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offgrid
Senior Member
Joined: 23 Jul 2018
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Posts: 5290
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Topic: new R-Pod owner 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.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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Brent S
Newbie
Joined: 25 Sep 2018
Location: SE USA
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Posts: 21
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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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offgrid
Senior Member
Joined: 23 Jul 2018
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Posts: 5290
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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.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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Brent S
Newbie
Joined: 25 Sep 2018
Location: SE USA
Online Status: Offline
Posts: 21
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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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offgrid
Senior Member
Joined: 23 Jul 2018
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Posts: 5290
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Posted: 26 Sep 2018 at 4:33pm |
To be honest, I personally wouldn't take "flexible" modules if they were given to me, I used to design solar modules for a living and know too much about it. Solar cells are made of crystalline silicon, which is a (very) brittle material. Nuff said, don't want to start a debate on that...
My objective with the ac is to run it overnight during campground quiet hours, not to run it 24/7 from solar. So the main thing is to have a very efficient ac unit and a large battery bank. The solar is there to reduce the cost of generator runtime to recharge during the day.
The cost will be a few $K, mostly for the Li Ion battery.
The benefit? DW has told me she won't camp with me on the beach here on the OBX without ac in the summer. Can't say I blame her, and neither of us like the private campgrounds with hookups around here much. So right now we either have to drive all the way to the mountains where it's cool or not camp.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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Brent S
Newbie
Joined: 25 Sep 2018
Location: SE USA
Online Status: Offline
Posts: 21
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Posted: 26 Sep 2018 at 4:25pm |
I’ve been a prepper most of my life, which is partly how I justified buying a camper. Seriously after growing up in Fla. with he hurricanes I was a prepper before I even knew what one was. Glad your home escaped any bad damage!
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Brent S
Newbie
Joined: 25 Sep 2018
Location: SE USA
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Posts: 21
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Posted: 26 Sep 2018 at 4:21pm |
I’ve seen more of the flexible panels out there now and think they would be ideal for doing the whole roof, front and back. I’m sure you could get an ac to run, just not sure of the cost/benefit being worthwhile. Cool to have the option though.
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offgrid
Senior Member
Joined: 23 Jul 2018
Online Status: Offline
Posts: 5290
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Posted: 26 Sep 2018 at 4:10pm |
My daughter and grandson live outside Savannah. I'm in Hatteras NC, aka hurricane alley . We were in the WV mountains in our 179 for Florence, one of the reasons I bought it was to bug out. Luckily, it missed us here, no damage other than a few shingles . I looked at tons of trailers before I bought my pod this spring. You're going to love yours.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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Brent S
Newbie
Joined: 25 Sep 2018
Location: SE USA
Online Status: Offline
Posts: 21
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Posted: 26 Sep 2018 at 4:00pm |
Thanks, I’m in NE Georgia, so sun isn’t usually a problem. Staying out of it can be! I researched campers a lot before deciding on the rpod due to its design. Can’t wait to take it out!
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offgrid
Senior Member
Joined: 23 Jul 2018
Online Status: Offline
Posts: 5290
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Posted: 26 Sep 2018 at 3:46pm |
20A controller is good, you should be able to add at least one more 100W module to that if you find it necessary. I don't know if you are aware of this yet but all the solar cells are in series so even shading one cell bottlenecks the whole dang module. So when you're using solar modules, try to keep them completely out of the shade. I see you live in the SE as I do, I know that can be hard to do here because we like to camp under the nice shady tree canopy in the summertime...have fun!
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold
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