# Headway to hell



## jackbauer (Jan 12, 2008)

Remaining photos:


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## Jan (Oct 5, 2009)

Very entertaining.


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## Woodsmith (Jun 5, 2008)

Thanks for the information Jack, that should be useful to those who are also using, or considering, the same cells.

Have you contacted the manufacturers to see what their recomendations would be as to bolt length tollorances?
It would seem that it would be easy for someone to make themselves a explosive pack by accident and a faulty charger set up.

Will you be installing a bms now or still planning on running without?


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## jackbauer (Jan 12, 2008)

I've not contacted headway yet and suspect even if i do i won't get a response. They are not the most verbose people i've ever dealt with

Regards the bms my tests have shown that an overcharge will damage a cell , under extreme conditions cause a popped disc and some smoke but thats it. I will certainly MONITOR the cells but i'm not a great believer in shunt balancers or top balancing. 

I've looked at the minibms on offer here and its not a bad solution. Any cell exceeds the setpoint charger is disconnected. If a charger failed full on then a 1 amp shunt across each cell will just make a bad situation worse.


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## major (Apr 4, 2008)

Nice tests, Damien. I'll bet it smells like hell also  How do you dispose of the "tested" cells? I was told to soak them in salt water for a couple of weeks and throw into trash can.


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## jackbauer (Jan 12, 2008)

Yeh the cells have that sweet aroma! Lithium no.5 

We have a battery disposal bin where i work so they can go in there. Bet its the first time they will have seen a lithium!


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## tomofreno (Mar 3, 2009)

> I've looked at the minibms on offer here and its not a bad solution. Any cell exceeds the setpoint charger is disconnected. If a charger failed full on then a 1 amp shunt across each cell will just make a bad situation worse.


 Many use the minibms to turn off an AC relay on the power input to the charger on an HCV event. I think Dimitri may even sell a relay for this. You can also purchase the minibms without the shunts.


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## MN Driver (Sep 29, 2009)

tomofreno said:


> Many use the minibms to turn off an AC relay on the power input to the charger on an HCV event. I think Dimitri may even sell a relay for this. You can also purchase the minibms without the shunts.


Is he still selling them without the shunts? The website seems to have removed many of the options previously available and the only choice now, at least provided through his storefront site is HVC voltage of 3.6v or 3.8v. No option for one without a shunt, if I remember right I think there was a part that said if you don't want a shunt to remove it. I know back when this was actively discussed in the development thread still, there was talk of a DIY option but I'm not entirely sure if that is still an option.


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## MN Driver (Sep 29, 2009)

Good to know about the length of bolt could disable the safety vent so that such a failure could be avoided.

Here is some more Headway torture from an ES forum member(mostly e-bike guys)
http://www.youtube.com/watch?v=wkJM8MZkFKU


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## Bottomfeeder (Jun 13, 2008)

MN Driver said:


> Is he still selling them without the shunts? The website seems to have removed many of the options previously available and the only choice now, at least provided through his storefront site is HVC voltage of 3.6v or 3.8v. No option for one without a shunt, if I remember right I think there was a part that said if you don't want a shunt to remove it. I know back when this was actively discussed in the development thread still, there was talk of a DIY option but I'm not entirely sure if that is still an option.


You can just clip off the shunt resistors.


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## dimitri (May 16, 2008)

MN Driver said:


> Is he still selling them without the shunts? The website seems to have removed many of the options previously available and the only choice now, at least provided through his storefront site is HVC voltage of 3.6v or 3.8v. No option for one without a shunt, if I remember right I think there was a part that said if you don't want a shunt to remove it. I know back when this was actively discussed in the development thread still, there was talk of a DIY option but I'm not entirely sure if that is still an option.


I hate to hijack the thread, apologies to OP in advance.

I no longer offer shuntless to simplify ordering and production process, but I stated in product description that clipping off ceramic resistors effectively kills shunting feature, while leaving red LED function, which can be useful to observe end of charge. AC relay is very effective to prevent rogue charger behavior.

Nice Headway testing, BTW, those poor bastards didn't stand a chance at 24V per cell


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## ahambone (Jan 13, 2009)

Thanks for the destruction tests - very entertaining! 

I had the same explosive results with headway's 18650 cells and a soldering iron.

I've been running a (5p) x 24s headway 38120 pack (10AHr) for a year now with several hundred EV miles on them with no problem. My recommendation: use a high voltage cutoff shunting BMS (mine is set to 3.69v) which prevents over charging of cells. I'm in the process of expanding to (8p) x 24s and will keep the same BMS in place. It's worked well for a year, I'll keep it as long as I can. I really think flying "naked" with no HVC/LVC on these cells is a bad idea. If you read voltages by hand on your cells then ok, but who as the time to do that?!

Thanks again for the forensics on HW cell failure.

Cheers,
--Adam


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## jackbauer (Jan 12, 2008)

Latest tests on some 8ah p cell samples from "ecitypower". Less cell and more mortar tube. Tested 2 just to be sure. More to come ........


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## jehan12413 (Feb 4, 2010)

Jack,
Do you have any idea how much space is required between the bolt end and burst disc to allow it to operate normally? I will be using slightly longer bolts on mine but still have a small gap. Thanks


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## lorraine (Feb 11, 2009)

Dear Jack,
Thanks for your test.
It looks like a man wants to test a parachute, but if someone lock the parachate-opening deployment parachute, if he jumped down from the airplane with this parachuat, what will happen then...? 
OK , it's just for an instance here.
But the same reason, you had used a long bolts, and the bolts had locked the burst disc. 
We had done this kind of destructive test already!
The length between the bolt end and burst disc can not exceed 6mm!!

E-mail: [email protected]
MSN: [email protected]
Skype: lorainy0


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## jackbauer (Jan 12, 2008)

Thanks Lorraine. I did the long bolt test just to prove the point. Can you please explain the differences in the codes on the cells ie JC23 etc and the revised design of the positive endcap?


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## lorraine (Feb 11, 2009)

jackbauer said:


> Thanks Lorraine. I did the long bolt test just to prove the point. Can you please explain the differences in the codes on the cells ie JC23 etc and the revised design of the positive endcap?


Yes, we had revised the positive endcap, there were 4 holes at the side of the old endcap, it's a little hard to do the holes on the side, even easy to cause out of shape. so we have the holes on the top of the endcap now, there are 8 smaller holes now.


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## Headway Headquarters (Nov 25, 2010)

jehan12413 said:


> Jack,
> Do you have any idea how much space is required between the bolt end and burst disc to allow it to operate normally? I will be using slightly longer bolts on mine but still have a small gap. Thanks


jehan,

Bolt/screw head, spring washer, flat washer, connector plate, then < 6mm of thread into the anode end of the cell. If more than 6mm it will prevent the anti explosion valve from functioning properly.

So in short, the length of the bolt or all-thread should not extend more than 6mm into the anode end of the cell.

Hope this helps!


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## jumpjack (Sep 9, 2012)

Woodsmith said:


> Have you contacted the manufacturers to see what their recomendations would be as to bolt length tollorances??


This is an old thread, anyway, just for the records...









Please note the "<=6 mm" on top right corner of picture.


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## ahambone (Jan 13, 2009)

2cm or 2.5 cm M6 setscrews worked fine on my pack. They would sit flush at full depth on the negative (pin) sides of the cell and play much more freely on the positive (can) side of a cell.


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## PStechPaul (May 1, 2012)

Good information to know about lithium batteries and their safety features, and what can happen when all "L" breaks loose!


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## jackbauer (Jan 12, 2008)

Can't believe it's been 5 years ...


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