May 4, 2009
I got this pack from someone in the US, it was purchased " new " and had problems with early cut-outs, advertised as 20ah it would only provide 10 to 15ah depending on the load and needed to be checked out.
Above is how it arrived, notice the charger on the bottom left side.. ouch..
Well... this is the kind of pack you take apart with a Knife !!!
No plastic boxes with fancy screws.. noooo. none of that
"ve been at this funky battery business for a while now.. heck.. i had my 1st pack before the chinese discovered Duct Tape as a battery material...
example 48v 24ah
Rules to Live by :
- Clean work area, no clutter, no metal jewelry...
- Have an exit plan ! worst case situation.. out the window it goes !!!!
- Take your time !
Carefully cut into only 1 layer of tape and peel back slowly.. looking for thin wires or any other battery tab material.. don't be tempted to just slice and dice here.. one layer at a time !!
Working on the corners .. peel peel peel.....
18650 Cells !
18mm wide, 65mm long.
ARRRGGGGHHHH....This thing reeks !... wooo. i think i'm high. .. I"d be dissapointed if this is not cancer causing..
Can't wear vinyl gloves as they stick to the tape and rip apart, and I had to wash my hands down with Zippo fuel to take a picture .
However, i'm getting there.. peeling layer by layer..
The BMS is next on my list, there are 2 of them to diagnose... but i want to see the ballance leads before i hook it all up for testing.
Whoa... that sucked ! Duct Tape Glue and sweaty palms are Conductive !!!!
Now... yes, i know better.. however.. having removed the outer Duct-Box shell , 90% of the cell ends are exposed.. I wanted to flip the pack over, so i go ahead and grab the pack with both hands, one on each side, flat palms shorting all those nicely charged cells !!!!.
Anyone who's played with fire likely know this feeling .. the type that makes you go " Uhm.. wow.. this feels weird.. " 0.005 seconds later you realize
"Yooooowwch " !!
All good tho.. i'm fine.. moving on.
There has got to be 5 lbs of Hot Glue over this thing.. everything is hotglued into place. and as much as i love the stuff for it's 1000's of uses.. it's a bastard to take it out of crevices ..
Going back to the pictures i took before starting the work:
And sure enough:
And ... why are Duct Tape and Hot Glue alone not proper battery pack building materials ? That's why !
May 11 , 2009
The fun's not over...
After picking at bits and pieces of glue for the last hour, i finally got the packs to let go of each other.. at the beginning I was trying to be careful with the tape and preserve the duct tape shell, but it's impossible, i ended up having to slice into it and ripping it off a chunk at a time..
The metal strips they used are very thin, the glue on the DT is enough to pull if out of shape, have to be careful not to rip the spot welds in the process.. if it was still cold enough outside i'd leave it out for a few hours in hope the glue would give up it's grip.. but unfortunately i had to get with the elbo grease and just have at it.. can't remember the last time my fingers were this sticky !
18 cells in parallel, the first 2 groups sitting at 2.9xx volts are likely suspects.. 1st group has a crushed cell so that has got to be dealt with either way....
So far, i think i'm going to make it into a 36v pack with BMS and salvage the extra cells however possible, likely wire them up for single cell chargers with andersons in a 3 series pack.
QC anyone ?
Using a dremel with a cutting disk, I zipped across the tabs a few times to weaken them up some.. then it pops apart easily with the help of a small screwdriver....
Below, I removed the shrink, no markings to be seen, incredibly, this cell still reads 3.35v !!!
What used to be a 48v pack, is now a 36v !
May 15, 2009
i finally got every group fully charged up with single cell chargers.. soldered on some wires with andersons.. and away we go !
Overnight voltage after the full charge .. start of capacity test..
And Results !
17.5ah at a very low 3.37 Amps..
This was done over 2 nights, got 12ah last night, finised it tonight.. damn day job and it's 8 hrs of my day.. grrrrr
Tomorrow night, we double the discharge for a 7 amp run !
But, rating of 20ah, actual output 17.5 ah
May 26, 2009
The fun continues..
The cells being offset, leaves a gap at the ends of the strings, filled this with corregated vinyl pieces and hot glue
Using thicker wires for the BMS leads, not that it needs to carry any high currents, but thicker wire is just simply stronger and longer lasting imo. Tack one strand, then line up the 2nd one.. solder.. hi ho , hi ho.. soldering i go..
I also used filament tape to hold the cells together, multiple layers of the stuff, it won't strech even when warm !!
Doubled up the + and - leads, one at each end of the string....
Not sure where i found this stuff, Black Duct Tape cast from the depths of hell, this stuff is thicker than usual off the shelf Duct Tape ( just now pondering what possible conductive properties this stuff may have... .. daaamn.. i hope it's not.. gulp.. cuz it's there for good ! ) meh.. onward we go.
Doubled up the edges where the - and + leads run.. and covered the whole deal
Used some pieces of corrugated plastic ( aka: colorplast ) to build up the thickness of the wires on the top of the pack, then filled all the gaps flush with industrial hot glue !
I also ran a bead of hot glue along the corners and edges to provide some impact resistance and form a solid edge..
This pack is not perfect, below is one of the corners i kept in it.. i mean.. if i look hard enough i can find a host of problems with every single P section.... and i'm not willing to peel the strips to get down to individual cells on this thing.. it's a compromise
The + end of the cell has a double layer, the spot welded section is suspended above the cop of the actual cell ( i suspect to help with preventing cell damage during spot welding ) .
Once fully wrapped in Black DT, i added strips of double sided commercial grade carpet tape, found this stuff at a flea market for 2 $ ! you only get one shot at lining up your piece, this stuff makes things kinda permanent !
Ok.. time to admit stupidity. . all the ballance leads were carefully soldered, routed clean so they don't overlap, hot glued in place, and taped up at the ends with masking tape, labeled 1(+),2,3,4,5,6(-)
However.. 6 cells.. 7 wires !!! .. and i only realized this AFTER sealing up the 1st pack...grrrrrrrrrr...
Good thing i took pictures all along the project !!!! .. by color matching and following teh visible pairs going into the pack.. i was able to relabel all my leads properly 1 thru 7 !
Doubled up the colorplast on the side of the pack with the discharge leads to build up the thickness and protect the solder joints..
Double thickness colorplast and check out the hot glue work !!! .. if the wires get tugged.. nothing is going anywhere.. !
Now for some " Armstrong " peel'n stick floor tiles !
These things are fairly easy to cut with good scissors
( Hey.. it may not be great.. but it's an improvement !! )
Below, Check out the thickness buildup.. this adds a fair amount of bulk, but a small tumble should be survivable...
I loaded a ring of glue at the edges before sticking down the floor tile..don't want water getting in there..
Now to repeat for the other side..
June 05, 2009
Well.. she's holding up so far.. i took the Tri-Rider on a run wednesday, went 33 kms and used 16.5ah.
All the way to 15ah the voltage stayed above 36v, even at 40 amps !! with a front wheel X5304 in 24" wheel it goes 38km/h on the flats, 33 up the steepest hills within my area, and 42 down hill !! .. a bit faster than i would like but powerfull enough to not bog down and that was the main goal.
the 2 amp charger is a bit of a pain, 16ah recharge at 2 amps.. 8 hours.. ugh... I'm spoiled with my TP1010 chargers getting the job done on my Norco in 1 to 2 hours !.
This pack was sold along with the Tri Rider !