Interesting... but not recommended...

[Mr Happy]

However...A123 cells have much lower volumetric capacity so if you are interested in useful range for your battery pack this is not a good option. Also, with any battery technology the opportunity for electrical fires is there, and is even greater with batteries that have a high power fast discharge capability.

 

[DIWdiver]

Does that have serious ramifications for the Californians I've read about who have converted their Priuses into plug-in hybrids? Is what they're saving in fuel - getting 100+ mpg economy - going to rebound on them when they have to buy a new battery early?

It doesn't even matter how long the batteries last. There's a more fundamental problem with the whole discussion.

For a plug-in hybrid, MPG numbers are meaningless. With a simple modification and some stupid driving habits, I could get 1000 MPG from my 1999 Ford Ranger pickup.

Here's how I would do it:
1. Defeat the interlock that prevents the starter from engaging when the cluch is engaged (clutch pedal NOT pressed). Not all vehicles would require this modification.
2. Reset the odometer.
3. Drive far enough to use 1 gallon of gas (about 18 miles in my case).
4. Disconnect the fuel line from the engine.
5. Drive the truck around the block using only the starter motor. This may need to be done in stages to prevent overheating of the starter.
6. Recharge the battery.
7. Repeat steps 5 and 6 until the odometer reads 1000 miles.

Viola! I have driven the truck 1000 miles on only one gallon of gas!!!

Note that I could have achieved any MPG number I chose, simply by changing either the distance driven on gas or the distance driven on 'plug-in'.

Of course this is stupid, but it serves to illustrate the illogic of using "MPG" and "plug-in" in the same sentence. Anyone doing so either doesn't understand reality, or doesn't want you to!

D

 

[LuxLuthor]

Been gone from CPF a lot, but this was a great thread & information. Thanks!

 

[cckw]

Back to the original topic:

I have some 07 dated Duraloops that I recently bought as new. In break-in they came in around 1920. I took 2 and tried the "Silver Fox method of battery refreshing" and then break-in again, they came out 1964 and 1967.

I discharged in a couple 1x AA lights and shorted for 48 hours.

 

[45/70]

Back to the original topic:

I have some 07 dated Duraloops that I recently bought as new. In break-in they came in around 1920. I took 2 and tried the "Silver Fox method of battery refreshing" and then break-in again, they came out 1964 and 1967.

I discharged in a couple 1x AA lights and shorted for 48 hours.

These results seem similar to what normally would be expected from cycling new cells. Interesting. Obviously their capacity has not been affected, but the question still remains whether their LSD capability has been reduced.

I also wonder if a potential increase in capacity might result in part, from running cells down with this "method", that had not been in use for that long a period. Large crystalline formation is known to occur during storage in standard NiMH cells. I can't help but think that LSD cells suffer from this as well, albeit to a much lesser extent due to their low self discharge rate. I would think however, that the possibility could certainly exist in cells that have been in storage for three years.

Dave

 

[cckw]

These results seem similar to what normally would be expected from cycling new cells. Interesting. Obviously their capacity has not been affected, but the question still remains whether their LSD capability has been reduced.

I also wonder if a potential increase in capacity might result in part, from running cells down with this "method", that had not been in use for that long a period. Large crystalline formation is known to occur during storage in standard NiMH cells. I can't help but think that LSD cells suffer from this as well, albeit to a much lesser extent due to their low self discharge rate. I would think however, that the possibility could certainly exist in cells that have been in storage for three years.

Dave

I did this with 2, I can set them aside with 2 of same that I didn't do and measure the remaining charge in 6 months.

 

[VidPro]

:twothumbs cool
will be interested in seeing any further information people arrive at about long term or continual effects of "running flat"
thanks Silverfox.

i have a singular discharger thing that was originally designed for ni-cd, and i have used it with Ni-Mhy and it has not destroyed anything as far as i can tell, but telling differences would require more sofistication in tracking the batts than i do.
it is 10x single battery holders with a pr2 light bulb, pretty lame but it is used to full discharge visually. i use it mostly to discharge singularly a whole big series pack (that also uses holders) so i can discharge the pack quick as singles. often i have revived the resistance and capacity of the pack using it, but what long term damage occurs ???
still it has to beat the heck out of series discharge cycling of the pack, but others have mentioned puttin in a diode to stop the discharge at more normal levels.

also there was positive results posted of discharging to .7 and .4 but no loooooonnnnng loooooonnng followup info.
problem is with looong term followup of something like an Energyser 2500 , Well you get the point 🙂

with enloops lasting long and long and long, a long term followup or testing is possible at least.

i have enloops that were run flat and overcharge endlessly and trickle charged endlessly , and i still cant tell the abused ones from the others (the fact that i dont really know which is which 🙂 well my fault, but a few of them have marks on them i dont remember what the mark means :wave:

 

[Lynx_Arc]

but a few of them have marks on them i dont remember what the mark means :wave:

I have learned to number cells with a sharpie and keep a text tile of the capacities. I also mark Xs on those I consider poor condition or problematic till I get around to running them through my analyzer. The X cells are used in devices that can overdischarge them or essentially are low current so the lower capacity is not a problem.

 

[Lynx_Arc]

I am in the middle of an interesting situation. I have a few rayovac hybrids that got overdischarged, possibly reversed and capacity on them tested out running refresh in my bc900 came out to be 250ma and 500ma. for fun I took the 250ma AA and put it in a taskforce 1AA and let it drain it to nothing (probably 0.4v) and then took the battery and stuck it in an energizer 15 minute charger for an hour making sure it was cooled off before I removed it. I then ran the same battery through the bc900 refresh cycling and it came up with over 500mah capacity. I now have a second one that is about 510ma I am doing the same torture test to, I shall see if capacity improves also. I am cycling them on the lowest setting.

 

[TakeTheActive]

I Don't Understand Your Logic?!?

...I have a few rayovac hybrids that got overdischarged, possibly reversed and capacity on them tested out running refresh in my bc900 came out to be 250ma and 500ma. for fun I took the 250ma AA and put it in a taskforce 1AA and let it drain it to nothing (probably 0.4v) and then took the battery and stuck it in an energizer 15 minute charger for an hour making sure it was cooled off before I removed it...

I don't understand your logic:

1. First, what Charge Rate did you use for the BC-900 REFRESH?
   - How many 'REFRESH' Cycles did it go through before 'quitting'?
   .
2. Second, WHY would you charge it at 4.0C for ONE HOUR?!? 😱
   - Did the 15-Minute Charger terminate at 15 minutes and you just left it there to cool?
   - Or was it CHARGING for over 15 minutes, with the fan valiantly trying to cool it?

...I then ran the same battery through the bc900 refresh cycling and it came up with over 500mah capacity...

• At what Charge Rate?
  .
• What were the Capacities of these two cells BEFORE the mishap?

...I now have a second one that is about 510ma I am doing the same torture test to, I shall see if capacity improves also. I am cycling them on the lowest setting.

Rather than STRESS the poor tortured cell with 4.0C, I would have NURSED it back with 0.1C (or less) for 16 (or more) hours. It was EMPTY - seems like a good opportunity for a 'Forming Charge', which we all know 'gets into all those nooks and crannies and stirs things up' MUCH better than a -DeltaV or MAX Voltage termination charge. :thinking: :shrug:

 

[Lynx_Arc]

Re: I Don't Understand Your Logic?!?

I don't understand your logic:

1. First, what Charge Rate did you use for the BC-900 REFRESH?
   - How many 'REFRESH' Cycles did it go through before 'quitting'?

1. several cycles

   [*]Second, WHY would you charge it at 4.0C for ONE HOUR?!? 😱 The charger is a smart charger it shuts off when it is nearly charged (but sometimes only 80-90 percent charged)

   - Did the 15-Minute Charger terminate at 15 minutes and you just left it there to cool?

   it terminated well before 15 minutes but continues to charge at a trickle rate to completion.
   

   • At what Charge Rate?

   • 
     I used the lowest charge rate (default) on the bc900

     [*]What were the Capacities of these two cells BEFORE the mishap?

   250 and 500mah

   Rather than STRESS the poor tortured cell with 4.0C, I would have NURSED it back with 0.1C (or less) for 16 (or more) hours. It was EMPTY - seems like a good opportunity for a 'Forming Charge', which we all know 'gets into all those nooks and crannies and stirs things up' MUCH better than a -DeltaV or MAX Voltage termination charge. :thinking: :shrug:

   tried that, ran it through the refresh twice at 200ma and it wouldn't improve, a AA nimh cell with 250mah capacity is useless so I figured maybe I could shock it back into shape. I seriously doubt the capacity of the 250mah cell will ever reach close to 1000mah nor the 500mah cell reach that either.

 

[TakeTheActive]

Re: I Don't Understand Your Logic?!?

(Ever-so-slightly re-formatted with LIST since with just QUOTE, your replies were 'running together'...

• several cycles
  .
• it terminated well before 15 minutes but continues to charge at a trickle rate to completion.
  .
• I used the lowest charge rate (default) on the bc900
  .
• 250 and 500mah
  .
• tried that, ran it through the refresh twice at 200ma and it wouldn't improve, a AA nimh cell with 250mah capacity is useless so I figured maybe I could shock it back into shape. I seriously doubt the capacity of the 250mah cell will ever reach close to 1000mah nor the 500mah cell reach that either.

So, you just said:

• Two Rayovac Hybrid AAs with an INITIAL Capacity of 250mAh and 500mAh accidentally "...got overdischarged, possibly reversed..."
• You then proceeded to run several BC-900 REFRESH Cycles @ 200mA/100mA and the Capacities remained at the original 250mAh and 500mAh.
• You followed that with a Taskforce 1AA Discharge to 0.4VDC, a 15-Minute Charge (for 1 hour), then another BC-900 REFRESH set @ 200mA/100mA and now the 250mAh cell is up to 500mAh.

As far as I can tell, you lost nothing, gained 100% - the cells were REALLY *CRAP* (250mAh) before your mishap and now they're 100% better (500mAH, but still *CRAP*).

Also, keep in mind that a 200mA REFRESH on a BC-900 is *NOT* the same as a 0.1C @ 16 hours 'Forming Charge' (unless 3200mAh went in 😉 ).

I still don't understand - if the cells were at 250mAh (12.5%) and 500mAh (25%) Capacity *BEFORE* the mishap, what's the problem? Nothing much changed by your accidentally over discharging them. 😕

 

[Lynx_Arc]

Re: I Don't Understand Your Logic?!?

So, you just said:

• Two Rayovac Hybrid AAs with an INITIAL Capacity of 250mAh and 500mAh accidentally "...got overdischarged, possibly reversed..."
• You then proceeded to run several BC-900 REFRESH Cycles @ 200mA/100mA and the Capacities remained at the original 250mAh and 500mAh.
• You followed that with a Taskforce 1AA Discharge to 0.4VDC, a 15-Minute Charge (for 1 hour), then another BC-900 REFRESH set @ 200mA/100mA and now the 250mAh cell is up to 500mAh.

As far as I can tell, you lost nothing, gained 100% - the cells were REALLY *CRAP* (250mAh) before your mishap and now they're 100% better (500mAH, but still *CRAP*).

Also, keep in mind that a 200mA REFRESH on a BC-900 is *NOT* the same as a 0.1C @ 16 hours 'Forming Charge' (unless 3200mAh went in 😉 ).

I still don't understand - if the cells were at 250mAh (12.5%) and 500mAh (25%) Capacity *BEFORE* the mishap, what's the problem? Nothing much changed by your accidentally over discharging them. 😕

The cells were probably close to 2000mah before the mishap, and at 2000mah 0.1C would be 200ma which is what the BC900 was refreshing them at. The 250mah one is still refreshing and is at 537ma while the 510ma one I just put in an hour or so ago is up to 359ma. I will probably shock the 250ma one again after it finishes the process to see if I can improve it more. I have tried refreshing these at 200ma and 700ma and 1000ma with no previous luck but this drain them dry and toast em seems to be doing something perhaps too little.

 

[TakeTheActive]

Re: I Don't Understand Your Logic?!?

The cells were probably close to 2000mah before the mishap...

AHA! So they WERE HEALTHY and VIBRANT *BEFORE* the mishap (that's not what you said earlier 🙄)

(It's EXTREMELY difficult to diagnose the problem when the patient provides you with INCORRECT symptoms! 🤢)

...and at 2000mah 0.1C would be 200ma which is what the BC900 was refreshing them at...

Yes, and again, 200mA with a TERMINATION method is *NOT* 0.1C for 16 hours TIMED. 😳

...The 250mah one is still refreshing and is at 537ma while the 510ma one I just put in an hour or so ago is up to 359ma. I will probably shock the 250ma one again after it finishes the process to see if I can improve it more. I have tried refreshing these at 200ma and 700ma and 1000ma with no previous luck but this drain them dry and toast em seems to be doing something perhaps too little.

IMHO, this is an EXCELLENT situation to add to SilverFox's "Let's Run *One* VIBRANT Cell Flat and See What Happens" scenario (i.e. *Two* VIBRANT Cells Turned to ABSOLUTE *CRAP* by ONE {I'm SO Sorry!!! :mecry:} Over-Discharge in Series Event). But, somehow, based on my *CRAP* cell experience with CYCLES vs "Forming Charges", I don't see your "SHOCK Treatment" as the answer. :shrug:

From my point-of-view, I can see a 0.1C (or even 0.05C) *SLOW* Charge as a way to GENTLY urge the cell back into maybe a somewhat HEALTHY condition. We all know (from our *VAST* reading of the CPF 'Batteries Included' Archives) that FAST CHARGING will *NEVER* achieve a 100% SOC before one of the 'Termination Methods' kicks in. Whereas, SLOW CHARGING is unrestrained... :thinking: (for 16 hours at least 😉 )

[Those of you who know me will certainly realize that my penchant for EXCESSIVE FORMATTING has been DILIGENTLY held under control for MANY weeks now. Unfortunately for Lynx_Arc, a certain series of events occurred this evening (now morning) forcing me to reply to posts "PAST MY BEDTIME" and thus - THE RESULT! Some of you will ENJOY it and SMILE, while others won't COMPREHEND it... 😉 ]

 

[Lynx_Arc]

Re: I Don't Understand Your Logic?!?

From my point-of-view, I can see a 0.1C (or even 0.05C) *SLOW* Charge as a way to GENTLY urge the cell back into maybe a somewhat HEALTHY condition. We all know (from our *VAST* reading of the CPF 'Batteries Included' Archives) that FAST CHARGING will *NEVER* achieve a 100% SOC before one of the 'Termination Methods' kicks in. Whereas, SLOW CHARGING is unrestrained... :thinking: (for 16 hours at least 😉 )

[Those of you who know me will certainly realize that my penchant for EXCESSIVE FORMATTING has been DILIGENTLY held under control for MANY weeks now. Unfortunately for Lynx_Arc, a certain series of events occurred this evening (now morning) forcing me to reply to posts "PAST MY BEDTIME" and thus - THE RESULT! Some of you will ENJOY it and SMILE, while others won't COMPREHEND it... 😉 ]

actually it is helping.... but probably not enough. my 510ma battery is up to 552ma now and this is only the first cycle. I could wire up my power supply to a timer and run it at 50ma for 24 hours and see what happens but this is more interesting 😀

 

[TorchBoy]

Re: I Don't Understand Your Logic.

IMHO, this is an EXCELLENT situation to add to SilverFox's "Let's Run *One* VIBRANT Cell Flat and See What Happens" scenario (i.e. *Two* VIBRANT Cells Turned to ABSOLUTE *CRAP* by ONE {I'm SO Sorry!!! :mecry:} Over-Discharge in Series Event). But, somehow, based on my *CRAP* cell experience with CYCLES vs "Forming Charges", I don't see your "SHOCK Treatment" as the answer. :shrug:
...
[Those of you who know me will certainly realize that my penchant for EXCESSIVE FORMATTING has been DILIGENTLY held under control for MANY weeks now. Unfortunately for Lynx_Arc, a certain series of events occurred this evening (now morning) forcing me to reply to posts "PAST MY BEDTIME" and thus - THE RESULT! Some of you will ENJOY it and SMILE, while others won't COMPREHEND it... 😉 ]

I did smile, but I also wanted to turn off the Christmas tree. 🙄 :thumbsup:

 

[TakeTheActive]

Re: I Don't Understand Your Logic.

I did smile, but I also wanted to turn off the Christmas tree. 🙄 :thumbsup:

Every so often, just typing the SAME OLD TEXT without the naturally accompanying 'Vocal Modulations / Facial Expressions' just gets so...

BORING!​

You can *ALWAYS* choose to IGNORE my posts. :toilet: 😀

 

[TakeTheActive]

Re: I Don't Understand Your Logic?!?

The cells were probably close to 2000mah before the mishap...

actually it is helping.... but probably not enough...

I dunno. For the CAPACITY to drop from ~2000mAh (~100%) to ~250mAh (~12.5%) after *ONE* mishap seems a bit extreme...

They're YOUR cells and you're free to do whatever you like with them. Personally, I would consider 0.05C for *MANY* hours.

I'm waiting to see what one of the Gurus / Chemical Engineers has to offer...

 

[TorchBoy]

Re: I Don't Understand Your Logic.

You can *ALWAYS* choose to IGNORE my posts. :toilet: 😀

I'd rather just be able to read them (easily). 🙁

 

[core]

Re: I Don't Understand Your Logic?!?

Lynx_Arc, I'd also put them on a timed charge for a while. They are basically useless to you so anything at all would be an improvement. Have you measured the voltage of one of them under a known load? And compare that to a healthy cell?

Those of you who know me will certainly realize that my penchant for EXCESSIVE FORMATTING has been DILIGENTLY held under control for MANY weeks now.

Oh wow TTA you had me laughing even before reading your aside there. And you were doing so well for a while? Kinda had me wondering if you were suffering from colour depression lately.

Just keep repeating to yourself:

Every day, in every way, I am getting better and better! 🙂