diy solar

diy solar

My journey FLA, AGM, LiFePo4 XW4024, Midnite E-panel, 4KW Enphase, 4-Overkill BMS, 4S 8P EVE280

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EVE 280 LiFePo4. No more lead in 2021
Joined
Jan 24, 2021
Messages
81
PART 1
I thought it prudent to at least begin my progress thread.
January/February of 2010 was the start of my journey with a massive week long ice fog, followed by a brutal Montana low/Alberta clipper/blizzard which knocked power out for weeks in some areas. We had highline towers fold like pop cans. Secondary poles snapped for miles in areas. It was ugly. To add insult to injury, the 6-8ft snow drifts, bitter -30*, no travel, no power, and no fuel made matters worse.. I managed to drain enough fuel out of everything (car, truck, lawnmower, snowblower) to keep the genny going a few hrs a day. It was ridiculous. Cords strung all over the house. Tripping genny breakers. Mass chaos..
Phase 1- My goal-24hrs of heat
I bought a Xantrex HF 2000W? series to at least supply our NG furnace with power. It was great, but not enough battery and the wrong kind of battery. (Mechanic at the time, so repurposed a number of old car and truck batteries to suit) I learned quickly, this was insanity and simply wasn't working...
I had been following the solar side of things for some time and became fond of Xantrex.
Spring 2010
Phase 2 -GOAL-2-4days of backup power

-During my annual junkyard crawl for hidden treasures, I found a 510Ahr, 24V forklift battery at the junkyard .. Retired for obvious reasons, but for the price, I load tested it with the old carbon pile tester, and I brought it home.
-Purchased my first REAL inverter charger, the XW4024 < I wish I had went straight to a 48V model now, but, I had a 24V battery.. Live n learn.
-Purchased a Airbreeze 400 W < hind sight is always 20:20. It did alright, but I could have spent that $$ on solar and been farther ahead.
-Outfitted a backup loads panel with the basics. Fridge, Freezer, furnace, a few lights. That cheap FLA battery was a perfect fit for learning the basics. charging, testing, maintenance, equalizing, etc. As time progressed, so did my backup loads. TV, Computer, Microwave, bedrooms, bathrooms. Funny how that works. Somewhere in the middle and a year or 2 later, that poor old forklift battery started showing it's limits. It had a hard life before me, and I didn't do it any favors being a newbie. Overcharged, Undercharged, Over-discharged. If it had been an AGM, I would have had fires.. Many many fires.... And probably and explosion or 2.


To be continued.. April snowstorm night #2 on snow removal duties.
 
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2012
with my poor old fla forklift battery beaten to very near death, another treasure trove was found at the local junkyard.
AGM BY ENERSYS
A fresh pallet of retired telecom 12 volt front terminal batteries from the phone company. Load tested and brought home 36. Quite the truck load. Recharged them all and chose the strongest 24.
Built a vertical steel rack, 6 shelves, 4 per shelf (2 strings/shelf). Built some beefy aluminum busses to handle 500a max (another junk yard find) and assembled my bank. All 12 strings were protected with a 100a breaker and fuse with 4awg wiring to 2 main +/- buss bars. From the busses, 4/0 cables to the 250a main e-panel inverter breaker.
This worked very well until individual battery voltages started to stray.
QNBBM-12V
i purchased 6 of these active balancers. I have to say, they do the job very well.
i wired them up to balance 2 strings per pair using a 500mA fused center tap down to each string.
But as time went on, AGMs dry out, sulfation, and age started to show.
Slowly but surely, cells had to be retired.
 
2021
Began with only 3 pairs of these AGMs left. Until our last 48 hr power outage. Apparently, 2 more batteries were well past their lifespan. So now down to 4 batteries, with only 1/3 of their capacity left, it's time to do a major upgrade thanks to this forum.
 

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LiFePo upgrade
I ordered 16 of the 32 I required cells from Aimee Lee at Basen.. There were too many questionable battery reviews at the time, so I ordered 50% of what I needed as a test run.
All arrived in 47 days. Beautiful cells. Immaculate for the most part with only a couple very small "tape overs" where the wrap had been damaged.
Series charged to 3.5V BMS cutoff, then parallel top balanced both 8 cell packs to 3.55 Volts. I don't intend on pushing these to their limits. 3.55 IMHO is well inside the upper voltage curve and should suit my needs well.

2 BMS's from Overkill feed a large aluminum bussbar. 4/0 cable from buss to the XW's 250A breaker.
Positive leads are 4 awg to 2 100A breakers in the E-panel. .
 

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Nice! I think I'm going to steal that battery bay light idea. I'm tired of using a flashlight.

Are you going to add solar next?
 
I used a couple cheap 24" 12v auto led sticky strips wired series for 24 volt on a simple toggle switch. Both BMSs are also switched, just incase.
Currently have 4kw enphase, which backfeeds the XW.
Hope no one minds the 2 - 4awg wires leading left. They're the temporary leads to my soon to be retired AGMs.
 
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Curious if that metal you used for containment was something off the shelf or custom fabricated?
 
The cabinet is an off the shelf unit with shelf capacity of 210lbs. I reinforced the underside of the shelf anyway..

Compression endplates are 3/32" plate with a 3/4" lip. I'm ex oilfield so had some "kickplate" left over from various hardrail repairs.
I have a local fab building a better, more rigid set (full cell height) with lip top and bottom. It's cheap. $30 for a 8ft piece.
1/4" all thread hand tightened with a nut driver at roughly 50% SOC.. Upon charging to full, I could hear them creaking as they tensioned from expansion..
Lined the shelf floor and the compression plates with simple foam "drawer liner" from Walmart. $10 per roll x 2.
 
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Capacity is good. 280ish. 2 bms's and a coulomb counter confirm 276, 278 & 284 respectively.

I should have top balanced to a higher voltage in hind sight. The same cells that bottomed out on discharge were also lagging at the top end of recharge. Today I spent nearly 10 hrs fine tuning the top end series balance to 29.1V or 3.633V per cell with my trusty old headlight bulb and jumper leads. It's surprising how a 1/2 second contact can drain 2mA, but it does work. They'll sit for 12 hrs to see where they settle to overnight.

My "fixture" was an interesting food for thought. With batteries at empty, the nuts were barely finger tip tight. 50% SOC nut driver snug, at 100% a small 1/4" ratchet tight. So with 2 sets in 1 fixture, I think I'm close enough to the 600KG EVE calls for in their documentation.

I did not expect the batteries to generate that amount of heat during discharge and recharge. I saw a climb from 18* to nearly 36*C. My cabinet will need some forced air ventilation before I install the doors. Maybe I'm overly concerned, I don't like heat in closed spaces.
The old XW4024 got up to 55*C during its 4 hrs of recharging at 140-150A too.

I have been experiencing some connectivity issues with the Overkill BMS's on android. "get device info fail. Please retry " It's weird. I connect for hrs on end, switching to either of the 2 BMS's with no issue, and out of the blue, I get nothing but connection errors, time outs and app crashes. 30 mins later, it's all good again.

I still need to tweak the 80%, 60%, 40% and 20% SOC voltages in the app as well. The preset SOC voltages were quite inaccurate compared to actual Ahr capacity. I have my 1st run numbers, but some additional data logging will nail it down enough to share with all.
 

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All is well. 3 forced cycles and all is stable just tweaking system settings.
I wish my xw had a broader setting range for bulk (min 27.1v) and LBCO(max 24v), but It'll have to do. A setting resolution of .1v is also problematic. The BMS's shouldn't ever have to act but are there just incase.
My goal is to maintain my UPS/battery backup at 50-80% SOC through my 4kw enphase solar, grid connection and some load shifting / charge blocking daily.
It will take time and numerous minor adjustments..
It sure is nice having 4x the power of what my old AGMs had left to offer. That's only 2 strings in place. To think, my design calls for 4 strings of 280s. That'll be 8x the storage. LiFePO4 is an amazing tech.
 

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My AGMs are officially offline. Now to work up some ambition to haul out another 550 lbs of dead lead.
Doors are on my battery cabinet.
Installed a simple breaker bypass/precharge.
Wired around the main 250A breaker through a 6ohm 25W a simple 5A momentary push button. (resistor left over from a led install on the wife's car. Momentary switch from a rocketry project)
Still tweaking settings on the XW4024 and working on a cooling fan for the enclosure.
Working on Aimee Lee for another 16 - EVE 280s

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