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Brent S View Drop Down
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Joined: 25 Sep 2018
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    Posted: 26 Sep 2018 at 5:28pm
Lol, my wife isn’t going to rough it either.  I got the propane generator for her, otherwise I coul go off grid pretty easily.
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Direct Link To This Post Posted: 26 Sep 2018 at 6:31pm
Using a propane genny is still going off grid. Just fossil fueled not solar. I have a 2kw Honda converted to propane as well. Runs the aircon just fine. 

The problem is noise. During the day we're mostly outside anyway so don't need the ac really. Its those hot humid nights....  

If you're in pretty much any campground rather than pure boondocking you can't run your genny at night. National park and national forest campground quiet hours are 10p to 6a, and if you run your genny at 9p or 7a you don't have happy neighbors. Most state parks have similar rules if not more strict. 

So, my objective is 12 hours of ac, 8p to 8a, with no input from a genny (or course there isn't much of anything from solar during those hours anyway). No way to do that without going to Li Ion batteries, lead acid is way too heavy. 
1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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Brent S View Drop Down
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Direct Link To This Post Posted: 26 Sep 2018 at 6:49pm
You’re definitely right about lead acid batteries being too heavy, and are limited in life cycles.  Lithium has potential, but is not where it needs to be yet.  I’m hoping within ten years there will be a much better option out there.  It is coming anyways.  As for now, I guess we’re way ahead of where people were 100yrs ago, so should be greatful.
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Direct Link To This Post Posted: 27 Sep 2018 at 4:42am
If you're looking at total life cycle cost and planning to keep your rig long enough Lithium is already there. And anyhow I can't wait 10 years for something better, I'm 65 now...

Easiest way to look at it is delivered amp hours. If maintained properly your lead acid batt is going to deliver about 500 50% cycles, so a 100AH battery can give you 25,000 AH. A Li batt can provide about 2500 80% cycles, so 200,000 AH from a 100AH battery. That's an 8x factor. 

So you can theoretically afford to pay 8x as much for the same capacity Li as you would for PbA. And that's just about what the current difference is. You can buy a Battleborn 12V 100AH Li battery for $950. And then the 4x weight benefit comes for free...

But you have to keep your rig 10+ years to see the full life cycle benefit depending on how much you use it.  

What I plan to do is buy a battery module out of a low mileage wrecked Tesla. Those are running about $1300-1400 and are about 23V, 230AH, so cost about $250 per kWh vs. the Battleborn at $800/kWh. That pretty much makes it a no brainer as long as you're willing to design the battery management system (the Tesla BMS won't work with the module out of the car) and do a custom install with a 24/12 dc to dc converter, etc. 

Those Tesla modules only weigh 55 lbs so they're about half the weight per kWh of the Battleborn batteries, 1/8 the weight per useful kWh of the PbA batts. What I'm still trying to determine is if I need 2 or can get by with 1 Tesla battery module to get through my 12 hour quiet period running the ac. If I have to buy 2 I want to get them from the same wrecked car so that they have the same number of cycles on them. 



1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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