Leaf Testing & Capacity

Very new to Second life. Wanted to ensure i'm doing at least something right. If not, please help guide me. To follow i will photograph and document my current process. These (48 Packs or Modules)will eventually be the startof my power-wall. After seeing this forum and current test findings i have come to the conclusion that as i add to the wall (Later) it will be in the form of 18650's. $'s to usable capacity seems to repeatedly bring me back to this conclusion. I wish i would have found this forum prior to jumping into the fire. As progress moves along (slowly) i will continue to update progress and anyirregular findings. Charging and discharging takes hours and hours, with the necessityto be present (Safety) it makes it even longer.

My goal? Through my actions-mistakes-and success, tohelp the next person simplify this.

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Step 1: Unboxing-checking voltage-and initial charge.
Seller shipped at 8.0v, so far 15 deep they have been received between 7.88and 8.01v (i believe that is good)
Cell balance (2 in parallel) have also been acceptable (i believe) from 3.94 to 4.01v each individual module has been within .01v on balance check.

I then did the first and only full BALANCE charge. Performed at 4amps. This alone takes 5 to 7 Hours each FYI. Using the B6 charger as shown.
So far the charger has displayed Mah results of 11,000 (+ or -8v shipped)roughly to 19000 (single 7.88V Shipped)roughly. Most are 11-13000Mah







My solders waiting there turn for discharge.

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Step 2: Discharging. After resting for 4-8 days depending on my schedule. (Not immediately)
I used 2each 12v Halogen 50w light bulbs as the load through the shown meter. At this point i recorded the voltage start from the meter and discharged to 6.5v for testing. The meter quits at this point. This is how i recorded the Wh capacity of each. Below is initial hook up.





Below is after 1 Hour of discharge

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Step 3: Bottom balancing.
Voltmeter was set to engage at 2.65v and disengage at 2.5v. More on this to come. Goals here are to get as close to2.95v as possible after resting. I have seen so much information on this that i felt i should do it. I'm sure the people on this forum can give perfect explanations for doing this as well as NOT doing it. Being new i felt it wouldn't hurt. If anything another data point, and a better test result of capacity whencharging to 8.1v for storage and comparing battery performance equality?
Below you will find set up and equipment (ALL FROM EVTV MOTORWERKS)

Step 4: Charging for storage? and build plans. My charger will only charge to 4.05v balanced.Ihope this is okay. Ideally i think i should be going to 8v. i charged them this time at 6amps to reduce time. This is only 1.25Amps per cell so i felt it to be also okay? Do to the delay of the build i will also be able to get a true data point of any self discharging. I truly don't know what the seller did prior to shipping or how long they have been at rest.





Below are charger screens I chose the isdt t8 because of its abilities and amount of info you canget while it is working.

Most recent data results. At first i was recording Volt-amps and calculating energy every 30 min (in gray: batteries 1 through 4). Then changed to meter as shown above. Empty spots or unknown are errors playing with computer and stopped process only to continue without info, had to leave etc etc etc. I suppose as long as those fall into similar results from the remaining 2 tests i can assume they are also similar in capacity, and performance. BATTERIES 12-13 and 14 are raising some questions already. i'm hoping it was user error maybe fast charging vs Balanced?

Attached is a capacity test report of one of my cells for comparison

The batteries are 64 amp hours when new

Yours seem to be testing pretty low

I have 4 packs from 4 carsand all cells range from 53-58 ah

farmerjohn said:

Attached is a capacity test report of one of my cells for comparison

The batteries are 64 amp hours when new

Yours seem to be testing pretty low

I have 4 packs from 4 carsand all cells range from 53-58 ah

Click to expand...

Thank you: Part of the reason i posted my testing methods. Yes i waslead to believe i would be in the near 80% life not 60% range. Not much i can do now. Your graph and your ah is what i thought i was buying. Huge lesson learned.

Where did you get your cells from?

I got mine from a quy in Quebec Canada - I live about 7-8 hours away from him and he delivered them to my house for about $120 Canadian per module

So far its been very worth it for me.

Even though your cells have less capacity does not mean they are no good - they will still last a long time if you keep them within safe voltage limits. A BMS is a must.. I am using Batrium

You could also speed up your testing process by connecting them all up in parallel.. then charge them to 8.2V. They will all equalize exactly. Then draw them down individually to 7v to test capacity. Then put them all back in parallel for a final balance charge before splitting them into groups

Edster said:

My charger will only charge to 4.05v balanced.Ihope this is okay. Ideally i think i should be going to 8v.
[...]
Below are charger screens I chose the isdt t8 because of its abilities and amount of info you canget while it is working.

Click to expand...

The T8 is a great choice Edster, but then I am a BIG fan of iSDT hardware, and have a T8 myself, ...

To go higher than 4.05V just go into its settings and tweak the voltage up. Not really sure why you say there is a limit... sorry if i missed something obvious here. the 4.10V charge limit that iSDT impose on LiIon program can be bypassed by selecting LiPo chemistry ... and you may want to play with LiHV settings ... which I use for putting cells into warm storage of 3.92V.

NB I would use the T8 over a B6 (or anything else I have) for any BIG balancing you have to do. It has a massive 2A per cell capability ... just very loud when its cranking ... but super fast and very capable at this task.

Nice pics and text. Well done I say!

Question for you well versed in leaf cell testing,

I recently did a discharge on my Leaf cell, from 4.1V -> 3.3V, @ 5Amp discharge.
USA 2013 cell: 39,77Ah
Italy 2014 cell: 43,30Ah

Does this sound like normal values? I guess when you start at 4.2V and discharge down to 3V you'll get closer to 60Ah?

When testing capacities of now vs new, as pointed out by daromer in another post, it's important to test over the manufacturers original full voltage range - otherwise your cells will test results will of course lower.
As I suggested in another post you might want to try holding the cells at 4.2V for a while eg an hour or two or until current has dropped away to ensure it's had time to "absorb".

Oh my:
My avatar says it all. I joined the forum for the vast amount of knowledge others have. This post was to document what i have done for others to help guide me and slap my hand when doing something incorrectly. I found SOOOOO much information on testing 18650 cells (Equipment, methods, the "Do's" and the "Dont's") Above is simply my method and results of my equipment and batteries. This spring i will be putting Panels on the roof. I have winter to prep my powerwall, so as i make progress i am hoping to get PROPER and CORRECT information from the books i read and the "Battery Gods" found on this forum. Most importantly i want to ensure this will be a SAFE en-devour that will work as well. I am in no rush to get this done.(Wink Wink)

Big lesson 1: When purchasing 48 batteries, go as far as paying the seller to test one from the pack. If they are in the business of selling batteries this should be simple for them. If not find another seller. I wish i would of thought of this when i was shopping around. (NOOB mistake 1, others to come)

Edster said:

Oh my:
My avatar says it all. I joined the forum for the vast amount of knowledge others have. This post was to document what i have done for others to help guide me and slap my hand when doing something incorrectly. I found SOOOOO much information on testing 18650 cells (Equipment, methods, the "Do's" and the "Dont's") Above is simply my method and results of my equipment and batteries. This spring i will be putting Panels on the roof. I have winter to prep my powerwall, so as i make progress i am hoping to get PROPER and CORRECT information from the books i read and the "Battery Gods" found on this forum. Most importantly i want to ensure this will be a SAFE en-devour that will work as well. I am in no rush to get this done.(Wink Wink)

Big lesson 1: When purchasing 48 batteries, go as far as paying the seller to test one from the pack. If they are in the business of selling batteries this should be simple for them. If not find another seller. I wish i would of thought of this when i was shopping around. (NOOB mistake 1, others to come)

Click to expand...

Myself being impulsive bought 20 Leaf modules without asking for a test. Thinking they only have about 43Ah each. Oh well, live and learn.

Dala said:

Question for you well versed in leaf cell testing,

I recently did a discharge on my Leaf cell, from 4.1V -> 3.3V, @ 5Amp discharge.
USA 2013 cell: 39,77Ah
Italy 2014 cell: 43,30Ah

Does this sound like normal values? I guess when you start at 4.2V and discharge down to 3V you'll get closer to 60Ah?

Click to expand...

No, there's very little capacity below 3.6v - the graph previously posted hints at how little, and shows the rapid Vd.