I looked at the forum to know what rate to use to charge my 18650 battery and found many post saying that 0.7A is a good rate charge.
I charged one at 0.7amp with my accucel 6 and let it go.
At around 2500mah, the battery began to get hot, around 68 celcius, so i disconnected it.
Previously i was using cheap charger that charge at 500mah and it never get that hot.
What is the maximum safe temp i should reach?
Should i charge at lower rate?
Most of my battery come from dead laptop battery pack and i want to test capacity to discard the bad ones
Li-on cells don’t need to get hot to charge. My understanding is that Ni-mh cells are designed to be charged as a function of temp change and ramping.
I know that heat harms Li-on cells number of lifetime capacity.
First I would get a 300, 500 Littokala charger because it comes with a resistance meter. The beat cells will have higher resistance after a few minutes you will probably be able to tell if a given cell is much higher resistance then the others. This will save you time.
Plus you can set the good ones to run a charge/discharge/charge test which to tell you the actual capacity, you then may want to move some to the side after that also.
Under 0.5C there is no reason for healthy batteries to get hot while charging, I always charge all of my 18650 (min capacity 2500mah) at 1A and they never get hot. IR of under 100 is acceptable for me.
The cell that reach 68 celcius had a resistance of 175mohm.
On the 20 cell i have, only 2 have a resistance below 100mohm. most of them had a resistance between 120 to 130mhom
Does it mean i can still use them but i’ll have to charge them at much lower rate to avoid heat buildup?
Or i guess i can still use them if they still have an acceptable capacity?
Would you dispose of them?
Most of the batteries were discharge… does it change the internal resistance of the battery?
Hey mate, with regards to li-Ion cells, especially older used cells, if in any doubt - toss it out. If the cells are heating up like that when charging at that low rate i certainly would not keep them no matter what the iR is.
The most dangerous part of our flashlights are the cells we use. Seriously, it’s crazy trying to save a few bucks in that area. I know it can seem like a great deal scavenging laptop packs etc. but i really recommend you just buy some nice new LG, Sony, Samsung, Sanyo, Panasonics etc. and you will never regret it.
Just make sure you don’t get confused by charger heating up the cells
all li ions should be cool to touch or even just slightly warm. make sure your elbow/forearm can accept the heat. Not any hotter than a phone running on heavy loaded apps for long
but you can get a good idea about how they are misused and how a good new cell should resist to stress.
Also, how much do you trust your Accucell charger?
the difference in the charging current of 0.2A for an IMR should be negligible….really….even more considering you are charging them at just 0.3C
I think i’ll give up on 18650. I think i’m better to buy some Nimh AAA eneloop and use the AAA adapter instead of the 18650 cell for my flashlights. More safe, less complicated and i can use them in many other devices…
time to pluck a pigeon
3AAA eneloop in series to get enough voltage to power an LED won’t put out a lot of current, the voltage sag will probably limit it to well under 1A
Also your then limited to 750mAh, not 2250
Most of the battery i have are cheap one or old taken from laptop battery.
I already have an Accucel charger.
I have 4 flashlight (cree XM-L T6)
I usually use the 4 flashlight during camping at summer and at fall at my hunting camp site.
The rest of the time i’m using 1 or 2 of them when nedeed but not so much.
Do you guys could tell me where i could get some (less then 10) good brand at good price? i’m in canada
I looked at ebay and aliexpress but there is so many fake out there and as you see , i don’t know much about these.
theres your problem :bigsmile:
buy the eneloop anyways, NiMH are good to have and eneloop are the gold standard of NiMH
Someone else with more current buying experience can hopefully link some good deals in authentic cells
if you are using in single cell lights your exiting cells will work (but will be a basically big resistor in the circuit) if running DD via a driver or straight wire job, monitor them accordingly or do not use. be much more on top of things if you want to run them in series.
HKJ does lots of reviews look a few over and read the comments in the threads.
there are lots of threads on where/what types of 18650’s to get (illumination supply, some east coast battery warehouse (I forget the name), the Europeans have a site that sounds like the camera Nikon (close but not exact), also Banggood and Fast tech?, Our good buddy Richard at Mountain Electronics and I think intl outdoor all carry quality cells.
There is nothing wrong with laptop pulls but don’t confuse (well used and stressed cells) with brand new ones.
Yes if you have high resistance cells (my definition is over 40 for new and 70 for used 18650 cells) it would make sense to charge them slowly because they are already over the hill and might give some more use if treated gently.
If you just need cells for every day use they should give some low cost charge-discharge cycles before the give up the ghost. But if you need big amp pulls or high performance results then you must get new cells.
here is my preferred go to low cost high performance cell. there are lots of opinions out there, do some research and choose what seems right for you.
