Alan B
100 GW
dak664 said:
I think he meant the "best" bang for the buck in terms of the "least" spark.
Headway battery pack FIRE! <lot pics>
- Thread starter chroot
- Start date
I think he meant the "best" bang for the buck in terms of the "least" spark.
I studied and conclusion wiring shorted fault cause the fire. Because the main wiring (pos/neg were zipped and secure together) might rubbed to the wall of the pannier bag and cause shorted build up heat then finally start fire from 1st cell.
I can be wrong because everything are completely destroyed and heavy melted hardly determined who is fault either wiring got shorted or something else.
The cells *NEVER* touch each other at all because of the metal sheet (dunno what it called) series between 1st-2nd cell 2nd-3rd etc really very tightly and secure. There was never loose between cells. I tested unscrew the bolt out the cell and it incident was very secure.
I can be wrong because everything are completely destroyed and heavy melted hardly determined who is fault either wiring got shorted or something else.
The cells *NEVER* touch each other at all because of the metal sheet (dunno what it called) series between 1st-2nd cell 2nd-3rd etc really very tightly and secure. There was never loose between cells. I tested unscrew the bolt out the cell and it incident was very secure.
dnmun
1 PW
you had a picture of a section of the charging wire. in one picture where it is over the BMS cover, i thought i could see where multiple strands had opened and there was a ball of metal sticking to one of the strands. the wire was totally bare and had no insulation on it from where it looped over the BMS and ran down through that wire tie and i assumed it tied into the positive terminal of the battery on the main cable below the fuse. is there some way that the charging plug chrome jack sleeve could have contacted one of the terminal of the battery, or even somehow come into contact with the BMS where the shunt wire connects.
can you check continuity between the red charging lead itself and the chrome sleeve to see if there is a possibility it coulda shorted out by a loose positive wire inside the jack? if it contacted the BMS. that is if the chrome jack had contacted the BMS pcb or solder pad where the black wire from the controller attaches.
if the red wire inside the jack was loose and the wire made contact with the sleeve of the jack then it would be hot and the sleeve could then short out directly to the battery through the shunt. if the current was not cut off by the output fets then it would continue to carry current, just below the shunt rating of the pack, maybe a single or two strands loose in the jack. BOL.
can you check continuity between the red charging lead itself and the chrome sleeve to see if there is a possibility it coulda shorted out by a loose positive wire inside the jack? if it contacted the BMS. that is if the chrome jack had contacted the BMS pcb or solder pad where the black wire from the controller attaches.
if the red wire inside the jack was loose and the wire made contact with the sleeve of the jack then it would be hot and the sleeve could then short out directly to the battery through the shunt. if the current was not cut off by the output fets then it would continue to carry current, just below the shunt rating of the pack, maybe a single or two strands loose in the jack. BOL.
@dnmun - The charging wire was on other side of the BMS and Main lead output only ONE positive coming from BMS and negative main lead coming from 16th cell (last cell). The charging connector wire connected to BMS.
I gladly take more pictures closely as anybody request to give it better determine who is fault. Here more pictures.
View attachment 2
I gladly take more pictures closely as anybody request to give it better determine who is fault. Here more pictures.
View attachment 2
bigmoose
1 MW
Alan B said:
English is so tough sometimes!
Good that the clarification is out there. I agree, fusing at the midspan of the pack is the most effective place for the fuse.
Alan B
100 GW
Thanks for sharing this thread with us chroot. Sorry for your loss.
Excellent to learn what we can.
Now, I need to order some more fuseholders. My first build has a fuse, but the later ones are less "protected".
All those who need to improve their wiring go directly to <your favorite vendor> and order some parts...
I think I will get some ANL fuses and holders. There are also 80 volt Maxifuses, but note that most are NOT that high.
Also some of the AGC 30 amp fuses are less than 2 milliohms, and waterproof holders with low resistance are available. Two of those in parallel on 12 or 10 gauge would be pretty good.
Excellent to learn what we can.
Now, I need to order some more fuseholders. My first build has a fuse, but the later ones are less "protected".
All those who need to improve their wiring go directly to <your favorite vendor> and order some parts...
I think I will get some ANL fuses and holders. There are also 80 volt Maxifuses, but note that most are NOT that high.
Also some of the AGC 30 amp fuses are less than 2 milliohms, and waterproof holders with low resistance are available. Two of those in parallel on 12 or 10 gauge would be pretty good.
Lessss
1 MW
So headway cells with plastic holders but inline fuses to connect all the batteries instead of the metal connecors. Hmm might make looking for a popped fuse like a needle in a haystack but definately alot of protection. Also alot of electricl loss?
Lyen
10 kW
chroot said:
Hi Chroot,
You are very welcome Chroot. Let me know if you need help or the next time you come to the city (San Francisco).
Judging from the blade fuse color, it would be 120A if it is purple color, or 100A for the violet color. See below:
Blade fuses use a common coloring scheme for the low-profile mini / mini / regular size fuses, and a partial color similarity with the maxi size fuses. The following table shows the commonly available fuses for each size group.
Regards,
Lyen
Jeremy Harris
100 MW
deVries said:
Might create more problems than it solves, adding lots of fuses like that.
Let's say that you choose to fuse at 50 A and you use good quality "maxi" style automotive blade fuses, installed with zero connection loss (in practice you'll get some resistance from the blade connections and wiring terminations, adding to the losses). This will have a resistance of about 1.2 mohm at 20 deg C, which will increase as the fuse warms up. Let's say you have a 16 S pack and decide to use 16 fuses, one between each cell and one on the output. You've now got 19.2 mohms of fuse resistance inside the pack, plus the internal resistance of the cells. The fuses will cause a loss of at least 17 watts at 30 A when cold, which will increase as the fuses heat up (which they will pretty quickly). At 40 A when cold the fuses will lose over 30 watts.
In many cases this loss may be greater than the losses from cell internal resistance, but either way the battery pack is now going to run warmer than without the fuses, and heat is as much the enemy as vibration and chafing.
I'd suggest fixing the cause of vibration and chafing related failure, securing and properly insulating wires, cells and terminations, making sure the pack is properly protected from mechanical damage and using the right sort of insulation materials, not materials that creep and distort under mechanical stress and heat.
deVries
100 kW
Jeremy Harris said:
What about the type of fuse that is "narrowed" & part of the actual "terminal connections" too, so you're not adding-in a replaceable 2-contact fuse with additional resistance connections?
Otherwise, your point proves there are better trade-offs in protecting the battery pack rather than using typical fuses for each cell, which, if used on each cell, will increase resistance & heat making the battery much less efficient.
Jeremy Harris
100 MW
deVries said:
Unfortunately, a fuse, even a fusible link, relies on having a higher resistance than the wires and terminations in order to generate the heat needed to make it blow. If the fuse has a resistance comparable to the wires then it won't heat up enough to blow.
deVries
100 kW
Jeremy Harris said:
Wouldn't there be a "happy medium" for protecting against a runaway reversal & high amp short that is still relatively low resistance? With these big Ah cells 16Ah or 20Ah or more I guess I get a bit "paranoid" about the heat-fire damage just one cell can do to create that cascade & total destruction scenario spreading to all cells going up in smoke or worse. :?
boppinbob
1 kW
Sorry bout the fire. Wow. That battery chemistry is not the usual suspect if you know what I mean, and I know you do.
etriker
100 kW
Thos thread has me thinking fuses. Lots o fuses.
Dewalt A123 pack. Notice the connector made smaller.
http://i180.photobucket.com/albums/x218/biodiesel_2007/SUNP0032.jpg
Packs can take a beating on a ride. I know mine do sometimes.
Glad the kids caught the fire !
Dewalt A123 pack. Notice the connector made smaller.
http://i180.photobucket.com/albums/x218/biodiesel_2007/SUNP0032.jpg
Packs can take a beating on a ride. I know mine do sometimes.
Glad the kids caught the fire !
Jeremy Harris
100 MW
deVries said:
Yes, but that's how fuses are designed. They have the lowest possible thermal mass at the point where the resistance is greatest and then enhance the local heating effect by trying to keep that bit out of draughts and airflow, whilst keeping it away from any material that might get damaged by the heat.
Fusible links are cheap and easy for manufacturers to build in (cheaper than adding a fuse and fuse holder) but less effective in some ways because they can dissipate heat away from the area that you actually want to get up to the melting point of the metal used. They also need to be kept clear of anything that might melt or catch fire.
The bottom line is that a fuse, or fusible link, needs to get the high resistance bit to the metal's melting point at the rated fusing current, so will inevitably produce some heat at lower current. There's no way around the fact that fuses generate heat and add resistance to the circuit, unfortunately.
Jeremy Harris
100 MW
etriker said:Thos thread has me thinking fuses. Lots o fuses.
Dewalt A123 pack. Notice the connector made smaller.
http://i180.photobucket.com/albums/x218/biodiesel_2007/SUNP0032.jpg
Packs can take a beating on a ride. I know mine do sometimes.
Glad the kids caught the fire !
Fusible links, like that DeWalt one, are just a cheap bodge to avoid them having to find the space (and pay the money) to fit a proper fuse. They work, but I'm not convinced they are good practice, for the reason given above.
Similarly, lots of fuses may create more problems than it fixes, as I mentioned in a previous post.
Building packs to resist vibration and chafing and to tolerate the impacts they're likely to get on a bike is the best measure, with just a single fuse, maybe wired in to the centre of the pack but mounted externally.
etriker
100 kW
Jeremy Harris said:etriker said:Thos thread has me thinking fuses. Lots o fuses.
Dewalt A123 pack. Notice the connector made smaller.
http://i180.photobucket.com/albums/x218/biodiesel_2007/SUNP0032.jpg
Packs can take a beating on a ride. I know mine do sometimes.
Glad the kids caught the fire !
Fusible links, like that DeWalt one, are just a cheap bodge to avoid them having to find the space (and pay the money) to fit a proper fuse. They work, but I'm not convinced they are good practice, for the reason given above.
Similarly, lots of fuses may create more problems than it fixes, as I mentioned in a previous post.
Building packs to resist vibration and chafing and to tolerate the impacts they're likely to get on a bike is the best measure, with just a single fuse, maybe wired in to the centre of the pack but mounted externally.
I like to take apart battery packs and see how others build them.
There is nothing cheap in those packs and are considered some of the best packs on the planet.
6 year old Dewalt packs that don't work still go for $30 and up on eBay.
I agree about building packs to resist vibration and chafing and to tolerate the impacts.
That is one reason I ride a trike. The extra lbs I added protecting the batteries made the whole battery setup heavy.
Dewalt dc9360 fire. http://www.google.com/search?q=dewalt+battery+pack+explodes&sourceid=ie7&rls=com.microsoft:en-us:IE-SearchBox&ie=&oe=#hl=en&gs_nf=1&gs_mss=dewalt%20d9360%20%20fire&pq=dewalt%209360%20%20fire&cp=9&gs_id=4d&xhr=t&q=dewalt+dc9360++fire&pf=p&rls=com.microsoft:en-us%3AIE-SearchBox&sclient=psy-ab&oq=dewalt+dc9360++fire&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=4600699899139f67&biw=1016&bih=563
dogman dan
1 PW
I'm still betting on a wire chafing on something while the battery bounced around in that bag. Then it shorted. Most likely culprit is the sharp edged bms rubbing on that wire that had all the insulation removed. In my book, that's likely to be the wire that took the dead short.
Fuses are good, but not as good as securing the battery, and putting some more chafe resistant cover on wires where they get close to something that can rub.
Tossed in a bag dont cut it.
Fuses are good, but not as good as securing the battery, and putting some more chafe resistant cover on wires where they get close to something that can rub.
Tossed in a bag dont cut it.
etriker
100 kW
dogman said:
I think so too.
kfong
100 kW
The type of wiring that can take abrasion is also a factor to concider. I know a lot of people like using the silicone wire sold by hobby king. It's good wire for heat resistance but it's lousy for abrasion resistance. I had a short in my Topeak bag right by the area where the wire exits the bag. I no longer use such wire in areas were wear can be affected. Automotive quality wires are best for such applications. Silicone sheathing can be easily torn by a sharp fingernail and wears down fast with abrasives, bad practice to use them in this application.
etriker
100 kW
kfong said:
Considering the amps that some RC lipo can deliver and the wire size they use I think those wires on the rc lipo packs are a cheap bodge to avoid them having to find the space (and pay the money) to fit a proper fuse. !
Hobby King RC lipo wiring is fuses.
Jeremy Harris
100 MW
etriker said:
I wasn't implying that the packs were cheap, just that a fusible link made by punching a narrow stip out of a connection tab is cheap, it's a lot, lot cheaper for the manufacturer to do this than add a separate fuse, and it takes up no extra space in the pack.
The fact remains that it's not as good as a fuse, as the current at which it will blow will be dependent on the heat that soaks out of that strip into the surrounding material. Also, when it blows it needs to be clear from anything that might catch fire, as that strip is going to be glowing white hot. I'm sure DeWalt sorted this in their design of their packs, but we don't have their R&D budget when building one-off packs and so cannot be at all sure that such a method would either work reliably or not be the cause of a fire. Imagine having a bit of flammable tape over that fusible link, or worse still, maybe some foam that would insulate it and let it get hot. DeWalt allow a mm or two of free space next to the fusible link, and ensure that the case is made of a either a thermoset or high melting point plastic.
etriker
100 kW
Jeremy Harris said:
Been searching and can not find any info on a Dewalt DC9360 burning up. If one did I can not find it.
There must be thousands out there in use every day with cells made in 2006.
Surely a design worth study.
Jeremy Harris
100 MW
etriker said:
Sure, but we're talking about folk building packs out of what they have, and then trying to calibrate a fusible link that's encased in whatever housing they've come up with to see if it blows at a sensible current and doesn't set fire to anything.
DeWalt will have done this with their packs, they will have spent hundreds of hours doing product design testing, simulations of heat build up in the packs, testing for a multitude of failure modes and will have fixed the design once they were confident it was safe. DeWalt have the advantage of knowing that every pack they make is the same, uses the same clearance around the fusible link, the same materials etc, so their link will behave as they have designed it when, and only when, it's inside one of their packs. Take that link outside one of their packs and it will behave differently, wrap it up in something better insulated than a DeWalt case and it'll get hotter and blow at a lower current. Leave it out in open air and it'll run cooler, and blow at a higher current.
A fuse has all this testing done for us, unlike a fusible link that is very installation and environment sensitive.
