Compressing cells in your battery builds is questioned in this video.

Terrapin

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I still will clamp my small terminal batteries I am building for on the road or water to protect them from moving in relation to each other. But i will be very light handed as far as deliberate compression given the variables and unknown factors discussed in this video that was based on a thread here on the forum.

 

Bob B

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Too me it seems pretty straight forward.
If you only consider the compression variable, the 80% capacity of the battery is increased from 2500 with no compression to 4000 with compression.
That is a 60% increase .... it is pretty simple to install springs to keep the pack in the optimal pressure area .... seems like a no brainer to compress with springs.

The other discussion that goes hand in hand with the acceptance of the fact that these cells expand and contract under normal use ..... is whether or not to use flexible bus bars.
 

Terrapin

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Too me it seems pretty straight forward.
If you only consider the compression variable, the 80% capacity of the battery is increased from 2500 with no compression to 4000 with compression.
That is a 60% increase .... it is pretty simple to install springs to keep the pack in the optimal pressure area .... seems like a no brainer to compress with springs.

The other discussion that goes hand in hand with the acceptance of the fact that these cells expand and contract under normal use ..... is whether or not to use flexible bus bars.
If I thought I had a way to accurately measure the pressure and maintain the optimum 12ft/lb I think this is a very good idea. I just don't have that capability.

But as long as I have your attention on this, what is your opinion on using these bus bars in 8mm hole size with the eve style 6mm batteries. I assume there would be very little contact loss. but I'd be interested in what you think?

Hmm... an air bladder maybe could keep a fixed accurate pressure. Something like a small innertube for a wheelbarrow between the closure wall and a second stiff board/plate against the battery it self. It would be really easy to fill to a specific pressure one you calculate the area of the battery side and convert from per SF to per that area.... The mind wobbles....
 

Terrapin

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If I thought I had a way to accurately measure the pressure and maintain the optimum 12ft/lb I think this is a very good idea. I just don't have that capability.

But as long as I have your attention on this, what is your opinion on using these bus bars in 8mm hole size with the eve style 6mm batteries. I assume there would be very little contact loss. but I'd be interested in what you think?
Hmm... an air bladder maybe could keep a fixed accurate pressure. Something like a small innertube for a wheelbarrow between the closure wall and a second stiff board/plate against the battery it self. It would be really easy to fill to a specific pressure one you calculate the area of the battery side and convert from per SF to per that area.... The mind wobbles.... Now off to seek that easy spring solution you suggest.
 

Bob B

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I had thought as the aid bladder as a possible solution as well .... but wasn't able to find one I thought would be suitable.

If using the braided bus bars, it doesn't seem to me to be necessary to have the elongated holes. I plan on making some myself and making them a little longer than necessary so I can have an "expansion bump" in them..... sorry, couldn't think of a good term. I have a shop press which should do the job and just need to get some annealed copper pipe or anneal some myself.
@upnorthandpersonal has done a thread about how he did his.

If you read thru the thread below, you will see quite a few who have done this with specific spring part numbers and the math for how they should perform.
 

Gazoo

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I have watched the video. I think I would prefer to trust the manufacturer and everything they said regarding compression. Personally I am not going to worry about it. My battery is mounted in a fixture using plywood and threaded rods. It is lightly compressed at a full SOC. I do understand the importance to limit movement in mobile environments but mine are stationary.

If a battery is fully cycled each day, it will last for 6.8 years and still have 80% capacity at the end of 2000 cycles, possibly longer depending on C rates. I am more concerned about the stress on the cell terminals using solid busbars and am looking at other options.
 

upnorthandpersonal

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these cells will lose 70-90% of their value in 5 years because newer technology will make these old news.

If solid state batteries truly become available and affordable, maybe. However a kWh storage is a kWh storage for solar applications, and with the minimal overhead running these, it will still be a valid choice 5 years from now. That said, I would not be surprised there will be a shortage of raw materials due to increasing demand and the price might even go up.
 

ArthurEld

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I crack up at the 25 year warranty on solar panels. How much is a solar panel from 25 years ago worth now. It is probably something you would have removed 10 or 15 years ago.

edit: I changed the subject again. :sneaky:
 
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upnorthandpersonal

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I crack up at the 25 year warranty on solar panels. How much is a solar panel from 25 years ago worth now. It is probably something you would have removed 10 or 15 years ago.

I don't know - if it works, and it's installed - very little maintenance or additional cost to just keep them where they're at.


Besides, solar panels weren't widely installed until the early 2000's, and many of those are still running today or are only now starting to get decommissioned. If you install a 10kW array on your roof today based on current energy needs, and you can lower your needs over time by installing more efficient appliances, there is no need to change the array if after 20 years it's still producing 80% of what it started out with. The system is paid off.
 

ArthurEld

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I'm sure many people will keep using 25 year old solar panels. But you will have the option of replacing 25 old ones with 3 new ones. lol
 

DerpsyDoodler

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Exactly...first start upgrading controllers then start replacing panels with newer higher producing modern ones. just do it out of pocket a little at a time.
 

Bob B

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I guess I'm not like most people ..... I keep things til they fall apart .... and can't be put back together because they are too rusted .... oh, and I do a lot of rustproofing with fluid film.
If you've got a perfectly good DIY battery, I don't understand not wanting to get as much life out of it as possible.
If I'm still alive to be using mine, I plan on using it beyond the point where it has 80% capacity.

I suspect that as these batteries get more and more popular they will get more expensive. I could be wrong, but it seems to me they are a low price point that will be going up.

If they come up with something that is 10 x more energy dense and is also cheaper ..... I won't replace mine til the bus bars fall off.
 

ArthurEld

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People have to take off the panels and racking to replace shingles. Some of them will put up the latest.
Solar farms replace panels every 5 years. I don't think they treat them worse than we do.
 

Terrapin

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I guess I'm not like most people ..... I keep things til they fall apart .... and can't be put back together because they are too rusted .... oh, and I do a lot of rustproofing with fluid film.
If you've got a perfectly good DIY battery, I don't understand not wanting to get as much life out of it as possible.
If I'm still alive to be using mine, I plan on using it beyond the point where it has 80% capacity.

I suspect that as these batteries get more and more popular they will get more expensive. I could be wrong, but it seems to me they are a low price point that will be going up.

If they come up with something that is 10 x more energy dense and is also cheaper ..... I won't replace mine til the bus bars fall off.
I am with you. I take tried, tested, paid for as the best value. What, a few years ago a few100 amp cells were plenty for a trailer like mine...80 % of 280. Is still going to run what I need. I won't retire a battery till I can't afford charging equipment because it's not on the market anymore or it can't pull it's weight vs my needs. Same with my trucks, for 90% of them I am the last owner they ever have.
 

Terrapin

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My batteries aren't cycled every day so they will last 20 years unclamped.
I agree with the video that these cells will lose 70-90% of their value in 5 years because newer technology will make these old news.
This was why I wanted to share this, Knowing how it will affect things lets people make informed decisions based on their needs.
 

ArthurEld

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This was why I wanted to share this, Knowing how it will affect things lets people make informed decisions based on their needs.
I like the fixture with threaded rod. But there are so many problems caused by using the fixture improperly that I have my doubts about whether it is worth learning.
People need to concentrate on making a safe battery and the fixture seems like a distraction.
 

Terrapin

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I like the fixture with threaded rod. But there are so many problems caused by using the fixture improperly that I have my doubts about whether it is worth learning.
People need to concentrate on making a safe battery and the fixture seems like a distraxtion
Guess I got to read even more.... but F#&$ yeah safety is job one!...
 
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