# Headway cell links



## jackbauer (Jan 12, 2008)

Perhaps its just my ignorance but do people know that the cell links supplied by headway are steel?. Not copper or ali. Thankfully i used custom copper plates and bars on my pack but i went today to make up a little 4 cell pack for a project and discovered the plates are magnetic quite by accident. I cut one in two and its steel! Surely (don't call me Shirley) , that can't be a good idea??


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## rwaudio (May 22, 2008)

jackbauer said:


> Perhaps its just my ignorance but do people know that the cell links supplied by headway are steel?. Not copper or ali. Thankfully i used custom copper plates and bars on my pack but i went today to make up a little 4 cell pack for a project and discovered the plates are magnetic quite by accident. I cut one in two and its steel! Surely (don't call me Shirley) , that can't be a good idea??


That is interesting, while I can't confirm the ones that I got are copper, mine aren't magnetic. Since I'm not using them anyways I'll have to cut one in half just to see.


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## major (Apr 4, 2008)

jackbauer said:


> Perhaps its just my ignorance but do people know that the cell links supplied by headway are steel?. Not copper or ali. Thankfully i used custom copper plates and bars on my pack but i went today to make up a little 4 cell pack for a project and discovered the plates are magnetic quite by accident. I cut one in two and its steel! Surely (don't call me Shirley) , that can't be a good idea??


Hey Shirley,

The new guy discovered that here: http://www.diyelectriccar.com/forums/showthread.php/battery-interconnect-resistance-55466.html 

Steel conductors for the battery high current path  BAD, BAD idea.

But on the other hand, are the cell terminals steel? A while back, one guy had a whole batch that rusted.

major


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## jackbauer (Jan 12, 2008)

Ah well old news then. Just made me glad used my own busbars.


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## rwaudio (May 22, 2008)

jackbauer said:


> Ah well old news then. Just made me glad used my own busbars.


The headway bars wouldn't be very useful unless you were making a pack for an electric bike anyways.


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## steven4601 (Nov 11, 2010)

Hi Jack

I have only three battery interconnects/bars. All three are different regarding Iron content (magnet test)

One was way off, also corroding on the 'dark side' when it was bolted on.

Heck its cheap, its available. 

Did the speedo signal get sorted? Just the speedometer being way off at low speeds?


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## Huub3 (Aug 16, 2009)

All,

looking at this discussion, I was wondering whether we really understand the current path between the batteries in the "typical" headway pack.

As I see it:
battery 1 with endcap and thread, grubscrew inserted
bussbar with hole, grubscrew going through
battery 2 with endcap and thread, other end of grubscrew

I see several paths, but the main seem to be:
a) endcap 1 - thread - grubscrew - thread - endcap 2
b) endcap 1 - surface contact - bussbar - surface contact - endcap 2

Depending on the contact resistances and material properties, the grubscrew might be the dominant path. Does this mean this grubscrew should be copper?

Regards,


Huub



steven4601 said:


> Hi Jack
> 
> I have only three battery interconnects/bars. All three are different regarding Iron content (magnet test)
> 
> ...


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## major (Apr 4, 2008)

Huub3 said:


> looking at this discussion, I was wondering whether we really understand the current path between the batteries in the "typical" headway pack.


Hi Huub,

I don't know about the "headway way". I have seen a few, but not used them up close and personal. However I have knowledge and experience in high current connections. It goes like this-----do not use the fastener to carry current. Use the fastener to clamp the two conductive surfaces together. And it is a bad idea to use ferrous metal as a conductor. UL and other agencies forbid it.

A common exception to the above can be found on a lot of motors where the terminals come thru the frame. In this case, the fastener is a large diameter bolt made of brass with brass washers and nuts. Some of the motors will use an insulated brass bar to conduct thru the frame and then use steel screws to clamp the cable lug to it.

Regards,

major


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## Jimdear2 (Oct 12, 2008)

We are going through some of this right now with our Headway pack.

Our pack design is 150 batteries in 3 cell buddy parellel packs 15 cells to a row and 10 rows to the pack. There is a 1/8 x 3/4 inch buss bar between each 3 cell buddy stack. This is similar to what Jack Bauer has assembled, except we used Headway's assembly blocks.

We originally assembled the pack using a bronze lock washer between the buss bar and the positive end. After the battery was assembled we put a 200 amp load across one of the 15 cell rows, testing showed a 1 millivolt drop on the side without the lock washer and a 10 mv drop on the side with the lock washer. We have the battery half disassembed and reassembled now without lockwashers and will finish this week end. 

So now the current path will be through the surface contact of each end of the battery and through the stainless 6mm by 12 mm set screws we used for connections. 

We hope to see 1/2 mv or less drop on both sides of the buss bar with a 200 amp load an a single row. 

Looking at the results you guys are getting and thinking about the battery construction I'm worried that Headway batteries are not going to be as good as we thought. I'm wondering just what those end pieces are made of.

I've noticed, through the years, that Chinese culture seems to equate a lot of "things that look the same are the same". A lot of the looks alike so it is alike.

I've seen this in the quality of some of their products, remember some of their early export wrenches that looked just like a Snap On, but bent like putty. So the idea that tin plated steel looks like tinned copper, so they must work the same comes out. (Plus it's a lot cheaper so there is a lot more profit). They eventually learn (especially when they need to use the stuff themselves) and the products improve, but a lot of people get hurt in the intrim.

I'm seeing batteries with the negitive end turning in the case. We only had 7 do this on the initial assembly of the pack but have at least 20 have turned so far on disassembly of 3 of the 5 rows. A really scarry part is we found two leakers while disassembleing the pack. It appeard that if the end turns in a counter clockway direction something may loosen and an internal plastic sealing disc starts leaking electrolite. 

It appears that the negitive connection terminal end is supposed to be retained to the case by a ring of epoxy. We've seen the ring either popping out of the battery entirely or not bonding to the case or the terminal block.

We've run a few tests on several batteries from the initial assembly that we repaired with super glue or a new application of epoxy. On the first couple of loads they seem to hold up, they are being recharged and we will test them again next weekend.

Has anyone tried a magnet on the end connectors of the batteries? I know a few of you have disassembled batteries. Can you look and determine what the metal is. The positive end appears to be plated steel, anyone have an idea what the plating is? (I figure it's steel because some of the batteries I received had rust pits under the plating). Is the plating conductive or just decoration.

Right now we are using stainless set screws as connectors because stainless is what Headway uses. Can anyone think of a good way to test to see if a substantial part of the load goes through the screw and we need to use copper.

Jim


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## DavidDymaxion (Dec 1, 2008)

Jimdear2, thanks for the real life data points.

Were they installed with the vents down? I was just thinking maybe a little electrolyte leak would cause loosening? Do you think one should grab the end piece to tighten, to prevent torque on the main part of the battery? Have these batteries ever seen extreme currents?

I'm the proud owner of 3 Headway batteries, still need to test them.


Jimdear2 said:


> ... I'm seeing batteries with the negitive end turning in the case. We only had 7 do this on the initial assembly of the pack but have at least 20 have turned so far on disassembly of 3 of the 5 rows. A really scarry part is we found two leakers while disassembleing the pack. It appeard that if the end turns in a counter clockway direction something may loosen and an internal plastic sealing disc starts leaking electrolite.
> 
> It appears that the negitive connection terminal end is supposed to be retained to the case by a ring of epoxy. We've seen the ring either popping out of the battery entirely or not bonding to the case or the terminal block. ...


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## Jimdear2 (Oct 12, 2008)

DavidDymaxion said:


> Jimdear2, thanks for the real life data points.


David, your welcome, we aim to please.



DavidDymaxion said:


> Were they installed with the vents down? I was just thinking maybe a little electrolyte leak would cause loosening?


The batteries were installed in a horizontal position. The lekage did not occure until we disassembled the pak and the batteries were turned in a counterclockwise direction.



DavidDymaxion said:


> Do you think one should grab the end piece to tighten, to prevent torque on the main part of the battery?


A good idea, except there is no place to grab. Look at your 3 batteries, imagine a flat bar between two batteries, you will see there is only about 1/16 of an inch of the actual negitive end exposed above the epoxy seal to grab onto.

Each battery could be modified by grinding 2 flats so a thin (0.060 to 0.080) sheet metal wrench could be slipped in between the buss bar and battery. 



DavidDymaxion said:


> Have these batteries ever seen extreme currents?


No



DavidDymaxion said:


> I'm the proud owner of 3 Headway batteries, still need to test them.


The initial load testing we subjected our batteries to seemed to go well, that was not worrisome until we started to wonder about these batteries with loose ends.

How is the negitive end attached to the plates? What happens to that connection when the battery end turns?

Who was it that did disassmbly of a Headway, was it Jack Bauer? I'll go search his thread to see if he has a video of it.

Jim


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## DavidDymaxion (Dec 1, 2008)

Many thanks, now I have a clearer vision of the problems. I don't remember seeing a recommended torque for the terminals.


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## Headway Headquarters (Nov 25, 2010)

DavidDymaxion said:


> Many thanks, now I have a clearer vision of the problems. I don't remember seeing a recommended torque for the terminals.


The torque for the terminals is 7Nm.

After reading this thread, I need to go check a lot of the terminal connections from Headway, I was informed that they were plated copper


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## Jimdear2 (Oct 12, 2008)

Headway Headquarters said:


> The torque for the terminals is 7Nm.
> 
> After reading this thread, I need to go check a lot of the terminal connections from Headway, I was informed that they were plated copper


Jim,

Thanks for the spec. 

A problem though, 7Nm = 61 inch lbs. We we twisting some cells loose with around 10 inch lbs. Others, when I bottomed the set screw in the negitive end felt as though they would hold that though.

When you say you are checking terminal connections, that is the link plates?

Just curious . . . what are the positive and negitive ends of the battery supposed to be made of? As I stated earlier I have cells that the the ends look to be rust pitted steel that has been plated with something. I'll check this weekend to see if it really is ferrous.

Jim


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## Headway Headquarters (Nov 25, 2010)

Jimdear2 said:


> Jim,
> 
> Thanks for the spec.
> 
> ...


No worries, you are welcome!

7Nm is what I was given about a month ago when I was double checking all the specs to make sure I had the right information. I will check with Headway tonight, well my night their morning, to find out some additional information about the torque problems at only 10 in/lbs 

Yes, the 2 hole and 4 hole bus bars/connection plates from Headway....sorry, should have have used correct terminology.

I will also find out what I can about the material used for the ends.


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## Headway Headquarters (Nov 25, 2010)

Jim, 

Here is an excerpt of my conversation with Michelle from Headway tonight:

A problem with the torque of 7Nm/61 inch lbs. we were twisting some cells loose with around 10 inch lbs. Is this a common problem with the cells? The epoxy end of the cathode end was cracking loose on some of them

What material is used to make the bus bars/connection plates?

_Michelle Lu (9:59:07 PM): 
for the first question, can you check the picture i send to you now?_ (See attached at bottom of post)
_2. bus bars is Nickle plated copper_

What metal are the positive and negative ends made from? I have cells that the the ends look to be rust pitted steel that has been plated with something.

_Michelle Lu (10:05:30 PM): 
3.the positive and negative ends made from nickle plated ferrous_

Have you or your engineer ever heard about or experienced the negative end epoxy cracking and turning while using less than 7Nm torque?

_Michelle Lu (10:12:51 PM): 
yes, before one of our customer from taiwan, had the weeping problem, so our engineer did a lot testing and find out that the torque must be less than 7NM_


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## major (Apr 4, 2008)

Headway Headquarters said:


> Here is an excerpt of my conversation with Michelle from Headway tonight:
> 
> What material is used to make the bus bars/connection plates?
> 
> ...


So he says Shirely doesn't know steel when he cuts in to it?  



jackbauer said:


> Perhaps its just my ignorance but do people know that the cell links supplied by headway are steel?. Not copper or ali. Thankfully i used custom copper plates and bars on my pack but i went today to make up a little 4 cell pack for a project and discovered the plates are magnetic quite by accident. I cut one in two and its steel!


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## frodus (Apr 12, 2008)

My bussbars apear to be nickel plated copper. I've cut into it and they're all copper colored metal, with a nickel colored coating, but I don't have any metallurgical degree or equip to test. 

Nickel is magnetic BTW, so is Iron and Cobalt. So the magnet test doesn't mean anything. Cut into them. Mine are all copper.


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## Huub3 (Aug 16, 2009)

All,

maybe a stupid idea, but given that these batteries were ordered over a certain period, and from different suppliers (even to different continents), what about the thought that not all of them come out of the same factory.

I mean, perhaps some of us have "chinese copies" of the original Headway in their possession? Sounds strange, but is it impossible? This is all assuming that there is such thing as "original Headway".

Regards,


Huub


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## jackbauer (Jan 12, 2008)

I'll have a better look tomorrow. I may well be wrong but the two i cut up were not copper inside.


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## crashnfool (Sep 26, 2009)

We just tested two different bussbars..One is an older batch ..the other is from our latest shipment..

The older ones are nickel-plated steel..

the new ones are nickel-plated copper..

Easy way to tell which is which is to use a magnet..

Jim are you sure you didn't torque yours to ten FT/lbs?
Because we've never had any spin at ten inch/lbs.

Fred Dupre 
Current EV Tech, LLC.
http://www.currentevtech.com
360-628-8471


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## major (Apr 4, 2008)

crashnfool said:


> We just tested two different bussbars..One is an older batch ..the other is from our latest shipment..
> 
> The older ones are nickel-plated steel..
> 
> ...


Pretty much a mute point by now because the Headway head told us the cells themselves use ferrous on both ends as the conductive material or in other words, the terminals. 


Headway Headquarters said:


> What metal are the positive and negative ends made from? I have cells that the the ends look to be rust pitted steel that has been plated with something.
> 
> _Michelle Lu (10:05:30 PM): _
> _3.the positive and negative ends made from nickle plated ferrous_


That sucks


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## Jimdear2 (Oct 12, 2008)

I have done a bit of looking around and found that Nickel is only slightly better then iron as a conductor. Way more resistive then copper. Why in the world would they Nickel plate a Copper buss bar?

Same question applies to the end caps of the batteries. Why use Nickel plating? Silver, Copper, Gold and even Zink are better conductors then Nickel.

This is "Shirely" a poor choice and seems cosmetic rather then good engineering. Especially on the 38120P batteries that are supossed to discharge up to 25C.

Could it be (gasp, a pragmatic decision) that Nickel can be plated over a lot of different materials (whatever's on hand) and will look consistent?

I'm glad enough of us have gotten our hands on these batteries and have had a chance to see some of the "little things" and had a chance to post the information.

*to Jim at Headway Headquarters*, 

Thanks for taking the time to look into this for a non (so far) customer. Next time you contact Headway, ask them why use Nickel when plain copper and copper plated steel would be much more logical.

A specal thanks for finding that tightening specification:

*Tighten to 5 Nm (44 inch lbs.) and do not exceed 7Nm (62 inch lbs). *

That should be posted and on all of the reseller sites and Headway should include the document they sent you in each box.

Jim


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## major (Apr 4, 2008)

Jimdear2 said:


> I have done a bit of looking around and found that Nickel is only slightly better then iron as a conductor. Way more resistive then copper. Why in the world would they Nickel plate a Copper buss bar?


Jim,

Surface plating is only to resist corrosion, not to be the primary conductor. It is so thin it really does not play into the conductivity of the bus bar at all. It does play into the contact surface resistance. But even a relatively poor conductor like nickel is way, way better than a layer of non conducting oxide because it is sooooo thin. Silver plated copper is my favorite, followed by tin plated copper. But those have some issues, like cost, so nickel plated copper is pretty much standard practice. Or even nickel plated aluminum. 

You'll get by for a while with high current steel regardless of the plating. You will suffer higher resistance from the beginning, but that can be compensated by increased cross sectional area. But time will tell. It will fail eventually. I guess all things do, but in this case, failure will pop up sooner than you think. And I don't know about now-a-days, but they used to use copper plated steel terminals on automotive cranking motors and solenoids. But those were made as cheaply as possible and expected to fail (to support the aftermarket auto parts industry).

Rust never sleeps,

major


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## Jimdear2 (Oct 12, 2008)

crashnfool said:


> Jim are you sure you didn't torque yours to ten FT/lbs?
> Because we've never had any spin at ten inch/lbs.
> 
> Fred Dupre
> ...


Fred,

I'm reasonably certain I used the inch pound scale on the wrench. I've been a tech for 45 years

I will say my wrench hasn't been calibrated in many years but I don't think it could be that far off. I'll get a spring scale and check. I stopped building engines about 20 years ago so the wrench has sat in the tool box.

We were using a bronz serrated lock washer during the initial build of the battery, I don't know if that could have cause false readings.

I do know that when disassembling the battery to remove the lock washers, overcoming the washer lock is for sure causing us to exceed that 7Nm limit. That must be the cause of the additional failures I mentioned.

It really doesn't matter if the problem was caused by us or is a bad batch from the OEM, discussing the problem and pointing fingers is really moot at this point. The damage has occured, this is a good warning to others, be careful. At least it happened to only a small number of batteries.

I hope that the tightening and don't exceed torque specification gets well circulated.

We will continue to reglue and epoxy the ones we have that are turning. We don't have a choice, I sure can't afford to replace them this year.

Be interesting to see how the cells hold up.

I will spot a number of thermal sensors throughout the battery and really keep an eye out on the parallel stack voltages. The two repaired cells we have checked seem to hold the load well.

You all have a good one.
Jim


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## Jimdear2 (Oct 12, 2008)

major said:


> Jim,
> 
> Surface plating is only to resist corrosion, not to be the primary conductor. It is so thin it really does not play into the conductivity of the bus bar at all. It does play into the contact surface resistance. But even a relatively poor conductor like nickel is way, way better than a layer of non conducting oxide because it is sooooo thin. Silver plated copper is my favorite, followed by tin plated copper. But those have some issues, like cost, so nickel plated copper is pretty much standard practice. Or even nickel plated aluminum.
> 
> ...


 
Major,

I guess you get what you pay for.

I think I would rather have plated aluminium ends or steel with a thick coat of copper. 

Thanks for the "lernin" 

I was taught, a long time ago, that current flow happened on the surface of a condutor, so I thought a good layer of a good conductor would be a big help.

Jim


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## major (Apr 4, 2008)

Jimdear2 said:


> I was taught, a long time ago, that current flow happened on the surface of a condutor, so I thought a good layer of a good conductor would be a big help.


Radio engineer tell you that  Yeah, true at higher frequencies, but down around zero Hertz where we live, the guts conduct


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## Headway Headquarters (Nov 25, 2010)

Jimdear2 said:


> *to Jim at Headway Headquarters*,
> 
> Thanks for taking the time to look into this for a non (so far) customer. Next time you contact Headway, ask them why use Nickel when plain copper and copper plated steel would be much more logical.
> 
> ...


You are welcome, and I agree.

Here was an excerpt from tonights conversation with Michelle at Headway:

I have a question...why did the engineers decide on nickel plated bus bars and not just plain copper or copper plated steel?

_Michelle Lu: (22:05:29): 
if just copper or steel, it is easy to be rust, so we have nickel plated copper and steel_

Although she said 'rust' for copper, I believe the intent was to explain that copper also corrodes, via patina, over time, albeit, a very long time in comparison to steel with rust. Although it is IMHO, nickel plating was most likely chosen for aesthetics for the soft shine it produces and it's ability to withstand corrosion depending on the thickness of the plating. 



crashnfool said:


> We just tested two different bussbars..One is an older batch ..the other is from our latest shipment..
> 
> The older ones are nickel-plated steel..
> 
> the new ones are nickel-plated copper..


Headway offers both nickel plated copper and nickel plated steel connection plates/bus bars, it just depends on how you order from them and if you know to order the copper in lieu of steel or just get lucky!


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