Got a toshiba laptop pack. I think its around 1.5 years old.
The pack contain 6 Sanyo UR18650A cells. rated 2200mAH
when I open pack, 4 cells at 3.3V ~ 3.5V and other two 2.9V
I slowly charged them to 3.8V first time (100mA)
when I charge the every cells at 500mA / 1A each, cell stay cool till battery voltage reach to 4.1V then start to heat up. It seems current never dropped even after cell reach it 4.2V voltage.
if I disconnect battery when it 4.1V and rest few hours and charge again, battery completes charge without heat or little heat.
sometimes battery charge without heat but mostly heatup and never complete full charge.
I charged with IMAX B6, TP4056 board and lab PSU CV,CC but same issue.
No fast self discharge found yet.
capacity test give ~1200mAH all cells
What could be the reason that cells heat up ? I found another set of sanyo cells that has same heat issue. never found another brand has that.
No. they charge same as others. Maintain 3.6~3.7V under 1A load. And this thing happen only after cell reach over 4.1V. it keep cool during almost empty to 4.1V
Can you measure how much the temperature increases?
Some batteries have a temp rise when approaching full charge.
In the CV phase / saturation charge, with some batteries the current may level off and won’t drop any further. This is “fully charged” for that battery.
The capacity test ~1200mAH, what type of charge was that? 4.10v, 4.10v rest then charge to 4.20v, pushing through to 4.20v (heating up) without rest?
i bet they self discharge badly too.
run them down and recycle.
this is a BIG BRIGHT RED FLAG!
they are growing dendrites and could short without warning.
i had some that were ok till they crossed the 4v mark.then they dropped and the current stayed at the max of my triton.
thats 2.5a.a reasonable rate for 6p 18650.
they all got hot. later they sat at 2.8 or so after hitting 4v and putting in 10ah!
If I had a cell that wouldn’t reach 4.2 volts it would be gone that day. I have some older cells that take a little bit to reach the end of the CV stage. But always complete. No way I’d let it continue at that stage for hours like one guy said he left it on for 10,000mah no way in hell. Cells are to cheap to risk any venting situation even though the new cells don’t really make flame anymore. I don’t want any cells to vent in my charger. I’d hope my vc2 would shut down when it heated up. I know the vc2 won’t charge a cell with a really high IR. Unlike some dumb smart chargers
Interesting is they reach 4.2V normally and in normal time and capacity if I let them cool for some time, othervise thermal protection in my Lii-500 stops charging.
just last week I had a cell get hot at 4.10v too …. An old ur18650 sanyo
Took it off the charger MARKED IT and finished it on another charger to 4,20+V … just checked it after a week of sitting and it’s 3.90V….Wow !! I’ve never seen a cell freefall like that
I believe Sanyo are the worst cells to find in a salvaged laptop battery pack. A youtuber actually went through a hundred or more laptop battery packs to salvage cells for an additional pack for his Nissan Leaf.
It appears that Sanyo were the worst performing cells by far and the Panasonics and Samsungs reined supreme. This is based strictly on the cell’s ability to maintain it’s original capacity. The guy in the video first charges the batteries to full and puts them on a 1A discharge test, records the mAH, recharges to full, let’s them sit for 30 days, and discharges them at 2A only if the voltage dropped no more than 0.04v. His data in the video is very organized on excel and his test methods appear to be very solid.
i put 10,000 mah into 6 parallel cells before they heated.they did NOT continue to charge for hours!
i watch things carefully when charging pack pulls.
its been my experience that sanyo cells in junk laptop packs are worn out rather than an arbitrary shutdown by the packs bms.i have some very old red sanyo cells that are still in great shape.and have been used daily.but they dont seem to last as long in a hot environment like a laptop.best so far are panasonic 2900 from lenovo packs.bms limits them badly.like planned obsolescence.never a bad cell or any reason for the pack to shut down. most have 2750 at that point.and still 60mohm ir.
like new for use in a laptop pack or anything else but subohm vaping.but even new they are not suitable for that.
I’m sorry to revive an old thread, but I’m not sure where else I can ask this.
I just got 2 of the On The Road U16 and for some reason one of the cells doesn’t want to charge fully to 4.2. I tried it on my Xtar VC4 and it seems to max at about 4.13v and then get really hot. I started charging from 3v. The cell capicity for the Orbtronic 16340 cell is 700 mah and typically measure 670-680 mah. This one cell will go on and on, past 900 mah and get really hot. Almost too hot to hold.
Would this be a sign that this new cell is defective?
