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Everglades Powerwall
#11
A/C isn't necessarily to "cool" the room. It just needs to dehumidify Wink Altho, you could get a dedicated dehumidifier. But, those are usually a bit more expensive and less capacity than an A/C unit. Just get an A/C that has that setting built in, as it has a humidity sensor as well.

I have one, and works pretty well. I didn't use the cooling function until partly into June
Proceed with caution. Knowledge is Power! Literally! Cool 
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#12
One year update... time sure flies when you're having fun! This will be a pretty long post.

Until recently, not a whole lot has actually happened on the Everglades project other than steady progress on the cell harvest. I'm now up to 2065 tested usable cells. Cell harvesting is for me a nice way to wind down after work. Very therapeutic. My supply has been steady, maybe even getting a little ahead of me.

So I know I should be kicked back relaxing at the camp by now with full AC power and ceiling fans blasting. But my biggest flaw is that, given a choice, I can't help but over-research everything. To the point that the "thing" never actually gets done. I'll spend hours reading forum posts, watching YouTube videos, and then follow the rabbit hole researching every idea that piques my interest. There comes a point where I have to either jump in, or move on to something else. Well, I've jumped in... just a little sideways.

My initial plan was to build my powerwall project sized for my needs at the camp in the 'glades. I was going to build it here at the house and test. Then haul it to the camp for final installation. But since I've accumulated so many cells, and we're often without power here at our rural Florida home, I've decided to build instead for an off-grid power backup system here. This will give me a better practical understanding of how to maintain a working solar system. Then I'll be better equipped to install something workable for the camp.

So I'm building my home system primarily as a "grid-down" backup and secondly to power as many loads as possible while the grid is up. The system will be located in the barn where my shop and mancave are. I'm hoping to power all of the loads on that subpanel and will backfeed to the house whenever we have a prolonged power outage. I've doubled the size of my battery from 14s60p to 14s120p which should be somewhere around 14 KwH.

Within the last month, I've actually started buying stuff!

Took a trip over to Sun Electronics in Miami Lakes. Picked up six Astronergy 305W panels at $0.30/W. They're testing well so I'll be going back soon to get some more. 



Also ordered an MPP Solar LV 5048 inverter charger. This is an off-grid hybrid 5000W split-phase unit with two integrated 80A MPPT charge controllers. Can't wait to get it hooked up and running.



Also made the decision to avoid soldering directly to cells in my packs. I ordered the Malectrics Arduino spot welder, and it's working great! Built a little 4s20p pack with lower cap cells a couple weeks ago just for kicks. It's been powering my LTE modem in the barn for over a week without charge. Using a buck controller to keep a steady 12.3 V for the modem. My cheap PWM controller can't charge above 14.4V unfortunately. I'll hook up the iMax B6 to finish it off.

I mocked up a 120p pack today using cull cells. Built a jig for the buss bars which are 3 twisted strands of 12AWG copper in a loop. Should be good to carry 240A which will be plenty if I ever load up the inverter. I'll be spot welding cells in pairs and tying those to the buss bars with either axial glass fuses or 30AWG fuse wire. We'll see what works best.
 

Waiting on a slow boat from China for some other things like an IR tester, shunt trip breaker, etc.. System is coming along slowly but surely.
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#13
I wish to go to get a cup of coffee over there.....
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#14
(10-29-2019, 06:07 PM)100kwh-hunter Wrote: I wish to go to get a cup of coffee over there.....

Come on over. But all I have is cold beer. It's 94℉ (34℃) today ... way too hot for coffee. Welcome to Fall in south Florida. ?
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#15
Just an update on the state of progress...

YR1035 IR tester finally arrived. Big job going back over more than 2000 cells, but it was a real eye opener. More than 10% of my cells were over > 75 mΩ. Many thanks to Wolf for his suggestion. The YR1035 also drastically improves efficiency going forward by eliminating bad cells before they're even tested. Here's a scatter plot of IR in mΩ to capacity in mAh.

 

This set me back a little since I was now short of the required 1680 cells I needed for a 14s120p powerwall. Fortunately I had just picked up 90# of laptop packs from my recycler and there were some quality cells in that load. I ended up with 2317 tested cells yesterday.

 

I then generated my "keeper" cell list by filitering out cells according to the following criteria:
  • Capacity ≥ 2000 mAh
  • Internal Resistance ≤ 75 mΩ
  • Self Discharge ≤ .05 V (min. 7 days - average 3 weeks )
  • Capacity Loss ≤ 20% Rating
I ended up with 1731 keeper cells, enough for my 14s120p plus another 51 to swap in if needed.



Last night I dropped the cell data into Nero's Excel Repackr and was pleasantly surprised at the result.


Next up, actually building the packs.
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#16
Things are coming together. First 5 packs are complete. Busbars, terminal lugs, and nickel strips are done on the rest.


Still lots of spot welding and soldering to do. Over 8000 spot welds on the Malectrics so far. Positive side is fused with 3A axial glass fuses:
 

Negative is using 40 AWG tinned copper fuse wire.


I set up three packs in series as a regenerative source for the iCharger X6.
 

First pack tested at 251 Ah. Was expecting 283 Ah. Not sure if I have the X6 set up wrong, or my Opus chargers have been lying.
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