Heyo, i’m new to all this but hope someone could help me out.
I got my hands on 9 18650’s from a dell laptop battery that was defunct. They are LG LGABD11865’s from what i’ve found out from the markings, pink wrap on them.
Had a cheapo charger that i bought arrive today, one of those UltraFire 3.7v ‘rapid’ chargers, i’ve had two of the cells charging in it for over 6 hours now and am a bit cautious of it all. The LEDs on the charger have stayed red all the time.
Is it usual for the charging to take this long? Are the cells dead? Should i try cycle them around until i find some cells that want to charge? Is the charger just useless?
It depends how fast your charger is charging and of which capacity the batteries are. Do you have a multimeter to check the battery voltage?
Welcome to the forum!
Full cells should have a voltage of 4.20v +–0,05V if the charger is any good. If they are over 4,25V then they are being overcharged and that isn’t good for the cells life.
Stop charging until you get that multimeter. The most basic multimeter will do. Ideally it shouldn't be more than 4.2V, but a couple hundredths more isn't that bad. Six hours might be okay if those cells were totally dead and you're using a slower WF-139, but it's a really good idea to use a multimeter when you first get a charger to make sure it's working correctly.
I’m not an expert but here’s my two cents. I make no guarantees to the accuracy of this information
For the sake of math, let’s play around with a little example:
Let’s suppose your batteries were discharged to 2V, are fully charged at 4V, and have a capacity of 2000mAh. Let’s also assume that they have a linear charge curve (in real life, it will take longer for batteries to go from 90-100% than it will from 20-30%).
Now let’s suppose your charger can pull at maximum 1A, or 1000mA. Split that between two batteries, and each battery receives 500mA of charging current.
In my perfect world, it would take 4 hours to get both of my hypothetical battery from empty to full. In the real world, it will take longer because charge and discharge curves aren’t quite linear, full charge voltages for 18650 Li-Ion batteries are >4V, batteries themselves have some internal resistance…so it makes sense that it’s going to take a while! The protection and charging circuitry in a laptop can enable the cells to intelligently charge and discharge, which leads to shorter charge times.
Totally agree about the MM. Without one you don’t know what the voltages were when they were pulled from the pack. They could have been at an unsafe voltage to start off with. Also did they feel hot to the touch when they were on the charger?
What did you mean “one of those UltraFire 3.7v ‘rapid’ chargers”? 3.7 isn’t enough to charge an 18650, but it’s just marks on a paper sticker. With no way to Know the Voltage, you might as well tape your eyes shut & take off running. You’ll probably be Just Fine, but your first indication of Failure will be intense Pain.
+1 to what everyone else said, especially the Voltmeter!!! A DMM is best, but anything that will show you 4.2vDC with some precision and accuracy will do fine for now.
For the time being, I would test the charger outside, in a place you don’t mind being destroyed (not by the front door!). I’d check the Temperature of the battery after the first minute and every so often for every battery forevermore. It should always be cooler than “remarkably warm” and never “hot”, however you define those terms.
And I’d grab the first Voltage Metering Device I could get my hands on.
The next test is to watch to see if they self-discharge (decreasing Voltage) rapidly. If it gets to 4.2v coolly and stays there steadily a few days, congratulations!
Meanwhile, there are gigabytes of information on this site which you can study, so I won’t try to repeat any more of it.
In my experience, the pink 18650s are from older Dell packs. They have upgraded significantly since yours was assembled! Yours are still excellent batteries, do not doubt!! I certainly never hesitate to pick up one of mine! You’re on the right track with Dell, as they seem to have the best available at their time.
That's also true. New used cells should checked before use, and possibly discarded. Brand new cells in packs that have never ever been charged can be okay even if the initial voltage is much lower, but I'd still check and record the data.
And new chargers should always be tested to make sure it works correctly out of the box. Waiting for it to not catch fire or explode isn't my kind of test, at least not one that I recommend.
Wow, loads of posts. Thanks for all the help, sure seems a good community on this forum!
It is the WF-139 charger that i have, yes.
When they were charging they did get slightly warmer, but it was nothing really. The charger also got a bit toasty but nothing more than what i get from any other chargers, say my samsung usb one. So i don’t expect that any explosions will be happening, at least not today!
Something else i noticed, when i took the mains power off from the charger, leaving the batteries in there. The LEDs turned green. Would this be a little tester built into the charger when there is no mains power supplied to indicate a charged battery?
As for when using the multimeter on the batteries/charger, i’ve heard a few horror stories where the multimeter blew from testing the batteries, what should i do to not have this happen on me?
I’ve only attempted charging two of the nine batteries, will test the remaining ones voltages before trying anything else.
On a slightly different topic, anyone recommend some reasonably priced beginner flashlights that use the 18650 batteries?
Again, thanks for all the help, wasn’t expecting anything like this response!
A. Don’t discharge Li Ion below 2.7vdc
B. Never charge OVER 4.2vdc
C. Don’t charge over 1C (capacity of battery in mA) (unless otherwise stated, stresses the batteries too much)
After a combined 9 hours charging, one of the LEDs for a battery has started flickering between red and green, so i’m guessing it’s finally getting there. These cells must be absolutely drained and/or this charger is hella slow.
I’ll be getting the multimeter in another couple hours so that’s good.
Thanks for those links, loads of interesting information there.
Just got my hands on the multimeter, and it was good timing because both LEDs had turned to a solid green after what must have been by now over 10 hours combined charging.
Measured the voltages of the two charged cells, both were as close to anything that matters to 4.2v
Also measured the cells that hadn’t been charged, all of them read exactly 0.88v, very low i’m guessing, hopefully able to revive them.
I’ve popped another two cells in the charger so i suppose its time to wait another 10 hours for them.
I’ll continue to measure the voltages of the charged ones though to make sure they’re holding the charge, here’s hoping that they do!
DO NOT CHARGE USED CELLS THAT ARE OF THAT LOW OF A VOLTAGE!!! Irreversible damage has already been done to them! (I'll let others speak as to what exactly.) Generally irreversible damage is caused when a cell is discharged below about 2.5v or so. New cells aren't that expensive and it's not worth risking an explosion / poisonous venting of gas over.
