batt volts drops then slooowly rises after vape

[edyle]

I have 2 batteries that are 8-9 months old;
they're merely labelled
18650 2200mAh 3.6V
blue wrapper

They've been noticeablely weaker than my newer efest red batteries which are about 7-8 months old.

I'm using 1 of them right now:
my vamo reads it at 3.9 volts right now.
vape.
3.9
vape
3.9
vape
3.7
vape
3.6
wait
3.7
wait
3.8
wait
3.8
wait
3.9

I'm thinking, symptom of pending death of battery.

Anybody ever notice that kind of behaviour? The voltage low after you vape, then slooooowly rising back up?

 

[Baditude]

What you are observing is the battery voltage drop "under load". The voltage recovers after a momentary work load and may climb slightly higher.

 

[edyle]

What you are observing is the battery voltage drop "under load". The voltage recovers after a momentary work load and may climb slightly higher.

Actually it's the voltage after load. Battery voltage; not voltage to coil.

unless its the electronics in the vamo still doing something after I release the button.

I'm seeing similar behaviour with the second blue battery.
When my red batteries charge tomorrow I'll try them too; maybe I'll get the same results.

 

[Baditude]

Actually it's the voltage after load. Battery voltage; not voltage to coil.

I'm not sure you are understanding the terminology of voltage sag and "under load". You're draining current from the battery when you vape. Voltage sags or drops "under load" as the battery is drained.

The battery soon recovers from the work load and the voltage rises accordingly.

vape. ----> current drained from battery.
3.9
vape -----> current drained from battery.
3.9
vape -----> current drained from battery
3.7 -----> voltage sag from the previous work

vape -----> current drained from battery
3.6 -----> further sag from work

wait
3.7 -----> battery recovers from voltage sag

wait
3.8 -----> battery recovers more from voltage sag

wait
3.8

wait
3.9 -----> battery recovers more from voltage sag

The above is completely normal. Your battery starts out at 3.9 volts, gets drained, recovers, and ends back to where it started.

 

[edyle]

I'm not sure you are understanding the terminology of voltage sag and "under load". You're draining current from the battery when you vape. Voltage sags or drops "under load" as the battery is drained.

The battery soon recovers from the work load and the voltage rises accordingly.

vape. ----> current drained from battery.
3.9
vape -----> current drained from battery.
3.9
vape -----> current drained from battery
3.7 -----> voltage sag from the previous work

vape -----> current drained from battery
3.6 -----> further sag from work

wait
3.7 -----> battery recovers from voltage sag

wait
3.8 -----> battery recovers more from voltage sag

wait
3.8

wait
3.9 -----> battery recovers more from voltage sag

The above is completely normal. Your battery starts out at 3.9 volts, gets drained, recovers, and ends back to where it started.

So I guess thats what is meant by voltage sag; the battery takes a noticeable amount of time to recover after the load.
People using mechs might even notice weaker vapes with each successive vape if the chain vape.


Makes me wonder what the heck is going on inside the battery during the recovery process

 

[Ryedan]

As Baditude said, it's normal behavior. I did think though that a 0.3V drop was a bit much so I tried it with one of my VTC4 cells that is around 6 months old and has as a rough guess around 80 charge/discharge cycles on it. I used my Reo Grand and a DMM, so had easy access to the battery but it took about 2 seconds to get it on the meter (slightly better result).

Initial V = 3.800
Atty resistance = 0.5 ~ +-0.03 ohms

After 15 seconds on
3.735V ........................................... 3.800-3.735 = 0.065V compared to your blue batteries at 0.3V
3.780V after ~1.5 minutes
3.789V after ~8 minutes

I then did a V-drop under load check, which is an immediate reading after hitting the button. Takes my meter a second to stabilize, so the voltage will be slightly lower than the immediate reading (worse result). I put the meter probes on the top of the atty posts.

Initial reading = 3.789V
Under load = 3.36V

V-drop = 0.429V

Considering the 0.5 ohm atty and the mod, I know from comparison to V-drop under load when these were new, 0.43 V-drop means my battery has very close to its original internal resistance and it's got a lot of life left still.

edyle, I think you vape significantly higher resistance attys than I do. If I did the voltage drop test over time (the first one I did above) with a 2 ohm atty I would expect much less voltage drop from my battery (amp draw at 3.8V would be 1.9 instead of 7.6). I know if I do the V-drop under load test with a 2 ohm coil I will get significantly less V-drop from my battery.

The VTC4 batteries are known to be pretty good performers. Your generic batteries are unknown so I have no idea how they would have done when new, but I do think they have high internal resistance and I wouldn't push them too hard. If you're vaping high resistance coils, I wouldn't worry about it until the batteries didn't hold charge for long. If you're sub-ohm, I would do a V-drop under load test and go from there.

 

[edyle]

As Baditude said, it's normal behavior. I did think though that a 0.3V drop was a bit much so I tried it with one of my VTC4 cells that is around 6 months old and has as a rough guess around 80 charge/discharge cycles on it. I used my Reo Grand and a DMM, so had easy access to the battery but it took about 2 seconds to get it on the meter (slightly better result).

Initial V = 3.800
Atty resistance = 0.5 ~ +-0.03 ohms

After 15 seconds on
3.735V ........................................... 3.800-3.735 = 0.065V compared to your blue batteries at 0.3V
3.780V after ~1.5 minutes
3.789V after ~8 minutes

I then did a V-drop under load check, which is an immediate reading after hitting the button. Takes my meter a second to stabilize, so the voltage will be slightly lower than the immediate reading (worse result). I put the meter probes on the top of the atty posts.

Initial reading = 3.789V
Under load = 3.36V

V-drop = 0.429V

Considering the 0.5 ohm atty and the mod, I know from comparison to V-drop under load when these were new, 0.43 V-drop means my battery has very close to its original internal resistance and it's got a lot of life left still.

edyle, I think you vape significantly higher resistance attys than I do. If I did the voltage drop test over time (the first one I did above) with a 2 ohm atty I would expect much less voltage drop from my battery (amp draw at 3.8V would be 1.9 instead of 7.6). I know if I do the V-drop under load test with a 2 ohm coil I will get significantly less V-drop from my battery.

The VTC4 batteries are known to be pretty good performers. Your generic batteries are unknown so I have no idea how they would have done when new, but I do think they have high internal resistance and I wouldn't push them too hard. If you're vaping high resistance coils, I wouldn't worry about it until the batteries didn't hold charge for long. If you're sub-ohm, I would do a V-drop under load test and go from there.

I vape 2 ohm coils so I don't use the high powered batteries;

I was just concerned whether the behaviour was a sign of something wrong with the battery because I know it's oldish, it's weaker than it used to be, plus the particular one I was looking at kind of looks like there's a slight bulging at the base so been watching it close.

But so far I feel reassured that it's more or less normal battery sag behaviour that I never noticed before.

 

[Ryedan]

I vape 2 ohm coils so I don't use the high powered batteries;

I was just concerned whether the behaviour was a sign of something wrong with the battery because I know it's oldish, it's weaker than it used to be, plus the particular one I was looking at kind of looks like there's a slight bulging at the base so been watching it close.

But so far I feel reassured that it's more or less normal battery sag behaviour that I never noticed before.

Yup, they all do it.

OTOH, a slight bulge at the base ... where is 'the base'? These batteries should not bulge anywhere, ever. Seriously.

Can you post a picture of it?

 

[edyle]

Yup, they all do it.

OTOH, a slight bulge at the base ... where is 'the base'? These batteries should not bulge anywhere, ever. Seriously.

Can you post a picture of it?

the base meaning the negative end.



The white stuff is because that part of the insulation was loose and I stuck it with some glue and rested it on some tissue paper to dry so the tissue made it whitish; that's the battery with the slight bulge.
The other battery I put next to it for comparison.
The bulging is very slight and probably not noticeable from the pic.



My red battery is performing alot better than the blue; the sag is only 0.1 volt and I have to push it hard to get that.
I already have 2 purple efests on order; I should get them next week.

 

[Baditude]

the base meaning the negative end.

View attachment 370742

That battery looks terrible. Please discard that battery immediately.

 

[edyle]

That battery looks terrible. Please discard that battery immediately.

forgot to add the description:

The white stuff is because that part of the insulation was loose and I stuck it with some glue and rested it on some tissue paper to dry so the tissue made it whitish; that's the battery with the slight bulge.
The other battery I put next to it for comparison.
The bulging is very slight and probably not noticeable from the pic.

 

[Ryedan]

the base meaning the negative end.

View attachment 370742

Hard to say what it is, but it looks like metal to me, much as I can't imagine that it actually is. edyle, I don't know what's up with that battery, but I would not use it like that.

My red battery is performing alot better than the blue; the sag is only 0.1 volt and I have to push it hard to get that.
I already have 2 purple efests on order; I should get them next week.

Good to hear that . Suggest you retire 'the bulge' and move on with the new ones

 

[Ryedan]

forgot to add the description:

The white stuff is because that part of the insulation was loose and I stuck it with some glue and rested it on some tissue paper to dry so the tissue made it whitish; that's the battery with the slight bulge.
The other battery I put next to it for comparison.
The bulging is very slight and probably not noticeable from the pic.

OK, that explains that, LOL. Hmm, do you mean there is still bulging there that is not noticeable to us?

 

[edyle]

Hard to say what it is, but it looks like metal to me, much as I can't imagine that it actually is. edyle, I don't know what's up with that battery, but I would not use it like that.



Good to hear that . Suggest you retire 'the bulge' and move on with the new ones

OK, that explains that, LOL. Hmm, do you mean there is still bulging there that is not noticeable to us?

Maybe bulge is too strong a word; when I look at it it seems a bit concave, but I think the pic shows there's no big obvious bulge and the other one is there for comparison;

the batteries stand upright; but the one with the concave end does have a bigger wobble to it .
By comparison both my red batteries stand solidly flat; so that says something.

 

[edyle]

that does it for me; the standing test proves its it's not just my eyes imagining a slight bulge; both those batteries are gonna have to go.

 

[Ryedan]

that does it for me; the standing test proves its it's not just my eyes imagining a slight bulge; both those batteries are gonna have to go.

Good on you for making the safer decision. Vape on edyle