Ok, I'm back with my 14-cell M1 pack build and DC9000 charger hack. I was nervous about the procedure for fear of shorting out the cells so I bought a great pair of rubber gloves for less than 4 bucks. These bad boys are snug so it won't get caught on anything, but not too tight as to constrict movement. And the rubber quality is so good it felt like I can climb walls like spiderman, great for butterfingers like mine.
Following the cell tab route and installing the prongs in the correct connector position was tricky but I was fortunate enough to have had a day alone without distractions. After straightening out the cells and inspecting BMS coil springs, things started to make sense.
I gained confidence after soldering the 4 cell string to the 10 cell string, and soldering the 15 balancing wires to the cell tabs . . however, I got careless by not insulating the wire ends after cutting the connector-end. . . .
one wire had a copper strand peaking out and managed to find its way to cell #4 "A04". When I heard the loud SNAP! I just froze to avoid moving the wires and carefully inspected each wire end before organizing them and insulating the ends
I labeled each cell A01, A02, ... A14 to avoid errors when I take volt readings directly from each cell. I will build at least 3 more 14 cell packs to parallel up to 9.2Ah so they'll be packs B, C, & D
All 15 balancing harness wires are 14 gauge. Only the pack's negative and positive leads that connects to the controller are 10 gauge. I didn't see a need to have thick gauge wires that go to the BMS pos and neg leads as the charger does not draw amp load - as I understand it - the charger puts out only a few amps during recharge.
This 14 cell pack is about 95.+ cm long and each wire gets longer towards the rear cell, cell A01 +pos being the shortest and cell A14 -neg being the longest. I checked for any significant resistance by comparing voltage read from the wires and voltage read directly from each cell and only cells A04 & A14 were .01v lower, possibly due to my shoddy soldering work. I need to invest on a soldering gun for 10+ gauge wire work.
Fitting this pack inside the frame tube will be a chore because the child seat will need to be repositioned to allow A Pack's tip to slightly stick out at the end of the frame. I planned on A & B packs inside the frame tube but the 14 gauge balancing wires added to the thickness of this first pack alone. I'm hoping to layout the wires side-by-side so that they don't overlap and add more to the diameter. I wish I would've thought of using ribbon harness to begin with! As for cell insulation, the only shrink wrap tube I was able to find was 25mm and M1 cells are 26.6mm.
The 10 gauge power wires will not run inside the frame. The + positive comes out with the first cell A01 at the frame's rear, and the - negative is A14's end which comes out of a hole near BB. So these power wires will be coming from opposite ends of the frame, run under tube frame and meet at the controller. Sweetness.
I plugged my new pack for a No Load test. With 47+ volts, I got 33 kph.
Controller temp was higher than normal. My 42v NimH (36v) 9Ah is about 22c when switched on, and 24+c under load. With the M1 pack, temp rose steadily to 30c and kept rising slowly. I would've been worried if the temp quickly shot up. The case didn't feel warm, didn't see or smell smoke. . .I may try ventilating the case by removing the rubber grommet during summer use.
As for the DC 9000 charger . . . during the procedure, I came up with a possible solution to charging the last 4 cells with the DC9000 charger: I soldered two sets of cell balancing harnesses to the BMS: one connector plugs to the first 10 cells, and another connector plugs to the last 10 cells, charging first or last 10 cells, one at a time. Note: DC9000 works at 100v, however, if it blinked "Problem Powerline" a few times but can be rebooted when unplugged. I now use 110v step-up and it works fine.
Prior to 10 ten cell recharge, I checked individual cell voltage:
I charged the First 10 cells:
First light blinked a few times, then solid
2nd blinked a few times, then solid
3rd blinked for about 1 minute then went solid
20 min balance charge
First ten cell recharge results:
Not too bad, I thought . . . But Last 10 cells??
Not too good, I thought . . . So guess what? Chicken Butt?
During the charging process, I decided to drain the 3.77v cells *using the extra BMS harness connector* to allow further charging of the low cells. (
ypedal ) Did it work? Yep!
Although with the last 10 cells, after draining one or more cells, the rest would only charge up to .02 volts unless I reboot the BMS by pulling the BMS shell out of the charger
Then I tried charging the first 10 cells again and I'm able to drain while the other cells kept charging. Do you know why? I can only say Chicken Thigh because I haven't a clue. Next step is to ride this pack down no lower than 37.8 volts and repeat the drain load recharge thingamajigger.