Bad lipo cell but IR is okay?

[Hector_Fisher]

Any thoughts on why this lipo can't hit 4.2v on one of its cells when charging at 1c? This is the 4th or 5th time I've charged this, on varying channels on my charger, and after an hour or two of charging, the last cell still sits at 4.1v. I usually have to discharge 500mah, then finish charging at 2 amps to get 4.2v on all cells. No problems with any of my other lipos.

My garage is warm (85F), but the lipo is observably warm right after charging. I just don't get it. Sure, IR is slightly higher on one cell, but no where near as bad as one of my 3s zeee's (18, 5, 4 mOhms). And that zeee still charges in 45 minutes, and doesn't get warm. So what's going on here?

 

[RedondoBeachRC]

If it’s spontaneously heating.. it’s going to catch fire soon. Store it in a BBQ grill for safety

Heating up during charging can be normal depending on how many amps. Sometimes balance chargers don’t quite work.. and there are a few ways to help fix it. DIY light to DC each cell down to the voltage to match that of lowest cell.

If you have access to an Icharger.. you can try the balance only mode.

 

[Av642]

If it’s spontaneously heating.. it’s going to catch fire soon. Store it in a BBQ grill for safety

Heating up during charging can be normal depending on how many amps. Sometimes balance chargers don’t quite work.. and there are a few ways to help fix it. DIY light to DC each cell down to the voltage to match that of lowest cell.

If you have access to an Icharger.. you can try the balance only mode.

Good advice, more info on the balance only mode. I haven't seen that.

 

[dure16]

If you have access to an Icharger.. you can try the balance only mode.

That Hota also has a balance only mode.

 

[Garcbomber]

Send it down to storage or just under and compare that cell with the rest, if it’s much lower voltage you’ll know it’s weak and ready for replacement from CNHL. I’ve had anomalies like that before, just needed a cycle and all was well on the next charge.

 

[Just a hobby]

Any thoughts on why this lipo can't hit 4.2v on one of its cells when charging at 1c? This is the 4th or 5th time I've charged this, on varying channels on my charger, and after an hour or two of charging, the last cell still sits at 4.1v. I usually have to discharge 500mah, then finish charging at 2 amps to get 4.2v on all cells. No problems with any of my other lipos.

My garage is warm (85F), but the lipo is observably warm right after charging. I just don't get it. Sure, IR is slightly higher on one cell, but no where near as bad as one of my 3s zeee's (18, 5, 4 mOhms). And that zeee still charges in 45 minutes, and doesn't get warm. So what's going on here?
View attachment 311405View attachment 311406View attachment 311407

First discharge and fully balance charge. Say your lipo is 5200mAh don't balance charge at 5.2 amps. Try charging at say 2amps max 3amps. This should get all cells to balance fully. That's what I do and it works. The 18,5,4. The 18 omhs is concerning, did the lipo come at these numbers? And is that the cell that won't get to 4.20? How old is the lipo?

 

[Hector_Fisher]

First discharge and fully balance charge. Say your lipo is 5200mAh don't balance charge at 5.2 amps. Try charging at say 2amps max 3amps. This should get all cells to balance fully. That's what I do and it works. The 18,5,4. The 18 omhs is concerning, did the lipo come at these numbers? And is that the cell that won't get to 4.20? How old is the lipo?

The 18, 5, 4 was an example of another lipo (a zeee) that I have, not the one I wrote the post for. The second picture shows the IR for the lipo that's having issues, (CNHL racing pack). 2.6, 2.0, 3.8 isn't that bad. Not what should be causing these issues.

If it’s spontaneously heating.. it’s going to catch fire soon. Store it in a BBQ grill for safety

Heating up during charging can be normal depending on how many amps. Sometimes balance chargers don’t quite work.. and there are a few ways to help fix it. DIY light to DC each cell down to the voltage to match that of lowest cell.

If you have access to an Icharger.. you can try the balance only mode.

It's not spontaneously heating, just when charging above 3 amps and the cells start diverging.

So what would be causing the issue? 2.6, 2.0, 3.8 IR shouldn't normally causes heat when charging at 1c. Again, I have packs with worse IR that don't heat up like that.

I have a hota d6 plus, so I usually balance if the charging doesn't sort itself out.

 

[Just a hobby]

The 18, 5, 4 was an example of another lipo (a zeee) that I have, not the one I wrote the post for. The second picture shows the IR for the lipo that's having issues, (CNHL racing pack). 2.6, 2.0, 3.8 isn't that bad. Not what should be causing these issues.

It's not spontaneously heating, just when charging above 3 amps and the cells start diverging.

So what would be causing the issue? 2.6, 2.0, 3.8 IR shouldn't normally causes heat when charging at 1c. Again, I have packs with worse IR that don't heat up like that.

I have a hota d6 plus, so I usually balance if the charging doesn't sort itself out.

How old is the lipo? Have you tried cycling the lipo 2 to 3 times? This might help the balancing of the lipo. Charge at 3 amps after each discharge. Just keep an eye out when charging. I've had a lipo or 2 that would not balance. And it got all cells to balance equally after a couple cycles.

 

[RudyD54]

Usually thats a sign of a bad/dying cell. That charger has a 1.6 amp balance circuit so it should be more than enough to balance out that cell. Definitely try bringing it down to storage voltage and then recharging, but the fact that it's heating up isn't very promising since youre only hitting it with 1c.

 

[Just a hobby]

Usually thats a sign of a bad/dying cell. That charger has a 1.6 amp balance circuit so it should be more than enough to balance out that cell. Definitely try bringing it down to storage voltage and then recharging, but the fact that it's heating up isn't very promising since youre only hitting it with 1c.

I agree!

 

[Hector_Fisher]

I'll try cycling it a few more times more slower.

Lipo is maybe 6 months old with a dozen or so runs on it. Strangely, it just started happening. Like a few charges ago. No slow change or warning. Can't think of any exciting events in its life that would have prompted the difference.

 

[RudyD54]

I had a couple of packs do that to me in the past. Luckily the vendor swapped them out.

 

[Just a hobby]

I'll try cycling it a few more times more slower.

Lipo is maybe 6 months old with a dozen or so runs on it. Strangely, it just started happening. Like a few charges ago. No slow change or warning. Can't think of any exciting events in its life that would have prompted the difference.

It sounds like that one cell is on its way to death. I've had 2 lipos do the same around 1 year of use. Contact the seller maybe they have a good warranty of 9 months to a year. Worth a call. Hopefully the cycling will wake it up? When you run the lipo does it seem to have less power?

 

[Hector_Fisher]

It sounds like that one cell is on its way to death. I've had 2 lipos do the same around 1 year of use. Contact the seller maybe they have a good warranty of 9 months to a year. Worth a call. Hopefully the cycling will wake it up? When you run the lipo does it seem to have less power?

Could be. I'll get ahold of CNHL and see what they have to say.

Honestly haven't run then. I usually charge them up and then just discharge them at the end of the day. I run them in my kraton, but all my other trucks have been so reliable (the kraton is the back up currently) this has just been cycling charges. Last time I remember though, it did fine while driving. Didn't get any hotter than usual.

 

[jkflow]

Very odd and I'm stumped.
Your current settings have nothing to do with balancing, different circuit and couldn't care less as to what you set the charge current at.
Go ahead and cycle one more time, but only charge to 4V (setting in charger), see if it balances at that level. Next, increase to 4.1V and if that works go to 4.2V.
Might be just an inherent imbalance, but the Hota should be capable enough to balance it out in ~ 30 min or less.

Try above, might be a bad manufactured cell. The IT is measured with an algorithm using an AC circuit, and it will give you a good approximation. It's completely blind to DC resistance. That is just the nature of doing these types of measurements.

 

[Just a hobby]

Could be. I'll get ahold of CNHL and see what they have to say.

Honestly haven't run then. I usually charge them up and then just discharge them at the end of the day. I run them in my kraton, but all my other trucks have been so reliable (the kraton is the back up currently) this has just been cycling charges. Last time I remember though, it did fine while driving. Didn't get any hotter than usual.

I believe CNHL has a good long warranty with their lipos. Keep your eyes on the lipo and charger read out while cycling. Good luck Dude!!
May you save a lipos life today

 

[Hector_Fisher]

Okay, i've got some data here that is genuinely -- and I mean genuinely -- confusing me. I did lots of testing yesterday to see what happens to the pack. Rather than try to post pictures, i've layed everything out in a table format based on the order I did these tests. As suggested, i did some charges and discharges, followed by a balance before repeating. And i tried charging to various cell voltages.

What's really odd here, is that the charger will perfectly balance charge the lipo to 4.0 and 4.1v per cell, but charging to 4.2v per cell triggers this..... anomaly.

To make sure it wasn't the charger or this channel, i charged this lipo's "sister" pack (same specs, bought at same time) on the same charger channel immediately after. The sister pack was fully balance charged in 40 minutes, with no appreciable temp increase on the packs. I then decided to charge to 4.15v per cell on the problem lipo and more closely watch the charger to see what was happening. This is the abbreviated timeline of the major events:

Unfortunately i don't have much more second for second granularity as I simply didn't have time or will power to stand by the charger in the 90f garage. The charging was going 100% normal when charging at 6.6amps (1c) everytime I checked, cells were aligned in voltage. But at some point the charger started ramping down from the 6.6amp charge and hit the "final balance" portion of the charge, the third cell voltage began dipping and the other two went up. Within a minute, the third cell was noticeably warm and then around 2 or 3 minutes it was 110f, but only on one side. I took this to mean that, for whatever reason, the third cell was being massively drained while the other two were being quickly charged--or in other words, it seemed like all of the third cell was being pumped to the other two. i stopped the charge, and restarted it at 4.17v per cell final to see if I could trigger it to restart. However, nothing changed, and cell 3 votlage dropped below 4.100 before i killed the test.

That would make me think this is a charger issue, but it has absolutely no issues balancing any of my other lipos, including this lipo's sister pack, just fine.

Again, i'm honestly stumped. I might try this again and take a video of the charger screen to see if I can catch any more minutia. Could this be an internal short of the lipo? Your brain power is appreciated.

 

[Just a hobby]

Okay, i've got some data here that is genuinely -- and I mean genuinely -- confusing me. I did lots of testing yesterday to see what happens to the pack. Rather than try to post pictures, i've layed everything out in a table format based on the order I did these tests. As suggested, i did some charges and discharges, followed by a balance before repeating. And i tried charging to various cell voltages.
View attachment 311881

What's really odd here, is that the charger will perfectly balance charge the lipo to 4.0 and 4.1v per cell, but charging to 4.2v per cell triggers this..... anomaly.

To make sure it wasn't the charger or this channel, i charged this lipo's "sister" pack (same specs, bought at same time) on the same charger channel immediately after. The sister pack was fully balance charged in 40 minutes, with no appreciable temp increase on the packs. I then decided to charge to 4.15v per cell on the problem lipo and more closely watch the charger to see what was happening. This is the abbreviated timeline of the major events:

View attachment 311882

Unfortunately i don't have much more second for second granularity as I simply didn't have time or will power to stand by the charger in the 90f garage. The charging was going 100% normal when charging at 6.6amps (1c) everytime I checked, cells were aligned in voltage. But at some point the charger started ramping down from the 6.6amp charge and hit the "final balance" portion of the charge, the third cell voltage began dipping and the other two went up. Within a minute, the third cell was noticeably warm and then around 2 or 3 minutes it was 110f, but only on one side. I took this to mean that, for whatever reason, the third cell was being massively drained while the other two were being quickly charged--or in other words, it seemed like all of the third cell was being pumped to the other two. i stopped the charge, and restarted it at 4.17v per cell final to see if I could trigger it to restart. However, nothing changed, and cell 3 votlage dropped below 4.100 before i killed the test.

That would make me think this is a charger issue, but it has absolutely no issues balancing any of my other lipos, including this lipo's sister pack, just fine.

Again, i'm honestly stumped. I might try this again and take a video of the charger screen to see if I can catch any more minutia. Could this be an internal short of the lipo? Your brain power is appreciated.

I have two 2s lipos that have the same issue. I found moving the balance plug will get the cells to balance. Check the balance plug and wires on the lipo. The female end might be opened just a little to much. From one lipo to another might balance #.
I've jiggled the plug on the charger and the balance # got closer together. So many different variables that can cause the resistance cell # and cell balance #
Just my observation with my chargers and problem lipos.

 

[RudyD54]

Okay, i've got some data here that is genuinely -- and I mean genuinely -- confusing me. I did lots of testing yesterday to see what happens to the pack. Rather than try to post pictures, i've layed everything out in a table format based on the order I did these tests. As suggested, i did some charges and discharges, followed by a balance before repeating. And i tried charging to various cell voltages.
View attachment 311881

What's really odd here, is that the charger will perfectly balance charge the lipo to 4.0 and 4.1v per cell, but charging to 4.2v per cell triggers this..... anomaly.

To make sure it wasn't the charger or this channel, i charged this lipo's "sister" pack (same specs, bought at same time) on the same charger channel immediately after. The sister pack was fully balance charged in 40 minutes, with no appreciable temp increase on the packs. I then decided to charge to 4.15v per cell on the problem lipo and more closely watch the charger to see what was happening. This is the abbreviated timeline of the major events:

View attachment 311882

Unfortunately i don't have much more second for second granularity as I simply didn't have time or will power to stand by the charger in the 90f garage. The charging was going 100% normal when charging at 6.6amps (1c) everytime I checked, cells were aligned in voltage. But at some point the charger started ramping down from the 6.6amp charge and hit the "final balance" portion of the charge, the third cell voltage began dipping and the other two went up. Within a minute, the third cell was noticeably warm and then around 2 or 3 minutes it was 110f, but only on one side. I took this to mean that, for whatever reason, the third cell was being massively drained while the other two were being quickly charged--or in other words, it seemed like all of the third cell was being pumped to the other two. i stopped the charge, and restarted it at 4.17v per cell final to see if I could trigger it to restart. However, nothing changed, and cell 3 votlage dropped below 4.100 before i killed the test.

That would make me think this is a charger issue, but it has absolutely no issues balancing any of my other lipos, including this lipo's sister pack, just fine.

Again, i'm honestly stumped. I might try this again and take a video of the charger screen to see if I can catch any more minutia. Could this be an internal short of the lipo? Your brain power is appreciated.

This all sounds to me like a symptom of a bad cell. ESPECIALLY the overheating. I'd retire that pack ASAP and maybe contact the manufacturer.

 

[Just a hobby]

I have two 2s lipos that have the same issue. I found moving the balance plug will get the cells to balance. Check the balance plug and wires on the lipo. The female end might be opened just a little to much. From one lipo to another might balance #.
I've juggled the plug on the charger and the balance # got closer together. So many different variables that can cause the resistance cell # and cell balance #
Just my observation with my chargers and problem lipos.

I've also found if you charge that lipo that won't balance at 1 amp lower charge rate it will help all cells to balance.

This all sounds to me like a symptom of a bad cell. ESPECIALLY the overheating. I'd retire that pack ASAP and maybe contact the manufacturer.

Definitely see if you can use the warranty. 6 months is way to soon. Bad cell from the start.