understood. i will do the last load test tomorrow. doing the discharge by stick level right now. let see where this lands me! lol

thanks again for all the feedback Steve.

 

You're very welcome... You could express your appreciation by sharing your charger/discharger design with me...

 

ah, lol that's what you meant. i'll see if i can dig it up. it's a long process took about a month for me to build, sort parts, solder, speak unbelievable amounts of profanity. LOL

 

btw, i just realized, i don't even have the installer of the program unless you have controller software this will not work. i am running it on my pentium laptop. that i clone over and over to keep that software alive LOL

the program name is "charger". some russian or asian dude wrote the code and again that would be hell of a time to even track down.

 

While I may not be capable of it, I'm sure the control software could be duplicated by some competent programmer. I'm more interested in the hardware design.


EDIT: and your description of the project "process" sounds exactly like every project I undertake...

 

LOL,

ok i think i have the parts list of all the diodes, drivers, rectifiers, caps and stuff like that somewhere.

but i don't know if i have the diagram - also i think i built my own pcb using the old permanent ink pen on a blank copper board LOL i think there are a total of 6 boards. but i will have to rip my charger apart(undo the superglue LOL, yea it's glued together, i had to just make due with what i had back then) to check that. Think that hardest part was the controller board that connects the computer and back. it was a ***** to find the parts for the communications part. was originally serial but changed over to serial to usb.
now that im talking about it. wow all the memories of burn fingernails and fingers are coming back LOL

i won't be able to redraw the diagrams but i'll see if i can dig through everything

 

so the last 2 pairs -

pair "G" unboxed voltage 11.99 - 5.74/6.25 after full charge voltage 16.09 - 8.00/8.09 settle for 4 days voltage 15.54 7.71/7.82 30 Second Mark at 100a load test @ 6.03/6.06
pair "H" unboxed voltage 12.25 - 6.28/5.97 after full charge voltage 16.21 - 8.16/8.05 settle for 4 days voltage 15.65 7.85/7.79 30 second mark at 100a load test @ 6.02/6.05

previous ones i didn't post

pair "D" unboxed voltage 11.51 - 5.78/5.73 after full charge voltage 16.11 - 8.06/8.05 settle for 2 days voltage 15.72 7.91/7.81 30 second mark at 100a load test @ 6.11/6.11
pair "E" unboxed voltage 11.53 - 5.81/5.80 after full charge voltage 16.18 - 8.09/8.09 settle for 2 days voltage 15.70 7.84/7.86 30 second mark at 100a load test @ 6.08/6.07
pair "C" unboxed voltage 13.27 - 6.71/6.56 after full charge voltage 16.66 - 8.35/8.32 settle for 3 days voltage 15.82 7.88/7.92 30 second mark at 100a load test @ 6.12/6.12
pair "A" unboxed voltage 11.68 - 5.83/5.85 after full charge voltage 16.15 - 8.06/8.09 settle for 3 days voltage 15.64 7.86/7.88 30 second mark at 100a load test @ 6.06/6.07
pair "K" unboxed voltage 12.10 - 6.21/5.80 after full charge voltage 16.33 - 8.18/8.16 settle for 2 days voltage 15.86 7.93/7.93 30 second mark at 100a load test @ 6.09/6.09

and the other 3 from the other post

pair "J" unboxed voltage 13.24 - 7.03/6.21 after full charge voltage 16.23 - 8.08/8.15 settle for 2 days voltage 15.77 7.88/7.90 30 Second Mark at 100a load test @ 6.08/6.11
pair "F" unboxed voltage 11.64 - 5.93/5.71 after full charge voltage 16.42 - 8.25/8.17 settle for 2 days voltage 15.51 7.79/7.72 30 second mark at 100a load test @ 6.07/6.03
par "I" unboxed voltage 11.69 - 5.75/5.94 after full charge voltage 16.36 - 8.11/8.25 settle for 2 days voltage 15.66 7.76/7.90 30 second mark at 100a load test @ 5.98/6.11


so can it be that i got a full box of good cells?

i am doing the discharge and recharge at stick level so it's taking some time but man... was i lucky?

and matching these things are gonna be a b1tch now LOL

 

Your resting subpack voltage variation across all 11 packs is ideally less than 0.1V. 0.2V is usually workable but is starting to suggest imbalance or other issues. The stick with subpacks should vary by less than 0.05V, so you have a few borderline ones, but this is compounded by 2-4 day variations in data points.


However, the loaded voltages are encouraging, particularly the .04V max variation, so we can take a little emphasis off resting voltages. On a stick basis, I'm seeing 5.98 - 6.12 variation under 60A load. That's a subpack variation of 0.28V (assuming both sticks are the upper limits - conservative assumption). That's pretty good for 60A.


We can conclude that they're potentially pretty decent; however, the variation in sit times prior to testing is suboptimal, and SD may bite you in the a$$.


You really need some kind of SD test. what I would recommend is a fixed time/current charge of each stick or subpack following a discharge to 6V/stick or 13.2V per subpack. Input say 0.7 * 5500 = 3850mAh. Let them sit for 7 days and then repeat high current discharge (20A) to 6V or 13.2V. If they are all within about 10%, you probably have a good pack.


BB sticks tend to sit around for some time. Your voltages indicate the sticks were completely discharged via self-discharge. This is generally beneficial to them as it consumes voltage depressed capacity somewhat and can improve IR and SD to some extent (if they self discharge to <4V/stick, you've essentially wiped out all voltage depression and restored near maximum potential capacity). 1C chg/dch (higher discharge is okay) cycling actually can do wonders for cells with SD. I've seen many recover from what I thought was unsalvageable to very workable with grid charging every 3-6 months (8-12 hours overnight). 3-5 cycles would only do good. HOWEVER, these results are usually temporary and will eventually need grid charging and reconditioning via whole-pack cycling.


Basically, the more you put into it up-front, the better your results and confidence of longevity.


What do you mean about matching them?

 

i did want to note that the resting time was different per pack. what i am doing right now is dchg/chged 4 subpacks and doing a 5th. the discharge was to 1v/cell at stick level and doing a charge to 80%(timed at the 42 minutes you suggested before) at subpack level which are landing me exactly in the 3800 range currently. i will have all the stats when done. after all the packs are charged to 70%, i am going to refer back to the date and times that the charge finished at and do the 100a load test next week(7 days) by subpack at +/- 5min difference so it can be almost exact to when the packs were done so it can be pretty accurate across the 11 subpacks. This can get me the data that will tell me which ones i need to deep discharge and cycle to bring back some life.

these were only cycled once, i did a charge to full and then a load test. i didn't do any discharges so far. so maybe that can bring back the balance in all the subpacks.

But given the fact that i didn't do anything else to the packs, it does lead me to believe as you said, there is potential in this pack and if ones that are off by a bit i can try cycling them to see if they can be in a margin where i can match the sticks so there are no uppers or lowers that can throw the computer off.

Also another thing that i am happy about is, most likely i can salvage SOME subpacks from my pack in the car so who knows?

 

heh... I remember that now. You'll find that I frequently forget the details of the thread even when I can just scroll up... Glad I'm consistent with myself.


Provided SD is not a **** show, you can probably just swap out all the subpacks and run the new ones while you test your old pack.


I would encourage you to go all vs. selective as it can reveal other inconsistencies that will eventually bite you in the butt. I know you want to save work, but if you decide to cycle them, do them all - at least 3 cycles before your SD tests.