connections when tightened. And it is also good to use a bit of grease which excludes air and water and retards corrosion.

But aluminum is a special case. Aluminum oxide is one of the best insulators known and it forms almost instantly upon exposure to air. You can use Ideal Noalox as a joint compound, and you can also get silver-bearing conductive grease. But it might be worthwhile to plate the aluminum with copper, nickel, or silver.

I have a small plating kit from this company, and although I have not tried it on aluminum, they have the following which says it works on "zincated aluminum", although I'm not sure exactly what that is:
http://www.caswellplating.com/elect...-kits/flash-alkaline-copper-plating-kits.html

Here is an article that describes how to zincate aluminum so it can be plated:
http://www.dalmar.net/aluminum_plating.htm

I am surprised that these batteries have aluminum terminals and aluminum screws. It also makes me wonder about the internal connection between the aluminum terminals and the electrodes.


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## pedm (May 2, 2011)

I found this:

Nut height 
Connection to a cell must be such that the current flows directly from the cell's terminal to the bus bar or cable terminal. You must not rely on the mounting bolt to carry the current.

Unfortunately, in some cells (namely Shandong HiPower) that can be hard to achieve:

The large nut securing the terminal to the case is installed with a locking compound
That locking compound creates an insulating layer
The large nut may be taller than the cell's terminal
The connecting bus bar (or the terminal on the connecting cable) rests on the large nut
Since the nut is isolated, current flows through the mounting bolt instead
The bolt is usually made of a coated steel which has a relatively high resistance
This results in a high temperature rise
The solution is to ensure that the large nut does not extend past the cell's terminal surface. If you cannot screw in the nut further, you may need to use a planer to file down the top surface of the large nut.


Original text from: http://liionbms.com/php/prismatic_tips.php

So If you have Hi Power cell it is an important tip.


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## pedm (May 2, 2011)

PStechPaul said:


> You can use Ideal Noalox as a joint compound, and you can also get silver-bearing conductive grease.


Can't find IDEAL Noalox in Portugal. Is there another product that does the same but with a different name?

I can see that it is a compost of Polybutene (80%), Zinc Dust (20%) and Silicon Dioxide (5%). I can't find a compost whit this specs.


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## PStechPaul (May 1, 2012)

pedm said:


> Can't find IDEAL Noalox in Portugal. Is there another product that does the same but with a different name?
> 
> I can see that it is a compost of Polybutene (80%), Zinc Dust (20%) and Silicon Dioxide (5%). I can't find a compost whit this specs.


Probably best to go to a major electrical supplier and ask for a joint compound designed for aluminum splices and connections, or bus bar compound. Otherwise, if you can brush or file the aluminum surface so that it has ridges and grooves, then coat with grease (petroleum jelly, or Vaseline), and then torque the connection, you should be OK.

You might be able to read the mV drop from the exposed part of the battery terminal to the bus bar, under a substantial load. If you can get 20 amps or so, then see what the voltage drop is. Maybe do a before and after test to see if it improves.

You might also try brass or silicon bronze bolts. Even though they are not as conductive as copper, the threads will have a lot of surface area contact with the aluminum, and if you put grease on the thread it will keep the aluminum from oxidizing. And the scraping action of the bolt in the threads will remove some of the aluminum oxide. In that case, use a brass or copper washer under the bolt head and make sure the surfaces are clean and flat.


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## nucleus (May 18, 2012)

*terminal paste*

What I use is a paste that is sold in the hardware stores for both copper and aluminum connections in house wiring. It is conductive and prevents dissimilar metal corrosion when you connect copper and aluminum.

Nucleus


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## GizmoEV (Nov 28, 2009)

*Re: terminal paste*

I use brass bolts and bronze split washers. In over 2.5 years I haven't had any problems and no bolts have loosened. I did use NOALOX in the threads and contact surfaces. If I were to do it again I'd use No-OX-ID A-Special. 

http://www.sanchem.com/aSpecialE.html


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## Zak650 (Sep 20, 2008)

Here's the item on ebay $5+$4 shipping:
http://www.ebay.com/itm/NO-OX-ID-A-...080?pt=LH_DefaultDomain_0&hash=item43b0e4e690


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## PStechPaul (May 1, 2012)

This company makes some good products, too:

http://www.cool-amp.com/

But that No-OX-ID A-Special looks good. I might get some. Thanks for the link. Do you know if it's also good for TO-220 transistor mounting to aluminum heat sinks?

And here's another company that has some good stuff:

http://www.caig.com/


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## mharvey (Oct 30, 2009)

I found this article some years ago that explains the mechanics of torque and force in electrical connections. Had to go back through the archives to find the guys name. Written by a PE, but a good primer if you're a noob at this, and a good reference to check that you haven't developed some bad habits if you're not. 

http://www.maintenanceworld.com/Articles/shackmann/thetrouble.html

And another on how to make em clean and tight from the same guy:

http://www.maintenanceworld.com/Articles/shackmann/creatingreliable.html


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## fb88vnasia (Feb 21, 2019)

Roy Von Rogers said:


> http://evtvshop.projectooc.com/products.php?cat=7
> 
> 
> Roy


Wow! thank for your sharing, i'm newbie here, this is my first good help


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