Initial charge on Eneloops, charging strategies.

[Muse]

Re: Initial charge on Eneloops (AAA)

Be careful to note what Marduke said: those increasing numbers are not "Measured Capacities", they are the amount of charge pushed into the cell. In this case, higher numbers are bad, not good. The more those numbers increase, the more they are telling you your cells are being damaged.

A refresh may help, and is worth trying.

However, remember to increase the charge current from 200 mA to 500 mA for future charges, and use the Test mode to get actual capacities. Also keep an eye on the charge progress when you can, and manually stop charging if the charge gets above 110% of the measured cell capacity.

OK, a Test cycle will give me actual capacity. Will I get actual capacity when running the Refresh mode as well? To do so the BC-900 would have to present the energy dissipated during the last discharge part of the mode, I presume.

 

[TakeTheActive]

Re: Initial charge on Eneloops (AAA)

I had one of the 4 La Crosse AAA cells that came with the charger die on me early on. My records indicate (not certain this is correct) that I'd only charged the cell once in the charger, a Refresh cycle using the lowest dis/charge rate...

I had TWO La Crosse 700mAh AAA cells, STILL wrapped in their 4-pack shrinkwrap, LEAK on me (bottom cell in 2 packs). Bought Dec 2006 and let sit at ~45° in a Plano Storage Box until a couple of weeks ago. IIRC, each pack was ~$3 @ Amazon so no great loss.

La Crosse 700mAh AAA             |  #5    #6    #7    #8
---------------------------------+---------------------------
mm/dd/yy C9000 Break-In          |
02/06/09 BC900 Cycle3:   200/ 100|  n/a   505   503   n/a mAh
02/05/09 BC900 Cycle2:   200/ 100|  487   503   492   441 mAh  
02/04/09 BC900 Cycle1:   200/ 100|  459   489   478   359 mAh
02/03/09 PS1   Charge:           |
02/03/09 BC900 Cycle3:   700/ 350|  392   435   n/a   202 mAh
02/03/09 BC900 Cycle2:   700/ 350|  205   407   437   132 mAh
02/03/09 BC900 Cycle1:   700/ 350|  119    94   152   103 mAh
[Bought: 12/22/06 - UNUSED; #8 leaking at top under wrapper]

...Not sure at this point but figure I'll use Charge cycle 2/3 of the time, Test cycle every 3rd time to keep tabs on each individual cell...

IMO, you can't just set one rule to cover all conditions. How are these cells being used? If the device they're in is:

• Discharging them down to 0.9V and automatically shutting off, they could go LONGER between 'forced' discharges.
• Sitting most of the time and the discharge is mostly SELF discharge, they will need 'forced' discharges.

CLICK on my Sig Line LINK and read about Charge Rates, 'Storage Box Queens' and Crystalline Formations.

...I'm no longer going to use the lowest rates but the 250/500 rate...

The '100mA Discharge' has it's uses (see the chart above).

 

[TakeTheActive]

Re: Initial charge on Eneloops (AAA)

I think it matters how much charge was fed into the cell before the charger switched to full. You would not normally want to see more than a 10% overcharge. If it were an 800 mAh cell for instance, you would hope to see a charge less than 900 mAh. If you get numbers over 1000 mAh on charging, it probably is not doing much good to the cell.

Qualified by Charge Rate...

You can safely pump 160% into a cell at 0.1C. (3200mA into a 2000mAh cell @ 200mA for 16 hours)

 

[TakeTheActive]

Re: Initial charge on Eneloops (AAA)

...are you also thinking that the figures don't conclusively suggest that termination was missed?

When folks are saying 'termination was missed', what they're REALLY saying is -DeltaV termination was missed.

When one of the "Backup Termination / Shutoff Mechanisms" is forced to intervene, excess charge can possibly occur (like in the early models of the MH-C9000 and BC-900). Maha addressed this by lowering Max Voltage and La Crosse chose to lower Max Temp.

CLICK on my Sig Line LINK and read the multitude of topics in the Rechargeable Battery section. Good stuff in them there CPF Archives! :twothumbs

 

[TakeTheActive]

Re: Initial charge on Eneloops (AAA)

OK, a Test cycle will give me actual capacity. Will I get actual capacity when running the Refresh mode as well?

It's all in your MANUAL. (Pages 24-27)

 

[Mr Happy]

Re: Initial charge on Eneloops (AAA)

Qualified by Charge Rate...

You can safely pump 160% into a cell at 0.1C. (3200mA into a 2000mAh cell @ 200mA for 16 hours)

Indeed that might be so, but note that I used the word "normally". A 0.1C charge for 16 hours is a conditioning charge, and you would not normally want to do that. It is only for occasional use. If you charged your batteries that way every time, it would still reduce their working life.

 

[Muse]

Re: Initial charge on Eneloops (AAA)

It's all in your MANUAL. (Pages 24-27)

Are we talking about the same manual? I haven't gone looking for the one that came with my BC-900 but just downloaded the manual and it has 8 pages.
It does not indicate how capacity is determined in the Refresh mode. On page 4 it says:
- - - -
REFRESH MODE

Old rechargeable batteries and those that have not been used for a long time require refreshing. This process will recover the optimum capacity of the rechargeable batteries. By pressing the MODE key within 8 seconds after inserting the rechargeable batteries, the Refresh mode can be selected.
Refresh mode will start with discharging the rechargeable battery, then charging it. The repeated discharging and charging cycles will be launched until
no further increase in the measured capacities is estimated.
Note:

By pressing the MODE key within 8 seconds after inserting the rechargeable batteries, the Refresh mode can be selected. (The mode key shall first
be pressed and held for 1 second to activate the mode change. The subsequent pressing of the mode key will toggle between the "Charge",
"Discharge", "Test" and "Refresh" mode.)

Then the user may also select different discharging current by pressing the CURRENT key (see "Note" in Discharge mode and Table 2), within 8
seconds after inserting the batteries. (Or the display will blink once to indicate the end of setting and the current cannot be changed afterward.).

It may take up to several days to finish the refreshing process, depending on the selected discharging current.

The maximum refresh current is 1000 mA and is not affected by the number of rechargeable batteries inserted.

 

[Marduke]

Re: Initial charge on Eneloops (AAA)

Are we talking about the same manual? I haven't gone looking for the one that came with my BC-900 but just downloaded the manual and it has 8 pages.
It does not indicate how capacity is determined in the Refresh mode. On page 4 it says:
- - - -
REFRESH MODE

Old rechargeable batteries and those that have not been used for a long time require refreshing. This process will recover the optimum capacity of the rechargeable batteries. By pressing the MODE key within 8 seconds after inserting the rechargeable batteries, the Refresh mode can be selected.
Refresh mode will start with discharging the rechargeable battery, then charging it. The repeated discharging and charging cycles will be launched until
no further increase in the measured capacities is estimated.
Note:

By pressing the MODE key within 8 seconds after inserting the rechargeable batteries, the Refresh mode can be selected. (The mode key shall first
be pressed and held for 1 second to activate the mode change. The subsequent pressing of the mode key will toggle between the "Charge",
"Discharge", "Test" and "Refresh" mode.)

Then the user may also select different discharging current by pressing the CURRENT key (see "Note" in Discharge mode and Table 2), within 8
seconds after inserting the batteries. (Or the display will blink once to indicate the end of setting and the current cannot be changed afterward.).

It may take up to several days to finish the refreshing process, depending on the selected discharging current.

The maximum refresh current is 1000 mA and is not affected by the number of rechargeable batteries inserted.

page 5/8 table 5 vs table 6 or 7

It states that it is displaying "accumulated capacity" rather than "discharge capacity" in "discharge mode"

http://www.lacrossetechnology.com/900/manual.pdf

 

[Muse]

Re: Initial charge on Eneloops (AAA)

page 5/8 table 5 vs table 6 or 7

It states that it is displaying "accumulated capacity" rather than "discharge capacity" in "discharge mode"

http://www.lacrossetechnology.com/900/manual.pdf

OK, then to get a _capacity_ that's meaningful I evidently have to do the Test cycle OR the Refresh cycle.

My capacities shown for the batteries I was worried about (Rayovac Hybrid AAA) after the Test cycle at 250/500 dis/charge rate today are:
828
774
761
799

Maybe this means they are in good shape. How does one determine if his batteries are in good shape?

I think that in my case I may have fared relatively well while using the low 100/200 dis/charge rate in Discharge cycles on the BC-900 because I have a unique situation. My charger sits in a custom made charging stand complete with a fan blowing down directly over the cells.

Assuming that damage to the cells has something to do with their temperature, they would not have suffered as much as otherwise. If the damage isn't so related to temperature but more to the fact of being force-fed 200ma in a full state, they still may have suffered damage. Is there a way for me to tell?

 

[PeAK]

Re: Initial charge on Eneloops (AAA)

page 5/8 table 5 vs table 6 or 7

It states that it is displaying "accumulated capacity" rather than "discharge capacity" in "discharge mode"
.
.
.

Given that purpose of the DISCHARGE mode's role is to deplete the battery (from any charged state), it only makes sense for the designers to display the "accumulated capacity" (i.e. charge put out by the charger) when it restores the battery to the FULL charged state.

While discharging is used in the TEST mode, the additional pre-step of charging is needed due to the requirement of having the battery topped up to FULL before discharging to EMPTY...clear as mud but until the terminology because standardized for these high-end charger/analyzers, we can expect that the terms will be different things for different manufacturers. For the next 5 minutes, it makes perfect sense....I'll see how I fee tomorrow

PeAK

 

[Mr Happy]

Re: Initial charge on Eneloops, charging strategies. (AAA)

Just use an MH-C9000 instead. Then all confusion will be avoided

 

[Mr Happy]

Re: Initial charge on Eneloops (AAA)

I think that in my case I may have fared relatively well while using the low 100/200 dis/charge rate in Discharge cycles on the BC-900 because I have a unique situation. My charger sits in a custom made charging stand complete with a fan blowing down directly over the cells.

You know, this actually could present a problem. The charger detects when to stop charging by an increase in the temperature of the cells (the increase in temperature is what produces the drop in voltage for the -delta V signal). If you forcibly cool the cells you may reduce the required temperature rise and thus fool the charger into overcharging the batteries.

Sometimes the best of intentions can lead you astray...

 

[Russel]

Re: Initial charge on Eneloops (AAA)

You know, this actually could present a problem. The charger detects when to stop charging by an increase in the temperature of the cells (the increase in temperature is what produces the drop in voltage for the -delta V signal). If you forcibly cool the cells you may reduce the required temperature rise and thus fool the charger into overcharging the batteries.

Sometimes the best of intentions can lead you astray...

At a 200ma charge rate, what kind of temp rise can you expect during overcharge if Delta V termination is missed?

 

[Mr Happy]

Re: Initial charge on Eneloops (AAA)

At a 200ma charge rate, what kind of temp rise can you expect during overcharge if Delta V termination is missed?

Well, not a lot of course, but it isn't just temperature that does the damage. If you have 800 mAh AAA cells being charged at 200 mA that is a 0.25C charge rate, and if they get an applied charge of 1300 mAh that is a 500 mAh or 60% overcharge. A 60% overcharge at a 0.25C rate is not healthy for NiMH cells no matter how cool you keep them.

 

[Russel]

Re: Initial charge on Eneloops, charging strategies. (AAA)

So...

AAA 800mah NiMH batteries.

Charge at 400ma to 800ma to insure proper BC-900 charge termination. (Especially with less the perfect batteries.)

Use the TEST CYCLE to measure battery capacity because test cycle measure and display the amount of energy actually drained from the battery. (As opposed to Discharge cycle, which will display the amount of energy used to charge the battery.)

Use the DISCHARGE CYCLE to simply discharge and recharge (fully cycle) the battery.



Am I missing anything else?

Russ

 

[Russel]

Re: Initial charge on Eneloops (AAA)

Well, not a lot of course, but it isn't just temperature that does the damage. If you have 800 mAh AAA cells being charged at 200 mA that is a 0.25C charge rate, and if they get an applied charge of 1300 mAh that is a 500 mAh or 60% overcharge. A 60% overcharge at a 0.25C rate is not healthy for NiMH cells no matter how cool you keep them.

True. The overcharge is bad, even with the extra cooling. I just doubt the charger would terminate on temp at that charge rate even overcharging. Does anyone know the charge termination temp for the BC-900?

I was leary of charging at higher rates until I tested some eneloops at 700ma. Still below the .5C to 1C recommended charge rate [edit: for AA 2000mah cells], but high enough to get an idea of temperature. Here is the highest reading I got. Note the room ambient temperature.

 

[Muse]

Re: Initial charge on Eneloops, charging strategies. (AAA)

So...

AAA 800mah NiMH batteries.

Charge at 400ma to 800ma to insure proper BC-900 charge termination. (Especially with less the perfect batteries.)

Use the TEST CYCLE to measure battery capacity because test cycle measure and display the amount of energy actually drained from the battery. (As opposed to Discharge cycle, which will display the amount of energy used to charge the battery.)

Use the DISCHARGE CYCLE to simply discharge and recharge (fully cycle) the battery.



Am I missing anything else?

Russ

The Refresh cycle gives capacity based on the last discharge portion of the process, and so also gives a meaningful reading of capacity.

Of course you can always just charge the cell, no discharge involved. I do this sometimes when I'm in a hurry such as I need to use my camera soon and want well charged AA's.

If the BC-900 doesn't see enough voltage on the cell it will refuse to charge it at all. Instead of a voltage the charger shows the cell as Null. In that event you have to put the cell(s) in another charger, one that will supply a current to the cell and charge it for a couple of minutes. Then the BC-900 won't refuse to charge it. This has happened to me a few times.

 

[Muse]

Re: Initial charge on Eneloops (AAA)

You know, this actually could present a problem. The charger detects when to stop charging by an increase in the temperature of the cells (the increase in temperature is what produces the drop in voltage for the -delta V signal). If you forcibly cool the cells you may reduce the required temperature rise and thus fool the charger into overcharging the batteries.

Sometimes the best of intentions can lead you astray...

Should I stop providing ventilation to the cells? :sigh: Part of the reason I did this was to put the charger in a position where if it did "melt down" it wouldn't damage anything. :thinking: The BC-900 actually senses the temperature of the cells in determining -delta V termination? How does it do that? Separate temperature sensors under each cell?

 

[Russel]

Re: Initial charge on Eneloops, charging strategies. (AAA)

The Refresh cycle gives capacity based on the last discharge portion of the process, and so also gives a meaningful reading of capacity.

Of course you can always just charge the cell, no discharge involved. I do this sometimes when I'm in a hurry such as I need to use my camera soon and want well charged AA's.

If the BC-900 doesn't see enough voltage on the cell it will refuse to charge it at all. Instead of a voltage the charger shows the cell as Null. In that event you have to put the cell(s) in another charger, one that will supply a current to the cell and charge it for a couple of minutes. Then the BC-900 won't refuse to charge it. This has happened to me a few times.

Refresh cycle - thanks, I missed that one.

I gave my Sister a set of 4 Eneloop AAs after seeing the old and mismatched set of batteries She was using in her digital camera. A couple wouldn't start the charge due to low voltage as you describe. With the charger unpluged I just set a charged cell in the bay next to the dead one with the negitive terminal touching the charger negitive terminal, but with the positive terminal of both cells exposed (before you push the battery in place) and shorted the positive terminals together with a paper clip. (Connecting the two cells in parallel.) After about 30 seconds, I remove the paperclip, plug in the charger and push the cell into place to begin charging. That allows the charged cell to charge the dead one enough for the charger to begin charging it. If that doesn't work, I consider the "null" cell a lost cause.

Russ

 

[Russel]

Re: Initial charge on Eneloops (AAA)

Should I stop providing ventilation to the cells? :sigh: Part of the reason I did this was to put the charger in a position where if it did "melt down" it wouldn't damage anything. :thinking: The BC-900 actually senses the temperature of the cells in determining -delta V termination? How does it do that? Separate temperature sensors under each cell?

The BC-900 measures voltage for Delta V termination. Delta V is where the battery voltage drops slightly when the battery is fully charged. At least that is a very basic explanation. Temperature termination is a different method of terminating, or at least pausing the charge cycle If the battery is too hot. If you look between the cell ports of the charger, near the top of the port, you can see flat metal strips. I think that is where the BC-900 measures the battery temperature. I think it measures temperature of the cells in pairs.

Edit: As long as you charge at the recommended rate of .5C to 1C or 400ma to 800ma with the BC-900 and your 800mah [edit: AAA] cells, using your cooling fan shouldn't be a problem.

Russ