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Old 09-28-2013, 10:18 PM   #1
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Default Planning to go full time

Guys (and gals?),

Very interesting discussion. I clearly need to do some serious reading on the topic of battery engineering. Are you cats engineers or scientists? As a tax consultant, I'm just barely smart enough to know that this discussion is relevant to me, as I'm interested in setting up a B rig with solar for the purpose of quiet boondocking. Will someone indulge me and opine whether I should spend the money on this project (i.e. dropping $$$ on lithium ions or AGMs) before this charging mystery is solved? I'd love to have confidence that solar charging would not diminish the lifespan of my batteries.

Thanks much for your brains. And your time.

Best,

Dave
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Old 09-28-2013, 10:37 PM   #2
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Default Re: Rules changing for battery charging?

Solar charging, as an addition to your normal RV charging system(s), will help increase the lifespan of AGM or wet cell lead acid batteries.

I'm not sure of the effect on LiFePO4 (lithium) batteries. I've read some stuff that indicates that LiFePO4 batteries do better when stored at less than 100% state of charge. One article I read gave 80% SOC in storage being good for LiFePO4 batteries.
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Old 09-28-2013, 11:22 PM   #3
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Default Re: Rules changing for battery charging?

Which RV systems you plan on running with your solar while quietly boondocking, will determine it's feasibility as a sole power source. It can do quite a bit, but not everything (A/C being the obvious one). Panels are heavy, expensive (including the supporting hardware and cost to install), and don't provide nearly enough output to replenish even a small (2 AGMs) battery bank like mine, when under heavy off grid use. However, as markopolo says, as an additional source of non-stop (except at night, duh?) charging for whatever type of batteries you choose to use (LiFePO4 is another way of spelling $$$$$$$$$), or to actually draw power from directly, will do a lot to help keep you topped up, or at least mitigate your eventual rate of reserve power draw down while camping off grid.

I have been meaning to add some solar power charging to my van for a while, but have repeatedly back burnered the project time and again for a variety of reasons. The primary one being, that I don't think I could do it myself without a very knowledgable solar/RV support person available 7X24X365, and I don't really have a good climate controlled environment to attempt to do it in. No garage.
I have toyed with the idea of using a US based solar installation service, like AM Solar or Northern Arizona Wind and Sun, to help me, or to do the install, but that would be logistically problematic based on where I live, and probably very expensive. Still, if we decide to keep our van for the duration, and to keep putting money into it, as required, until it can't be repaired any more, it may be worth it to pursue that option. This is looking more and more likely lately, due to some other issues and discussions.

Does all that help, or make things worse?
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Old 09-29-2013, 12:30 AM   #4
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Default Re: Rules changing for battery charging?

Thank you both for your replies. Yes, they are helpful. It seems if I could eliminate the need for RV AC, my power needs would be drastically reduced, right? I'm planning on retiring in 18 months, and go full time--with my wife--in a to-be-purchased Sprinter until we find a reason to stop. We plan on following the weather, like Campskunk does. I'm looking at Advanced-RV, as they specialize in customization. (Mucho bucks, though.) I'd like to find a calculator that simulates myriad RV systems power requirements to determine how much power we'll need given different scenarios. Also interested in your thoughts on the cost-benefit of lithium versus AGM.

By the way, you probably know this already, but I understand there is a tax credit for upfitting your RV with solar. Make sure you look in to it before you pull the trigger.

Thanks, guys.

Dave
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Old 09-29-2013, 01:31 AM   #5
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Default Re: Rules changing for battery charging?

Quote:
Originally Posted by Dhowie
Guys (and gals?),

Very interesting discussion. I clearly need to do some serious reading on the topic of battery engineering. Are you cats engineers or scientists? As a tax consultant, I'm just barely smart enough to know that this discussion is relevant to me, as I'm interested in setting up a B rig with solar for the purpose of quiet boondocking. Will someone indulge me and opine whether I should spend the money on this project (i.e. dropping $$$ on lithium ions or AGMs) before this charging mystery is solved? I'd love to have confidence that solar charging would not diminish the lifespan of my batteries.

Thanks much for your brains. And your time.

Best,

Dave
Some engineers here, probably some scientists also (the mad variety, more than likely), but all interested in the nuts and bolts of how all this works, as well as looking into the rumor and innuendo that often permeates the internet. You will find this a very good site for tech stuff, I think. You will find us splitting hairs on details that aren't of major concern in the real world, I think, but that is part of the evaluation end of it.

This whole battery and voltage discussion came up because a fellow on another board had a quite new Trojan battery go belly up on him. Trojan said it was because it was sulfated and stratified from too low a charge amperage, and presumably the corresponding low voltage. He had been testing his solar install to see how it would do, fairly long term, without ever being plugged in. That made for low charging rates and less than full conditions a lot of the time. Trojan stated they like 14.7-14.8 volts to get a good, full charge. The only way you will get this with solar is to have enough solar to supply enough amps (compared to your battery capacity) to get to the higher voltage, at least by the end of the charge cycle, plus you have to have a charge controller set to go that high as most do 14.4 volts. (as do the shore power chargers in the vans)

I think the actual need for the higher voltage is still not resolved, especially if you can charge for longer periods regularly (weekly?) and periodically equalize.

In the situation of a lot of boondocking, the damage from the low charging voltage from solar would almost certainly be less than the damage of repeatedly running the batteries down to 20% charge. So, I wouldn't get too worried about it, especially if you are using wet cells, that are relatively inexpensive, and can be equalized to rivive them in many cases. The costs we are talking about are small compared to a years worth of fuel, or the $130K for a Sprinter.
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Old 09-29-2013, 03:13 AM   #6
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Default Re: Rules changing for battery charging?

Ah, well, that changes everything. Since you have some time (18 months?) before you plan to buy, might it be worth a call or visit to a Sportsmobile location? Or, some other similar custom van converter? You might be able to get a better deal on an unconverted Sprinter as your base chassis, and give it to them to convert for you, with the knowledge that it will be a full timer's van? Most class B RV's seem to be designed primarily for inexpensive touring, for a few weeks at a time. Some use them as a second vehicle that you can sleep in. You'll be living in yours, which is probably not very common. It might be advantageous to consider picking some amenities over others, to be more comfortable in your van for longer periods of time. For example, one of my pet peeves is the bathroom/shower situation in almost every class B van. If I were designing a van from scratch, I'd figure out the best combination of tanks, water pumps and power sources, and target installing a better than average shower. After that, I'd add systems and equipment based on my personal priorities for comfort, off grid capability, and anything else I can think of. I would ask the conversion company what they could do, to give you what you want in a van that you plan to live in. Pick their brains, they may have done this sort of thing before and could suggest things that might work for you. If you plan to follow the weather, like campskunk, there may be something that might make you more comfortable at the beach, where he seems to spend a fair bit of time. Even a better way to get the sand off your feet and clothes before you enter, would be a bonus.
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Old 09-29-2013, 09:43 PM   #7
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Default Re: Rules changing for battery charging?

booster, thanks for the perspective. Cost will be a big issue as I will be essentially fixed income once I retire. Much appreciated.

Dave
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Old 09-29-2013, 09:50 PM   #8
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Default Re: Rules changing for battery charging?

Mike, thank you for your thoughts. Good points, especially re the shower. The trouble with the Bs is the small size (also a positive), and making the shower larger impacts the rest of the living area to a degree much more than it would in a larger motorhome. That said, if we're full timing, versus part timing, you're right in suggesting that the layout may need to reflect as much. Good thoughts. Thanks for taking the time.

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Old 09-30-2013, 03:14 PM   #9
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Default Re: Rules changing for battery charging?

One idea I saw for a shower in a shorter RT was having a shower pan right by the rear van doors, and storing a Porta-Potti in that. It took up very little space. That is one way a bathroom can be done to use up as little square footage as possible, although I prefer a wet bath and a black tank commode just for convenience sake. (To me, it is far easier to pull out the slinky or a 1" dump hose, plop it down the dump station hole, and let fly than to worry about dumping the grey, then trying to get rid of the toilet's stuff somewhere.)
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Old 09-30-2013, 08:48 PM   #10
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Default Re: Rules changing for battery charging?

Good point, mlts22. I think I agree with you.
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