18650 won't charge?

Ok, I have a relatively new set of 4 Tenergy 18650 batteries I bought in December from all-battery.com

Per Tenergy it is ok and a good thing to discharge them all of the way.
I did this with two batteries and now they will not recharge at all.
I've left them in the charger over night but no charge. The charger shows the green light right from the start.
What's going on?

I tried them in another charger and same thing. Green light. Does that not always indicate they are seen as fully charged? But they do nothing in my Fenix tk-11.

Was it a bad idea to fully discharge them?

I do not know much about these types of batteries yet other than what I'm starting to read on this forum. I don't even know how to test for voltage and such like I'm reading to do here.
Thoughts?

Thanks,
Nick

Protected or unprotected ...?

If there protected , it could be the PC is not re-setting ...
If you discharged them to where the over discharge protection kicked in , then the PC may not be allowing the battery to recharge ..

This seem to happen often enough :
And I dont remember the fix from the top of my head , hopefully some one else will chime in ...

If there unprotected cells , oh oh ! :mecry:

If you over-discharge an unprotected li-ion cell to a certain voltage, they will either lose alot of capacity or die.

If it is protected, the PTC may have shut it down forever.

When you say that you fully discharged the cells , was that to the 3.6 volt point ? ... A 18650 cell that measures 3.6 volts is virtually fully discharged ... Did you measure the open circuit voltage or did you discharge to the point where the torch/battery stopped working ?

Also are the cells protected ? ... If so , the protection circuit should have disconnected the cell to prevent damage to it ... It will need to be reset ... If the cell was unprotected then it has probably died ... There are ways to try to revive it , but I (personally) wouldn't trust it now.

Do you live near to the Fire Station ? ... You will find that most people strongly suggest that you don't leave Li-Ions on charge unsupervised and certainly not overnight ... Even with the best charger in the world , it is strongly recommended that the cell is taken off charge as soon as the "green" LED comes on.

I hope your cells are the protected type as there is a much better chance that they are not ruined.
.

Sorry, they are the 3.7v 2600mah protected cells from Tenergy here:
http://www.all-battery.com/4tenergyli-ion1865037v2600mahrechargeablebatterieswithinternalpcb.aspx


Unfortunately I do not know if they were discharged to "the 3.6 volt point" nor how to measure the "open circuit voltage" etc.

Tenergy told me directly it was a good thing to run them all the way down. To do this I just left the flashlight on until it quit working, (Fenix TK-11).

So if the "protection kicked in" is there any way to reset the batteries to make them work again?
Why would Tenergy have told me to do it if it's actually not good for the battery?
Is it then a bad thing to actually ever run them all the way down?
I've always heard about rechargables in general to run them down and do full charge for best life but what is the general concensus for these Li- ion 18650 batteries then?

I was recharging them once my flashlight kicked down to the 50% power level.

Thanks for any direction and advice.
As I said I'm just learning about all of this.

Probably it overdischarged and the PC kicked in, not allowing it to be recharged. What I did last week and worked, was to get a 9 volt battery, touch the positives and negatives to the 18650 for 3 to 5 seconds. It should charge after that. Try and let me know if it works.

Touch it with a 9 volt battery for 3-5 sec.?
Sounds interesting but what is the concept behind that?
Also, I see so many posts concerning these batteries blowing up if mistreated I'd like to be assured doing that is perfectly safe.

The slightly higher voltage of the 9V battery triggers the PC and releases it from the blocking state, thus allowing the battery to work normally. It will not blow up with a 9V tension and a very low current for a few seconds.

Thanks for the reply.
I'll try that out tonight!

the charger should do that
(and I would not do it with such a high voltage)

other idea:
is it possible that the flat top does not make contact with the positive part from the charger?



PS: a "fully discharged" Li-Ion (which is about 2.6 Volts) is ok, when it happens during use.
But there is no need to discharge a half-used cell for charging.
On the contrary, that adds to the already limited lifetime.
It is better to leave them as is, recharge them before use and use them then.

(in short: do not discharge them with cause before recharging, do not keep them stored when fully charged)

The charger should do it, but it doesn't. It was either throwing the cell away or trying to apply higher voltage. The higher voltage worked

I have 2 different chargers and both were immediately throwing the green light as if the batteries were already charged. So in this case, the charger is not solving the problem.

Interesting note about not storing a fully charged battery.
Why? And how do I avoid it?
For example, my charger will only charge 2 batteries, not 1 at a time.
I have 4 batteries and I use 1 at a time. That one will last 4-5 hours in my flashlight which actually means it is good for several weeks or more based upon my typical usage.

So by default I'm going to have at least one fully charged battery sitting around all the time.

Is it not also bad to leave an uncharged battery sitting around for weeks or longer?

Keep in mind that the low voltage IC in most 18650's will only kick in if the discharge current is about 500mA and higher. So if you had the light on a very low setting, it is possible that the battery was way over discharged...

NB68 said:

I have 2 different chargers and both were immediately throwing the green light as if the batteries were already charged. So in this case, the charger is not solving the problem.

Interesting note about not storing a fully charged battery.
Why? And how do I avoid it?
For example, my charger will only charge 2 batteries, not 1 at a time.
I have 4 batteries and I use 1 at a time. That one will last 4-5 hours in my flashlight which actually means it is good for several weeks or more based upon my typical usage.

So by default I'm going to have at least one fully charged battery sitting around all the time.

Is it not also bad to leave an uncharged battery sitting around for weeks or longer?

Click to expand...

Same here, both chargers wouldn't turn the red light.

Storing them charged for a few weeks is OK. Storing for long periods, like months is not good. Your batteries should be fine.

You should not store Li-Ion's completely discharged for a long time. It will damage battery. Recommended charge for prolonged storage is 40% of charge which is about 3.8V open circuit. Also you can put them in refrigerator (but don't freeze them).
You don't need to discharge it completely. It is ok with Li-Ions to use them partially and then top them off. I believe that number of cycles specified by manufacturer applies to full discharge-charge situation (or almost). Charging and discharging battery causes it to "breathe". Internal crystalic structure expands and shrinks damaging itself over time. Avoiding full discharge somehow lessens this effect.

See some useful info here and here.

So neither full charge or full discharge is good.
Interesting.
Thanks for the battery U. links good information.
Taking another direction here, how to I test the real voltage of my battery and what tool is needed?

Also I've read a lot of comments about good / bad chargers. I thought they were all the same. Mine are supposedly is made by Tenergy but I've since seen the exact same wall plug type with different or no brand label on them so I'm sure it's pretty generic.
When I search for chargers there's not much info from the retailer so how do you know if the one you get is good or bad performing?

I'm going to try the 9 volt kick start tonight and report back.

yellow said:

PS: a "fully discharged" Li-Ion (which is about 2.6 Volts) is ok, when it happens during use.

Click to expand...

Do you mean 3.6 Volts ?
.

NB68 said:

Sorry, they are the 3.7v 2600mah protected cells from Tenergy here:
http://www.all-battery.com/4tenergyli-ion1865037v2600mahrechargeablebatterieswithinternalpcb.aspx


Unfortunately I do not know if they were discharged to "the 3.6 volt point" nor how to measure the "open circuit voltage" etc.

Click to expand...

You really need a Digital Voltmeter to check the state of the cells ... For example a 3.6 volts reading means that the cell is empty whereas 4.2 volts is 100% fully charged ... 4.0 volts is 80% left and 3.8 volts is 40% left ... To check the open circuit voltage , all you have to do is remove the cell from the charger and measure the voltage with your meter ... If the voltage is below 4.2 volts , put the cell back on charge for a while and try a little later ... It's really easy but you will need a meter ... Open circuit voltage just means that nothing is connected to the battery , except of course the voltmeter ... I personally prefer to charge my cells when they get to about 3.8 Volts though you can top up the cells on the charger whenever you want as long as you remember to keep them over the 3.6 volt lower limit.

So if the "protection kicked in" is there any way to reset the batteries to make them work again?

Click to expand...

To reset the protection you first need a fully charged (4.2 volt) cell ... With a paper clip or similar , connect the two bottoms (-) of the good cell and the bad cell together ... Then with another paper clip do the same with the two tops (+) of the cells for just a couple of seconds ... If the bad cell has reset OK you will be able to measure a voltage across it ... You should then be OK to charge it ... Unfortunately if the bad cell has been discharged at a low current , the protection might not have tripped and the cell might be over discharged ... It then needs to be disposed of properly.

I hope that everything works for you ... By the way , a cheap digital meter is OK , so there is no need to spend more than a few dollars (or pounds).
.

You can buy multimeter at HomeDepot, Sears, Radio Shack and many other places. It does not have to be digital but digital is certainly easier to read. Analog will be probably cheaper though, you may be able to find one below $10. Depends how much you like to spend.


Once you have it, it is like march.brown wrote: take a battery and measure its voltage. Here is a great tutorial written by HKJ.

"Real" voltage will depend on load. Voltage will always drop under load. You don't need this information to charge batteries. The information you may be looking for is that your charger does not overcharge batteries meaning that when it goes green and you measure open circuit voltage of fresh battery it is 4.2V or little lower. On the other end you may want to check voltage of discharged cell taken out of flashlight. This way you may learn to estimate when to change batteries.


Personally I tend to replace Li-Ions pretty often. For some devices with fuel gauge it may be necessary to discharge battery fully from time to time to keep it calibrated but for most flashlights I don't think it is important. I would run Li-Ion to the end only in emergency.

Tanergy protection circuit kicks in at 2.5V but it is possible that flashlight stopped working before that. Did it die suddenly or it was dimming for very long time (like few hours). If it died quickly then probably your voltage is higher that 2.5V because driver in your TK-11 was not able to supply enough voltage to power LED. But if it was running long time dimming gradually then it would mean that driver went into direct drive and was passing directly to the led whatever was left in battery and 2.5V is enough to be higher than Vf of LED at very low current.

march.brown said:

To reset the protection you first need a fully charged (4.2 volt) cell ... With a paper clip or similar , connect the two bottoms (-) of the good cell and the bad cell together ... Then with another paper clip do the same with the two tops (+) of the cells for just a couple of seconds ... If the bad cell has reset OK you will be able to measure a voltage across it ... You should then be OK to charge it ... Unfortunately if the bad cell has been discharged at a low current , the protection might not have tripped and the cell might be over discharged ... It then needs to be disposed of properly.

Click to expand...

march.brown, that's a great idea, I haven't thought of that. I used a 9V battery, but what you said makes total sense. Using another 18650 is OK because the tension is equal but the current is much higher than a charger.

NB68, you should try that and see if it works. If it doesn't work, then try the 9V battery. Good luck! :twothumbs