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diy solar

diy solar

Roll the dice, battery gamble.

Mattb4

Emperor Of Solar
Joined
Jul 15, 2022
Messages
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Not here.
Probably a Sucker bet but I went ahead and made it. I found 48vDC 100ah batteries for sale on Aliexpress that allowed a choice of either 100A, 150A or 200A BMS. The price is incredible low and the possibility of new Tariffs causing issues during the long (2months) of shipping are another concern. The merchant is a gamble with being recently registered and no feedback. With coupons and the 3% discount for 2 or more batteries ordered plus tax the 150A BMS version is costing me $859.95. Arrival by March 7th. A 48vDC 100ah (dumb) LiFePO4 battery for $430 is a gamble that I will get anything worthwhile. But nothing ventured, nothing gained.

I will update in March how it all turns out.

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Got notice that these batteries are now with UPS to be delivered (says predicted tomorrow (2/7)) however they were in Cali this morning so I would doubt it all the way to AR. More likely will be Monday the 10th. Looks like these made it in ahead of the new Tariffs since no mention is made of owing anything.

Not bad shipping time from China all things considered.
 
Well... after watching UPS ship the batteries to Georgia, Tennessee and back to Arkansas they finally were delivered today. They look OK in the sense they are big and heavy and it is nice to get the additional 10A chargers with each battery. The voltage/charge readout on the batteries LCD screens seems good. Whether they are good in terms of capacity and longevity it will take some use to tell. Were they worth the ~$430 I paid for each one? Don't know but at least they were not a complete fraud. Plus I did not get caught up in the Tariff Wars so that is something.

I presently am charging both up so that tomorrow they can be connected up to my AIO in parallel with my homespun 105ah battery.

Here's some pictures: Note the 2 batteries are reading almost identical for charge and voltage.
 

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Any comms other than the display? Can you see individual cell voltages?
No comms, they are just sealed batteries. I do notice that my clamp amp meter is showing about 4A from the chargers instead of the 10A rating. They may take a bit longer to charge from 78% resting to 100% at 4A. By math it would appear to be 6 hours versus 2.5h if it was charging at 10A and it needed 22ah to be full.
 
Are you gonna do a teardown of one of these?
I'm curious about the build quality and components used...
 
Are you gonna do a teardown of one of these?
I'm curious about the build quality and components used...
Not planning on tear down unless they do not perform. I am curious myself about the build quality but being of limited means I can not afford to damage expensive things for the sake of satisfying my curiosity.

Incidentally the batteries took around 7 hours to fully charge using the supplied chargers. Possibly the ~4A measured charge was caused by the alligator clip connectors the chargers came with. May try them with ring terminals at some point to see if they can output the claimed 10A.

I will be connecting the batteries up in a couple of hours this morning. Been perfect weather this last week to do rewire and rebuild of things solar wise since the weather has sucked big time. (This morning it is freezing rain and thunder). May be a few days until I can actually see how it turns out.
 

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I am curious myself about the build quality but being of limited means I can not afford to damage expensive things for the sake of satisfying my curiosity
I can see at least two others reasons:

1-The curiosity of hundreds of member here 😆
2-Security. If those batteries have really poor build quality, concern can be a fire. Not necessarily cells fire, but terminals, busbars, BMS or leads can cause problem.
 
I can see at least two others reasons:

1-The curiosity of hundreds of member here 😆
2-Security. If those batteries have really poor build quality, concern can be a fire. Not necessarily cells fire, but terminals, busbars, BMS or leads can cause problem.
1. Maybe the 1 or 2 members that read my Threads.
2. Good enough reason. If that happens it will make a dandy Thread in "Up in smoke" Forum :p
 
Minimal padding, about 1" of Styrofoam on the sides. I think 3" of crush zone is safer.
How heavy is it? Lucky the carrier didn't drop it on a concrete floor.

I suppose there is no way to read individual cell voltages (one more reason to open it).

If you charge it CV/CC and plot voltage over time, that should show the first runner and give an estimate of balance. See what voltage it disconnects at, if it does, then apply lower CV to give balancing time and plot current decrease.
 
Minimal padding, about 1" of Styrofoam on the sides. I think 3" of crush zone is safer.
How heavy is it? Lucky the carrier didn't drop it on a concrete floor.

...
It is listed at 26kg or about 57 pounds per battery. However the shipping weight as reported to UPS was 55lbs. I have found that shipping weights are not always direct weight because there is a usage of a size weight (an average weight for given box size) used for some shipments.

The most padding was on top and it was a really long piece of inflated plastic tubes. I agree that more package protection considering it is a higher voltage battery probably would have been best. The one difference with shipping for these batteries over all my previous ones was it was handled through UPS (once it reached US port) and all the rest were FedEx. UPS in my experience has been more careful with packages than the gorillas over at FedEx Ground.

ETA: I think I know why the chargers are outptutting ~4A. On the back they list an input of up to 290W . You can not get 10A of charging for a 290W input to a 48vDC LiFePO4 battery.
 
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Yes. Then you can sleep easily knowing what you have in your home.
Here is one of many example of poor quality build battery: https://diysolarforum.com/threads/u...-pro-power-12v-306ah-lithium-batteries.53381/
I went with rack-mount battery packs with the EVE cells and a proper BMS. The last battery was ordered Jan 8th and all 5 battery cases have arrived but the cells are still in transit due Mar 7th. I'm not sure what impact the tariffs will have and whether a tariff fee will be due before delivery.

The delivered cost (including tax) is about $1200 (cells) $500 (Case) = $1700/(51.8*320) = $0.10 / Watt-Hr.


The OPs' battery costs about the same $0.10 / Watt-Hr.

XR08-48Vwheel PCBBMS, CHINA

16PCS-3.2V 320AH, CHINA
 
I went with rack-mount battery packs with the EVE cells and a proper BMS. The last battery was ordered Jan 8th and all 5 battery cases have arrived but the cells are still in transit due Mar 7th. I'm not sure what impact the tariffs will have and whether a tariff fee will be due before delivery.

The delivered cost (including tax) is about $1200 (cells) $500 (Case) = $1700/(51.8*320) = $0.10 / Watt-Hr.


...
Lets us know how it goes. I do like the case setup that allows you to get all the needed components (minus cells) to assemble your own battery.

5 cases would indicate you are building a huge battery bank if using 320ah cells. 1600ah capacity. ~83kWh!
 
5 cases would indicate you are building a huge battery bank if using 320ah cells. 1600ah capacity. ~83kWh!

Well in actuality there are 3 setups and another SOK 48V 100Amp-hr ($899 delivered in Dec).
Primary Residence:
560Amp-Hr back up for a split (Grid Tied/Battery backed-up essential loads) solar system​
Off-grid Property in Apache County Az:
Primary 220VAC Split phase EG4 6K Watt Offgrid inverter/ 8200 Watts Solar/ and 2x310Amp-hr 48V Rack mount batteries​
Secondary (thermal control center for equipment)​
110VAC EG4 3K Watt Off-grid inverter / 3000watt solar / 1x 320Amp-hr 48V Rack mount battery​
120VAC 9K btu mini-split, water supply filtration, storage​
Travel Trailer
2100 watts roof mount solar​
SOK 100Amp-hr 48V / EG4 3K off grid invertor​

Architecturally the off-grid is hierarchical where 6K 220VAC can be charged with a larger 5K+ generator and can charge the smaller EG4 3K inverter thermally controlled solar/water supply room. The Trailer can operate independently or use a small 1500-watt generator or be supplied with excess power from the 110V Eg4 3K in the thermal control room.

220VAC Generator
-> {6K 220VAC/8.8Kw PV or 110VAC 1500W generator }
-> {3K 110VAC/3Kw PV of 110VAC 1500W generator}
-> (Trailer EG4 3K 110VAC inverter/ 2100w PV }

The property is bare land, and so we will need to develop it in stages starting out with a Travel Trailer then Connex, septic, well ,and then a large shop with a porch and providing for an additional cottage. Turns out the land is cheap ($1.1 acre) the improvements are expenses.

I did not want to do the solar in stages but rather build it out pretty much all at once. The thermal control is for relatively mild summer weather at 6200 ft, but cold temperature swings at night that are usually in the teens.

I think I scored a great deal on 540W Bifacial solar panels (Meyer Burger Panel+ White XL) at $140 apiece. they are brand new factor Grade B factory blems from a German manufacturer producing in Pheniox. they are sold as private label from SanTan Solar.
 

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Some data from the new batteries: During today I was able to observe during charging using a DC clampon meter that for a 72A charge rate at 54.2v reading my 1 year old 105ah rated battery was pulling ~32A and both of these new batteries were pulling ~20A.

That would suggest they are of lesser capacity than the older self built battery but it may be that over time they will get closer as cells get better balanced with usage. The battery cables are all the same length to the busbars and of the same size gauge. I checked for any heating at terminals, cables, fuses and busbars , nothing was detected over ambient during my full load tests of my new 10kW split phase AIO.
 
You could be seeing a difference in cell resistance. I see swings like that between my mix of EVE, AESC and REPT depending where they are in the curve.
 
You could be seeing a difference in cell resistance. I see swings like that between my mix of EVE, AESC and REPT depending where they are in the curve.
I don't know all the factors but I have observed that when I have batteries of different total capacities in parallel that the current demands are split such that the larger capacity battery has more amperage flowing to and from it during operation.
 
I don't know all the factors but I have observed that when I have batteries of different total capacities in parallel that the current demands are split such that the larger capacity battery has more amperage flowing to and from it during operation.
I have seen the opposite once. Cable resistance was that bad
 
As long as it stays nice and sunny I'll update throughout the day.
 

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