Did I damage my NCR18650B?

[LarryDFW]

@olympus620

@djozz

I am also curious how you tried to charge them, a real charger does not allow series charging (never heard of anyone trying to charge batteries in series at all, for that matter). What did you use?

The charger is an imax acb6 charger.

The total voltage your charger was delivering was 8.9 VDC.

This would have overchaged ANY two 4.2VDC cells.

Something was not set correctly in the charger.

I have charged similar cells in series without balance issues.

LarryDFW

[olympus620]

@LarryDFW

@olympus620

@djozz

I am also curious how you tried to charge them, a real charger does not allow series charging (never heard of anyone trying to charge batteries in series at all, for that matter). What did you use?

The charger is an imax acb6 charger.

The total voltage your charger was delivering was 8.9 VDC.

This would have overchaged ANY two 4.2VDC cells.

Something was not set correctly in the charger.

I have charged similar cells in series without balance issues.

LarryDFW

Are you using balancing sockets or connecting straight from the output? Mine was from the output. I don’t know if this is a problem or not. What setting could have caused this issue?

[olympus620]

@xmint

@olympus620

@olympus620

@Pulsar13

It’s gone. I hope you don’t try to salvage this one.

Expensive lesson - don’t serial charge without balancing. Or easier - just use parallel charging - this type of overcharge doesn’t happen that way.

I think I will stick to parallel

I made one other mistake in trying to get the voltage down. I tied all four batteries together in parallel hoping they would balance each others voltage without any input. So far that worked but now I do not know which battery was to high.

Now you are in the proverbial Do a internal resistance test on each cell. Get a brick and metal box, or stick the brick outside on a window ledge. do a discharge test on each cell sitting on top of the brick (the battery! though with your luck!) :Sp . Should give you a clue.

Problem is I have been doing (or was doing till the shipping fiasco) abuse testing of cells and with pans they can take an enormous amount of abuse without really showing it in the short term so that cell might be difficult to detect, BUT that does not mean that it is safe especially in the long term and without careful monitoring.

As you will now have gathered best to mark each battery as a set and individually.

I tested the capacity of all four batteries and still cannot figure out which battery I overcharged. Below is the discharge time for each cell at 1Amp rate. Each cell was charged to 4.20 volts and allowed to sit for a day before discharging. It is unbelievable how similar these battery discharge times are. I suspect I dodged any damage to the battery and if I was to select a cell that is not like the others the capacity went up on that cell at 147:54 minutes…

cell 1: 146:42 minutes(3400+ mah) / resistance 11.17 M ohms
cell 2: 145:05 minutes(3400+ mah) / resistance 11.14 M ohms
cell 3: 145:13 minutes(3400+ mah) / resistance 11.14 M ohms
cell 4: 147:54 minutes(3400+ mah) / resistance 11.08 M ohms

[xmint]

@olympus620

@xmint

@olympus620

@olympus620

@Pulsar13

It’s gone. I hope you don’t try to salvage this one.

Expensive lesson - don’t serial charge without balancing. Or easier - just use parallel charging - this type of overcharge doesn’t happen that way.

I think I will stick to parallel

I made one other mistake in trying to get the voltage down. I tied all four batteries together in parallel hoping they would balance each others voltage without any input. So far that worked but now I do not know which battery was to high.

Now you are in the proverbial Do a internal resistance test on each cell. Get a brick and metal box, or stick the brick outside on a window ledge. do a discharge test on each cell sitting on top of the brick (the battery! though with your luck!) :Sp . Should give you a clue.

Problem is I have been doing (or was doing till the shipping fiasco) abuse testing of cells and with pans they can take an enormous amount of abuse without really showing it in the short term so that cell might be difficult to detect, BUT that does not mean that it is safe especially in the long term and without careful monitoring.

As you will now have gathered best to mark each battery as a set and individually.

I tested the capacity of all four batteries and still cannot figure out which battery I overcharged. Below is the discharge time for each cell at 1Amp rate. Each cell was charged to 4.20 volts and allowed to sit for a day before discharging. It is unbelievable how similar these battery discharge times are. I suspect I dodged any damage to the battery and if I was to select a cell that is not like the others the capacity went up on that cell at 147:54 minutes…

cell 1: 146:42 minutes(3400+ mah) / resistance 11.17 M ohms
cell 2: 145:05 minutes(3400+ mah) / resistance 11.14 M ohms
cell 3: 145:13 minutes(3400+ mah) / resistance 11.14 M ohms
cell 4: 147:54 minutes(3400+ mah) / resistance 11.08 M ohms

As I said would be very difficult to tell. mirrors my own results in tests. Choice is now yours I suppose,

In my own tests I have found that sometimes after more cycles there can be a slight increase in cell temp compared to non-abused cells while charging. It is way too early to say whether the panny cells will actually do something nasty or just lose longevity, :quest: time will tell

Does show just how good pannys are and how they make a decision on what to do very hard.