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Old 10-09-2016, 07:41 AM   #113
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This is what I accomplished yesterday as my husband spent the day with 106,248 of his closest friends watching A&M struggle almost endlessly against Tennessee. If you were ever curious about what's beneath the closet floor of a T1N Interstate, here's your answer.

The bad news is that it's a dog's breakfast. The good news is that it's going to make a helluva "before and after" presentation, with this mess being the "before".


Also good news is that it will be extremely easy to convert this closet floor into removable form for future lithium battery system access. You can already see that it basically just rests on two rails (plus there was an aluminum L-bracket along the back wall to secure it there). All we need to do is trim down the corner that is typically covered by the wooden shroud that hides the vent / wire rise, and the aft side, maybe expanding that aft rail so that the resulting floor can be small enough to easily clear the door frame during removal.

Why we didn't make that mod well before now is a mystery to me. All that solar apparatus went in - somehow - without ever removing this floor. But it is what it is, and it's getting done now.

It is frustrating to me that Airstream put the water lines and valves for the outdoor utility shower literally in physical contact with important electrical components. I looked at this and asked myself... why?! To the best of my ability to speculate, it's because the city water inlet is located just to the right of the edge of the photo, and so they had a cold line coming there anyway, and it was easy to junction it off there and run it to the shower for close supply.

The resulting morass has inspired my first item of scope creep on this lithium project. We are going to have to modify those lines no matter what, because they intrude too far into the space. We can't really remove the shower entirely, because we do use it and value it, and also because it would leave a gaping hole in the body (however, if in the future we decide that we need the resulting lithium chamber to be externally ventilated - presto - a Sprinter body cut is already right there in that exact location). We hope to keep the shower but we only need those lines to be pressurized on those occasions when we use it, so I'm advocating for safety valves to be installed upstream so that it's only pressurized when we activate it, rather than being pressurized automatically along with the rest of the water system, as it is right now. It's just too much of an unnecessary risk to have water lines running straight through the heart of the electrical system like that. We have already had one of those PEX connections spring a leak, that being on the opposite side of the vehicle (and what a mess it made). If the same thing happens in this location, the results could be disastrous.

Anyway, ^^ there are some thoughts on this small portion of the project.
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Old 10-09-2016, 06:16 PM   #114
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(but if MCRIDER ever decides to take the lithium plunge, this is something for him to contemplate also).

I
I'm following with great interest. We just returned from TN where the temps were fabulous. Our Solar and battery set up are working great even with that cheap Atkinson Controller. I'm considering the Morningstar Sunsaver MPPT, but not sure I want to take on that task at the moment.

The rig will be a year-old later this month and we just rolled over 19.3K miles.
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Old 10-15-2016, 07:09 AM   #115
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...

You may be relieved to know that I sleep right on top of mine with no fire stop! ...
....
Today in the theme of, "I've done just enough additional research to be even more dangerous", I note that, in the category of DIY battery bunkers for fire stop purposes, the two most common construction methods appear to be gypsum wallboard and HardieBacker.

We in Houston are generally very fond of the Hardie line of fiber-cement sheets and planks because they liberated us from cellulose-based products of yesteryear, which were the source of who knows how many class-action lawsuits (natural fiber exterior cladding products do not have a history of standing up to subtropical humidity). The exterior portions of our stick-and-brick that are not actually brick are mostly HardiePlank.

So HardieBacker is appealing to me greatly as a material source for this application. The space is not large so a HardieBacker liner would not add much weight, and it would not be as potentially subject to crumbling due to road vibrations as wallboard might be.

Model airplane people are a sobering lot - they regard Lipo battery fires as a foregone conclusion. The only questions are which cell and when will the fire start. My husband has explained that RV systems (DIY and commercially-produced) have additional tech integrated that is designed to prevent the precursor conditions from arising that may give rise to certain kinds of fires. And obviously those design elements are absolutely essential, but tech has a way of failing at times, hence the relevance of redundant measures.
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Old 10-15-2016, 10:03 AM   #116
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And the US Navy doesn't allow Li on their subs.
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Old 10-15-2016, 10:31 AM   #117
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Today in the theme of, "I've done just enough additional research to be even more dangerous", I note that, in the category of DIY battery bunkers for fire stop purposes, the two most common construction methods appear to be gypsum wallboard and HardieBacker.



We in Houston are generally very fond of the Hardie line of fiber-cement sheets and planks because they liberated us from cellulose-based products of yesteryear, which were the source of who knows how many class-action lawsuits (natural fiber exterior cladding products do not have a history of standing up to subtropical humidity). The exterior portions of our stick-and-brick that are not actually brick are mostly HardiePlank.



So HardieBacker is appealing to me greatly as a material source for this application. The space is not large so a HardieBacker liner would not add much weight, and it would not be as potentially subject to crumbling due to road vibrations as wallboard might be.



Model airplane people are a sobering lot - they regard Lipo battery fires as a foregone conclusion. The only questions are which cell and when will the fire start. My husband has explained that RV systems (DIY and commercially-produced) have additional tech integrated that is designed to prevent the precursor conditions from arising that may give rise to certain kinds of fires. And obviously those design elements are absolutely essential, but tech has a way of failing at times, hence the relevance of redundant measures.


I've been keeping my eye on the battery industry and I think in the not-too-distant future they will completely solve this with a different design and/or chemistry (and increase energy density at the same time). As a result, by doing what you're doing now, you'll have the "bones" in place to take immediate advantage of the new tech when it becomes available. Sure, you'll likely need to swap out charge controllers and depending on your setup, inverter/chargers, but in the mean time you will be able to enjoy this new era of propane and generator freedom. Once the new tech is available, I'll certainly be moving to it!
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Old 10-15-2016, 10:59 AM   #118
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If only Samsung had used a Hardibacker board case for their new Note 7 phone.
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Old 10-15-2016, 11:43 AM   #119
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And the US Navy doesn't allow Li on their subs.
They are not having to camp overnight with no power source in middle of nowhere.

Seriously, what is the source of this statement? I just did a search and the first hit was this document which stipulates how to use Lithium battery in all naval facilities including subs and boats: http://www.public.navy.mil/navsafece...3FList%3D8006e

"LITHIUM CELLS AND BATTERIES. The use of lithium cells and batteries in Navy systems and equipment offers the advantage of increased voltage and longer life, when compared to other power sources. Lithium batteries can provide increased energy density, extremely high currents, and can discharge very rapidly when short-circuited. Although these characteristics are useful in applications requiring sustained high current, a too-rapid discharge of a lithium battery can result in overheating of the battery, rupture, and even explosion. Because of these risks, lithium batteries shall be considered hazardous at all times. The Department of the Navy has adopted a Lithium Battery Safety Program to minimize hazards associated with their use"

I have not read the rest of the doc but does not at all admonish their use.
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Old 10-15-2016, 11:57 AM   #120
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If only Samsung had used a Hardibacker board case for their new Note 7 phone.
Samsung is one of my case-study darlings that I use to argue against just taking on faith that nothing can go wrong with these things. Stuff keeps going wrong and the best minds in the business can't always figure out why.

Airlines are in a similar groove. E.g. this news story published yesterday that describes how they are now adding the equivalent of a fire stop mechanism to commercial aircraft just in case they are forced to isolate a flaming phone battery at 36,000 feet. I'm also looking at those materials, which I think are probably more fabric-y / Nomex-like. I'm not done with that part of the research.
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Old 10-15-2016, 02:20 PM   #121
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They are not having to camp overnight with no power source in middle of nowhere.

Seriously, what is the source of this statement? I just did a search and the first hit was this document which stipulates how to use Lithium battery in all naval facilities including subs and boats: http://www.public.navy.mil/navsafece...3FList%3D8006e

"LITHIUM CELLS AND BATTERIES. The use of lithium cells and batteries in Navy systems and equipment offers the advantage of increased voltage and longer life, when compared to other power sources. Lithium batteries can provide increased energy density, extremely high currents, and can discharge very rapidly when short-circuited. Although these characteristics are useful in applications requiring sustained high current, a too-rapid discharge of a lithium battery can result in overheating of the battery, rupture, and even explosion. Because of these risks, lithium batteries shall be considered hazardous at all times. The Department of the Navy has adopted a Lithium Battery Safety Program to minimize hazards associated with their use"

I have not read the rest of the doc but does not at all admonish their use.
Was based on what were told about 20 years ago about products we produced for subs.

Did some research and couldn't find anything that prohibits or allows their use on subs. Did find that laptops and watch Li batteries were OK.
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Old 10-23-2016, 12:51 AM   #122
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I'm still planning to use the solar BMS and here is one of 6 pictorial schematics I have put together. This one is my favorite. As I said, this is a pictorial schematic and omits things like fuses and any return or grounding connections. I would like feed back since my electrical background is a bit weak. If I'm missing some obvious parasitic load or if I'm missing a big fire hazard, please let me know. I'm still a couple months from having to lock this schematic down.

I don't have a cut off for the inverter because the spec sheet claims it only draws 4 mA when turned off. I like the large solid state relays discussed either in this or one of the battery threads but since one of my design goals is to eliminate the parasitic loads, I'm hoping there won't be much need for those space heaters.

The total parasitic load in this schematic when the system is turned off is about 25 mA. On a full battery, that would take over a year to discharge. I did however add a switch on the battery ground to assist in maintenance and long term storage.

I'm not really sure if the Sterling battery to battery charger on the left is really necessary or if I could just get away with a battery isolator. My main hesitation is where to locate that box since it is preferable to have them close to the alternator and chassis battery. Unfortunately I don't think it can go under the hood and there isn't really any room under the driver's seat.

On the AC side, I'm a bit conflicted about reusing Airstream's automatic transfer switch vs a manual three way switch. I put the refrigerator upstream of the inverter because I don't want to ever accidently power the 2-way fridge's resistive heating element using the battery.

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Old 10-23-2016, 08:38 AM   #123
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I'm still planning to use the solar BMS and here is one of 6 pictorial schematics I have put together. This one is my favorite. As I said, this is a pictorial schematic and omits things like fuses and any return or grounding connections. I would like feed back since my electrical background is a bit weak. If I'm missing some obvious parasitic load or if I'm missing a big fire hazard, please let me know. I'm still a couple months from having to lock this schematic down.

I don't have a cut off for the inverter because the spec sheet claims it only draws 4 mA when turned off. I like the large solid state relays discussed either in this or one of the battery threads but since one of my design goals is to eliminate the parasitic loads, I'm hoping there won't be much need for those space heaters.

The total parasitic load in this schematic when the system is turned off is about 25 mA. On a full battery, that would take over a year to discharge. I did however add a switch on the battery ground to assist in maintenance and long term storage.

I'm not really sure if the Sterling battery to battery charger on the left is really necessary or if I could just get away with a battery isolator. My main hesitation is where to locate that box since it is preferable to have them close to the alternator and chassis battery. Unfortunately I don't think it can go under the hood and there isn't really any room under the driver's seat.

On the AC side, I'm a bit conflicted about reusing Airstream's automatic transfer switch vs a manual three way switch. I put the refrigerator upstream of the inverter because I don't want to ever accidently power the 2-way fridge's resistive heating element using the battery.

LB_3,

If I may comment?

Nice work! You don't necessirally need that Sterling DC to DC unit. The newer Interstates use a solenoid based battery isolator from Precision Circuits that seems to work well for lead batteries, but I believe that the voltage set points are not really suitable for alternator charging of lithiums as the voltage of same is significantly higher than lead types and they dos not exhibit voltage drop. The result will be a one way charging system to your coach battery rather than the intended 2-way system.

You could look at Victron's answer, as they have a great deal of experience in the marine industry where alternator charging is the norm on large power boats. Look at their Cyrix-Li-ct isolator that we use for their lithium systems. https://www.victronenergy.com/upload...n-230-A-EN.pdf

Also, from my experience with the Interstate and Airstream trailers, there have been many failures reported from the Parallax auto transfer switch. There are better quality units available for a 30 amp coach like the Progressive Dynamics unit.

With a lithium system, why not dump your 3-way inefficient gas/absorption fridge and go with a DC compressor (Danfoss) marine unit. I have installed many of these and they receive universal praise for the operational characteristics of them.

Are you showing that shunt on the positive side of your circuit? I have never seen one used there......only for all negative DC loads....

Hope this helps a bit in your lithium quest!
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Old 10-23-2016, 09:08 AM   #124
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LB_3,
If I may comment?
Absolutely, I was counting on it.

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Are you showing that shunt on the positive side of your circuit? I have never seen one used there......only for all negative DC loads....

Hope this helps a bit in your lithium quest!
Yes, the shunt is on the positive. I don't really like it there either but the BMS I'm hoping tracks any loads passing through it and uses the shunt to track the loads external to the BMS. If the shunt were in the proper place, it would double count the current through the BMS.

The software for the BMS is open source and from my quick peak at the code, it looks pretty easy to update the calculations to make current draw the difference instead of the sum of the two currents. Unfortunately, just the thought of trying to successfully compile and install the software makes me dizzy so I've put most of my energy in trying to find a small plastic project box to enclose the shunt.

I'm not opposed to a DC fridge and love the idea of our propane lasting months instead of a two weeks. But our current fridge works and is relatively new so I don't want to risk our most important appliance during the shake down phase of this project.

Thanks for the input.
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Old 10-23-2016, 01:16 PM   #125
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With a lithium system, why not dump your 3-way inefficient gas/absorption fridge and go with a DC compressor (Danfoss) marine unit. I have installed many of these and they receive universal praise for the operational characteristics of them.
Lew, along the lines of DC compressors being more efficient, do they make DC air conditioning units for RVs, or ones that can be modified to work in a RV? It seems the two biggest draws on the batteries are the refers (which are readily available in DC, like the new AS Interstates) and the A/C. For battery operation I can definitely see people switching to DC refers if they don't already have them, but so far I've not seen any chatter about DC A/C units...... ???
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Old 10-23-2016, 01:58 PM   #126
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Lew, along the lines of DC compressors being more efficient, do they make DC air conditioning units for RVs, or ones that can be modified to work in a RV? It seems the two biggest draws on the batteries are the refers (which are readily available in DC, like the new AS Interstates) and the A/C. For battery operation I can definitely see people switching to DC refers if they don't already have them, but so far I've not seen any chatter about DC A/C units...... ???

WHAT A GREAT CONCEPT!!!!! AFAIK, I have never seen this done.

Now see what you did!!!!!! I'm going to have to resurrect an old roof unit with a blown compressor and see what it will take for pure DC operation.

Any Go Fund Me investors???? ;-))


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