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18650 Cluster grenades
#11
(01-11-2017, 09:02 PM)DIY TESLA POWER WALL Wrote: "there is no way it's going to dump enough current in to one cell to cause it to blow up"

Says who?
This is exactly why the cells kept failing in Mikes DIY video.
Unless you have current monitoring of every cell, don't make those assumptions because current is dictated by ohms law.
Please link to his videos so I can check them out, I haven't seen them yet and am not sure who you're referencing. Says the fuses we're using that break around 5A. Also, you would have a greater chance of winning the lottery than having 19A of 20A charge current going to 1 cell in a 80 cell pack.

(01-11-2017, 09:02 PM)DIY TESLA POWER WALL Wrote: "nothing happened"
Another assumption. Watch x-ray footage of a cell getting hot. Just because nothing is outwardly obvious does not mean damage has not been done
Duh? My point was it did not vent or otherwise cause damage. It reacted in a safe way like it was supposed to - as do most cells.
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#12
You need to understand.
Thermal damage is progressive. A healthy cell does not explode unless it's an abnormal amount of quick abuse.
All these laptop fires occur because a small amount of damage is done each time. Eventually Lithium builds up on the separator and causes a short circuit.
If you have cells that you have witnessed get hot, they have a much higher probability of going into thermal runaway. Since you don't know the history of each cell, you have no idea how much Lithium has built up and how easily they might short internally
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#13
(01-11-2017, 09:14 PM)DIY TESLA POWER WALL Wrote: All these laptop fires occur because a small amount of damage is done each time.

So then you're saying the protection circuits built in to each battery, that you were saying we all throw out, doesn't actually do what it's supposed to in regards to preventing the fire? Interesting.

Also, you neglected to link to the videos I asked about.
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#14
Dear DIY TESLA POWERWALL: 

Yes, all of your points are valid, yes all of your warnings are understood, yes we know this is risky, yes we know of the dangers, yes WE KNOW that many think of our creations as time bombs. But guess what...

We're gonna do it anyway. 

Listen, there are plenty of people out there including me building DIY battery packs from these salvaged cells. The truth is that this sort of thing is just going to happen and there is nothing you can do to stop it. Sort of like how people that can't afford children have sex and have children anyway, or how people still smoke knowing very well how bad it is for them, it is just going to happen.

This forum gives us a place to collaborate. This forum gives us a chance to share our methods. This forum gives us a place for all powerwall builders to come together and share our safety tips. Without this forum, everyone would be doing something different and people wouldn't have a chance to learn. Some people don't even know li-ion cells need to be balanced of that fusing is a necessity, and this forum gives them a place to learn about these techniques and integrate them into their own packs.

Without this forum, our packs would be even more unsafe. 


So yes, we have heard your warnings a million times from others and we simply do not care. It is our business and our risk alone if we blow up our houses, not yours. It is our decision and our decision alone to build these extremely cheap but also dangerous battery packs. If our house explodes or many of the other terrible things happen your videos show, that is our responsibility and our responsibility only.

Oh and by the way, you think your lifepo4 cells are safe? Here is a video that would contradict that:
 https://www.youtube.com/watch?v=52h8IK0IdqI&t=453s

The truth is every single battery chemistry is dangerous to some degree, but we are willing to accept the danger of lithium-ion. Hell, even lead acid batteries can explode given enough abuse:
https://www.youtube.com/watch?v=d_TnsHu2u4c

NIMH battery fire:
https://www.youtube.com/watch?v=NV_CBLxIczc

NICD batteries can burn too if dead shorted:
https://www.youtube.com/watch?v=CiUGgh_fuTk

Every battery chemistry CAN be dangerous! Yes, li-ion batteries are more likely to catch fire than others, but that doesn't mean that other battery types are totally safe either. Your warnings are ultimately falling on deaf ears. We know all of this and WE DON'T CARE! Because we're gonna do it anyway no matter what you say. And of anything bad happens, it is our responsibility only, and nobody else's. If our powerwall's go up in flames, fine you warned us. But it is not your right to be our nanny, and tell us what we can and can't do. We are all adults here, and we take responsibility for our actions, no matter what those actions shall be.
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#15
"So then you're saying the protection circuits built in to each battery, that you were saying we all throw out, doesn't actually do what it's supposed to in regards to preventing the fire? Interesting."

Correct. If you actually read what I said, the protection circuit prevents over charging, over discharging and ensures balancing. It does not have thermal sensors to detect thermal runaway. Your little potshot just backfired.

CUD, I don't believe that. It's obvious that 90% of people building these things have never heard of thermal runaway, let alone how and why it occurs. 95% of people were unaware of short circuit current issues until I brought it up. The fact is, these things simply are not mentioned in the videos. Therefore, noobs are getting only the positive side of the story. Everyone, assuming they have a conscience, has a responsibility to ensure that people are not harmed as a result of following advice in a video.
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#16
(01-11-2017, 11:37 PM)DIY TESLA POWER WALL Wrote: "So then you're saying the protection circuits built in to each battery, that you were saying we all throw out, doesn't actually do what it's supposed to in regards to preventing the fire? Interesting."

Correct. If you actually read what I said, the protection circuit prevents over charging, over discharging and ensures balancing. It does not have thermal sensors to detect thermal runaway. Your little potshot just backfired.

CUD, I don't believe that. It's obvious that 90% of people building these things have never heard of thermal runaway, let alone how and why it occurs. 95% of people were unaware of short circuit current issues until I brought it up. The fact is, these things simply are not mentioned in the videos. Therefore, noobs are getting only the positive side of the story. Everyone, assuming they have a conscience, has a responsibility to ensure that people are not harmed as a result of following advice in a video.

"If you actually read what I said" twice now, this is the third time, please link to the videos by "Mike" that you mentioned above.
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#17
I don't take orders from rude people, in fact the more orders they bark at me the less successful they are in getting what they want. Funny how that works eh
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#18
(01-11-2017, 11:51 PM)DIY TESLA POWER WALL Wrote: I don't take orders from rude people, in fact the more orders they bark at me the less successful they are in getting what they want. Funny how that works eh

I asked nicely. I said "Please link to his videos so I can check them out". That's not rude.
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#19
(01-11-2017, 09:02 PM)DIY TESLA POWER WALL Wrote: Another assumption. Watch x-ray footage of a cell getting hot.

Wow dude, you should read what you write. Who is testing with a LINAC ?  Just show me someone who is heating up a battery under one of these to show thermal stress.



(01-11-2017, 09:02 PM)DIY TESLA POWER WALL Wrote: "there is no way it's going to dump enough current in to one cell to cause it to blow up"

Says who?
This is exactly why the cells kept failing in Mikes DIY video.
Unless you have current monitoring of every cell, don't make those assumptions because current is dictated by ohms law.

"nothing happened"

Another assumption. Watch x-ray footage of a cell getting hot. Just because nothing is outwardly obvious does not mean damage has not been done

Firstly, mike is a bad example, he still thinks the cells are at fault instead of his LVD being wrong and not bottom end balancing.

Saying "Just because nothing is outwardly obvious does not mean damage has not been done" is a cop out, we can all test cells, so when things go wrong, thats what we do, the math shows you if there is a problem, capacity, self discharge specs. simple

(01-11-2017, 09:14 PM)DIY TESLA POWER WALL Wrote: You need to understand.
Thermal damage is progressive. A healthy cell does not explode unless it's an abnormal amount of quick abuse.
All these laptop fires occur because a small amount of damage is done each time. Eventually Lithium builds up on the separator and causes a short circuit.
If you have cells that you have witnessed get hot, they have a much higher probability of going into thermal runaway. Since you don't know the history of each cell, you have no idea how much Lithium has built up and how easily they might short internally

The cells blow up due to shorts in wiring nearly universally, which then locally heats inso and causes more shorts.  Its nearly always inso fires that lead to runaway thermal situations where multiple cells fail.

What about the sudo 'lithium build up'

... are you trying to make up science ?

<chuckles>

(01-11-2017, 11:37 PM)DIY TESLA POWER WALL Wrote: CUD, I don't believe that. It's obvious that 90% of people building these things have never heard of thermal runaway, let alone how and why it occurs.

Its not an issue.  You can easily see the symptoms as the battery will waste energy.

You seem to think all 18650s catastrophically fail, definitely.  This is so not true, just as true as most cars dont kill their occupants screaming with sharp things in their heads, its just an eventual decline, eventually things just 'dont work'

Most cells just continue to pass voltage with no current and have little to no capacity and dont get hot.

Most cells are in laptop batteries and the bms stops charging and discharging as then get below the LVD zone.

Those same cells due to ohms law just dont take a charge, dont get hot and reside in a series module that now has less capacity and gets lower on the low end.

Again, bottom end balance ppl, it shows when your getting cells out of balance in CAPACITY

kind regards
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#20
"Just show me someone who is heating up a battery under one of these to show thermal stress."

https://youtu.be/o6xrDxvel-0

"What about the sudo 'lithium build up'

... are you trying to make up science ?"

You.....do realize that Lithium batteries have Lithium inside them right? It's not just a catchy name. You also realize that in order to have an internal short you need a metal to conduct between the anode and cathode? What do you think this metal is if not Lithium? It's a compound called Lithium dendrite. Google it. Ahh never mind, you already know everything.

http://m.jes.ecsdl.org/content/162/7/A1352.full

"It can also be Li dendrite formed by Li plating due to overcharge or degradation"

Once again, you are wrong.

"Wow dude, you should read what you write."

Chuckles a plenty. They are not laughing with you. They are laughing AT you

"The cells blow up due to shorts in wiring nearly universally, which then locally heats inso and causes more shorts.  Its nearly always inso fires that lead to runaway thermal situations where multiple cells fail."

Please provide evidence that all these laptop and phone fires are due to wiring shorts. In fact, show me an example other than a dodgy DIY Powerwall

http://www.mpoweruk.com/lithium_failures.htm

"With excessive currents the Lithium ions can not be accommodated quickly enough between the intercalation layers of the anode and Lithium ions accumulate on the surface of the anode where they are deposited as metallic Lithium. This is known as Lithium plating. The the consequence is a reduction in the free Lithium ions and hence an irreversible capacity loss and since the plating is not necessarily homogeneous, but dendritic in form, it can ultimately result in a short circuit between the electrodes. "

Mic drop
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