33.3V 31.2Ah eZip RMB Pack Build
Well, I keep claiming that I have squeezed the maximum number of 18650s into the oem eZip pack.
7s12p .. 8s12p ...
Finally ... this might be true.
Next build was going to be a "hybrid" 18650 & flat Lipo project ...
but I got tired of all the old Sanyo 18650s laying around.
So I gathered them all up and selected all that measured a retained voltage higher than 4.10V.
(After being equally charged to 4.20V+ 8+ month ago)
9s12p (33.3V 31.2Ah) eZip Rebuild = 1kWh!!!
By staggering the cells I am able to fit the cells in 9 wide.
Case will stack 12 1/2 cells high if I remove center screw and use only a 3/16" Masonite bottom support-protection "shelf".
I chose the 90 best retained voltage cells and stacked so as to have "equal" capacity per stack.
Now, 9 x 12 is more than 90 cells ... and sorting solely by retained voltage is a poor measure of capacity! ... ?
I rated and sorted "build" cells solely by "bleed down" - "retained voltage", and will assemble and test as a 9s10p pack.
After initial discharge-recharge cycles, I will "equalize" pack using precisely capacity rated Sanyo cells pulled from my last batch of recycled Lenovo packs.
By adding them as the final 9s2p.
Pack will be used on my Snow Beast and as a testbed for a future build using "new" (NOS) cells.
I have 2 eZips that run nicely on 33.3V batteries.
These Sanyo cells are 3.6V and after learning my lesson by damaging with 4.20V charging, I will be charging at 4.0-4.05V, for increased life.
I will add 1/2 cell height (9mm) "blanks" as additional support for the alternate "banks".
Well ... this leaves a couple hundred "lesser" condition-capacity old Sanyo 18650 cells laying around.
Leftovers and re-recycled from 6 years of multiple builds.
So, a "true" bulk build!
I have a couple "antique" 200w inverter packs.
2 - 18Ah SLA outputting 200w continuous through a GFCI 110V AC outlet.
Well I'll pull the 12V 36Ah Lead Acid and pile in all the 18650 cells that will fit.
3s66p might fit = 171Ah
(Check bank voltages after 1st discharge, add cells to any low bank - re-cycle - repeat.)
But, probably be lucky to get 72Ah actual capacity out of these ... rejects.
Still, that is 200% the oem capacity at 1/2 the weight.
I have those old cells safely stored and not laying around.
And, of course, a nice supply of emergency-portable power.
It also has a 12V "cigarette lighter" outlet for a more powerful inverter or 12V.
Will add pictures ...
22.2V 30.24Ah Battery Build
22.2V 30.24Ah NOS Laptop Lipo ... ""100701" = 2010 July 01 dated cells.
Originally Posted by DrkAngel
I know, I know ... I said 22.2V was too wimpy!
But, I tried my latest 25.9V 25.92Ah battery build on my latest ...
2013 eZip Trailz LS w/13T motor sprocket ... cruised at 22-23mph.
Exceeds "legal" - 20mph.
Running at +22mph strains the battery well past my recommended .5C.
Running the numbers ... 22.2V looks to cure both problems.
Took the 7th"s" and split it up between the remaining 6s.
Dropped top cruising requirement by 100w.
1st build using the newer black eZip "RMB" pack.
I had to chisel "ribs" out of pack, to provide proper clearance.
Used Formica as shelves to support cells.
Wedged a wooden block as additional support under lower cells-Formica.
I did add a balance connector ... had the silicone 22ga balance connector anyhow ...
Just cause I could ... I balanced all banks to precisely 4.186V.
Ooh! Tried bleeding down a bank using jumper wires connected to ends of soldering gun tip. Worked pretty good ...
Speed settled perfectly ... just a fraction under 20mph.
Ran 20 miles at 19mph+ and have all banks still at 3.84V.
Likely another 7-8 miles at 19mph?
Oh ... motor only, no pedal assist.
40miles plus @ 16mph?
Will mod a MeanWell S-150-24 as 25V 6A charger.
The 24V 40mm fans seem a bit fast-loud so I tested with a 2watt 47ohm resister, in series, and resulted in a moderately quit fan with minimal resister heat.
Upgraded charging wire to 14ga for rapid charging ... if I care to try ...
Reread the post...
Sounds like I rebuilt my 25.9V into a 22.2V.
I still have both and need 25.9V for my 16T mod eZips.
22.2V 6s LiPo Bulk Charger (24.84V 6A)
Built 24.84V 6A MeanWell charger (S-150-24) ... for 22.2V LiPo pack.
Yes I labeled it.
Don't want to plug into wrong pack!
18ga computer power cord fit through wire hole.
4.14V per bank looks optimal.
MeanWell will be outputting 6A continuously for nearly 5 hours so I felt it advisable to add a 24V fan.
At about 25V it seemed annoyingly loud , so ... I added a 47ohm 2w resistor in series.
Dropped voltage at fan to 21V and quieted to ... acceptable.
Fan placement appears optimal.
25.9V 25.92Ah eZip LiPo Build + Rebuild
Originally Posted by DrkAngel
Sadly my "repair" with added support etc. failed miserably!
Originally Posted by DrkAngel
2 banks showing additional damage, after a few cycles.
So, rather than another "repair" I pulled the 6 major banks and replaced with new 2010 cells.
I did position to prevent further damage!
I have run a few cycles and then a deep discharge for capacity check.
Discharged to 25.66V.
All cells were equal within 2/1000th V at 3.666V!
This shows excellent matched capacity!
Beyond any reasonable expectation.
The quality control and durability built into these 4 year old cells is astounding!!!
Did a metered recharge using iMax B8 (Blue).
3.666 - 4.156V = 25.376Ah
#1 Laptop LiPo Build
2011 - 24.0Ah (25.9 to 29.4V)
2012 - 20.8Ah (25.9 to 29.4V)
2013 - 15.8Ah (25.9 to 28.7V) 6500+ miles
2014 - 13Ah+ (25.9V to 29.2) 7000+ miles
#2 Laptop LiPo Build
1st metered recharge 3.82V to 4.16V = 18Ah.(Blue iMax B8)
2nd metered recharge 3.695V - 4.170V = 24.264Ah (Blue iMax B8)
3nd metered recharge 3.666V - 4.185V = 27.647Ah (Black iMax B8)
4th metered recharge 3.70V - 4.182V = 24.42Ah (Black iMax B8)
#3 Laptop LiPo Build - Rebuilt 25.9V 25.92Ah 2010 Laptop LiPo (Dell)
1st metered recharge 3.666V to 4.156V = 25.376Ah.(Blue iMax B8)
1000 Laptop Cell Recycle Job
Half way into the process of evaluating a large batch of LiPo cells ... the deal for my chosen motorcycle, for electric conversion ... fell through.
So, might have some tested and rated cells available ... ?
Self-discharge testing about 1000 2.16Ah cells.
(3.7V x 2.16Ah x 1000 = 7.992 kWh)
All cells in each stack precisely equalized to within 2/1000th V.
Wove tinned copper braid in parallel of closely voltaged cells ... to precisely equalize
Discharged 1st batch as 30s2p using 2 60w light bulbs for a 1 Ah per hour capacity test.
120V DC electricity can be very dangerous - use extreme care!
Nearly 1000 cells running self-discharge test
Finally started evaluating the Dell packs that used the Sony cells
Will eliminate any self-discharging cells;
test all cells for a comparative IR;
confirm all banks in each pack of same IR;
run 30s discharge evaluations (discharge capacity test).
Comparative IR as Capacity Estimate
Using Comparative IR as Capacity Estimate
With the large quantity of cells that I am testing, it seems proven out that ...
With cells of same manufacture, (age, batch etc.), and same starting voltage, the degree of voltage sag under a specific load-discharge indicates a reasonable comparative estimate of capacity.
With the large quantity of cells in my project I was able to separate cells by "Ver: #" and when indicated, group by actual date of manufacture.
(several dozen more 6 packs not in picture)
After self-discharge test, and removal of defective packs ...
Next test will be a 1 minute discharge using a 12V 3.33A 3D printer heating element, in cup of water.
(4.32Ah battery with 3.33A discharge = .77C discharge rate)
At a timed 1 minute, I will meter and mark pack by voltage sag, EG. .58V.
Then I will quickly confirm individual banks of nearly identical sag. (any notable divergence will be segregated for cell level testing and use.)
Capacity test banks of 30s2p will be grouped by similar Comparative IR and starting voltage.
Most stacks were charged precisely within a couple thousandths of 4.100V/cell.
With 4320mAh (2p), I will likely discharge for 3 hours = 3000mAh, then label with resultant voltage for direct battery capacity comparison.
Might meter samples further for more accurate capacity rating - (3.75V -3.6V = 850mAh + 3000mAh for 3850mAh capacity )
Will use my capacity map of these cells to estimate full capacity: