Battery end of life - how do you know

[Marc411]

I really can't find what I'm looking for doing a search.

I date my batteries when I get them and recharge between 3.5 and 3.8 consistently. I also check them with an 510 meter when I drop them into a PV.

I have some batteries from 4/2014 and after charging them I'm still get 4.1/4.2 but they seem to discharge faster then some of my other batteries. I don't often build below 1 ohm so they way they are used is fairly consistent.

And I'm not sure how many times I have cycled them each, they are VTC's

Any problems continuing to use them even though they discharge quicker then others?

 

[Ryedan]

Which VTC's are they, 3,4 or 5? And what batteries are you comparing them to?

As for cycles, just estimate for both. It doesn't matter if they have 100 or 125. It does matter if they have 50 vs 250.

As for how you know when they are getting old, reduced time between charges is a good one for you as you don't push them hard. I run mine around 0.3 ohms all the time these days so I put more importance in voltage drop under load. Might not make much difference in the end, but it eliminates having to estimate ml of juice vaporized so it's way more accurate.

 

[Marc411]

Thanks for the response Ryedan.

They are VTC5's from April of 2014. The reason I asked the question is because they always charge to 4.1/4.2 but seem to discharge quickly. Very rarely am I doing anything below 1 ohm. I use them in both regulated and mechs and I can honestly say I've never drained them below 3.5.

What I've learned about batteries has all come this site and most from bother Baditude through PM's. My understand was that a battery would stop taking a full charge as it became end of life.

I just want to make sure that as my batteries age I'm continuing to be safe and toss them when they are no longer usable.

 

[twgbonehead]

Wish Baditude was still around!

I don't believe there's any increased danger as these batts get old (particularly the way you're using them). I would take a look at how "soft" the holding voltage is getting.

The batteries should drop relatively quickly from 4.1V or so to 3.7V. They then should hold at the 3.7V for much of the cycle, and taper down below that only when they have delivered most of their power. If you're not seeing that "plateau" at 3.7V it means it's time for the battery to go into the recycling bin.

ETA: My experience is more with other battery chemistries. The "plateau" for Li-Ion batteries is apparently a bit "softer", in the range of 3.7V to about 3.4V. It should hold within this range for most of the cycle, however.

If a battery won't hold a charge (almost perfectly) while it's on the shelf, that's an even stronger indication it wants to go. Charge it to 4.1V, let it sit on the shelf for a week, and check it. If it's dropped more than .1V, it is time for it to go. (Leakage like this is a strong sign that the battery is starting to fail in a bad way, as opposed to just getting a little tired).

ETA: Leakage is one of the most concerning symptoms, since it means the battery has started to develop tiny shorts internally. These start out as high-resistance, but they will grow larger fairly quickly, and at some point will go into runaway (meaning that the short starts carrying more current, which makes it grow, carrying even more current, and so on, and this can happen very abruptly!)

Of course, anything abnormal - battery getting hot while charging, any leakage or distortion, and get it the heck out of there!

I know Bad would have given you a more precise answer, sorry, this is the best I got.

 

[supertrunker]

They are safe - what happens to a battery is as it ages the internal resistance it develops over many charge cycles increases.

So every time you fire it, it has to over come this before it can deliver the power you need. So it discharges fast, but it's not unsafe because of this.
You can get meters to measure the ir of the battery, but they ain't cheap. Whereas new batteries are.

T

 

[supertrunker]

No - but if you discharge it below 2.5v, then there's a chance your charger cannot resurrect it and you will have a paperweight!

In a regulated mod, with electronics, you will likely never encounter this - but if you use a mechanical mod and do that, you will wreck batteries fast and that is why for mechanicals at least, most people don't go below 3.6v or so.

T

 

[Kevin littell]

I also go by leakage and charge volts.


If they wont take or hold one they hit the recycle bin. Run time varys battery to battery

 

[twgbonehead]

IM new and use the battery until it no longer works, could I have a problem,like leakage? or explosion or something?

It's actually fairly bad to discharge these too low. In addition to the possibility that your charger won't be able to charge them, you are also risking the battery going into thermal runaway when recharging. When you say "use it until it no longer works" are you talking about a regulated mod (which will shut off if the voltage drops too far) or a mech mod?

 

[Ryedan]

Thanks for the response Ryedan.

They are VTC5's from April of 2014. The reason I asked the question is because they always charge to 4.1/4.2 but seem to discharge quickly. Very rarely am I doing anything below 1 ohm. I use them in both regulated and mechs and I can honestly say I've never drained them below 3.5.

What I've learned about batteries has all come this site and most from bother Baditude through PM's. My understand was that a battery would stop taking a full charge as it became end of life.

I just want to make sure that as my batteries age I'm continuing to be safe and toss them when they are no longer usable.

Your welcome and thanks back to you

You didn't give me much info to work with about your particular batteries. An estimate of the number of cycles and what batteries you're comparing to would have been very handy.

To say they charge to 4.1/4.2v doesn't give much info. Mine charge to 4.20-4.21v right when the charger stops and after an hour they are at 4.19-4.20v. If my charger charged to 4.23v or above I would get another charger.

As batteries age through charge cycles and being pushed hard their internal resistance goes up. This makes them heat up more at the same amp output so their max amp ratings go down. It also takes away from how long their charge lasts because the higher internal resistance is wasting energy, so their effective mAh goes down. In mechanical mods it also means the voltage under load delivered to the coil goes down so if I have a new battery and an old one and the fully charged new battery delivers 3.8v at 0.5 ohms and the old one 3.2v, I have to make a lower ohm setup for the old battery to get the same power and that will take even more vape time away from a charge. They will however still charge to 4.2v until they get really bad, so if you have a battery that only charges to 4.10v on a good charger, IMO it's way past time to retire it.

As far as safety goes, well it all depends. If you're never going above 5A draw on 30A batteries they will be safe when they are quite worn out. If you're drawing 25A from them, I would not let them get too bad.

To compare how long different batteries will last down to a certain voltage I use this site. If you plug in your batteries and chose the appropriate amp draw, you'll get a good idea of what to expect with good batteries. If your results are way off what the chart says, something is wrong with some of your batteries. Keep in mind that the voltages are under load and how low you take battery voltage affects the run time per charge.

 

[Ryedan]

It's actually fairly bad to discharge these too low. In addition to the possibility that your charger won't be able to charge them, you are also risking the battery going into thermal runaway when recharging. When you say "use it until it no longer works" are you talking about a regulated mod (which will shut off if the voltage drops too far) or a mech mod?

This ^^^.

Repeatedly discharging a VTC battery under 2.5v under load will cause changes to the chemical structure in the battery and if that gets bad enough it can cause an internal short, which is IMO the worst type of failure besides puncturing the battery. I believe these shorts happen most often while charging but they can happen to a battery damaged this way at any time and IMO may cause an otherwise safe IMR or hybrid Li-ion battery vent with flame or explode.

 

[Marc411]

Your welcome and thanks back to you

You didn't give me much info to work with about your particular batteries. An estimate of the number of cycles and what batteries you're comparing to would have been very handy.

To say they charge to 4.1/4.2v doesn't give much info. Mine charge to 4.20-4.21v right when the charger stops and after an hour they are at 4.19-4.20v. If my charger charged to 4.23v or above I would get another charger.

As batteries age through charge cycles and being pushed hard their internal resistance goes up. This makes them heat up more at the same amp output so their max amp ratings go down. It also takes away from how long their charge lasts because the higher internal resistance is wasting energy, so their effective mAh goes down. In mechanical mods it also means the voltage under load delivered to the coil goes down so if I have a new battery and an old one and the fully charged new battery delivers 3.8v at 0.5 ohms and the old one 3.2v, I have to make a lower ohm setup for the old battery to get the same power and that will take even more vape time away from a charge. They will however still charge to 4.2v until they get really bad, so if you have a battery that only charges to 4.10v on a good charger, IMO it's way past time to retire it.

As far as safety goes, well it all depends. If you're never going above 5A draw on 30A batteries they will be safe when they are quite worn out. If you're drawing 25A from them, I would not let them get too bad.

To compare how long different batteries will last down to a certain voltage I use this site. If you plug in your batteries and chose the appropriate amp draw, you'll get a good idea of what to expect with good batteries. If your results are way off what the chart says, something is wrong with some of your batteries. Keep in mind that the voltages are under load and how low you take battery voltage affects the run time per charge.

Excellent information!

I can't even guess at the amount of times they have been cycled. I have a good amount of batteries and rotate them with a ton of discipline. Freshly charged batteries are placed at the back of the drawer and batteries are used from the front. Like I said I don't sub-ohm often and most are used in regulated mods.

I'll keep an eye on them and probably pick up some LG's or Samsung's and rotate them out. They are cheap so I'd like to safely squeeze as much out of them as possible.