are revived batteries "safe"?

[Barkuti]

The Dragon VP4 has a nice and consistent internal resistance feature. I bet it does AC resistance measurement, values frequency and cell/pack size dependent and likely to be a lot lower of the actual DC ones.
It may be your cells are fine and it is just you being slighly paranoid, Vesh. Of course, no one called me for advice.


P.S.: fixed quick explanation.

 

[Vesh]

The Dragon VP4 has a nice and consistent internal resistance feature. I bet it does AC resistance measurement, values likely to be square root (lower) of the actual DC ones.
It may be your cells are fine and it is just you being slighly paranoid, Vesh. Of course, no one called me for advice.

nope, i very much value your input.. i do think it was a fair topic to make though.. because i literally had batteries at almost 0 volts and was legitimately worried.

 

[Mooch]

"12um"?

Interesting.. the second set of 3x VTC5A's has settled on 2497, 2525 and 2535 mah.
So, overall the same as the first set. Resistance is also 12. Therefore impossible to ascertain which is good or bad set. The only thing i know for sure, is that i took one set from a mod that i noticed had lowered them, but they were still around 3.5 volts, so had never been under volted, ever. Therefore, i am shocked i am not getting the 2600 mah out of any of them, and this has led to the confusion of which set was good or bad. So what i am going to do is simply keep them all, in specially coloured cases, and just use them till whenever, in a year toss them and go back to my others which i will keep put away at nominal volts in good cases. That'll do. I guess that's it..

Oh i have to ask, what should the resistance be on 30Q's? Mah was great as i said, 3032, no capacity loss there.. so just really need to know what resistance is ok, if it tests ok, i will keep those too. The aspires i am tossing, well, giving to recycling. Too risky, they are the less safe chemistry and have dropped 100 mah so they have definitely been affected.

To get 2600mAh back into a 2600mAh rated battery it has to be discharged to 2.5V.

30Q DC IR is about 21-25mOhms.

The DC and AC refer to the type of internal resistance test done. It's important because the AC IR of a cell is always a lot lower than the DC IR.

DC IR testing is done by switching between two different continuous discharge rates and measuring the voltage change. AC IR is measured using a 1kHz sine wave discharge.

The AC IR rating is probably the most common in the datasheets but the DC IR is the one that's much more useful for us.

 

[Mooch]

"12um"?

Interesting.. the second set of 3x VTC5A's has settled on 2497, 2525 and 2535 mah.
So, overall the same as the first set. Resistance is also 12. Therefore impossible to ascertain which is good or bad set. The only thing i know for sure, is that i took one set from a mod that i noticed had lowered them, but they were still around 3.5 volts, so had never been under volted, ever. Therefore, i am shocked i am not getting the 2600 mah out of any of them, and this has led to the confusion of which set was good or bad. So what i am going to do is simply keep them all, in specially coloured cases, and just use them till whenever, in a year toss them and go back to my others which i will keep put away at nominal volts in good cases. That'll do. I guess that's it..

Oh i have to ask, what should the resistance be on 30Q's? Mah was great as i said, 3032, no capacity loss there.. so just really need to know what resistance is ok, if it tests ok, i will keep those too. The aspires i am tossing, well, giving to recycling. Too risky, they are the less safe chemistry and have dropped 100 mah so they have definitely been affected.

To get 2600mAh back into a 2600mAh rated battery it has to be discharged to 2.5V.

12mOhm sounds about right for the AC IR or your device is reading a bit low if that's the DC IR.

30Q DC IR is about 21-25mOhms.

The DC and AC refer to the type of internal resistance test done. It's important because the AC IR of a cell is always a lot lower than the DC IR.

DC IR testing is done by switching between two different continuous discharge rates and measuring the voltage change. AC IR is measured using a 1kHz sine wave discharge.

The AC IR rating is probably the most common in the datasheets but the DC IR is the one that's much more useful for us.

 

[Vesh]

ok so are there any cheap ways i can "dc" test battery resistance? I wouldn't mind a meter that can do that. Can you recommend anything inexpensive?

 

[Vesh]

Ok, things are not looking good.. for what it's worth, the dragon displays the result as "xx" xx being the number, then, mu.. the u is actually not a u but the shape of an ohm.. so it's milli ohms.

I can not find anywhere, including the manual, whether it's ac or dc checking.

But, after testing about 30 batteries, including some that have only ever done 2 cycles and never gone below 3.5 volts, i am devastated in that i think i have been sold nothing but fakes, except from one seller. the LG HE4 were over 100, (then say 50 on a second try, then say 80 or 100 on a third), the vtc5a are lowest of absolutely everything and the vtc5a is what i only bought from the seller i trust..

The aspire 1800's are toast IMO.. dragon even has issues getting resistance reading in half the cases, then they are like 150. All 6 of them. These were genuine of course as direct from aspirecig.com
Basically i ruined them with the voltage drain.

I am so confused right now, and need to sleep, as i have devoted 30 waking hours to this so far..

I am going to donate some more to you tomorrow mooch and i really need your help.. just know it's appreciated.

I basically have a few more simple questions and results to share, but my brain can't process it now at 2am. Thank you everyone.

PS the vtc5a's that were 12, fluctuate as high as 35.. i have read this means they are bad.
However, they are about a year old and have done a few cycles. this is why i am trying to work out what's normal or not.

lesson learned, test resistance of absolutely every single battery the moment it arrives, and then do a mah test. Every time. Lesson learned alright!

My first, "bad lot" of vtc5a where i posted mah figures yesterday, have given entirely different results in the dragon (which discharges to 2.6)
2490, 2535, and 2620 mah! This was using the full, LOOOOONG test mode.
So they are really quite a but different from one another.. resistances fluctuating today also.
peace all

 

[Mooch]

Ok, things are not looking good.. for what it's worth, the dragon displays the result as "xx" xx being the number, then, mu.. the u is actually not a u but the shape of an ohm.. so it's milli ohms.

I can not find anywhere, including the manual, whether it's ac or dc checking.

But, after testing about 30 batteries, including some that have only ever done 2 cycles and never gone below 3.5 volts, i am devastated in that i think i have been sold nothing but fakes, except from one seller. the LG HE4 were over 100, (then say 50 on a second try, then say 80 or 100 on a third), the vtc5a are lowest of absolutely everything and the vtc5a is what i only bought from the seller i trust..

The aspire 1800's are toast IMO.. dragon even has issues getting resistance reading in half the cases, then they are like 150. All 6 of them. These were genuine of course as direct from aspirecig.com
Basically i ruined them with the voltage drain.

I am so confused right now, and need to sleep, as i have devoted 30 waking hours to this so far..

I am going to donate some more to you tomorrow mooch and i really need your help.. just know it's appreciated.

I basically have a few more simple questions and results to share, but my brain can't process it now at 2am. Thank you everyone.

PS the vtc5a's that were 12, fluctuate as high as 35.. i have read this means they are bad.
However, they are about a year old and have done a few cycles. this is why i am trying to work out what's normal or not.

lesson learned, test resistance of absolutely every single battery the moment it arrives, and then do a mah test. Every time. Lesson learned alright!

My first, "bad lot" of vtc5a where i posted mah figures yesterday, have given entirely different results in the dragon (which discharges to 2.6)
2490, 2535, and 2620 mah! This was using the full, LOOOOONG test mode.
So they are really quite a but different from one another.. resistances fluctuating today also.
peace all

I don't think any of your batteries are the problem.

The resistance testing function of these chargers is almost useless IMHO. The readings are wildly inaccurate most of the time and very inconsistent. I had hope since your 12mOhm readings were reasonable but I strongly urge you not to use the IR function anymore.

Get one of these, they measure D.C. IR and are verrrry accurate. I spoke with the designer when he created them and like what he did. I have two of them.

Universal ESR Analysis Meter - ProgressiveRC

 

[Barkuti]

One of the biggest hurdles for precise battery/cell internal resistance measurements are the probe contact resistances, which can be larger than the DC internal resistance of a high discharge cell and are wildly unpredictable (as any freehand cable/probe contact can be). This is the reason many (if not all) chargers with internal resistance measurement functions are dismissed in this regard. By soldering the cell to be tested to the charger rail I am pretty sure the IR measurements would look good and be repeatable, pretty inconvenient though. You could also buy a proper battery holder and do some sort of frankenmod, inconvenient stuff too. Finally, you can buy a properly designed tool like the stuff Mooch pointed out.

Cheers

 

[Vesh]

One of the biggest hurdles for precise battery/cell internal resistance measurements are the probe contact resistances, which can be larger than the DC internal resistance of a high discharge cell and are wildly unpredictable (as any freehand cable/probe contact can be). This is the reason many (if not all) chargers with internal resistance measurement functions are dismissed in this regard. By soldering the cell to be tested to the charger rail I am pretty sure the IR measurements would look good and be repeatable, pretty inconvenient though. You could also buy a proper battery holder and do some sort of frankenmod, inconvenient stuff too. Finally, you can buy a properly designed tool like the stuff Mooch pointed out.

Cheers

yes but i have read that the dragon is very accurate. It has been tested and reported as such. This is not using the internal battery trays but a separate proper probe like the ones you get with battery testers. I agree the resistance measurements when using the trays are not accurate. The guy that reviews all chargers, Flashlight information, says the opus is not accurate for resistance which makes sense, as it uses the slider contacts, but the dragon is. I have seen reports of the dragon accuracy of the probes being confirmed to within +- 1%

 

[Vesh]

I don't think any of your batteries are the problem.

The resistance testing function of these chargers is almost useless IMHO. The readings are wildly inaccurate most of the time and very inconsistent. I had hope since your 12mOhm readings were reasonable but I strongly urge you not to use the IR function anymore.

Get one of these, they measure D.C. IR and are verrrry accurate. I spoke with the designer when he created them and like what he did. I have two of them.

Universal ESR Analysis Meter - ProgressiveRC

ok i'll get it, but when it gives the same measurements, at least we will know.

So the question remains..

and i'll make it an easy generalisation so much less to answer..

does a battery resistance change with age, and how many cycles before a significant change?

As far as individual resistances, any idea what the ijoy 20700's should be, as i have brand new ones coming tomorrow.. and this is a way of testing the accuracy of my meter, well, isn't it! hehe.

any idea also what 26650 should be, ijoy is fine as i have them, and aspire 1800's or LG HG6's?

 

[Mooch]

yes but i have read that the dragon is very accurate. It has been tested and reported as such. This is not using the internal battery trays but a separate proper probe like the ones you get with battery testers. I agree the resistance measurements when using the trays are not accurate. The guy that reviews all chargers, Flashlight information, says the opus is not accurate for resistance which makes sense, as it uses the slider contacts, but the dragon is. I have seen reports of the dragon accuracy of the probes being confirmed to within +- 1%

If true then the measurements would be consistent, which is more important than accuracy as any consistent offset is easily accounted for.

You could be right about its accuracy but then, and I mean no disrespect here, there are one or more unaccounted for variables in your testing. The batteries are typically quite consistent in their IR, even if damaged.

 

[Mooch]

ok i'll get it, but when it gives the same measurements, at least we will know.

So the question remains..

and i'll make it an easy generalisation so much less to answer..

does a battery resistance change with age, and how many cycles before a significant change?

As far as individual resistances, any idea what the ijoy 20700's should be, as i have brand new ones coming tomorrow.. and this is a way of testing the accuracy of my meter, well, isn't it! hehe.

any idea also what 26650 should be, ijoy is fine as i have them, and aspire 1800's or LG HG6's?

Yes, resistance increases as the battery ages. Check the datasheet's for the batteries you want to test. The info should be in the cycle life specs.

I don't know the resistance of the iJoy's but if you get consistent readings then even if not accurate it's ok as you can still use them as the starting values for the cell's.

Hmm...not sure if that meter will read just passive resistance, i.e., read the value of a resistor and not a cell. If it did you can use precision resistors to check the accuracy of the meter.

The Aspire is now using a crappier cell and its resistance is higher, a bit over 20mOhm IIRC. The HG6 is about 18-20mOhm IIRC. Most of the cells we use are in a very tight group around 20mOhms (DC resistance). A very accurate meter and very controlled testing methodology is required to sort them out.

 

[Mooch]

Yes, resistance increases as the battery ages. Check the datasheet's for the batteries you want to test. The info should be in the cycle life specs. The changes start immediately but are greater for each cycle at the start.

I don't know the resistance of the iJoy's but if you get consistent readings then even if not accurate it's ok as you can still use them as the starting values for the cell's.

Hmm...not sure if that meter will read just passive resistance, i.e., read the value of a resistor and not a cell. If it did you can use precision resistors to check the accuracy of the meter.

The Aspire is now using a crappier cell and its resistance is higher, a bit over 20mOhm IIRC. The HG6 is about 18-20mOhm IIRC. Most of the cells we use are in a very tight group around 20mOhms (DC resistance). A very accurate meter and very controlled testing methodology is required to sort them out.

 

[Vesh]

it could be my fault after all this.. i have been watching some video and i have noticed everyone that uses the probes to test, as they are spring loaded, puts some pressure. I have literally just been touching it to the battery. I will try by applying a bit of pressure either end and see if that changes.

I just double checked the review at CPF as well, and he says the resistance measuring is accurate. As far as chargers go this guy is pretty much what you are to batteries..

i am sure the vtc5a's are ok then as all of them at least a year old.. the he4's are not, only a few months and a couple cycles, so i am sure they are fakes.. specifically after i asked the guy up front if they were legit, and a well known vape store to boot.

I would think all my HG2's are fake also as they are consistently reading 3x the vtc5a's. I wish there was a way to tell fakes from real, visually.

I am only buying batteries from supersports 600 from now on.. he doesn't carry hg2's and stuff so I am just going to use vtc5a's for absolutely everything, no exceptions, as i know his are good and he tests each and every battery, as well as answering some 15 odd emails i have sent which was awesome. I'll just respect their amp limits and if i want high wattage, i will do it in my 3 or 4 battery mods rather than 2 battery. 200 watts should be ok with vtc5a's in 3 battery, and 270 watts in 4 battery. Rather than worrying about getting 200 watts on the rare occasion i want it, from twin HG2's.

 

[Mooch]

it could be my fault after all this.. i have been watching some video and i have noticed everyone that uses the probes to test, as they are spring loaded, puts some pressure. I have literally just been touching it to the battery. I will try by applying a bit of pressure either end and see if that changes.

I just double checked the review at CPF as well, and he says the resistance measuring is accurate. As far as chargers go this guy is pretty much what you are to batteries..

i am sure the vtc5a's are ok then as all of them at least a year old.. the he4's are not, only a few months and a couple cycles, so i am sure they are fakes.. specifically after i asked the guy up front if they were legit, and a well known vape store to boot.

I would think all my HG2's are fake also as they are consistently reading 3x the vtc5a's. I wish there was a way to tell fakes from real, visually.

I am only buying batteries from supersports 600 from now on.. he doesn't carry hg2's and stuff so I am just going to use vtc5a's for absolutely everything, no exceptions, as i know his are good and he tests each and every battery, as well as answering some 15 odd emails i have sent which was awesome. I'll just respect their amp limits and if i want high wattage, i will do it in my 3 or 4 battery mods rather than 2 battery. 200 watts should be ok with vtc5a's in 3 battery, and 270 watts in 4 battery. Rather than worrying about getting 200 watts on the rare occasion i want it, from twin HG2's.

Depress the springs about 50% of their full travel length when using the probes. If they are designed correctly this is typically the depth of travel recommended by the manufacturer of the spring pins. Make sure both pins on the probes are depressed about equally.

You can detect fakes visually but, depending on the fake, it can be difficult. If you want, unwrap an HE4 and an HG2 and post well-lit, in-focus pictures of the top and full side view. I'll take a look. If either has a self-adhesive top insulating ring then it's definitely a fake. If the ring is free-floating it's likely, but not guaranteed, to be genuine.

 

[RayofLight62]

Hybrid batteries suffer less of de-lithiation with respect to LiCoO2 batteries. The problem remain the integrity of the crystalline structure of the graphite electrode, which often fails when the battery is left at low voltage for more than few hours.
Copper current collectors start corroding in the days and weeks later the total discharge.
As others already said here, if you can measure the battery capacity and it is the same previous the discharge; AND the internal resistance stays below 30 milliohm after the event, yes the battery is still safe.
If you can't be sure that it hasn't been a capacity loss and/or an internal resistance increase, it is safer to retire the battery.
My G-class has already destroyed two cells in two pairs. It contains a Ni-Mh battery for the clock, which keeps charged by depleting the 18650.