Do You Maintain *CRAP* NiCD/NiMH Cells?

[TakeTheActive]

• *CRAP*:
  - meaning their current Capacity is LESS THAN 80% of their 'Originally Stated Capacity' (as per SilverFox ).
  .
• NiCD/NiMH Cells:
  - meaning a SUBSTANTIAL (~40% or MORE!) of your total cell inventory.

Basically, I'm looking to see if there's ANYONE besides *ME* READING the CPF 'Batteries Included' Archives *AND* EXPERIMENTING with their *CRAP* (i.e. formerly abused, neglected, overcharged, 5/10/15+ year old etc... *BEFORE* they bought a 'SMART' Charger/Analyzer) NiCD/NiMH cells.

*IF* you decide to reply to this POLL, please post:

• Your (Active *AND* Inactive) CHARGER inventory.
• Your (at least approximate) *CRAP* cell inventory (i.e. Manufacturer / Chemistry / Capacity / Age / Number of cells).
• Your current MAINTENANCE procedure(s).
• Your SUCCESS / FAILURE picture.

Note: I recently at PeAK for a LACK OF MEMBER PARTICIPATION in his new thread: Test for how well batteries suit your charger. So, *IF* CPF Members are interested in 'INTERACTIVE' threads like these, you need to ACTIVELY RESPOND!

[TakeTheActive]

Chargers:

Active

• Maha MH-C9000 0H0AA
• La Crosse BC-900 v33
• RadioShack 23-428 Universal Battery Charger (Smart; AAA/AA/C/D/9V)
• Rayovac PS23-B
• Duracell CEF-23 Mobile Charger
• Rayovac PS3 (Smart; AAA/AA/C/D)
• Digital Concepts CH-1800 Digital Camera Charger (SAKAR Dumb 150mA Series AA/AAA)
• RadioShack 23-418 13 Hour NiCd/NiMH Charger (Timed 140mA Series AA/AAA)
• DieHard 93558 7-hour Fast Charger (Timed; AAA/AA/C/D/9V)

Inactive

• Sanyo MQN06U
• RadioShack 23-250 Universal Battery Pack Conditioner/Charger (Maha MH-C777 clone)
• Rayovac PS1
• Saft Again and Again (Dumb; AAA/AA/C/D/9V)
• GE ??? (Dumb; AAA/AA/C/D/9V)

Cells:

AA - *CRAP*

• _4 La Crosse 2400mAh NiMH (12/xx/2006)
• _4 Rayovac 2000mAh NiMH (2004?)
• 28 Rayovac 1600mAh NiMH (1999-2001?)
• _4 Rayovac 1300mAh NiMH (1999-2000?)
• _8 RadioShack 1300mAh NiMH (2002-2003?)
• _4 Sears DieHard 1300 mAh NiMH (2002-2003?)

AA

• 12 Sanyo Eneloop 2000mAh LSD NiMH (12/31/08, 05/08/09)
• _4 Duracell Duraloop (MIJ) 2000mAh LSD NiMH (11/xx/08)
• _6 Duracell Durabrid (MIC) 2000mAh LSD NiMH (09/19/09, 10/24/09)
• _8 Kodak 2100mAh LSD NiMH (11/xx/08)
• 10 RadioShack 2000mAh LSD NiMH (09/xx/2008)
• 16 Rayovac 2000mAh I-C³ NiMH (2005?)
• 20 Philips 1400mAh NiMH (2004?) (Sanyo? Lime-green wrapper, no button)
• _4 Sanyo 1700mAh NiMH (2002?)

AAA - *CRAP*

• _4 La Crosse 800mAh NiMH (12/xx/2006)
• 12 La Crosse 700mAh NiMH (12/xx/2006)
• _4 Energizer 700mAh NiMH (2004?)
• _4 Rayovac 700mAh NiMH (2004?)

AAA

• _2 Sanyo Eneloop 800mAh LSD NiMH (05/08/09)
• _8 Duracell Duraloop (MIJ) 800mAh LSD NiMH (09/03/09, 09/19/09)
• _4 Duracell Durabrid (MIC) 800mAh LSD NiMH (10/24/09)
• _4 Kodak 850mAh LSD NiMH (05/27/09)
• 32 RadioShack 750mAh LSD NiMH (09/xx/2008)

D

• _6 Vinic 6000mAh NiMH (2002?)
• _2 RadioShack 4500mAh NiMH (2004?)
• _2 Energizer 2500mAh NiMH (2002?)
• _2 Energizer 2200mAh NiMH (2000?)
• _2 Maxell ???mAh NiCD (1998?)

C

• _4 Tysonic 4500mAh NiMH (2002?)
• _4 Millennium ???mAh NiCD (1998?)
• _3 GE ???mAh NiCD (1994?)

Maintenance Procedure:

BRIEF Version (Cell Inventory took a *LONG* time).

I used to COOK my cells, starting with the Saft Again and Again, then the Rayovacs PS1 ("cool" COOK - missed terminations @ 200mA) and PS3 ("Hot" COOK - high internal resistance, missed terminations @ 500mA), and finally with the La Crosse BC-900 running 200/100 REFRESHES.

Today, I track Impedance Check Voltage and CAPACITY @ 0.2C with the C9000. When I find cells with an Impedance Check Voltage over 1.60VDC, I attempt to lower it via the Cell Recovery techniques listed in my Sig Line LINK (such as the Deep Discharge Technique). This process may take 10-20 REPETITIONS, so it's something you do when you're doing something else in the same room and can keep 'checking progress'.

As PeAK mentioned in his reply, Internal Resistance plays a major role in getting the CAPACITY out of your cells. And, the C9000 makes it EASY to track. Cells that read:

• 'HIGH' go to remote controls, non-critcal flashlights.
• ~1.80-2.00VDC go to thermometers, clocks, etc...
• <1.80VDC go to non-critical, but high current, devices (i.e. GPS, camera)

I've measured and recorded the current draw of most of my devices and I attempt to utilize MATCHED CELLS with a ~2-3 month "CAPACITY to Power". Then, at either ~90 days, or when the device shuts down, I run a 100mA DISCHARGE on the BC-900, followed by a 0.5C (watching the heat) CHARGE on the C9000 - 25% if the cell's going into storage / rotation, 100% if it's going back into service.

Success/Failure Results:

BRIEF Version (Cell Inventory took a *LONG* time).

45/70's 'Deep Discharge Technique' has worked on most cells, dropping usually ~0.1VDC, sometimes more. It's also important to be consistant and pay attention to WHEN you perform the 'Impedance Voltage Check' - it varies by cell temperature and 'State-of-Charge'.

A "Forming Charge" also plays a major role. I've CYCLEd cells 5-10 times on both the C9000 and BC-900 (0.5-1.0C CHARGE; 0.2C, 50% of CHARGE or 100mA DISCHARGE) and recorded either no improvement or DECREASED CAPACITY. Then, on a whim, I tried a "Forming Charge" (or two) and the CAPACITY increased a bit (nothing EARTH-shaking).

...to be continued... WHEW!

[Henk_Lu]

While I've been using Eneloop type batteries (Panasonic Infinium) for over 3 years now, I'm still completely new to this...

The 2-cell charger provided by Panasonic should be a smart one, but I think it sucks. I often had problems that a light worked for 10 minutes and then switched to Low, once pretty new cells vented and I had trouble opening the Fenix L2D-Q5. In the GPS those cells normally last 12 hours or more, sometimes they died within 2 hours. No cell could be identified as "bad" though. I started "double-charge" them, when the charger has finished, I put them in once more in the other bay, the charger may take another 5 hours to complete. The charger had been replaced by the same model, same result.

So, I recently bought a Titanium 8800 AA/AAA charger, when I have it, I will recycle and test all cells, bad ones will be eliminated and replaced if I can identify them. I guess my procedure could have hurt them over the years, no idea, my knowledge od these things lacks. I hpe that charger qualifys as a smart charger. I'll also start with Li-Ion, but I guess that isn't asked here.

Sorry for the slight off-topic, if it is...

[PeAK]

• Your (Active *AND* Inactive) CHARGER inventory.
• Your (at least approximate) *CRAP* cell inventory (i.e. Manufacturer / Chemistry / Capacity / Age / Number of cells).
• Your current MAINTENANCE procedure(s).
• Your SUCCESS / FAILURE picture.

Here you go:

1. Your (Active *AND* Inactive) CHARGER inventory.
   Active:
   -Meijer/Camelion BC-905 : smart/negative delta-V/fast/independent channels
   -Multiple Power" MP-809 : smart/non-negative deta-V/Slow/independent channels (under evaluation)
   -Radio Shack 23-425 : smart/0-dV/medium speed/Two batteries at a time
   -Home made variable power supply (2 to 20V). 10 mA constant current source capable of sourcing up to 30 volts.
   
   Not Active:
   -Panasonic BQ-4B : dumb/slow overnight /two at a time
   -Radio Shack 23-427 : dumb/slow overnight/two at a time
2. Your (at least approximate) *CRAP* cell inventory (i.e. Manufacturer / Chemistry / Capacity / Age / Number of cells).
   See this link for my inventory of 47 NiMH cells as of Jan '09. Since then it has expanded with 8 eneloops and 8 no-name Eneloop.
   
   
3. Your current MAINTENANCE procedure(s).
   The capacity is over-rated. I'm interested in how long the battery can maintain a voltage so that my Digital camera does not shutdown. So regular "on-resistances" is a key measurement to determine which cells make it to my "non maintained crap pile".
4. Your SUCCESS / FAILURE picture.
   The chargers all work great with the few NiCads that I did not damage with the dumb chargers. Similarly, I have excellent results/life with older/lower capacity cells less than 1400mA-hr. The worst cells are the large capacity (2200/2400/2600/2650 mA-hr) cells. I'm very happy with the lower capacity path that is being taken with the LSD cells.

Current Charger Evaluation:
One of the latest promising discoveries that is under evaluation is a "smart charger" that does not use negative delta-V (Multiple Power MP-809). Here are the specs:

1. Constant 250 mA up to 1.41V
2. Switch over to trickle charge of 25mA for one hour and stop.
   Update: The above was found to be false as the unit was found to maintain a 100mA charge to beyond 1.8V forever. For now stay away from this charger

[Black Rose]

My regular use NiMh AA/AAA cells that were CRAP went to the recycling depot this past summer. There was about a dozen of those.

This post isn't really what TTA was looking for, but I answered yes to the poll and am tossing in my 2 lumens, as what I do is very similar to what someone would do with CRAP cells.

First the chargers...

Active Chargers:
Maha MH-C9000
Maha MH-C800S

Occasional Use/Backup:
Eneloop NC-MDR02NU
Rayovac PS16

Not Active:
Sanyo NC-452B (Cadnica AA charger from the mid-80s)

Not Active (but pulled into service in extreme cases):
Rayovac PS13 (22 hour timed dumb charger)
This is the charger that did most of the damage to my older cells, but it still has it's uses (at least until I get a hobby charger)

OK, onto the batteries.

Inventory:

All of these cells are used in solar lights over the spring/summer/fall and get beaten up pretty bad.

NiMh:
IDC AAA - 4 - 600 mAh - Currently about 55% capacity

NiCd:
I haven't had a chance to put these on the C9000 to get capacity numbers, but based on last years results, these guys are in the 30 - 40% capacity range, if not worse.

Unknown AAA - 3 - 350 mAh -
Unknown AA - 2 - 600 mAh -
IDC AA - 3 - 600 mAh -
Paradise AA - 2 - 300 mAh -
Lumisol AA - 1 - 600 mAh -
Moonrays AA - 2 - 600 mAh -
Golden Sun AA - 12 - 600 mAh -

What I do with them....

Last week I pulled 4 600 mAh NiMh AAA cells out of a set of our solar lights to work on in the off season.
These guys were pretty much empty since the sun decided our back yard was not worthy of it's presence

I put them on the C9000 to drain them @ 100 mA. Only one had any charge left in it (70 mAh).

Put them in to charge at 200 mA to see how they would do. No HIGH from the Maha, so that was a positive. 3 of the 4 terminated normally, one missed termination. Discharged and repeated charge 2 more times. At this point they are showing 350 mAh capacity.

I will follow this regime with all of the above listed cells until they show better numbers.
Once they show progress on the C9000, they get drained and then over to the C800S for a slow condition cycle (if they have enough capacity to handle a 500 mA charge).

For any of the above cells that show HIGH on the Maha chargers, they get a few hours in the Rayovac PS13 dumb charger before they get discharged and a charge is attempted in the C9000 again.

Once I get the hobby charge (Turnigy Accucell 6), the PS13 will most likely be retired.

Why do I do this instead of simply replacing the cells? I'm cheap

These cells are expensive to replace at retail, web stores that carry equivalent cells have expensive shipping, and the only other place I know that has equivalent cells has a less than stellar rep for cell quality (why replace crap with crap?)

Besides, I have these chargers...may as well use them.

[Lynx_Arc]

chargers active
rayovac 1 hr
BC900
Duracell Mobile

cells:
12 AA 12AAA duraloops about 4-18 months old
16 AA 12AAA rayovac hybrids 2 1/2 years old
15 AAA nimh greensleeve 550/650 mah
18 AA nimh greensleeve 1200mah (generic cell phone battery)
15 AA nimh greensleeve 1500-1600mah

I have tested all but the LSD cells for capacity I retest only when I
have what I consider a weak cell on my BC900 and I pull the weak ones and match them
with other weaker ones or toss them when they are 1/2 or less capacity approx.

I have found my rayovac charger the most easiest forgiving charger able to recharge most without a problem even
jump starting cells refused by my bc900 and charging cells my duracell mobile has errors on with no errors. The
bc900 will charge most cells but will not start charging them if voltage is too low and you have to sometimes set the
charge rate up to 500mah or higher to get it to terminate well. If charging 4 cells at 1000mah sometimes channel 4 doesn't want to complete as fast I have had to pull cells out of it that were marginal. I don't trust the bc900 with damaged or junk cells.

junk cells are good for lots of things. if you rarely use something or have a low drain device you use on occasion that has no standby drain like a small LED light or LED taplight it replaces alkalines and doesn't tie up expensive LSD cells. I worry none about destroying junk cells and if they will run the things I put them in well enough lower capacity only means more recharging. If I find myself recharging more than once every 4-6 months I start using better rechargeables in them. I have a magnetic message thing on my fridge with a clock that is going on 2 years using generic nimh AAAs in it... some of the batteries may be toast but I only had 33 cents in each of them and have recharged them a dozen times already.

compare $1.50-$3.00 for high end nimh cells with 25 cents to $1.25 for low end nimh cells and start accidentally destroying them and it adds up. I tend to toss nimh when they get below 500mah capacity for AA and 300mah for AAA cells as in most things that requires recharging too often and becomes an anoyance instead of a savings. I have a taplight that averages 50ma over the life of the batteries so can run for about 12 hours off 600mah AAs and at times I accidentally leave it on killing the batteries sometimes reducing capacity some. The cheaper junk batteries can sometimes take a tremendous beating that high end nimh would lose considerable capacity. It is also nice if you have a fast charger you can top off low end junk cells in no time vs 2000/800mah AA/AAA cells which take several hours to *protect* them from losing capacity. I have charged some 1200mah nimh in an energizer 15 minute charger in 5 minutes to top them off.... they got hot and I didn't care and 5 months later I recharged them in my 1 hour rayovac charger in 12 minutes. The advantage of fast worryfree recharging with throwaway nimh cells is a plus. You can also put them in stuff and give them away to someone that has a charger instead of giving them no batteries or disposables vs giving them a high end cell.

[n3eg]

• *CRAP*:
  - meaning their current Capacity is LESS THAN 80% of their 'Originally Stated Capacity' (as per SilverFox ).
  .
• NiCD/NiMH Cells:
  - meaning a SUBSTANTIAL (~40% or MORE!) of your total cell inventory.

• Your (Active *AND* Inactive) CHARGER inventory.
• Your (at least approximate) *CRAP* cell inventory (i.e. Manufacturer / Chemistry / Capacity / Age / Number of cells).
• Your current MAINTENANCE procedure(s).
• Your SUCCESS / FAILURE picture.

I never maintain crap cells. Actually, the way things are now, anything that's not a "loop" or a "hybrid" is a crap cell.

Active chargers: BC-900, Cadex 7000 series (at work), 3 Eneloop chargers, and one miscellaneous vehicle charger.

Crap cell inventory: I try to maintain that at zero. Crap NiMH cells will never improve. Deep discharge, repeated cycling, etc. usually fails.
Nicads are a different story, where a battery can sit for years and cycle 5 times back to 100%. NiMH is a use it or lose it situation. When it's gone, it's gone for good.

Maintenance: Recycle bin at 79%. So far, no hybrids or "loops" have made it there. I'm down to 4 Duracell 2500s in the regular category, which are headed there for self-discharge REAL soon now.

Success/failure: When I first got the BC-900, I had some junk Eveready 1800s which got real hot. Also, some Nexcell 1200s from the first days of NiMH melted an old trickle charger at 100 mA. No pictures, since these were my camera batteries. Never had problems with Eneloops/Duraloops/Hybrids/Kodaks - and I trickle charge them all the time.

[brted]

• Your (Active *AND* Inactive) CHARGER inventory.
• Your (at least approximate) *CRAP* cell inventory (i.e. Manufacturer / Chemistry / Capacity / Age / Number of cells).
• Your current MAINTENANCE procedure(s).
• Your SUCCESS / FAILURE picture.

I bought a MH-C9000 after reading these forums and it is my primary charger. I also have a Maha C-204F which is a good charger, even though it charges in pairs. I recently got the crazy DX universal one-cell charger, which works with NiMH's so I will count it as active also.

Inactive chargers include two Zeikos AA chargers (I got a Zeikos charger free with my Fenix L2D on eBay this year, and the batteries were crap so I asked for new ones and they sent 4 more crap batteries and another charger). Also an Energizer 1-hour charger and a Digipower charger. I may have thrown away my Rayovac Renewal charger. I also have a second C-204F with only one bay working.

The bulk of my batteries were bought in the last year (Eneloop, Duraloop, and some Rayovac 4.0), so they are not crap. After getting the C9000, I culled some batteries but still have a couple of batteries that are over 60%-80% of their nominal capacity. I have enough newer LSD cells that I won't ever need them though.

Maintenance. They mostly sit in the drawer until I need them. I leave them full, which may not be the best thing, but they are ready immediately. The non-LSD cells I will charge every few months when I remember.

Success/failure? I can live with 60% instead of 80%. 60% of a 2700 mAh battery still isn't that bad.

[Vikas Sontakke]

I am with Lynx. I have RayoVac 1hr, Sanyo MNO5 and recently purchased Thunder AC6 hobby charger. I have some old Panasonic 1600s and 2100s, many 6-7 year old white Singapore Dynacell from MCM-InOne, Infamous Energizer 2500, some Eneloops and some Duraloops. I have lost majority of the Energizers. Surprisingly, all AA Dynacells are still going strong but I have lost few AAA Dynacells. Both Rayovac and Sanyo refuse to charge them.

I have tried to measure capacity using the hobby charger but I have not mastered it yet.

I still remember how some folks here were warning about the Rayovac 1-hr charger but it is still my go to charger after so many years. It is one of the best one in terms of recognizing a full cell. If I recall correctly, it charges at around 1800mA x 4, faster than most of the newer and fancier chargers and very rarely has missed a termination for me.

I had many older Sanyo NiCd but they have all spewed out their electrolyte.

- Vikas

[Eugene]

I got rid of all my crap chargers but kept the old crap batteries. Those go in the kids toys, the little race cars or trains that take one AA and you find them underneath furniture weeks after they fully discharged the battery.

[qwertyydude]

I don't care about capacity, I just re-bin them with similar capacity cells, I only care if they can output a stable current. When they can no longer output at least 1c, in my case 2 amps on a dead short then they go in the trash can.

[MarioJP]

That's one thing I don't understand? Why is the cell pushing out less and less amps??. I did a similar test with some old cells I used to have, and the amps that the cell pushes out is weak. Whatever happen to pushing tons of current from the cell??

And what causes this strange phenomenon??. That is one thing I can't quite understand why this happens??. Another set i have are quite old but they are lsd duraloops (black top). They lose their charge to the point where its half way but not completely drained in matter of days. I don't even use these cells except in my flashlight because of this problem.

That's why I end up buying brand new duraloops to replace the old ones. But here is the thing those old cells still perform better than any alkaline cell but not good enough like a brand new duraloop.

Question is toss them or keep them??.

[Lynx_Arc]

That's one thing I don't understand? Why is the cell pushing out less and less amps??. I did a similar test with some old cells I used to have, and the amps that the cell pushes out is weak. Whatever happen to pushing tons of current from the cell??

And what causes this strange phenomenon??. That is one thing I can't quite understand why this happens??. Another set i have are quite old but they are lsd duraloops (black top). They lose their charge to the point where its half way but not completely drained in matter of days. I don't even use these cells except in my flashlight because of this problem.

That's why I end up buying brand new duraloops to replace the old ones. But here is the thing those old cells still perform better than any alkaline cell but not good enough like a brand new duraloop.

Question is toss them or keep them??.

black top LSD duracells are NOT duraloops (eneloops) but are instead what I call durabrids or rebadged rayovac hybrids. I have had two or three rayovacs I discharged too low and it damaged them to less than half capacity.

[MarioJP]

Right Durabrids lol. how low did you discharge them?

[Lynx_Arc]

Right Durabrids lol. how low did you discharge them?

one of them was below half a volt, another I think measured 0v? one was in a lantern and it discharged faster than the other 3 which were still over 1.2v.

[MarioJP]

Sounds like the weaker cell in you lantern might of went into polarity reversal.

[Lynx_Arc]

Sounds like the weaker cell in you lantern might of went into polarity reversal.

I don't remember but I think not. I have rarely seen nimh cells go into reversal but have had an alkaline AAA that went backwards 1v.....

[OpenGuy]

Please post:

• Your (Active *AND* Inactive) CHARGER inventory.
• Your (at least approximate) *CRAP* cell inventory (i.e. Manufacturer / Chemistry / Capacity / Age / Number of cells).
• Your current MAINTENANCE procedure(s).
• Your SUCCESS / FAILURE picture.

Active chargers:

Maha MH-C9000
Rayovac PS4 (at work, emergency use)
Sanyo NC-MQH01U (travel charger)

Inactive chargers:

Rayovac PS4 (at home)
Quest CH-1000
Rayovac PS1 (US)
Rayovac PS1 (French)

Active Batteries:

18 Sanyo Eneloop 2000 mAh (where did the other 2 go?)
12 Powerex Imedion 2100 mAh
4 Sanyo 2100 mAh

Inactive, known useful batteries:

4 Sanyo 2700 mAh
4 Powerex 2700 mAh
4 Duracell 2650 mAh
4 Energizer 1850 mAh
4 Rayovac 1600 mAh

Inactive, unknown state batteries:

4 Sanyo 2700 mAh
4 Energizer 1600 mAh
4 Rayovac 1600 mAh

Inactive, known rocks:

4 Sanyo 2700 mAh
2 Lenmar Non-mem pro 2300 mAh (recycled 6 others long ago)


Current maintenance procedures:

Periodic deep discharge (300 mA on MH-C9000, rest, 100 mA on MH-C9000, rest, discharge to between 0.9 and 1.0 volts on slow discharger (battery connected in series with rectifier and 10 ohm resistor), terminal clean, fast charge (1000 mA to 1400 mA depending on capacity), rest, and a few hours of slow charge (using "break-in" mode on MH-C9000 and removing batteries after 2 to 3 hours).

Results:

Doing it once or twice perks them up a bit, but capacities slowly declining.

Newer (non-LSD?) cells will eventually develop rapid self discharge.

[jhellwig]

I don't care about capacity, I just re-bin them with similar capacity cells, I only care if they can output a stable current. When they can no longer output at least 1c, in my case 2 amps on a dead short then they go in the trash can.

Is that how you are really testing cells?

[Turbo DV8]

Originally Posted by qwertyydude
When they can no longer output at least 1c, in my case 2 amps on a dead short then they go in the trash can.

Is that how you are really testing cells?

"Tough Love."

[LuxLuthor]

I like Eneloops.

[paulr]

Life is too short for crap. I recycled a bunch of crap cells but find I still have a few. If you want 'em enough to send a few bucks for postage, PM me.

[s0lar]

Since I have made a MAX712 based charger as part of a school project, I am checking this forum a lot.
I trew away 20 cells and still have 50 left or so.
Most of them are neglected, some are new and in better shape.
Some suffer from voltage deprevation, how can I best cure them?
One is a sanyo 2300.
I have done 5 cycles at 700mA charge and 300 to 1000mA discharge.
It starts out at 0.92-0.95V and climbs up to 1.0-1.1V after 15-45min. I still get 1700mA out of it in the end but I don't trust the cell if used as part of a pair.

[TakeTheActive]

Since I have made a MAX712 based charger as part of a school project...

You mentioned your school project a few times - if you haven't already, please post an overview (or a LINK).

...I am checking this forum a lot...

I noticed that you've been going through the Archives. As one who personally spent SEVERAL hours per day for SEVERAL MONTHS doing just that, I commend you for 'Hours Well Spent'.

...I trew away 20 cells and still have 50 left or so.
Most of them are neglected, some are new and in better shape.
Some suffer from voltage deprevation, how can I best cure them?...

Since you have a 'Maha MH-C900 clone' (which I looked up, posted LINKs about and was chastised' for going OT here: Duracell 2650mAh NiMH, test result ), the information in Post #2 above and in my Sig Line LINKs regarding Impedance Check Voltage and Deep Discharge is where you should begin.

Too bad you already RECYCLED 20 cells - it would have been interesting to know their ICV's and CAPACITY.

...One is a sanyo 2300.
I have done 5 cycles at 700mA charge and 300 to 1000mA discharge...

IME, Deep Discharges and Forming Charges yield better results from *CRAP* cells than repeated CYCLES.

...
It starts out at 0.92-0.95V and climbs up to 1.0-1.1V after 15-45min. I still get 1700mA out of it in the end but I don't trust the cell if used as part of a pair.

You also touched upon this idea 2 days ago:

...Would it be possible that the cell reaches the termination point (1.47V) faster and faster as it has undergone cycles?... ...As the cell ages, it sure is possible that it reacts different to a charging current, making it increase its voltage faster...

and from my 'Non-Engineer / Non-Scientist' point-of-view, I attribute the faster voltage rise to 'Spent Chemicals' and/or 'Large Crystals' (blocking access to potentially useful chemicals). For #1, you're SOL; but for #2, you can 'Experiment'.

...I would like to do these test again with a different charger, one that does not terminate at 1.47V.
I would discharge in the maha after 1h rest.

If the cells are HOT (~120°F) when your PRO 1 Geniux (C9000) terminates @ 1.47VDC, I personally wouldn't switch to another charger with a higher MAX VOLTAGE - you'd only COOK the cells further. I would investigate their Internal Resistance (there are MANY methods posted) and see if Deep Discharges and Forming Charges have any effect.

[s0lar]

I still have some of the cells ready to be trown away, so I will check the Impedance with my charger. The bag with crap is still sitting at home.
I find 0.1C forming charges so slow, so that's the last thing I wanna try. I will create a topic with my project later today.
Thanks for the answers.

[s0lar]

I just tried 3 crappy cells.
One Top Craft 2300mA gave 1.58, I trew it away because my other charger missed termination a couple of times with that cell.
Then 2 sanyo 2300.
In one I still believe.
It gave 2.68, the other gave 2.71 before both going to high a second or 2 later.
I charge them with my dumb charger and will test further after deep discharges.

[Lilien]

I voted with "YES", because I used over months some AAA cells in my
mouse, that were rejected by my MAHA C-9000 charger (>2,5V "HIGH"),
but otherwise still worked fine. Actually I had to keep my old crappy
charger to be able to still charge these "crap" cells.
I just bought an new mouse (1xAA), so maybe it's time to say goodbye.

Regards, Juergen

[TakeTheActive]

I just tried 3 crappy cells.
One Top Craft 2300mA gave 1.58, I trew it away because my other charger missed termination a couple of times with that cell...

An ICV of 1.58VDC is a nice, low number - typical of VIBRANT cells. What's its measured CAPACITY? A 100mA DISCHARGE followed by a LT 2300mAh (I'd start with 1800mAh) BREAK-IN (or 2 or 3) might 'perk it up'. What's the MAKE & MODEL of the 'other' charger?

Then 2 sanyo 2300.
In one I still believe.
It gave 2.68, the other gave 2.71 before both going to high a second or 2 later.
I charge them with my dumb charger and will test further after deep discharges.

Those 2 are pretty deep into HIGH territory (over ~2.10VDC) . I have a few DUMB 140mA and 150mA series (2 cells per channel) AAA/AA chargers that I use for cells like that. Also, my TIMED Sears DieHard 7-Hour Charger switches to 45mA/80mA/100mA/100mA for AAA/AA/C/D after 7 hours so if I don't unplug it, I can utilize those low Charge Rates too. What's the mA of YOUR DUMB charger?

"High Capacity / non-LSD / Neglected" could mean separator damage. But, if their Self-Discharge isn't too bad, they could still deliver plenty of their Capacity in clocks, thermometers, remotes, etc...

[Battery Guy]

I love testing, comparing performance, abusing, misusing and otherwise getting as much data as possible out of batteries....

BUT...

This testing takes a lot of time to do right, so when I do it I use good cells that have a known history. Using "crap" cells would just be a waste of time. Just like they taught you in computer programming class: garbage in equals garbage out. (Ok, give me a break...the last computer programming class I took was FORTRAN).

Anyway, life is too short and I am too busy to be messing around with crappy old batteries.

Cheers,
Battery Guy

[s0lar]

My dumb charger is a GP Powerbank 4, charge rate is 180mA for AA and 80mA for AAA.
Other chargers:
Memorex MRX4000: smart (-dV, max V, T and timer), 700mA AA, 350mA AAA.
Top Craft TCU-810 (no info available anywhere...): smart (-dV, max T, charges only per pair in series and 9V!), 800mA AA, 300mA AAA, 13mA 9V.
Memorex Pro 1 Geniux (MAHA 9000)
Just bought:GP 30min U-Smart: smart (-dV, timer, very picky!), 3400mA AA and 1700mA AAA and that's effective charge, I tested!
now recently a BC 700 also to do more discharge tests at the same time and charge my lower capacity AA and all AAA cells.
The GP 30min came with 2500 cells but one missed termination is 2nd charge...
It was still a good deal, I paid $20 for the charger and 4 2500 cells.