Battery integrity question

[Cranberry Juice]

I bought a 3s 5000mAh battery yesterday, and I ran it through 2 cycles. When I would charge it my charger would hit 4 volts per cell and then suddenly jump to 4.2 volts and say it was full. Today I plugged it in and it said cells 1 and 3 are at 3.7 volts and cell 2 is at 3.4. I have been charging it using the balance lead, so I know it wasn't that. Is the battery bad?

 

[CreepyQuarryCrawler]

What are you using for a charger?

I have had batteries out of the package slightly off per cell. The most recent one was cell #2 as well.

Another thing I have noticed over the years, some cell checkers will always show cell one as low because it is using it to power the device.

 

[Cranberry Juice]

What are you using for a charger?

I have had batteries out of the package slightly off per cell. The most recent one was cell #2 as well.

Another thing I have noticed over the years, some cell checkers will always show cell one as low because it is using it to power the device.

For now I'm using an iMax B6. It's a 5 amp charger, I'm going to get a 15 amp soon.

 

[PonkyKong]

The charger is at the limit. If the new charger is a 15 amp I bet it charges just fine in like 30 minutes. If the battery is economy grade is will have less life and power but still work fine. However. If you are using the charge and not the balance charge setting it assumes you're racing and don't have time to balance. So settings can be off.

 

[Cranberry Juice]

The charger is at the limit. If the new charger is a 15 amp I bet it charges just fine in like 30 minutes. If the battery is economy grade is will have less life and power but still work fine. However. If you are using the charge and not the balance charge setting it assumes you're racing and don't have time to balance. So settings can be off.

I'm charging on balance mode. I just don't get why it would jump from 4 to 4.2 randomly. I don't remember the brand of battery, I'll tell you later. Today it seems to be struggling to get past 3.9 on all cells. It charged from 3.7 to 3.85 in 45 minutes and then I gave it a break. It has charged for another 30 minutes and it only went up .05.

 

[Mrgoodwrench35]

Any idea of what the IR of the cells are?

 

[Cranberry Juice]

Any idea of what the IR of the cells are?

No, I don't have a way to test that.

 

[Cranberry Juice]

I plugged in my low voltage monitor to check the accuracy of my charger. My charger read 3.90 per when I stopped it. The lvm reads cell 1: 3.86, cell 2: 3.88, cell 3: 3.92.

 

[PonkyKong]

That's a good balance for partial charge.

 

[PonkyKong]

The B6 logic I think starts with a slow trickle. Then if gets the amps up. Then first balance. Then more charge. Then it balances toward the end. Which can take a long time.

 

[Cranberry Juice]

The B6 logic I think starts with a slow trickle. Then if gets the amps up. Then first balance. Then more charge. Then it balances toward the end. Which can take a long time.

Yeah, I charged it for an hour and 45 minutes yesterday and it wasn't full, that's when I noticed that it would register 4 volts per cell and then jump to full. I'm wondering if the charger is just slow to register it. I didn't think to check with the lvm yesterday. It runs for a decent time on 3s, about 20 minutes. I'm going to get 4s batteries when I get paid next, but my hobby shop didn't have the right size when I went so I got the 3s.

 

[PonkyKong]

Yeah, I charged it for an hour and 45 minutes yesterday and it wasn't full, that's when I noticed that it would register 4 volts per cell and then jump to full. I'm wondering if the charger is just slow to register it. I didn't think to check with the lvm yesterday. It runs for a decent time on 3s, about 20 minutes. I'm going to get 4s batteries when I get paid next, but my hobby shop didn't have the right size when I went so I got the 3s.

Yeah the B6 would minimum need a bigger power supply. And might need to be set to charge twice just to finish a charge. It's bare minimum.

 

[Cranberry Juice]

@PonkyKong I had another question.
I want to get these batteries, but I'm kinda skeptical. The dimensions are the same as these batteries, but the first ones are 600mAh bigger than the second ones, and somehow the same size. I don't know how all of that stuff works, but is that possible? Can they really cram another 600mAh into the same size battery?

 

[Cranberry Juice]

Yeah the B6 would minimum need a bigger power supply. And might need to be set to charge twice just to finish a charge. It's bare minimum.

Oh, definitely. It's a 6 amp max. I was using it for 2s 2000mah batteries, and it did those in 20 minutes. Obviously, not even close to the 3s I have now.

 

[PonkyKong]

@PonkyKong I had another question.
I want to get these batteries, but I'm kinda skeptical. The dimensions are the same as these batteries, but the first ones are 600mAh bigger than the second ones, and somehow the same size. I don't know how all of that stuff works, but is that possible? Can they really cram another 600mAh into the same size battery?

Its just a density and cell quality and cell matching issue with batteries. CNHL and Hoovoo seem to work well. They all fit standard cases

 

[Cranberry Juice]

Its just a density and cell quality and cell matching issue with batteries. CNHL and Hoovoo seem to work well. They all fit standard cases

Ah, makes sense. I guess you could just use the same size case with a less dense material for ease of production.

 

[RustyUs]

Generally, if doing 1C charge rates on LiPo batteries and cells are near "empty" (I try my hardest to not let my LiPo batteries get below 3.2v/cell) it will take approximately one hour to fully charge the battery. If doing 2C charge rates... it will take approximately a half hour to fully charge a battery. But a person has to factor in health of LiPo cells and how far apart they are from one another when a charger reaches the constant voltage part of a balance charge's constant current/constant voltage (CC/CV) algorithm. This is were a charger's balance current, or balance drain spec comes into play.

Your charger, @Cranberry Juice, has a very low balance current compared to other chargers that are out there. If your LiPo cells are far apart (health wise) when charger gets to the CV part of a balance charge, it may take a very long time to finish up balancing a battery. I went through this years ago and went on a mission to find out why.

I would recommend looking at chargers that have balance current/balance drain specs (like shown below) in the 1000mA~2000mA (1A~2A) range.

I'm charging on balance mode. I just don't get why it would jump from 4 to 4.2 randomly. I don't remember the brand of battery, I'll tell you later. Today it seems to be struggling to get past 3.9 on all cells. It charged from 3.7 to 3.85 in 45 minutes and then I gave it a break. It has charged for another 30 minutes and it only went up .05.

I think it's time for a new charger, 'cause something seems wrong with your charger not charging a LiPo cell past 3.9v in a reasonable amount of time.

 

[81exige]

piling on the post above, if you were to shop for a new charger @Cranberry Juice what's your budget looking like?

 

[Cranberry Juice]

piling on the post above, if you were to shop for a new charger @Cranberry Juice what's your budget looking like?

$150 max, I've been looking at something that can charge two at one, preferably with compatibility with balance leads as a backup if the "smart" function of the battery fails.

 

[81exige]

$150 max, I've been looking at something that can charge two at one, preferably with compatibility with balance leads as a backup if the "smart" function of the battery fails.

assuming that's just for the charger...
- SkyRC D200 Neo (fastest of the 3 on DC power, also can be used with a smartphone if that's your kind of thing)
- Hota D6 Pro (the "no frills" option, also has a 1.5A balance current like the D200, usually the higher the balance current the better, there's an explanation as to why on this forum as well but i can't seem to find it, @RustyUs loves them)
- Gens D300 (the one everyone defaults to, i personally don't understand the hype when this has the lowest balance current of the three)
that said i don't think you can go wrong when picking one of these