What would be the general conclusion of 18650 shell life?
Lets say you charge them like 50 times per year, would Panas green protected still hold charge/volts good enough and not losing more then lets say 5-10% output or any at all after 2/3 years?
At what poing you guys replace your batteries and how do you notice it? output drop? any hints on how to prolong the life? (just don’t say charge them to 50%) when i use my light on daily basis….
Thanks!
Keeping most lithium ion batteries between 40–80 of charge prolongs their life cycle from around 500 cycles to about 2000 cycles.
Phone, Ipod, Iphone, Laptop, Digital camera batteries are examples of what I use the 40-80% rule for.
I keep my 18650 between 3.8V-4.0V. I don’t let them go lower than 3.8 and stop charging them at 4.0V.
I do have some laptop pulls which I charge to 4.22v every time. I simply don’t much care about performance or battery life on those. But I still won’t take them lower than 3.8V.
Here are some links:
How to Prolong Lithium-based Batteries
Check out table 4: Table 4: Discharge cycles and capacity as a function of charge
My ipod touch is 3.5 years old with a bit more than 1400 charge cycles on it and I still get 85% of runtime of when it was new.
Lets not forget temperature and abuse factors are very important as well.
I dont’ quite get the first part of your post.
“Keeping most lithium ion batteries between 40–80 of charge prolongs their life cycle from around 500 cycles to about 2000 cycles”
How can i keep them like that? lets say i fully charge my light, and use it for 1/2 minutes to check out my yard. I use 400 lumens mode on my TK 75 most of the times……so lets say i use it for 2-5 mins every day or once every 2 days. How can i get it do 40? i mean i don’t get the idea, should i intentional discharge to 40 and then re-charge? what if i use it once per week? its really confusing to me. If you use just a little your flashlight per day, you cant discharge or recharge like that, its way to complicated.
Edit, i guess charging them at 4.0 volts, while having like 80% of the maximum capacity is the best way to do it? its a bit easier to understand that to me now, thanks!
Sorry I didn’t explain my reasoning well.
What I meant to say was I won’t let the battery voltage go lower than 3.8V. If it takes you one day to get there or one month it doesn’t matter. Use your flashlight and when battery reaches 3.8v, then charge them.
You can use an inexpensive multimeter to check the voltage. After a few times you’ll get an idea of how fast batteries are going down in voltage and then it gets very easy.
I use this very inexpensive meter to check for voltage. Link
So charge them to 4.0, and dont let discharge to lower then 3.8? isn’t this to little of a difference, and will make me recharge every few days? at what capacity (generally) does high quality cells go to 3.8V?
Please notice, I only do this to expensive cells I want to keep for a long time. I am sure its not very practical to do for very high powered lights.
3.8v to 4.0v is aprox. 40% of battery capacity. For example on my AW 18650 Protected 3400 mAh, 40% of 3400 is 1400mAh. That’s a little more than 4 hours on low on my light. So its not very inconvenient for charge every 4-5 days or so.
The Panasonic 18650 A,B & CH and Sanyo 18650 2600 really rock for longevity & capacity.
That’s why a lot of the top brands have these cells inside.
I started this hobby about two years ago so i’m still a newb but i can’t really notice any decline in my very first panasonic cells, an 18650 A and an 18650 CH which may have been slightly abused due to my ignorance at the time.
The cheaper brands really are not worth buying as far as i am concerned - i must have thrown out five “DubiousFire” cells to every panasonic that i still have.
I have Sanyo 2600’s from laptop pulls that must be five years old at least and are still going strong.
When you use your flashlights frequently you really get to know them and can tell good cells not so much from visual output but from runtime and especially from how hot the light gets in high mode.
I even use this as an indicator of when to recharge batteries, there’s a noticable decline in the heat of the light.
I have ruined a few cells and would say the number 1 causes of destroying a Li-Ion is running it to below about 3v, shorting them out or cutting them in half with a hacksaw. 
So best to treat them with respect in those regards.
As to prolonging the life of cells, i keep all my cells near enough fully charged at all times and cycle them at least once a month.
I really don’t see the point in storing them at a third or half capacity or whatever because the whole point of batteries is to use them for convenience or when you need them most, probably when there’s no power for your charger…
Sure it may decrease the overall life of the cells but with so many good batteries coming out and the technology improving constantly you’ll want to be buying and replacing cells every 2, 3 or 4 years anyway.
That’s just my thoughts.
I always thought it’s best to cut them in half using a blowtorch :bigsmile:
I was out of gas at the time
Thanks alot guys, i’m realtivley new to flashlights/chargers/batteries, i got my Panas green protected 3400 mah, (NCR18650B) having use them for around 1 year, so i always wanted to know what is the best way to prolong life, while having the max output - and optimal charge.
i now know the “best” way of doing it.
Charge to around 4-4.10V and don’t discharge lower then lets say 3.7 - 3.8V i think this is the best balance generally, i also keep my TK 75 (with batteries) in room temp not over 25-30c at most. Thanks one more time.
Edit, my incmong Efest LUC V4 (updated version) will be great in order to know when to get them of the charger, ~ 4.10V without having to check the volts, it has voltmeter on the LED screen, making life so much simple!
Check your Efest LUC V4 charge termination with a multimeter too though if that light runs in series. I notice some bays tend to terminate lower than others, 4.12-4.17, very dissappointing since I bought it to charge all evenly to 4.2V when I needed 4 at a time, as an alternative to the TR-008, which only has 3 bays and always charges all bays to 4.14V. Its kind of nice in a way, a charger imposed battery life increaser.
I also have had some Panasonic 3400mAh batteries that I have had for over a year, with heavier use than most I have heard on here, I tend to have 1+ hr/night average, sometimes up to 3hrs of usage of a light/night walking dogs. No difference in capacity that I notice yet. I do have more lights and batteries that I cycle through, so at least a couple hrs/wk usage is what they get. The only cells I’ve had a problem with (other than crappy Ultrafire in the very beginning) is a red Sony I got from someone else, they got very hot on charging, so I tossed them.
Thanks for the tips, but can’t you use the leds on the display to see the volts? or its in-accurate? i plan to remove the batteries from the charger @4.10 ±
What are the downsides of different volts (after termination)? not sure if TK 75 batteries are in parallel or serial tbh.
Also good to here about the panas doing great.
P.S. Do you have the updated version of the LUC V4?
You could also hook up the volt meter Kodachrome40 linked to a TP4056 charger board to make one of these and have a handy compact charger/volt meter in one.
You might find this information from HKJ useful too
For batteries you using,
Charge them maximum to 4.1V (90% SOC) and keep cool and recharge when resting voltage 3.8V or higher —> maximum life expectancy
charge them 4.2V and use them till empty and keep hot —> lowest life
Cycle life:
if battery has 300 cycles before capacity reduce to 70% its 100% full charge cycles.
that battery may have around 1000 cycles if you discharge 50%
I’m new to 18650 Li-ions and was wondering how it can have 0% capacity at 3.3 and 3.2. If it has no capacity left at 3.3 how can you still run the cell down to
3.2 and still have light?
BTW that’s a nice chart on capacity TY. I’m keeping a copy for reference.
I just (dis)charge my cells to 3.8v checked with a DMM and then leave them in their battery boxes.
Mine stay at 3.8v for 6 months+. Not sure how much longer because that’s the longest I’ve ever kept them in storage.
I’m no expert but as far as i understand it, about 3v is the lowest a li-ion cell is happy to go to, any lower and damage occurs so the voltage range for these cells is 2.8-3v to 4.2v
3v= fully depleted and 4.2v= fully charged. 3.7v is the nominal, average or working voltage of the cell.
This was confusing to me at first too.
They will still be able to output some power below 3v but like i said, it’s really bad for their chemistry.
Check out my signature links for more useful charts 
Great TY CRX I think I understand. Also two more good links to bookmark.
There is a large difference in voltage, depending on when you measure it, when loaded it is significantly lower.
In some cases that difference can be more than a 0.5 volt.
In the chart below I am switching a 3A load on/off. The red line shows the voltage and it jumps up and down with load/no load:
%20-%203A-Capacity.png)
How low a LiIon cell can go depends on the chemistry and if you measure loaded or unloaded voltage. A modern Panasonic cell can usual go down to 2.5 volt when loaded, but will recover to 3.3 volt when the load is removed.
Thanks alot guys! its alot clearer now