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creeky
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# Posted: 18 Oct 2018 12:28pm - Edited by: creeky
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Lithium is like chocolate. Lots of flavours.
There are 3 good lithium candidates currently.
LifePo4:
Lifepo or lithium ferrous phosphate was an early runner for lithium king. It was thought prices would drop quickly as the technology and materials were inexpensive. This hasn't really happened.
Benefits of lifepo4:
* very stable. You can put a bullet through these things and they won't explode
* pretty good lifespan
* somewhat inexpensive
* availability is good (bargains to be had on ebay)
NMC and NCA
Nickle manganese Cobalt and aluminum
These are the Tesla "powerwall" and the LG Chem home use batteries.
They are very stable. Have high energy storage per weight
Benefits:
* very long lifespan
* probably the best price/kw. These are being mfct in the highest quantities due to automotive demand.
* availability is tricky. Good at the ebay diy level. Harder to source/more expensive at the high end.
LiTO
I would be remiss if I didn't discuss Lithium Titanate.
This chemistry or flavour has the longest life. While specific energy per weight is lower they are incredibly safe. They are relatively expensive.
Benefits:
* longest life (50+ years)
* very stable
* charge even at very low temps. Widest temp range tolerance. Ideal for northern off grid.
* available thru ebay/diy channels.
You can learn more here.
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redwolfguild
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# Posted: 18 Oct 2018 02:42pm
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Thanks Creeky, looking to change out my AGM battery pack this spring as it is not holding a good charge anymore. Def want to go with Lithium this time around.
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paulz
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# Posted: 18 Oct 2018 03:46pm
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ICC mentioned lithium charges faster than lead acid. For someone with only generator recharging (a big one with lots of power) this would be a consideration. Which is best suited? How much faster?
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rockies
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# Posted: 18 Oct 2018 06:47pm
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Creeky - so which ones would you recommend?
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creeky
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# Posted: 19 Oct 2018 10:15am
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I like the NMC. The new studies on longevity, as witnessed by the chevy volt use, shows they are lasting longer than expected. And lifespan can be extended with a 70% dod window instead of 80.
If I had the money I would probably go LiTo. Would have to be a DIY build tho. The idea of a lifetime battery appeals to my off grid sensibility.
Paulz. The charge rate is better two ways. One, the resistance is lower with lithium. So your power goes into storage not heating lead. With lead the higher rate of charge the more heat you create.
If you have a big genny, lithium can be charged at a higher rate. Saving run time.
So you can charge at a higher rate. And the battery is more efficient. Overall you're looking at at least 20%. In practice its more. You don't need the long "absorb" at all. You can basically just bang X kwh into the batteries and then turn off the gen.
You don't need to get to full charge. Sunny tomorrow. Bang in what you need overnight and you're done.
With lead you have to get to full charge. So you're looking at running the genny for long periods of time where very little power is going into the "absorb" or finish time.
Redwolf: How long did you AGMs last? I'm always interested in real world data.
Data. Real world experience is the key to making good decisions.
Recently I've been replacing some very highest quality very large lead acid battery systems. I've seen documented systems that have lasted 12 years.
12 years is nothing to sneeze at. Still. When you see the look on the homeowner when they see the space they recover.
It will be interesting to see what 15-30 years of lithium brings for replacements.
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offgrididaho
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# Posted: 19 Oct 2018 11:19am
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Any advice as to how to navigate the choices out there then? You mention Fleabay, but that's nerve wracking enough for me with things I know about (I can find a nice laptop, no problem, but I know what I'm doing there), but can I really trust some random seller who claims to have a good battery with a BMS but I know nothing about the product or the seller?
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offgrididaho
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# Posted: 19 Oct 2018 11:29am
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As an example, is this something someone would feel comfortable buying on eBay:
https://www.ebay.com/itm/12V-110Ah-Energy-storage-Lithium-Iron-Phosphate-Battery-LiFe PO4-with-BMS/352424595183
??? Can a standard MPPT controller (like Victron 250/xx) be set for proper charging voltages (do products like these even come with proper specs for charging voltage levels)? Or a standard inverter/charger?
Sorry to be dense, I have some FLA experience and am still leaning that way as cabin won't be getting a lot of use next couple of years so maybe way to start is FLA and next time around do LifePO4 but...
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redwolfguild
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# Posted: 19 Oct 2018 03:28pm - Edited by: redwolfguild
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Quoting: creeky Redwolf: How long did you AGMs last? I'm always interested in real world data.
Well, I am a little disappointed with the performance. It is a Trojan 31-AGM at 100 AMP. It lasted 4.5 years. It has been continuously hooked up to 1 - 210W 24V panel with an MPPT Charge controller. My system is 12V and rarely use an inverter. I use the power to run my Dometic Fridge when I am at the cabin and to charge lights, phone, and a cell phone booster. I do not abuse the system and was really looking to get 5 years out of it, which now that it is winter I will not make a change until Spring. I noticed that with cloudy days, my voltage was dropping pretty quickly and they just were not able to hold up while the fridge cycled on. I have a IOTA 25AMP charger I use with my EU2000. In the early years I would run it each morning to top off my battery, but in the last few years, I got lazy and relied on the solar to charge them. Maybe that is where I went wrong.
I went with the AGM as I store the battery inside the cabin and couldn't have the off-gassing and need to water them. Lithium is looking like the way I am going to go this next round. 100 AMP of Lithium would go a long way but I want to convert to 24 volts for efficiency.
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rockies
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# Posted: 19 Oct 2018 07:16pm
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Creeky, as an example, could you design and detail the equipment you'd recommend for a complete system (wiring, solar panels, batteries, etc) using the lithium battery you recommend? It's probably a lot of work but since you've been involved in solar design and building systems before you seem to know where to get all this stuff.
The reason I ask is there are a lot of threads asking about one particular component of a system but not much info on what to hook it up to, what else is needed or where to buy it.
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Ontario lakeside
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# Posted: 19 Oct 2018 11:58pm
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These two videos detail my system that was designed by Creeky. Its been solid for more than a year and I would highly recommend lithium to anyone that is getting set up with a new system.
https://www.youtube.com/watch?v=ZfilBtej3t4&t=1s
https://www.youtube.com/watch?v=yCudeUYf52Q
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creeky
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# Posted: 20 Oct 2018 10:12am
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Rockies. I have the raw footage for a complete build spec. But my laptop died and with it went my video software.
You can also find a "simplified solar schematic" here; as well as drawings and pictures on my website.
I will be updating this info this winter. But right now I'm still getting projects out the door.
My advice to diyers. Take your time.
Solar systems have a lot of variables. Which makes them appear confusing. And to build one takes a lot of steps. Which makes it appear difficult. But if you take it one step at a time. And either buy a kit or anticipate a longer build schedule. Its not crazy hard.
One thing I can say. Solar today is far more robust and easy than any time previous. The new batteries. The new charge controllers. The app based monitoring and control. Solar has just improved so much in the last two years.
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rockies
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# Posted: 20 Oct 2018 06:40pm
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What I find confusing are all the extras that make the system more versatile. Things like adding in switches to start the generator from the house, or running a line to an exterior outlet or combining AC and DC lines.
A lot of people here have a basic system but don't know how to add on to it. Plus there's all the conflicting advice on different invertors, what will power what, which companies have improved or slid in quality. Too many variables, and then you have to worry about finding an installer that will work with all your research and product list rather than sell you the products he prefers to use.
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rockies
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# Posted: 20 Oct 2018 07:02pm
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Creeky, this is one of a series of articles written by a guy in Quebec who built his own solar PV system (links to the other articles are located on the left side of the article).
Some of his observations about what he did wrong are quite interesting.
https://www.greenbuildingadvisor.com/article/off-grid-in-canada-solar-was-the-only-re al-choice
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creeky
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# Posted: 21 Oct 2018 12:56pm
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Rockies, depending on your level of expertise, listen very closely to your euipment supplier.
PS-you cannot mix DC and AC.
The fellow in Quebec there, had he listened to a reliable source, would have known about setting his panels at 60 degrees. Also, his battery is far too small for his solar and the wrong voltage for the size of his system. He should have known he would need to sweep his panels. Etc.
If I had a dollar for everytime someone who thought he knew about solar or electronics told me "this is wrong" and then later after considering further apologized or admitted I was right in the first place. I would have a lot of dollars.
The biggest complexities of solar really revolve around cost and ego. Over sizing inverters is a common problem. Visiting an install recently the homeowner boasted, 3500w is our highest load to date! He has 8kw with dual inverters on tap. So he has never turned on the second inverter. Hmmm. And just one of his 4kw inverters alone was capable of surging over 8kw.
Another two off grid guys got into a boasting war. I have a 13kw genny. I have a 40! Both would have been better served at around 7. Ego!
After that its proper sizing of BOS (balance of system) components.
The good thing is folks are getting that solar is far more robust and reliable than was the case even a few years ago. Huzzah!
I'll be writing about this quite a bit this winter. I plan a series of education articles. I hope you and others will help support my efforts. More anon.
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