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Old 11-22-2019, 12:42 PM   #21
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DING DING DING DING!!!!!!


I have a good overall summary on LFP, including links to some good learning resources for DIY.

Needs some updating, cleaning up, so if you start a new thread remind me I'll get a round tuit.

And do please post your potential sources for quality cells, lots of scammers out there sell used as new, or QA rejects as Grade A.

Best is dealing with the factory directly, you def want all from the same production run.

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Old 11-22-2019, 01:02 PM   #22
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Quote:
Originally Posted by TheHubbardBus View Post
That is EXACTLY the same bank I had planned before I started worrying about heat killing my $2700 investment. A line of thought I started going down thanks to your comments in the 'battery tender' thread, Steve


Obviously, there are other advantages - weight & size - but the main reason I'm now toying with the idea of LFP is our heat.


If I'm off base, let me know! I'd love to stick with my original plan which cost way less up-front dinero!
I am looking at around $1300 for my batteries.. I suspect that the batteries that you are looking close to $3000.
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Old 11-22-2019, 04:10 PM   #23
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Originally Posted by john61ct View Post
DING DING DING DING!!!!!!


I have a good overall summary on LFP, including links to some good learning resources for DIY.

Needs some updating, cleaning up, so if you start a new thread remind me I'll get a round tuit.

And do please post your potential sources for quality cells, lots of scammers out there sell used as new, or QA rejects as Grade A.

Best is dealing with the factory directly, you def want all from the same production run.
Anything you feel could be useful I'd love to hear, John. I'll make sure to hit you up if you don't post the info on this thread.

As for suppliers, that's very much a concern. Asking me who I plan to go with may not be the be the best option, because I'm shooting blind. There are a number of 'official' vendors on the CALB USA Inc. - Making a large order? page. If anyone has any experience w/ 'em. I'm not sure if dealing w/ the factory directly for 16 cells is doable or practical?
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Old 11-22-2019, 04:15 PM   #24
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I am looking at around $1300 for my batteries.. I suspect that the batteries that you are looking close to $3000.
A bit over @2K for the cells & hardware, based on a sampling of suppliers. BMS I'm still researching but I figure $300 tops. The AGMs I was looking at were Lifeline.
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Old 11-23-2019, 11:00 PM   #25
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Why are people offended by what John said? He’s not wrong. When you start disconnecting car BMS’s and coolant systems for batteries you remove all the safety mechanisms that the manufacturers spend millions to develop precisely because they are not inherently safe.

Lifepo4 is inherently safe. It will probably be the only option until either solid state or that new battery tech from Australia becomes mainstream.

It’s zinc bromide gel I was thinking of, here’s the video I watched

https://youtu.be/yxABosWfuus
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Old 11-12-2020, 09:55 AM   #26
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Hey y'all, hoping on this thread as it sounds like y'all (or @TheHubbardBus) might have more info.

Right now, I'm thinking of getting 2 of these Sok 12V 200AH LiFePo4 batteries for my-almost-entirely off-grid solar set up.

My question is simple and rather silly: how much solar should I have to power these batteries? I think I might be confusing myself when I consider LFP batteries' ability to discharge entirely, when really this rate has nothing to do with the solar array (or correct me if I'm wrong). Right now, I'm thinking of getting 500W in solar panels in combo with the 400AH battery bank.

I'm new here, please don't ridicule my lack of knowledge any help is much appreciated!
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Old 11-14-2020, 05:42 PM   #27
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We "amateurs" who choose to "play" with EV batteries are clearly incapable of doing so safely; so says the official skoolie.net lord god of solar. I yield my time back to John...

I don't see why you are getting so upset over this, John is giving good (and common) advice to someone who has stated they do not know a lot on the subject and do not want a steep learning curve.


I could care less what chemistry you personally use, but everyone who considers non LFP/LTO chemistries should hear about the risks and should make an informed decision. Everyone can make their own choice, but it should be an informed choice with full awareness of the additional risk. There is nothing wrong with caution, and I don't see why its being taken so personally in this case.
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Old 11-14-2020, 05:51 PM   #28
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My question is simple and rather silly: how much solar should I have to power these batteries?
Really has to do more with your Ah per day consumption.

1000W is going to supply about 300Ah per day in ideal conditions (depend on latitude season weather etc)

The only difference using LFP is their ability to accept everything the SC is putting out.

So going to 2000W would actually pay off if you wanted overkill for sub-optimal conditions, like Oregon in winter.

But say 800W as a conservative minimum.

Do not make a habit of allowing voltage to go below 12V

12.4V would be better, or higher for good longevity.
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Old 11-14-2020, 05:55 PM   #29
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Well, I've come full circle.
I'm going to build my own LFP battery after all. Been reading up on the topic since making this post & it appears to be within my capabilities. Plus it sounds like a lot of fun.

2p8s of CALB 100h prismatics, for ~200AH @ 24V. Even when topped off w/ a spendy BMS it prices out to about what a comparable AGM bank would cost, at almost 1/4 the weight. And about $1300 less than the Battle Born batteries of the same capacity, without the excessive parallel connections.

Best of all, while the bus is parked here in the summer, I can easily just pull the pack & bring it inside.

I think you have made a good choice so long as you are willing to tackle the learning curve.


This is a good intro article, and here is a great in depth series on designing and building your own LFP based system


CALB makes 180Ah and 200Ah cells as well, it may be worth considering 8S with larger cells as opposed to 2P8S with 100Ah cells. As John mentioned, be cautious/selective about who you buy from. CALB USA has a list of official distributors for warrantied grade A cells, there are other options that will be cheaper, but there are trade-offs and risks.


What BMS are you considering?
If your max continuous current will be below ~80A-100A continuous the overkill solar 8S BMS is worth considering. The Daly BMS is a reasonable basic option if you don't need low temperature protection.


Quote:
Originally Posted by veglorde View Post
My question is simple and rather silly: how much solar should I have to power these batteries?

While it is important to consider battery bank size in relation to PV array size (or vice versa), I feel the primary consideration here is PV array size to daily consumption. If you have a good idea how much energy you will consume per day, it becomes a lot easier to size the rest of your system.
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Old 11-14-2020, 05:56 PM   #30
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We "amateurs" who choose to "play" with EV batteries are clearly incapable of doing so safely; so says the official skoolie.net lord god of solar. I yield my time back to John...
Sorry I missed this.

Of course there may well be people with the knowledge and infrastructure to DIY those chemistries for this use case safely.

Or who travel only by themselves and are not risk averse.

Giving advice in a public forum, I would rather err on the side of caution.

And speaking for myself with family members around, just avoid.
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Old 11-14-2020, 06:40 PM   #31
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I have a lot of batteries around, most are LiFePo, but I even caught a pack of those on fire a couple days ago being careless and shorting the tabs when I tossed it in the back of my truck. I have a lot of LiPo too for r/c cars, have one on the charger for days now didn't even think about it until just now. They can really be quite dangerous when you are not careful.

And this my friends is NOT being careful, my hacked charger for the battery powered earthquake ratchet..
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Old 11-14-2020, 07:10 PM   #32
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Yes if you are so careless as to short the terminals even old school lead can kill and explode.

Everything is relative, like comparing an alcohol stove vs propane

proper design and care protocols can compensate for inherent danger.

Given the knowledge required (most don't bother) and proper gear (wow so expensive!)
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