Battery replacement

Alternative energy sources
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The usual. As I have two large solar PV systems here, and my lab assistant just put one in, and others are interested in things like this, here's where that stuff goes. This is mostly for things that work now, not "gee someday a fusor will do this" -- we know that, but it's not someday yet.
The hope is to save anyone embarking on this sort of thing a lot of wasted time and money, as at least I have been off the grid since 1980 and have had a lot of practice (and made mistakes you won't have to).

Battery replacement

Postby Doug Coulter » Sat Mar 31, 2018 12:16 pm

During an unusually long and unusually cold spell, my main batteries "failed" - after ~ 18 years in service. That doesn't mean "dead", what it meant to me is that they dropped below 24v under a 100 amp load early one morning (microwaving that cup most of us have in the AM) having been fully charged the night before (the sun wasn't up yet either).

This is kind of analogous to a car battery failing in the cold of February - darn,if we just made to March, we'd make it to November, as all these work better in the warm. Oh well - I'll maybe put the best of the old ones into another system I don't use much - but which can back up the main one in a pinch (buried wire with 120V can push power either way and run a battery charger).

At any rate, I kinda panicked and ordered a new batch of lead-acids (newer tech is mostly a pipe dream so far, you can't buy it for a reasonable price per WH, if at all). Not cheap...$7800.
I'd ordered 1300 ah cells, but they shipped 1800 ah ones at no extra charge and they paid shipping - no complaints here. (Wholesale Solar) You can tell them I sent you. I also bought some nice panels to replace a few of my older ones and gain around 1kw of output (more on that when I'm putting them up) and like the batteries, the old ones can go on the backup system (for a storage trailer I have). Or who knows. I could divvy them up between the east and west sides of the shop and pick up a few more sun hours on lots of days - just postponing the time things start to discharge can be a real big deal especially in winter.

The new ones look real nice:
20180331-1255-battery-1.jpg
Near the destrination, and uphill from there - important when you have > 1 metric ton to move by hand.

I spent this morning making those really nice and beefy copper terminal blocks for the new guys, all nice and tapped holes and so on. You want this to be easy to do and mistake resistant...

I also did some improving on the box, as it should be more insulating and it's pretty old now - OSB lasting > 20 years outdoors isn't too bad but...
20180331-1256-battery-2.jpg
A new front door that's easy to remove.

The old one was pretty beat -
20180331-1259-battery-6.jpg
TOO easy to remove - it came off in my hands.


So, all these nice puppies gotta move (ugh) to make room for the new guys. These were nominally 1080 aH total.
20180331-1256-battery-4.jpg
The main set of old ones

This wasn't all I had in the box. In the next compartment over was a bank of L16'S and a couple of deep cycle trolling batteries contributed by Bill to the cause to keep me going till now.
Those are all new enough that they should match well enough to stay and be in parallel with the new ones, but of course I'll check...

This is kind of the dirty underwear of that box. 2 inverters and a small charger (modified from one for a forklift - ferroresonant) as well as a raspberry pi and arduino that take data and make plots for my LAN, as well as control the water pump and fan on that big Lister diesel.
20180331-1258-battery-5.jpg
The upper inverter only runs my 5hp air compressor and can serve as a charger in an emergency - all the backups have backups.

After a glitch on that upper inverter (a square wave one) involving mouse pee and such, I just left the cover off. Now they don't have place to rest and pee without getting hammered with the HV.
The lower inverter is a sine wave one - Trace SW 4024 - that's run 99% of this place for many years, and is heating me a shower right now. Those things will easily make huge peaks - short it with 20' of #16 for a huge ball of plasma. Dead short it and it shuts off in mid half cycle without a spark. Pretty cool.
I now have a larger 240v one inside with the charge controllers for the big machines and fusor power as well - same brand (now Schneider electronics). This is a case where these are just better than what even a really good engineer would do for himself.

While I was at it, I put a new back wall on there too - the old one was getting weak, and I just slapped this on top of it - as well as adding some thermal insulation. The little Wen gennie runs the forklift charger, or my chainsaw etc. Those little inverter generators are nice - and worth the extra bucks in reduced hassle alone - they are FAR easier to start, use tons less fuel...clean output...if you use a gennie any amount - this is what you want. The old 3600 rpm hardware store ones make good boat anchors and doorstops, I hear.
20180331-1256-battery-3.jpg
A new back too - and better insulation not shown. The little Wen replaces that Honda I had, which ate a broken piece of sparkplug ot it'd still be in use - and the best ever. The Wen is good for half the bucks...
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Battery replacement

Postby Bob Reite » Sun Apr 01, 2018 4:33 pm

Did you consider Nickel-iron cells? They last nearly forever. The energy density is real low, but you've got lots of room.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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Re: Battery replacement

Postby Doug Coulter » Sun Apr 01, 2018 8:19 pm

Yes, and I've owned both in the past. Both let me down in various ways - NiCds especially do go bad, even the flooded ones (or maybe especially those). Got a batch retired from locomotive service that didn't meet specs by a very long way, and had some cells fail. Used, they were $2700 for 120 amp hour rating (80 achieved) at ~~ 24v Had to use home-brew inverters as nothing commercial then really worked at that much wider charge-discharge voltage range.

I consider dipping into those hugely expensive (even used) and dramatically under performing batteries to be one of the two times I've been seriously ripped off in alt energy. The other was Ovshinky's amorphous solar cells. Which never met spec but the lifetime warranty was no good as the company went out of business before the ink was dry while the good doctor absconded with the VC money.

The NiCDs hold the active metal particles as plating on carbon or ceramic dust in sacks in the cell. Those sacks get eaten through same as LA plate grids and it's game over for the same reasons.

I'd do redox batteries if there was a decent substitute for Nafion, which does seem to be in the works, but is always "maybe next year". Those keep getting better choices of the chemicals and yes, I do have the space and the ability to control the interesting pumping situation and logic.

Meanwhile, these good ol LA's have just been working and working and working...
All of the inverters and charge controllers only work with some variation of lead acid; that you can buy, the Tesla stuff you can't buy says it works with LiIon...but you can't buy it in real life. They keep announcing it's going to be available...but it never gets here. Per WH, it's hugely more expensive...

These as just delivered
45120Wh/$7800=5.7wh/$

18650 cell (other packaging costs omitted)
10wh/$4= 2.5 wh/$.

Back when I did them, NiCds this size were around 8x the cost of lead acid.

In real world tests here, good quality batteries of pretty much any type (treated well) give you around 1k full cycles. Lead-acid (the sort designed for deep cycle, not lead-calcium or AGM) scale linearly - 10k 10% cycles. Other types, not so much. Believe me, I've checked and tested and really wish it were otherwise...these bucks would have bought a lot of other fun.


Redox - no one will sell you a home sized system - they will sell you skyscraper size and it comes with an engineer you have to pay - and at the moment, ongoing license fees. You could DIY if you could get the all important membrane that lets H ions through but not electrons (Nafion: https://en.wikipedia.org/wiki/Nafion). No small trick, it's super expensive stuff and a gander at the chemistry and synthesis says why. The stuff for my peak needs would cost more than these batteries - which are likely to last longer than I do. Then there's the tanks, pumps, and other plumbing.
The vanadium oxides version has been tested here on the bench and is interesting, but using filter paper it doesn't last long...The colors are cool.

It comes down to total system costs and availability...
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Battery replacement

Postby Bob Reite » Wed Apr 04, 2018 11:34 pm

Did you have NiCd or NiFe? I would not consider NiCd at all practical.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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Re: Battery replacement

Postby Doug Coulter » Thu Apr 05, 2018 8:16 am

I had flooded NiCd from locomotive service. Couldn't find NIFe. From my experience I'd bet those long lives were in float service, like those PbCa phone co batteries that go 40+ years.
One hassle with potassium hydroxide electrolyte, even with oil floating on top is that it grabs CO2 out of the air and ruins things....

Another issue with well, all existing electronics for this stuff (around $10k worth here) is that the voltage range of NiCd at least - .9v/cell to 1.56v/cell is way past what they can adapt to for any number of cells to approximate 24v nominal.
Say 24 cells. So that takes you down to .91v per or so for the universal 22v safety cutoff. Now at full charge we have 37.44v, FAR past what will fry any inverter or charge controller (they go to 30v or so, tops).
I'm not expert on the values for nife, but just kinda gave up on that stuff...
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Battery replacement

Postby Doug Coulter » Thu Apr 05, 2018 4:54 pm

Well....that's done and seems pretty good. I left out a little of the complexity on re-wiring it all, because...do I really need a separate low current 24v feed on poorly buried wire up to the shop to run nightlights, perhaps just in case the other stuff fails - none of which has ever failed since 1980 or so (oh no...I said that in my out loud voice).
So, looking pretty good now.
Curtis Faith is back in town and did the heavy lifting on this job, and a real big thanks for that - I'd not have managed. We used the tractor to pull the hand cart uphill with the old (red) batteries, maybe we can get someone on Craigslist or something to come get the old stuff...

And of course, we'll see tonight how things go with the new guys. The vacuum system was a little bent out of shape being powered down for the 5 hours or so this took to do, and is still hunting around on the turbo power, so I had to set the forepump trigger power way up for now...it'll just have to use some extra power tonight till it all gets normalized again..it was 4e-7 mbar last I looked....
So, the pictures or it didn't happen:
20180405-1751-battery-1.jpg
installed

20180405-1752-battery-2.jpg
A forlorn 2v spare for the old guys, died a virgin

20180405-1752-battery-3.jpg
The old guys. Anyone want 1k amp hours nominal at 24v bad enough to come and get it.


So, testing....
Everything on the LAN came back up with the exception of a pi on it's own UPS but wireless and it all got confused about DHCP...
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Battery replacement

Postby Doug Coulter » Wed Apr 11, 2018 6:41 pm

So, some data. It took awhile for the vacuum system to start acting right again after a day of off...and I then left the air compressor on all night...but the new guys stayed above 24v - and most importantly, the integrated amp hour curve stopped climbing at 50ah+ per day - that was a huge fraction of my energy supply going up in ... hydrogen, whatever.

So, a couple curves. On the first night with the new guys, the volts curve is flat - a nice marker.
bats.png
Plot of a week of data (part of the LAN of things)

Screenshot at 2018-04-11 19-33-59.png
Taken just now, some days later


This includes charging up the Volt twice - you can't really tell from the plots that easily, as they show net battery current and so on. I've yet to add shunts that see all the innies and all the outies as separate things. I did get one of those cheapo logic analyzers (~$15) and my reverse engineer the "Xantrex bus" my electronics use for most of this...but since I have too many (poor me), they can't all be on that bus (horrible design on their part - publish-subscribe and no backoff for collisions) and even that wouldn't do it all....
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Doug Coulter
 
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