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Old 10-05-2016, 09:15 PM   #99
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AMIRM, you mentioned that you were NOT going to steal closet space for your system, as we are planning on doing with ours. Physically, where and how did you achieve the install? I don't think there's much detail about that in this thread thus far, unless I missed something.
I don't know that my solution to that applies to other configurations of Interstate other than our dual bunk. But in ours there was a half space lower cabinet that all it had in it was this stupid subwoofer. I say stupid because it took a ton of space and pumped its output into a closed enclosure! I shot it in the head and took it out and that small cabinet now houses 300 amp hour of lithium! I took a lot of thinking and maneuvering to get it all to fit in there. Using 100 amp hour cells that were not pre-configured like yours allowed me to get them to fit.

I am going on a business trip this week but when I come back I will document and post pictures for more.

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I'm still thinking in terms of adding some sort of fire stop material as we enlarge the area under our closet.
You may be relieved to know that I sleep right on top of mine with no fire stop! With good design it is as safe or safer than lead acid. I have had two instances of lead acid batteries exploding on me, throwing acid everywhere but thankfully not on me.

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Research is in its infancy and I don't have a plan, or even a short list of potential solutions yet, as far as that goes. I'm interested in how Roadtrek does their installs, hence my attempt to re-access their video.
I watched their video a few times and can explain it all. But let me see if I can find the video for you. When I post my project there won't be any information you need from them but their video does make for good inspiration.

While my custom solution won't be ready for good number of months, it will be far more advanced than anything they have done. All of these systems are kludges, theirs just less so.
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Old 10-05-2016, 10:44 PM   #100
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I have read both 20 minutes and 30 minutes. The latter reference came from Advanced RV saying it is the EPA limit for running the engine.

But sure, use your judgement. I usually run it for 10 to 15 minutes and at nearly 100 amps/hour, it doesn't take much to build confidence that you have plenty of power then.

When I do idle the engine, I make sure to give it a good workout on the freeway or mountain road.
I've read everything from early death of EGR valves to leaking oil seals as a result of idling, but the amount of time seems to be highly variable before these things can happen.

One common comment seems to be if you must idle, then a high idle is best for the health and longevity of the engine.....but then the definition of what exactly constitutes "high" idle is also debated. Sigh....

I think I'll just use the genny. That's what it's designed for......
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Old 10-06-2016, 12:00 AM   #101
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I think I'll just use the genny. That's what it's designed for......
In my system, that puts out 60 amps through the charger. Using stock Magnum 1KW inverter, max is 50 amps. That means double the run time of the main engine for similar charge. That little lawnmower engine in the generator is not going to last long relative to the main engine, costing money to replace/repair down the road. To say nothing of the racket it makes.

In our case, we use our AI to drive around a lot anyway so idle is only if we are staying put which is not often. But if I have to idle it, I do so without guilt. The machine is there to be used. If it costs money later, it will be worth it in all the enjoyment it has provided up to that point.
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Old 10-06-2016, 06:30 AM   #102
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...But in ours there was a half space lower cabinet that all it had in it was this stupid subwoofer. I say stupid because it took a ton of space and pumped its output into a closed enclosure! ...
Oh my word, is Airstream still doing that?! Same thing in our 2007 T1N. I looked at ours and marveled at the fact that someone would even consider that to make sense.

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I am going on a business trip this week but when I come back I will document and post pictures for more.
I'm looking forward to it!

Incidentally regarding battery placement, we have a potential consideration that you do not, on account of your geography (but if MCRIDER ever decides to take the lithium plunge, this is something for him to contemplate also).

I was a bit disturbed by Technomadia's report on temperature degradation, from which I've excerpted the following quote:

"This means at 33C (91F) usable battery life will be cut in half, and presumably to a quarter at 43C (109F). This is VERY substantial."


Here in the subtropics, we go for months at a time when our rig never falls below 91 F (due to the thermal inertia in our storage unit), and it routinely hits 107 F for short periods when taken into the open in the summer (we don't travel in such conditions, but I take it over here to our stick and brick house to work on).

The issue got me thinking... is there a way we could incorporate a quick disconnect for the batteries? A physical disconnect, not just a conventional electrical disconnect?

This might sound absurd, but I could spend $120 on a dormitory refrigerator that, when set on minimal cooling, would keep about $2,000 worth of lithium batteries at an optimal temperature, if only I could pop them out of there easily, and shift them ten feet into the fridge that I could run in the storage unit next to our rig, because we do have electrical service in there. And then when we get ready to travel, pop them back in. IF they could be made to be poppable.

Conversely, might there be a way to place a 110 V device in or near the battery storage chamber, or run a line from an external device, such that it could provide a measure of in situ cooling? A few of the Airstream trailer folks who park for long periods do run temporary ducted a/c to their rigs from external sources.

Anyway, no decisions on that point, but it's something to weigh as we design going forward in the immediate future.
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Old 10-06-2016, 12:00 PM   #103
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I've read everything from early death of EGR valves to leaking oil seals as a result of idling, but the amount of time seems to be highly variable before these things can happen.

One common comment seems to be if you must idle, then a high idle is best for the health and longevity of the engine.....but then the definition of what exactly constitutes "high" idle is also debated. Sigh....

I think I'll just use the genny. That's what it's designed for......
The MB Sprinter has a high idle option but I can't remember what the rpm was for it but suspect it's probably between 1500 and 2000 rpm.
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Old 10-06-2016, 12:07 PM   #104
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Conversely, might there be a way to place a 110 V device in or near the battery storage chamber, or run a line from an external device, such that it could provide a measure of in situ cooling? A few of the Airstream trailer folks who park for long periods do run temporary ducted a/c to their rigs from external sources.

Anyway, no decisions on that point, but it's something to weigh as we design going forward in the immediate future.
Might check out thermionic plates to put in the battery compartment.
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Old 10-06-2016, 01:40 PM   #105
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Incidentally regarding battery placement, we have a potential consideration that you do not, on account of your geography (but if MCRIDER ever decides to take the lithium plunge, this is something for him to contemplate also).

I was a bit disturbed by Technomadia's report on temperature degradation, from which I've excerpted the following quote:

"This means at 33C (91F) usable battery life will be cut in half, and presumably to a quarter at 43C (109F). This is VERY substantial."


Here in the subtropics, we go for months at a time when our rig never falls below 91 F (due to the thermal inertia in our storage unit), and it routinely hits 107 F for short periods when taken into the open in the summer (we don't travel in such conditions, but I take it over here to our stick and brick house to work on).
I have not studied this in detail but my understanding is that cycle reduction at high-temp includes high current usage. Plain storage, or light usage will not cause the same issue. Other than inverter to power microwave or inverter, these batteries will cruise with so little consumption. On my installation, current consumption is around 6 to 7 amps per hour. The total capacity of the cells is 300 amps which would put this at "0.02C." Life cycle testing is often done at 1C to 3C. That data would not at all represent what happens in our light duty consumption.

FYI my BMS has a built-in profile for my batteries that calls for reduction of current discharge above 45 degree C. For every degree above that, it drops the discharge rate by 30 amps or so. In that sense, it follows the above notion of not stressing the battery when it is at elevated temps.

To the extent you use the microwave/AC, and you place the batteries in living quarters, high temps should not be a concerned.

But let's put all of this aside and look at this philosophically. In my view, batteries are consumable part of the RV. Just like gas and DEF that you buy, you should assume the batteries will degrade and at some point you will buy fresh. My total cost for the batteries including shipping was about $1,500. If I get usable capacity for five years out of it, that is just $300/year. Cost of gas alone will dwarf that.

Micro analysis of battery performance when it comes to LifePO4 just cannot be done anyway. These are produced by Chinese companies and who knows what recipe they use now versus last year. The science of them is very lightly studied since they are one of the least desirable types of Lithium batteries from market potential point of view. Use them until they die and buy new.
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Old 10-06-2016, 03:09 PM   #106
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The MB Sprinter has a high idle option but I can't remember what the rpm was for it but suspect it's probably between 1500 and 2000 rpm.


I've read that there are two options offered but not sure if they can be retrofitted. One is a fixed rpm high idle and the other is adjustable. In either case even if they are available as a retrofit, I think the least expensive of the two options is $650. I think if someone planned to do this a lot the expense would make sense, otherwise the "stick" method might be a good option......

http://www.tooldiscounter.com/ItemDi...zA4aAtz18P8HAQ
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Old 10-06-2016, 07:17 PM   #107
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Interblog is overthinking the life cycle reductions from elevated temperatures. We're not retired so we're only going to put a few dozen cycles on the batteries per year. The lithium choice wasn't driven by lifecycle costs but by energy density and charge rates. If we only get a quarter of the rated cycles, these batteries may last us the better part of a decade.

Our T1N has the coach battery under the passenger seat so there is no room for additional capacity in that location. Additionally, that location is nearly impossible to fish a really fat cable so adding an inverter to run the microwave is not an option. That means that in order to increase capacity we must relocate our battery somewhere else in the coach and that is where the deeper discharges and higher energy densities of lithium batteries will earn their keep. My hope is that the higher charging rates for lithium means more effective charging on the road. If true, we may offset some of the volume displaced by the new battery bank by not installing a charger.
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Old 10-06-2016, 07:19 PM   #108
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Edit for double post.
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Old 10-07-2016, 02:13 AM   #109
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With engine and AC charger going, I have pumped nearly 130 amps into my bank and they don't even blink! Done the same with generator powering the AC charger and main engine. I call it "turbo charging."

How much capacity did you end up with LB?
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Old 10-07-2016, 08:06 AM   #110
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I'll continue to over-think the system, too, because everything about it has been under-thought to date, from Airstream's initial design (which failed repeatedly on our 2016 Canada trip) to that lousy electrical converter that failed catastrophically earlier this year due to the manufacturer's self-admitted defect which almost burned down our rig, to the fact that the converter retrofit doesn't even charge how it was supposed to charge stage-wise, which is the reason why we spent the money to replace it to begin with.

Engaging in over-thinking doesn't mean that every resulting idea has to be adopted. It just means that someone is putting some effort into evaluating all the ancillary possibilities on any given project. If I hadn't over-thought the cab roof while we were installing the rear and side cameras and front monitor, then we'd have no Dynamat and radiant barrier up there today, and those things were a big improvement.
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Old 10-07-2016, 05:44 PM   #111
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We purchased 300Ah of batteries. I'm pretty excited about seeing more than 6-7 charging amps getting pushed to the batteries but if they can take over 100A, well I may want to install a bigger alternator.

Amirm, when you get some time can you post a schematic of how you integrated your BMS, chargers, inverter, etc....

IB, we're a great team because your continuous scope creep gets us things like overflow valves on our grey water tanks :-) And for anyone confused by this conversation, I'm working nights this week so this back and forth isn't me antagonizing IB in public so much as us leaving breadcrumbs for each other to find when the other is asleep or at work.
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Old 10-07-2016, 08:53 PM   #112
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On track to do that next week LB. I am on a trip this week through Sunday so no time.
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