New little Powerwall in Germany

Klommer

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Joined
Nov 16, 2017
Messages
33
Hey There,
i just wanted to show a bit of my diy powerwall beginning.

I got a bunch of cell of my work and i would like to unbundle them and combine them in a 24V or 48V combination with my existing pv system that has 5,61kWp. Maybe ill use a pip as a simple battery-charger. I think that would work

So this diyPW will become an ac-couppled system.

As you can see on the picture i have two chunks of those big blocks on the left. This are 10Ah LiFePo4 cells, so in total 360Ah == 1188Wh.

image_bymoqd.jpg

Im not sure how ill could implement them, im thinking about a buck/boost converter that lifts the voltage of this block to the "normal" lithium packs. Maybe anyone has done something similar? But thats futurework to do. right now im busy with charging and sorting all cells.


Regards


Carsten
 
8S and 16S configurations of LiFe cells can be used in 24V / 48V systems very well!
 
Not sure what to pitch in on but yes i run 16s LiFe in paralell with 14s LiIon :) So just ask away.
 
Little Update here:

Finally worked it out and got the first cells charged and sorted.

Looks like ill get a 14S43P that will lead to about 6,4kWh


image_almczj.jpg


For the few left cells at the bottom ill need to find additions cells to fit the right capacity.

Maybe 50-100 to fill those up with new ones.

I got a mass of cells that are broken/deeply discharged (0,5V), anyone interested?


image_vfchag.jpg
 
Have you tested the low voltage cells? You will get suprised that you most likely find useable ones in that too :p
 
daromer said:
Have you tested the low voltage cells? You will get suprised that you most likely find useable ones in that too :p

Hello daromer,
Approximately what percentage of cells do you find "usable" under 1vand under .1v?
 
Approximately what percentage of cells do you find "usable" under 1v and under .1v?
Any cell that won't take a charge and maintain SOC for a few weeks/months and don't have much of a usable capacity.
There are plenty of cells that are <1V that can be revived by slow charging (<200mA) and then doing capacity tests on them come out just as strong as ones that at >3V
 
daromer said:
Have you tested the low voltage cells? You will get suprised that you most likely find useable ones in that too :p

No i didnt. Maybe there are some in the bunch of NCR18650PF and also inside the NCR18650A but i want to be sure to have only good cells. I dont want to go into any risks, also if somebody here is saying that no problem no "recover" those cells.


Regards


Carsten
 
If an old vehicle has an empty gas tank (or oil), does that mean the motor is no good? You won't know till you fill it and try it out.
 
I think thats hard to compare.
See, i got a few really new cells that i can use to build a pack. I also got some that are quite low and maybe not in good conditions.
why shall i go for the risk to build those into my pack that maybe will build after a few cycles nasty dendrites and discharge my hole pack? Im not intended to disassemble my pack after 3-4 month again to find the bad ones again. Or do you know how they will behave? Can you guarantee? i can not ... ;-)
 
Under proper charging conditions the dendrites won't appear. They only appear when the cells are continually dropped to very low voltages.

If you don't wanna use those cells, I'm sure there are several on the forum who'd love to have them. Depending on your location, I'd be one of them.
 
Well, im located in germany, so i guess that you are not interested anymore ;)
Ill do a chargeup and measure the capacity and put them then into the marketplace
 
Klommer said:
Well, im located in germany, so i guess that you are not interested anymore ;)

Yeah, that's a little far to drive to pick up some cells :p
 
Klommer said:
Well, im located in germany, so i guess that you are not interested anymore ;)
Ill do a chargeup and measure the capacity and put them then into the marketplace

Charge them very slowly!! Ive managed to revive those exact model ofcells from also about 0.5V and they are testing well at about 2700mAh on the OPUS. I revived them with just about 100mA to 3V. Then at 400mA for aobut 1hr before charging them at 1000mA.
When I revived one at 300mA and then 1000mA from about 2.5V, the cell tested to only 2200mAh.
So take you time. I used my iMax to revive them one at a time.


Im in Germany too so if you really don't want them ill take them off your chest ;)
 
Just a small hint: TP4056 is doing a good job on putting a low current when the batteries are very low and increase that current when/if the battery reach a high voltage.
Otherwise... a lot of us would like to give them a try.
 
The-J-Man please make a video when you charge an 18650 with 1000A :p
 
ROFL!!!! daromer, I didn't catch that when I read it this morning. Yeah, I'd like to see that too :D
 
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