Hey Philaphlous, I have been wanting to make an extra battery pack for my 48v ebike. Just curious what method are you planning on using for putting the cells together? Im leaning towards carefully soldering them instead of using a spot welder. Theres a guy on youtube that uses a freeze spray to cool down the cell after soldering or spot welding. My battery pack I bought with my ebike kit has 52 cells but I bet 91 cells will get killer range.
I just picked up a 60w soldering iron. Tested it last night…gosh got it way too hot, apparently it has a temp controller, whops. The 60/40 solder was charring it was getting so hot. lol. I found someone on endless sphere that used 3.5mm solder wick as the main voltage lines for the cells so I’m going that route. I hope 10ft of that stuff is enough for 91 cells. I’m pulling either old laptop battery packs or new cheap Chinese packs out and spreading the brand name with the chinese cells to try and even out the voltage sag because I’m sure I’m going to get that. Hopefully I can keep each of the 13 banks balanced or else its going to take like days for my BMS to balance everything. lol…
I might chill my batteries before I solder them but I’ve read that thermal shock also degrades cells so I’m not sure yet. I have a 120mm computer fan to evac the soldering fumes…
It’s going to take forever to put it together but I think I have a great design. I’ll post my build on here once I have everything. Still 1-2 weeks out for my BMS. My battery isn’t the most robust and I’m going to have to keep my wattage under 800w draw. <3A per cell.
Ive read so many conflicting things on what degrades the cells I just feel like if I can get free cells from laptop pulls and get only 100 or even 50 cycles Id be happy just because I made it and it works. Of course, I dont want a fire either. I also came across an interesting video on youtube about not using a bms at all would be beneficial by using a balance charger here:
Im considering going this route but those balance chargers are kinda pricey.
Anyways, I have never tried going to home depot to check the recycling for batteries. I think I might try sometime this week.
I haven’t gone quite that far to check HD or any other place for old cells but I did pick up a few used laptop packs off ebay. Moderate success. LG cells get me about 2200-2400mAh while the other LG cells get only about 1400mAh and the Samsung cells were completely bad with only about 200mAh usable.
Yea its about $1.5/cell for the 2000mAh Chinese cells but they’re consistent in their voltage drops, capacity, and I know they haven’t seen either extreme loads or heat that could potentially damage the cells. I’m hoping that my commute won’t fully drain the battery pack as my charger is only a 2.5A 48V charger so that’ll take forever to recharge plus I hope to keep the discharge depth to a minimum. I’m in-between jobs right now and so once I nail down a new job I’ll go full steam ahead on this idea. I may be moving, may live closer to my work, may end up absolutely needing to bike to work with outrageous parking prices…who knows right now…
Well I wish you the best of luck with the job hunting. I actually sold my car and got an ebike kit so I can do the 2 mile commute to and from work. Its working out great so far however the weather forecast is showing 105 degrees on Wednesday so that might make me regret my decision. Well see.
Oh yea! Broke open a genuine Dell and genuine lenovo laptop battery pack. The dell came with LGDBB31865. Charging one up to test the capacity. ALSO, wait for it! Panasonic NCR18650D cells! 2700mAh cells. woohoo! All 3.6-3.83V which means they’re all good! Testing out the Chinese cells again. Just realized my imax B6 is recording the voltages pretty far under what the cell is currently at. I’m using both a multimeter and the Imax. Imax says 3.56V right now and multimeter on the cell says 3.71V…dang… Definitely more capacity in these cells than I think. Now after this run I’ll test the 1A draw to make sure its really 1A or else I’m screwed…lol
either you have a fake b6 or a lot of resistance in the leads/holder.
maybe both.
aftermarket pack for my alienware m17x r3.
no model number.
was doa. no lights when pushing the test button.
red x in windows.
9 grey bak 2600.
all checked around 2700@1a.
ir 45mohm.
hp mu06 generic.
died after 1 cycle.
another recycle it and we send replacement.
twist.pop! crunch!
and we have 6 red yik lik 2200.
all at 3.95v
near 2300@1a
HP MU06 = 6 Green Samsung ICR18650-22FU (3.7V 2200mAh)
another m17x r3 pack.
original 90wh.
damaged by lightning.
took mobo,power supply,battery.
customer had me repair it and left the killed parts.
9 samsung 28a.lilac/light purple.
all like new.average so far 2580@1a 4.2v.
these are 4.35v cells.
lb1 “high performance”
replacement for alienware m17x r4.
came with machine when i got it so unsure of age.
would not give me anything with batteryinfoveiw.
and “high performance” is a joke.this is a 6600mah pack.
the stock is 8400.
the joke continues…
thermal sensor wadded up behind board not in contact with any cell.
brittle case that crumbled with no effort when i disassembled pack.
one drop would have meant big problems.
no tape anywhere on the cells.
plenty of opportunity for strapping to dig into cell sleeves and short.
and cause of death?
wire MISSING from a cell tap to board.
this pack was stillborn!
so add no qc to the list of ills.
the good?
9 dlg n18650 at shipping voltage.
i suspect they are as new.
all 9 at exactly 3.51v.
decent cells for most flashlights.
Found a few Makita 18V power packs - water damage or corrosion on several cells. Easy enough to disassemble but only 4 - 6 potentially useful cells, If those don’t pass testing then about all I’ll get from this “pull” is the dividers for cell storage and some insulator disks.
Dell PC764 = 6 Green Panasonic CGR18650EA (3.7V 2550mAh)
Found some old HP batterypacks in the electronics bin
the MU06XL battery used samsung ICR18650-28A
other HP pack, used some LG 2600mAh cells, LGDBB31865 - I3494F04127-NL154D7B3, which are charged according my LI-500 with 2475 mAh
Unknown use: bundle of 5 nimh AA’s 4 volt pack - individual cells appear to be Sanyo and test out at just under 1000 mAh 
Old thinkpad laptop battery with part # 92P1121 (4400 mAh) or 92P1125 (4800 mAh) 6 Samsung ICR18650 - all stone cold dead 
generic hp mu06 replacement from 2014.
controller burned up.
6 fp 1800 green.
2 at 0v so recycled.
4 remaining average 1830@1a
ir 70mohm.
another “5200mah” pack that is really 3600.
anyone know who fp is?
Another Thinkpad 92P1101 = 6 CGR18650D (Panasonic) cells were junk but salvaged insulator disks for future rewrap needs.
My dad approached me with a 5000mAh powerbank with a broken micro-USB charging port. I was happy to pull the two decent 18650's out until I measured they were at 1.45V. Double-checked with my AA NiMH to make sure the multimeter wasn't broken. I don't have any experience bringing dead cells back to life, so I've thrown both away...
hp mo06
blinking charge led meaning bad battery.
x out battery in windows.
6 grey panasonic ncr18650 at 3.96v/pr
testing now.
customer stated they were getting 3+ hours from it and had only used it to warning 2 times in the 6 months since they bought it from hp.
so likely a bms failure.and good cells.