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Old 05-14-2013, 11:48 AM   #81
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I've gotten so lost at this point in this thread. Did I ask what the failure modes actually are for LFP batteries? I though I did, but maybe it was in another meandering thread.

Does anyone what the actual failure modes are? What are we actually protecting against with LFP?
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Old 05-14-2013, 12:00 PM   #82
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skidgear - yes, many questions remain. Its still relatively new technology, and it can be dangerous. We certainly know a bit more about gasoline and how to handle/use/transport it. I am still not in fear of deckofficer and his home assembled lithium battery storage though. Or anyone else. I have yet to hear, "Mom sets house on fire with home assembled lithium battery bank".

I believe there are more pressing concerns than guidelines or regulations at this point for DIY boaters. Most guidelines and regulations will most likely be aimed at the manufacturers of products for use in the field for now. Until they exist, and even after it pays to be careful in your approach. And of course there may eventually be guidelines or regs that we need to adhere to. Most likely it will be because Joe Blow urinated on his cell pack after a night partying on board.

But Joe Blow doesn't have a case of beer under one arm and solar array components under the other as he's walking down the dock to his boat. Yet.

When Harbor Freight begins to offer a lithium based solar array for homes, cars and boats I might begin to worry about whether my neighbor has one.

Twisted - page 9 of this link was most succinct I believe.

http://www.ntsb.gov/news/events/2013...ry%20Forum.pdf

Original link courtesy of skidgear
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Old 05-14-2013, 12:15 PM   #83
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Rick - Yes you are correct about water. BUT, the changes occurring to expand water as you progress from 4 degrees Celsius down to 0 degrees Celsius ARE the changes occurring from change of state, liquid to solid. At any one time the energy level of molecules in a given mass of water varies. At 4* C some of the water molecules have aligned their H molecules with the neighboring molecules. This is a less dense state, and what happens to all the molecules by the time the mass reaches 0* C.

The change from liquid water to a gas also doesn't happen at once for all molecules in a given mass. Some molecules manage to obtain more energy than their neighbor and make the jump first.

But yes, I stand corrected about matter in general expanding as temp increases, though I meant it as a general statement to indicate that BULGING does not = BAD (wish I could draw a line through the equal sign here! lol).
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Old 05-14-2013, 12:16 PM   #84
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In tests they have punctured the cells, overcharged to the point that expansion breaks the case open, and shorted the cells, and no fires in any of these cases. The only aspect that can cause a fire holds true with other batteries, and is the foreign object that has come in contact with the terminals could melt and cause a fire. The amount of amps a LiFePO4 cell can deliver when shorted is quite large, so don't drop your wrench across these cells. Here is a picture of a split second short of just one cell when I accidentally brushed this alligator clip on the terminals.
Notice the crater in the bolt's head and the vaporized piece of screw thread from the alligator clip. Amazing what 3.2 volts can do.
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Old 05-14-2013, 12:28 PM   #85
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Hey Phil, no argument on the A/C units, use what works for ya . I don't think I'd have enough room to walk around my decks comfortably with the A/C units protruding from the windows. The decks are only 24" wide, which is quite comfortable if there is nothing sticking out.

I also like the marine reverse cycle air because its taking water that is usually 70 something degrees at max and usually less and using it as the heat sink to cool the refrigerant. On a regular window A/C unit the aluminum fins are out in the 90 degree heat doing the same job, so it takes more energy to produce each BTU.

But I think it may be possible now for the first time to have a solar setup that will do the job if you are willing to just air condition the zone you are in, MAYBE for a price that equals what someone would spend on fossil fuels, or even at a savings perhaps! There are several people doing it, and I think their numbers will increase.
They are in inside the boat not on the decks as we have no side decks. Most of the time we have on fan and/or energy saving setting. In the summer I been leaving the plex a glass up and we close the thermal curtains to keep the sun and warm air out. We try to keep the cool morning air inside the boat so in the summer the boat the same as in winter. The roof is gloss white and silver tarp is laid on the dark teal deck, so the heat is reflected and not absorbed.

If we were in warmer climate, we would probably have solar and wind, but in the PNW they are not worth it. In the PNW wind gen would be better than solar as it blows most days even in the summer.
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Old 05-14-2013, 12:43 PM   #86
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Rick - Yes you are correct about water. BUT, the changes occurring to expand water as you progress from 4 degrees Celsius down to 0 degrees Celsius ARE the changes occurring from change of state, liquid to solid. At any one time the energy level of molecules in a given mass of water varies. At 4* C some of the water molecules have aligned their H molecules with the neighboring molecules. This is a less dense state, and what happens to all the molecules by the time the mass reaches 0* C.
All the molecules may not be rearranged until around -40*C ... ever heard of or experienced "supercooled water droplets"?

Rather than look at water as freezing at 0*C it may be better to look at ice as melting at 0*C and liquid water between 0 and 4 as liquid water, not incipient ice.
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Old 05-14-2013, 01:05 PM   #87
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Rick - again you are correct. I hadn't actually heard the term, but just did a quick read. I understand the principles. I was going off long term memory from days long gone saying that all molecules changed state at 0, and that was apparently erroneous info to have stored. lol. Most likely I knew better at one point and my brain corrupted the info. Makes sense though. I always knew these changes were over a range and dependent on multiple factors.

I do realize that water between 0 and 4 is still water. Those molecules aligning their H's are not "frozen" that way. They are in a state of flux. Neat stuff water is...unique.

My thrust though was to point out that there need not be fear over a lithium pack bulging as its temp increases. Someone not aware of all the facts might read this thread and think, "OMG, he's right! (skidgear) The packs bulged!" and automatically think that is a bad sign and associate it with hazard. Does the bulging have meaning? Sure. I just wanted to make sure that readers had some context so they can find the answers to that meaning as I did.
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Old 05-14-2013, 01:18 PM   #88
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No problem, it was just a fun exchange that unless you are flying around in cumulus clouds doesn't (pun intended) impact most people.
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Old 05-14-2013, 01:51 PM   #89
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Its a great exchange. A little off topic, but I love learning. Whether I try solar as a main power source right now is still up in the air as I continue to research it, but its exciting to me that it may finally be possible and financially feasible.

I have a couple of muscle cars, one that is a quiet (relatively) and comfortable ride, but makes 1200 hp using a turbo on pump gas. But they are fun vehicles I use here and there. Not as regular transportation. For many years I drove a little beat up Toyota tercel as my main vehicle because with almost 40 mpg it just didn't make sense to go get something else since it ran perfectly. I put brakes, tires and one sensor on it in 130,000 miles.

But truthfully I hate the idea of my $s going overseas for fossil fuels, and of course there is the pollution of our world to think of. Every time I open a package of something I think about the waste, and where it is going. And yes, I know I bought a boat that isn't fuel efficient, but like the muscle cars I don't plan to take it everywhere. I may someday repower her with something better. Electric propulsion is still a pipe dream, but who knows...someday...
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Old 05-14-2013, 02:56 PM   #90
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Twisted - page 9 of this link was most succinct I believe.

http://www.ntsb.gov/news/events/2013...ry%20Forum.pdf

Original link courtesy of skidgear
But all the NTSB stuff, including the above paper, is about Li-ion, not LFP. If I understand much of what this thread talks about, these chemistries have little in common other than the use of Li. I thought we shouldn't be comparing them, and that doing so was a large source of confusion on this subject? Or am I just confused? It surely wouldn't be the first time.
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Old 05-14-2013, 03:15 PM   #91
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Twisted - Lithium as a molecule is an ion. So the NTSB is not looking at just one type. But most of the link skidgear provided is not informative really. Its an overview a few pages long on each subject each of those panels was assigned to look at. But yes, these cells appear to be far superior.

So far Lithium technology has been through 2 generations and is currently in its 3rd.
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Old 05-14-2013, 04:01 PM   #92
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Thurman - LOL

Bob, I'm sorry. I'm Aron. Meant to include that in the last post. Yes, I'm right there with you on the different type of "hit" you get with the types of boost devices. While a turbo or centrifugal blower is a softer hit, it is in not as limited at the upper end in the way positive displacement units are. I could run double the boost if I chose to, and I don't have to change pulleys and add more friction to do it. But I can't. Its still a Pontiac engine, and the head bolt spacing is not sufficient for long term high boost. It does nicely though at 15 psi, and I usually just run it at 10...which is still over 1000 hp and in the neighborhood of 875 ft lbs torque.

Forgot to mention. Its set up with a gated road race oil pan and a 3 qt oil accumulator with a 2 qt racing filter. All told with the oil cooler in line 13 qts oil.

And that lightweight car of yours with a 427 small block is a serious machine.
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Old 05-14-2013, 04:05 PM   #93
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Twisted - Lithium as a molecule is an ion. So the NTSB is not looking at just one type. But most of the link skidgear provided is not informative really. Its an overview a few pages long on each subject each of those panels was assigned to look at. But yes, these cells appear to be far superior.

So far Lithium technology has been through 2 generations and is currently in its 3rd.
That's correct, lithium ion encompasses the family of chemistries. The confusion arose when deckofficer stated that LFE is not a lithium ion battery. I also scratched my head when I read his statement. Note that most of the discussion in the NTSB forum was not in regard to the Boeing 787 battery chemistry. Of particular interest to me were the topics associated with individual cell monitoring, construction, cooling, and venting of the case. Of course that leads to questions regarding what gets vented, and fire fighting. When I see the actual minutes of this forum, I will post a link.
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Old 05-22-2013, 10:33 AM   #94
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Old 05-22-2013, 10:47 AM   #95
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2.7 megawatt-hour lithium polymer battery, now that is a big bank. I remember for cleaner port ops we had to switch from bunker to diesel, now to really clean things up in port their switching from diesel to battery. Thanks for the post.
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