C9000 missed termination but why?

[crofty]

So I bought an Energiser DUO which came with 2 AAA 900mAh.

The code on the side is 07/07, I presume that`s the date code. Voltage measured .92 and .93 out the pack, dead, no supprise.

Put them in my BC700 on a 200 mA charge and they terminated in 2 hours showing 403 and 381 mAh respectively.

Well that`s a bit rubbish, these are going to need some lovin, so I pulled them of the BC700 and put them on a 200/200 R&A on my C9000.

That was last night and when I woke today they were showing about 1400 mAh, obviously they missed termination but were still quite cool so I left them.

Went back a while later and still going..

2062 mAh
686 Min
1.42 V

2047 mAh
686 Min
1.42 V

They were still just warm but thought that was enough.

I understand new cells, especially none LSD`s can have trouble terminating at low rates when they have sat for a while. But why did the BC700 terminate while the C9000 did not?

AAA usage is small for me and I have a few eneloops spare so not to bothered about the batteries.

If you would like me to do anything specific I`d be glad to, otherwise I`ll probably let them rest for a few hours then do a discharge and break-in before storing them.

 

[Black Rose]

Does your C9000 have the first version of the firmware or one of the updated versions?

I think the very first version of the C9000 had issues with terminating at low charge rates.

I've only experienced one missed termination with my C9000 so far, and that was due to the cell being bad.

 

[fireguy]

The C9000 manual says that you should charge the batteries above .3C. 200 mAh charge in a 900 mAh battery is .22C. I believe that this isn't sufficient to cause the voltage drop when the battery is full, and at that rate the batteries won't get hot enough to trip the thermal sensor. I don't know the C700, but I'm thinking it is either a timed charger or else the batteries got hot enough to trigger a thermal sensor to stop the charging?

I would try a discharge at .2C (180 mAh) and then charge them at 500 mAh (.55C) to see how they do. However, I'm far from an expert, so I'm just thinking this from some other posts I've read.

 

[Mr Happy]

It's interesting your cells were only reading 1.42 V. That's really low for a fully charged cell. I've only seen such a low voltage reading on some very low quality and very cheap NiMH cells from China.

Most often the C9000 stops charging on the high voltage set point of 1.47 V, which has not been reached in this case. Therefore it is looking for the -dV signal and apparently it has not recognized this due to the low quality cells and low charge rate.

I think perhaps that the BC700 has a more sensitive end of charge test, since many people seem to use it to charge cells at low rates without missed terminations.

 

[N162E]

It's interesting your cells were only reading 1.42 V. That's really low for a fully charged cell. I've only seen such a low voltage reading on some very low quality and very cheap NiMH cells from China.

Most often the C9000 stops charging on the high voltage set point of 1.47 V, which has not been reached in this case. Therefore it is looking for the -dV signal and apparently it has not recognized this due to the low quality cells and low charge rate.

I think perhaps that the BC700 has a more sensitive end of charge test, since many people seem to use it to charge cells at low rates without missed terminations.

+1 on all of the above.

 

[SilverFox]

Hello Crofty,

Let me speculate for a moment...

I think that had you put the cells into the C9000 at the very beginning, it would have refused to charge them due to high internal resistance readings.

OK, you put some cells that have been stored for a longer amount of time into the BC-700 and experience a "false peak" that the charger interprets as an end of charge signal and the charge is terminated. This is not unusual, and is expected with new cells.

This 2 hours of charging has reduced the internal resistance of the cells enough so that the C9000 will accept them for charging. At this point you continue the charge on them in the C9000 at a charge rate of 200 mA, and they fail to terminate.

At this point the cells have pretty much a full charge on them, and it is not known if their reduction in internal resistance is temporary or if they are actually getting a little better. If you don't need the cells urgently, set them aside for a couple of days after discharging them.

Now you can run another test. Put the cells into the BC-700 and charge at 200 mA again. If they false peak again, simply start the charge again and leave them charging in the BC-700. If the initial charge/discharge cycle did not fully condition the cells, you may find the same thing happening while charging with the BC-700.

You did noticed that the cells were below 1.0 volts and should have recognized that they would need some care to try to bring them back. The first charge should have been a 16 hour charge at 0.1C (90 mA in this case), only terminated with a timer. Then you could do a 0.2C discharge (180 mA in this case) and compare the capacity you get from this to the labeled capacity of the cell. If your test results indicate that the cells have less than 80% of the labeled capacity, you should contact Energizer and tell them that you have some defective cells that were recently purchased and want replacements.

If you want to use the cells, you may need to do a couple of "Break-In" cycles on the C9000, followed by a few charge/discharge cycles to get them to the point where they are "less than crap."

If you get cells that have low "out of the package" voltage and don't have the capabilitiy to do a standard charge, you should set a timer and "expect" the cell not to terminate properly. When the timer goes off, stop the charge.

The hobby chargers allow you to specify the maximum amount of charge that goes into the cell. For example, with my Schulze charger I would have simply set the maximum charge at 900 mA and charged at a low rate of charge for the initial charge. I would then set a timer and use a top off charge for an hour, then I would run a discharge test to see if it would be worth trying to save these cells or not.

Tom

 

[N162E]

Hello Crofty,

Let me speculate for a moment...



Now you can run another test. Put the cells into the BC-700 and charge at 200 mA again. If they false peak again, simply start the charge again and leave them charging in the BC-700. If the initial charge/discharge cycle did not fully condition the cells, you may find the same thing happening while charging with the BC-700.

You did noticed that the cells were below 1.0 volts and should have recognized that they would need some care to try to bring them back. The first charge should have been a 16 hour charge at 0.1C (90 mA in this case), only terminated with a timer. Then you could do a 0.2C discharge (180 mA in this case) and compare the capacity you get from this to the labeled capacity of the cell. If your test results indicate that the cells have less than 80% of the labeled capacity, you should contact Energizer and tell them that you have some defective cells that were recently purchased and want replacements.

If you want to use the cells, you may need to do a couple of "Break-In" cycles on the C9000, followed by a few charge/discharge cycles to get them to the point where they are "less than crap."

The hobby chargers allow you to specify the maximum amount of charge that goes into the cell. For example, with my Schulze charger I would have simply set the maximum charge at 900 mA and charged at a low rate of charge for the initial charge. I would then set a timer and use a top off charge for an hour, then I would run a discharge test to see if it would be worth trying to save these cells or not.

Tom

Or, you could throw them away and get new ones.:welcome:

 

[jhellwig]

What fun is that?

Discharge them and run a break in on the c9000. Be sure that you enter the capacity correctly.

 

[N162E]

What fun is that?

Discharge them and run a break in on the c9000. Be sure that you enter the capacity correctly.

LOL ya got me on that one!!

PS JH I went to Parsons in the mid 60s and remember a place called Pinkys, in Ottumwa.

 

[TakeTheActive]

Re: Inexpensive Entertainment With a Possible Knowledge Gain...

Or, you could throw them away and get new ones...

Sacrilege!!! :eeksign:

Some of us actually ENJOY partaking in the various 'experiments' presented here. :sick2:

For around the cost of running a 4-7 watt nightlight, we're ENTERTAINED for DAYS! :twothumbs

Fred's Helicopter

Sometime in the mid-to-late 90s, during a vacation to Florida which included DisneyWorld, as a PVT ASEL w/IFR I convinced a R-22 instructor to convert a 'Scenic Tour' into 'Dual' with a logbook entry. Two points that I remember most are:

1. Don't move the PTT button outside of the imaginary circle of the cyclic handle.
2. Keep the yarn in the middle of the windshield balanced like a 'V'.

LOTs of fun, but, I'll stick to fixed wing. (At least I can scratch my nose whenever I feel like it!) :nana:

 

[crofty]

I think I just reached critical mass because it`s all clicking into place, thanks guys

I realized they would need some maintenance but wanted to get a benchmark before a break in to see how much they improve. All part of the fun

With LSD`s I usually do a discharge to see how much they`ve held onto, then a refresh and analyse for a benchmark, break in then another R&A.

...If you don't need the cells urgently, set them aside for a couple of days after discharging them.

Now you can run another test. Put the cells into the BC-700 and charge at 200 mA again. If they false peak again, simply start the charge again and leave them charging in the BC-700. If the initial charge/discharge cycle did not fully condition the cells, you may find the same thing happening while charging with the BC-700...

Will do, discharged them on the C9000 at 200mA last night..

508 mAh
201 Min
1.23 V

562 mAh
189 Min
1.24 V

Resting voltages this morning are both at 1.24, a bit high I thought, maybe the voltage sag under load is severe because of high internal resistance causing them to terminate early on low voltage. The discharge on the C9000 is pretty harsh too compared to a CC discharger.
That`s something to watch and see if it imporves once they`ve been properly prepared.

Also, they had not leaked but did feel slipery when I picked them up this morning, on closer inspection they had a bit of white residue around the outside. Probably due to the overcharge. Wiped it off and washed hands.

...If your test results indicate that the cells have less than 80% of the labeled capacity, you should contact Energizer and tell them that you have some defective cells that were recently purchased and want replacements...

Will do too, even though I don`t need them and probably wont use em, that`s not really the point. I`d be interested to see how the replacements perform too if they send any.

...The hobby chargers...

That`s next.. sometime this year

Or, you could throw them away and get new ones.:welcome:

I don`t like your attitude! :nana:

Thanks

 

[crofty]

Got these cells back on the BC700 at 200 mA today, neither terminated early, one may of missed termination and the other terminated OK or maybe a bit late.

Cell 1 still going
1093 mAh
5:41 h
1.42 v

Cell 2 terminated
999 mAh
5:11 h
1.40 v

Both are warm but not hot.

As you said Tom it seems the initial charge/discharge cycle has gone some way to condition the cells. Maybe if I charged them again on the C9000 or BC-700 they would terminate now.

I`ve never seen this low a voltage before, especially on the BC-700. Will start a break in tomorrow and report back how they do after that, if anyone is interested that is.

 

[N162E]

Bad cells would explain everything that is happening here.

 

[crofty]

I think your right N162E.

What interests me now is if a break in will have them show any sign of improvement or if they are just bad.


Thank you guys for your help and , it is much appreciated.