Valence cell refurbishing and battery pack build

[agniusm]

Cells ripped out of the damaged pack:

Making the shape:

Re-wrap:

Internal insulator replaced:

For consistency:

Beginning:

Placing additional insulator:

Done:

Specs:
Cell: Valence IFR-18650EC 1350mAh (i am a bit confuse as whether this cell is 3.2V or 3.7V nominal or both)
After 2 year use (summer season) gives full rated capacity at 1.5C
(according to unofficial talks, cells are capable up to 8C but i dont know if this is reliable info. If any one knows more please do share, cause i need to pick a BMS, the right power)
Cell holders, tab material and insulation gaskets from supower.
Internal insulation gasket reused
Shrink tube from ebay, PVC, size D20mm, best cut to 72mm. Replaced shrink tube is twice the thickness, feels better.
Thinking of ways to terminate the pack. It will be soldering, but i will use 4mm nicket tab material soldered to main copper bus and cell so minimal heat builds up. I have tested and as soon as you remove soldering iron you can touch soldered surface and it is barely warm, so i assume that cell outer case absorbs heat without doing damage to cell internals.
I will update as soon as i will finalize interconnect method. Good stuff.

P.S. Attached cell spec. Looks like it is 3.2V nominal but can be charged to 4.2V, confusing
Looks like pulse discharge is 7A so 5C for 30 seconds, and 2C continuous max.

View attachment 18650ec_li_ion_cell_3_2v_1_5ah_lifepo4_cells-92334648.pdf

...so i am guesstimating that 30-35A should be the limit on the controller and BMS

 

[docnjoj]

Those specs look like regular LiFePO4 cells. I would follow them and charge to 3.65 only. Great, professional work as always. I love the use of the jig for the outer shrinkwrap evenness.
Great! I'm looking at this thread for the soldering results since I can solder very well but will not buy a new welder just for cells. I have had great luck soldering cells from Nicads in the 1960's through Sony VT from Fatpacks. I hope this goes well and I am subscribed.
otherDoc

 

[dnmun]

you can charge lifepo4 to 4.2V, done it more than a few times myself, but anything over 3.65V is beyond full charge.

i never left mine sitting there after i recognized the voltage was that high so i do not know if they will sustain the 4.2V after charging to that level. i always immediately dumped the charge off the top into a load when i saw it was overcharged.

 

[999zip999]

If using 4mm copper strips. I would like a small hole over the termanil to see solder melt for good contact and faster heat transfur and quiker solder melt. Less heat and maybe a wet sponge on a stick for cooling.
You could stack the strips drill 5 holes.at once. Oh sorry it was a news flash for me. I know you have great building skills. But 5 at a time. Ha ha

 

[agniusm]

Its a bit diffetent design. Copper strip will be the main bar and cells will be connected with 4mm nickel strip to copper bus.

 

[999zip999]

Still think a little hole thru the nickel strip would help heat transfur for soldering ?

 

[agniusm]

Not really needed. The instant you remove iron it is just little warm to touch. It is .1mm thick and takes brief moment so get it soldered.

 

[agniusm]

 

[docnjoj]

subscribed
otherDoc