Bravo!
This thread was an interesting read. Pulled from the bash-em-all-to-hell toilet, at the brink of being closed, only to end up being constructive and informational.
All I have to add is that the UL, in UL 1974 entitled "Standard for Safety for Repurposing Electric Vehicle Batteries" says "UL wants to help manufacturers make sure the batteries that power these vehicles are used to their full potential. Today, rather than simply disposing of the batteries when they no longer provide the power needed by EVs, they can be repurposed. However, for this to be possible, the batteries must first be safe, meaning every pack must be evaluated according to established standards to determine its condition, safety and energy capacity."
I am not currently in this business (repurposing batteries) so haven't bought and read the 41 page UL document, but it's out there. Perhaps in the near future, we'll see UL rated Repurposed EV Batteries on Ebay. Time will tell, but there sure will be a ton of batteries available over the next decade compared to the last. Companies are forming in this space to address the (mostly future) market.
It goes without saying, but this business (ESS) is a new industry using new technologies, so in the big picture we should expect growing pains.
Tesla battery pack?
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Actually it would be good for another topic thread.
The way these cells are shoe-horned into solar bank use is if they are excessively large in capacity compared to the need (which usually *never* meet the typical solar 2-3 day minimum!), or are so cheap, because the cells are either old stock, surplus crash damage, counterfeit, and the like that this is the only way the project makes any financial sense.
But back to life-cycle - the way we get any cycle life beyond about 360 (maybe a year's worth of cycling) cycles, is to purposely engineer the use-case to only use a small amount of cycle capacity.
Which brings us back to LFP vs other chemistries:
Salesman-type data: (only used for comparison since we murder our batts in the real world)
LifePo4 - 2000 cycles or more to 100% DOD
NON-LFP - typically about 360 cycles to 100% DOD
So right off the bat, there's no comparison. When one takes the vehicular use-case data away, and put into our application, things don't look so bright for non-lfp, unless on is doing a "one-off" diy project that nobody else is going to duplicate - at least not over the counter.
And that's kind of the point - NOBODY would "diy" a non-lfp bank, if they had to pay FULL PRICE for quality Tesla cells, bought directly from Tesla as if they would! It's one reason why A123 stopped selling to diy'ers long ago, and the gray market, rejects, and counterfeits showed up. Heh, we've been through this all before.
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Also, I agree with the rest of your post.Leave a comment:
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Well, yeah - most people don't realize that like all cobalt-based li-ions (or anything non-lifepo4), the cycle-life is ridiculous in our application.
Basically the wrong battery for the wrong application. Yes, we can shoehorn these cells into our application if one know what they are doing and willing to accept the cost/benefit.
Unfortunately, what we see mostly happening is diy'ers trying to turn lithium trash into gold on the cheap, without investing any knowledge, and crying when we won't tell them how to wire up their trash. Just like we don't go deep into depth on the guy wanting to build a bank out of 100 little 5ah agm's found at the dump.
I think the differentiation is this: does the forum serve to discuss "over the counter" projects from reliable distributors, or just support the diy'er trying to cobble stuff together without regard to his/her own safety on the cheap.?
Not everyone here fits that description obviously. That's usually seen when they take safety seriously - regardless of battery chemistry. When they get offended, that's when I become suspicious of a marketing agenda for crash-victim battery projects.
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Funny thing is we get sucked into long discussions about a battery chemistry (NON-lifepo4) that is not ideal for adequate solar storage, and thus getting off on the wrong foot from the get-go.
Much like discussing how to make a solar storage bank out of vehicular starter batteries. Not only that, but the Tesla batteries aren't purchased from Tesla or a direct authorized distributor directly - they are from vehicular crash dumps.
Hi, I want to build a 48v solar storage bank out of batteries that I got from the wrecking yard - and you guys are too uncool to tell me how to do it!
Whether li-ion, or even lead acid, such foolish threads don't even need to get started. Safety, even if you know li-ion like the back of your hand, doesn't START with cells of unknown pedigree. Game over.
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But "Who Knew" ? Or that deeply discharging a bank and then rechargeing it, sets it up for dendrite shorts in a month. Nobody ever connected last months deep discharge, with the fire.
and the different flavors of Li batteries, all have subtle charge/discharge differences. I got this pack from a dead XYZ, and stripped off all this extra stuff and use 3, 48V golf cart chargers to charge it. Why is it smoking all the time ?
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If you go back to the original post it has to do with used Tesla batteries wired for a home energy project. Not Tesla EV's, Powerwalls or other manufactured home storage systems. All of those have been engineered with charging and cooling systems that will help reduce the potential for a fire or worse.
An EV (or an indoor battery storage system) is designed from the ground up around a battery. There are BMS systems, cooling/heating systems, different charge and charge protection systems and limited draws. There are protection devices, often several. There are contactors to isolate the battery when the car is off. There's a smart controller limiting charge and discharge. And the manufacturer has a very detailed tracking system that tracks the cell from receiving all the way to the finished product rolling out the door.
In other words, they are pretty safe.
A second life EV battery has none of that. Generally it does not have a BMS. It doesn't have the contactors and protection devices. It doesn't have that cooling/heating system. It doesn't have a very smart controller deciding whether to continue charging. It may have been in a wreck. It may have been partially submerged in water. It may have been abused by an idiot with a homemade charger or homemade battery tester. It may have endured a guy with the wrong size impact wrench trying to remove it from the car.
In other words, they are less safe.
UL has begun to address this, and now has testing and handling standards for second life EV batteries. It is safe to say that most people working with them do not bother with such testing.
That's not to say they are deathtraps. I have two 3kWhr Tesla batteries that I am experimenting with; they are connected to a charger, inverter and charge controller set up to reduce my house load to zero during "reduce your use" days (which the utility then pays you for.) But they are also in a steel box outside my house, set up with a bib that lets me flood the box if they go up in a fire. There's no way I would keep them inside my house - and anyone who does so is literally playing with fire.
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Hi All,
Just thought I would chime in here, as someone stated the mods and admins dont and cant be expected to know everything about all subjects all the mods are unpaid volunteers who spend some time here to keep the wheels turning for all members and lurkers benefit. Some days the mods or admins have a bit of time to deal with matters that arise other days they have the delete or ban buttons, the mods are all knowledgeable good people and I support their decisions 100%. This is not a democracy, posts will be deleted and people banned as we see fit, cheersLeave a comment:
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There was no judgement, but there didn't need to be to cause real damage. It cost me over $8000 to hire a lawyer and defend in a case that was eventually dropped because (according to my lawyer) it was a weak case that should never have existed. He told me that by moderating the forum and not editing or deleting certain posts I was implying that they were true and that was why I was named in the suit. The first amendment doesn't protect you from the consequences of saying things, it just means the government won't stop you from saying them. I don't speak for the forum owners or other moderators, but liability is something I consider when I see what I think is dangerous advice that's unchecked. Sometimes I might err on the conservative side, but I'd rather occasionally throw the baby out with the bathwater than have the forum owners involved in the kind of thing that I went through, or worse, hear that someone's home has been destroyed or someone is dead.Leave a comment:
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A long time ago I ran a forum (actually a BBS) and ended up as a defendant in a suit because of something that happened on the forum. A lot of details have faded from memory but one that stands out was my attorney telling me that I was liable for things said on the forum unless I did no editing or moderating, Since the owner isn't going to let this turn into a free-for all, we'll be moderating as best we can with safety in mind, but also to keep things civil.
Not applicable to private forums. Besides, if someone suggests something that we think is dangerous, free speech notwithstanding, we'll remove it.
For example, I was timed out six months ago and I don't know if it was because I disagreed with a moderator or he did not understand what I was suggesting. As Aaron has said, it would have been a better educational experience for the lurkers and participants to understand what the moderator thought was dangerous and what was not. Since then I have posted virtually the same comment that in California there is no legislation that says I have to ask permission of the POCO to install a UL certified Hybrid inverter if it is behind the meter and not connected to the grid. Same as a generator. Of course in the case of a hybrid inverter one has to obtain a building permit and I assume the same for a transfer switch for a generator. I went so far as to ask a building inspector in Sonoma County and he agreed. I also asked a lineman from PG&E and he could not refer me to anything or anybody that said anything different.
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A long time ago I ran a forum (actually a BBS) and ended up as a defendant in a suit because of something that happened on the forum. A lot of details have faded from memory but one that stands out was my attorney telling me that I was liable for things said on the forum unless I did no editing or moderating, Since the owner isn't going to let this turn into a free-for all, we'll be moderating as best we can with safety in mind, but also to keep things civil.
Not applicable to private forums. Besides, if someone suggests something that we think is dangerous, free speech notwithstanding, we'll remove it.Last edited by sdold; 04-29-2019, 03:48 PM.Leave a comment:
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The real issue with the moderating on this site is that it puts the mods in a position of needing to be subject matter experts as well as behavioral moderators. Yet, you guys cannot nor will ever be true experts on all the possible things people will want to discuss here.
When those two things get conflated, the forum loses value and membership -- relative to other places where open discourse is permitted. Already this subforum has been essentially reduced to a quiet wasteland.
To your point you made a few posts ago, you all made a conscious choice to have it this way. And that is fine! But, I'm not convinced that your measures have to be so draconian. It may well be possible to permit open discourse, to minimize liability, and still to be able to sleep at night after you've read what others have posted. Goodness knows, a bunch of other forums have managed to figure it out.Leave a comment:
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So if you feel my posts are not reaching the bottom 99%, then think again. I have to make sure anyone that comes to this forum gets answers to their questions and are given safe instructions to use the Solar pv technology. If I have to be a little stern or abrupt in my posts then suck it up because you are not responsible for the people that come here. I have been tasked with helping and keeping them safe. You have not.
There is also risk telling people what a safe process is unless you cover every aspect of the procedure. As noted above I think the First Amendment covers that also. I think a disclaimer at the beginning of this forum or something that people acknowledge when they sign up would be more effective but that is the owner's call not mine.
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Maybe you are right in that my approach by using a temporary ban is not a good action. Yet I have given a temporary ban or "time out" to other members t
I am thankful for some of what you have posted because I consider I should always keep my mind open and be learning from others. But I do not have to always agree with what others have said or change my attitude 100%.
When those two things get conflated, the forum loses value and membership -- relative to other places where open discourse is permitted. Already this subforum has been essentially reduced to a quiet wasteland.
To your point you made a few posts ago, you all made a conscious choice to have it this way. And that is fine! But, I'm not convinced that your measures have to be so draconian. It may well be possible to permit open discourse, to minimize liability, and still to be able to sleep at night after you've read what others have posted. Goodness knows, a bunch of other forums have managed to figure it out.
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