LiFe P04wall

Joined
Aug 10, 2018
Messages
242
Lifepo4 cells recovered from electric bikes or 12v batteries

Tested and tested with OPUS 0.5A
Cells with Ah between 0.9 and 1.6.
Average well above 1Ah but will be considered as such.
Nominal voltage : 3.2V
Full charge voltage 3.65V
Set maximum effective charge voltage 3.5V

Inverter 24V
Charge controller for lead (very lead-like curves) 24V

Test system :
Balanced charging with ISDT T8 loader/bms

Discharge with inverter and 250w sampling to verify the yield of the system in "average" conditions

BMS:
1S balancer on single series with discharge of 1.6A max at 3.6V

In test also 16S balancer (in case of 48V) that will be used at 8S only.

Future test of a real BMS with lower balancing currents but completely "different" parameters. Maximum charge and discharge 20A.


Accumulator configuration : 8 Series 80 Parallel (8S16P5P)

5P:
The parallels are made by spot welding 5 cells with cheap welding machine bought in Germany.


16P:
Each parallel packet has a fuse on the positive, which in case of absorption/erogation of more than 3A jumps (fastblow)

8S:
S are mixed together with the parallel of the 16 blocks of 5 cells.

To do: 8 packs like this when time will allow.

Accumulated energy :
80ah x 25.6V = 2048 Wh
Maximum project peak :
3A * 16 *25.5V = 1.22 Kwp
Expected peak at full speed for each package :
3000w / 8 = 375w

Parts:
Holder 4x 18650 =32 pieces
Fuses 3A = 144 pieces
Cable 4 Msq = at will
Nickel strip : 30 meters
Hours : various


image_vqnoqd.jpg

image_hkalgn.jpg


image_pktfbw.jpg

image_etcwkt.jpg
 
384+cartridge (5P) - overall average 1080 mAh per cells

image_mkfkda.jpgimage_qdoprr.jpg


image_fugfti.jpg


now is time to build firsts 6 kWh

Code:
mAh 	pcs	ah	wh
3000	15	45	144
4000	40	160	512
5000	151	755	2416
6000	149	894	2860.8
7000	40	280	896
			
Avg mAh |Tot. Pcs |Tot. Ah	|Tot. Watt/H
5.403	|395	 | 2134	|6828.8
Avg Cells			
1.081
 
Nice!

Note that you wrote BMS but then you talked about balancers. Its not the same thing. A BMS protects and notifies as well so you should divide that upp. You need cell level protection in first hand not balancing. And most likely not 1.6A balancing. When you need to balance that much you have an issue. With that said its not bad to have the capacity.
 
yes Daniel, you're right.

i haven't updated first post.

i was trying a balancer, then i've changed my mind.

actually thinking about a diy balancer /monitoring cells and then some kind of safety.

in first pic my thermal cam Seek Reveal

i have i think around 300/400 kg of lifepo4 to open test and assemble... but it's a long work
 
How do you know they're all LiFePo, some cells seem to have very little information printed on them and look like "chinese" Li-Iions I found in generic Laptop packs.
 
emuland-metroman said:
384+cartridge (5P) - overall average 1080 mAh per cells

image_mkfkda.jpgimage_qdoprr.jpg


image_fugfti.jpg


now is time to build firsts 6 kWh

Code:
mAh 	pcs	ah	wh
3000	15	45	144
4000	40	160	512
5000	151	755	2416
6000	149	894	2860.8
7000	40	280	896
			
Avg mAh |Tot. Pcs |Tot. Ah	|Tot. Watt/H
5.403	|395	 | 2134	|6828.8
Avg Cells			
1.081

on that third picture I see a cell with ICR 18650 3.7V on it, I think they might be Li-ion and if so, you're testing could be totaly wrong
 
working project now 4 24v 8s 60ah each atleast ++++ 24v 360 ah lead acid.... i'm trying to charge them together (day check of what's going on because of i'm pretty jobless at the moment in italy.... as a freelancer safety teacher...) they are disconnected from charge, while lead go on bulk stage (over 30v) then when lead go on float they come back to finish their charge.

i have to spotweld the missing 3000 cells (2000 in that foto)
lithium charge up to 28.4v and then

image_vfgnrs.jpg
 
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