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Are there any RELIABLE, low, light, Roof, electric AC's/heaters on the market
(12-27-2017, 09:23 AM)breeze Wrote:
I see nothing new to me there.

Yes if you are

driving on a very regular basis, and

willing to spend thousands on a good and large LFP system

then a high-output alternator setup

(**if** your vehicle can be so adapted, very much harder with new Euro-style high-mpg designs)

can deliver all the power you need.

Is that what you're on about?

It may even be worth the wear and tear on your propulsion engine to generate while idling, but I would only recommend this approach if you're driving many hours per week.

How do you figure one hour charging per 5 hours of aircon? Please show your work.

And what is special about that Nations alt?

Have a look at Zena, and there are CEN units that put out over 10kW from a single unit, go for $4-500 on eBay NOS.

To me Eco-Tech is the best, 200+A at 1800rpm, they'll tune your charging profile to your specs, excellent post-sale support.

But all said and done, a quiet pair of paralleled eu2000i IMO delivers much better flexibility and value engineering.
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There is a 12v 9000 BTU roof air that pulls 600 watts and runs just under $2000. I use a 5000 BTU window shaker mounted in a cabinet that pulls 410 watts. It can run all day off of my solar system without affecting the batteries. Then again you will have issues getting that kind of wattage on a van. It is possible with the right panels but that does not do anything for you at night.

In the short run a small inverter generator to run a smallish AC can make sense due to the simplicity and limited up front cost if you can do without the very best. A 2000 inverter generator can easily run a 6000 BTU window unit pulling 500 watts or even the 9000 BTU roof A/C mentioned above.
Sparky created, (Sparkles on some Saturday nights)  Max the Wonder puppy approved

2011 Ameri-lite 25 ft bunkhouse with 750w of solar and a 675 Ah bank
2003 Ford Expedition with 435w of tilting solar.
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The following 1 user says Thank You to jimindenver for this post:
breeze (12-28-2017)
Note that Jim's most excellent advice above is **not** talking about running the aircon off batteries, but from an active power souce that you would also use to charge your batteries, likely not trying to do both at the same time.

LFP lets you get the bank charged up very quickly if those kind of amps are available, but the AH capacity you'd need to feed aircon **without the power source running** overnight would be massive, as in many thousands of dollars, probably a $10+K system done properly.

Also, compressor startup amps is much higher than continuous, so you may want to check out capacitors, "solar maximizers" so you don't need to oversize your power source as much.
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On that last note, some kombi style inverter/battery chargers have a "power boost" feature, that will when needed combine the available genny/grid power and supplement with power from the battery bank to handle short-term startup and surge loads.

So switch between charging to the bank or drawing from it dynamically as needed.

Not cheap, but they let quite large aircon or other huge-amp shore-power loads be carried by muge smaller (quieter fuel efficient more portable) gennies, so well worthwhile for some situations, including when you'd otherwise be blowing circuit breakers at an inadequately wired campground.
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I am packing up today and decided to try the Sportsman 800 watt inverter generator running the new 5000 BTU window shaker that replaced the old one that drew 450w. The Sportsman could not start that older A/C possibly due to age but it started and is running the new one just fine. I am thrilled because it gives me the after dark solution for my A/C needs and should run it for 5 or 6 hours on .6 gallon of gas too.
Sparky created, (Sparkles on some Saturday nights)  Max the Wonder puppy approved

2011 Ameri-lite 25 ft bunkhouse with 750w of solar and a 675 Ah bank
2003 Ford Expedition with 435w of tilting solar.
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The following 1 user says Thank You to jimindenver for this post:
breeze (12-28-2017)
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(12-28-2017, 11:02 AM)John61CT Wrote: How do you figure one hour charging per 5 hours of aircon? Please show your work.
*180 a/hr/5hrs = 35 a/hr for ac

And what is special about that Nations alt?
* They are the ONLY SECOND alternator ADVERTISED for rv's (and NV3500's too Big Grin

** In AC's it IS or it Ain't. My  oem 130 A/HR alt. on Nissan is perfect, and since this is the ONLY second alternator (at 180 a/hr) it IS and does support ac breaks when required while parked. That is all the relevant math required. You can probably wash and dry a load of clothes too on that generous estimate of 35 a/hr for ac estimated average for 5 hrs (the all in one wash dry machine for van space), but I have not got that far yet.  :-o
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OK, I've gone back a bit, and think I'm understanding more, please correct or clarify.

You have a Nissan NV3500, which comes with a stock alternator rated to in theory produce a maximum 130A.

You want to fit a second alternator as well, and believe the Nations 180A version to be a good choice (it certainly is not the only one, nor the most powerful)

You plan to leave the original factory alt alone, dedicated to the vehicle requirements.

You plan to buy an LFP system, how many AH in size?

> 180 a/hr/5hrs = 35 a/hr for ac

Note a/hr looks like you mean amp-hours (AH), while I assume you just mean amps.

Also, a normal 180A alt will likely only output 120-140A, and is likely to overheat pretty quickly at that rate even while driving, cutting output drastically. Very few alt can actually put out near their rated output for more than 15-30 minutes, and will do far worse at idle.

Maybe the Nations can, I don't know, but I would make sure before buying one.

In order, to properly charge LFP from an alt, it will need to be converted, to use an external voltage regulator, ideally the Balmar MC-614, so the voltage setpoint and charge profile can be custom adjusted.

I don't know if the Nations alt is suitable for that.

OK, assuming you overcome those issues, and can put 120A into your LFP bank, hypothetically 500AH in size.

You say your aircon unit draws 35A (450W?), let's say you want to use it 10 hours per day, so 350AH per day. There will be some inefficiencies, especially with an inverter involved, so let's say 400-450AH per day to be conservative. You may need a 600AH LFP bank.

So 3-4 hours of driving will supply enough energy for ten hours of aircon.

Parking and idling the engine to try to charge tgat much would be very expensive, foolish IMO.
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I'll repeat:

A little quiet portable genny usually makes a lot more sense, and combined with as many solar watts as you can fit on the roof, maybe a shore power charge overnight once in a while, you don't need to go LFP.
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A 420 a li-ion (dedicated house) battery fully charged should supply more than a couple of man-shift-weeks (or 10 ea, 8 hr shifts) of ac no problem. (3) Solar panels would slow the usage rate of the battery down, and then there may need to have electrical hookups and/or run your 180a alternator (at 8x the max rate of Solar charging, rain or shine) randomly and/or periodically to replenish the fully charged battery. 1 trailer park day per month (or per couple of weeks) to fully recharge, fill water tanks up, and clean the pooter out does not sound too unreasonable with quality battery monitor gages. Monitoring 'one' hi-tech 65 lb. li-ion battery is not going to be anything similar to monitoring 500 lbs. of 50% capacity lead-acid batteries that you can scrap the whole toxic pile of batteries if you do not maintain them 100% correctly (or significantly reduce their life, each and every recharge cycle(!), if not perfectly maintained.) Li-ion batteries conversely are very robust and last 10x longer approximately without the variable lead-acid scrap rate. (Plus if you get lead-acid spills in cuts on your hands, they have a healing problem, and you can constantly get holes in your clothing to boot.)

More importantly, you have to be a highly trained battery technician monitoring lead-acid batteries with not-exact methods (a losing battle for the lower 95% of the population.) And if you do get the 'more' exact measuring devices for lead acid batteries, you could almost have bought li-ion batteries and not work a solid part time job maintaining them: that you could have been part time employed paying for your next 500 lbs of lead acid batteries.

How in the world are you going to keep lead acid batteries charged on a 50% charge level, depending on perfect Sun days, and THEN a few hours of Sun per day charging (based on 50% max level in the Winter) will not do too much good except to require you to spend your 2 week limits in trailer parks just recharging your batteries?? And if you live in AZ in baking Sun days in the Summer, LOOK at the all the heat you now have to deal with. It's a lose-lose proposition with Lead Acid batteries w/o doing any number crunching at all; but I understand the technology has just changed enough for people now to experiment and feel (much) safer with the new battery alternatives.

Li-ion would have the perfect battery characteristics to prolong recharging (almost effortlessly) with a variable mixture of conditions and alternative lifestyles without the impossible task of Lead-acid 50% charging limits ONLY on perfect Sun-days. Because the electrical charging diagram on the Fit RV article (posted earlier) printed out on a page break on the article above (due to advertising), I had to copy and paste the diagram on a full page to better understand it. It is definitely tomorrow's technology TODAY for all intensive purposes. Pareto the high volume 2nd alternator use for charging (at 8 times Solar charging rate minimum) and li-ion batteries for lead acid, and you are done. And it can be more economical too: but I don't have time unfortunately to cost it out with a range of usages. But for my dollars, lead acid just does not get the job done in today's (or last century's) technology. Ymmv. I'm just glad I did not get sucked into the heavy lead acid battery technology sales pitch: I will not have room for them in my floor plan! And no loud, smelly genny either.

See you next year!
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