I learned something new about the C9000 today

[Mr Happy]

I came across some NiMH batteries that had been in storage for so long that they read 0 mV on a voltmeter. I thought the meter was not working for a minute, but sure enough the cells really were flat lining.

The cells might be a lost cause, but I put them in the C9000 for a break-in cycle to see what comes out of it. What I found was the C9000 didn't try to start charging them right away. Instead it tickled them with a 125 mA charge current until the voltage went up. Only then did it do the impedance test and switch to the normal C/10 break-in charge.

That's something new I didn't know the C9000 would do.

Now I wonder how long batteries have to be sitting on the shelf before the voltage gets down to zero?

 

[lctorana]

If they're Energizer 2500's, about a week.

 

[viorel00]

If they're Energizer 2500's, about a week.

or duracell 2650, about 4 days

 

[shobhitk]

good to hear that mr happy. btw i had previously read somewhere that when the voltage drops below 0.5v then the C9000 first trickle charges it to bring it to 1.00 volts and then resumes with the set mode.

 

[Egsise]

I came across some NiMH batteries that had been in storage for so long that they read 0 mV on a voltmeter. I thought the meter was not working for a minute, but sure enough the cells really were flat lining.

The cells might be a lost cause, but I put them in the C9000 for a break-in cycle to see what comes out of it. What I found was the C9000 didn't try to start charging them right away. Instead it tickled them with a C/20 charge current until the voltage went up. Only then did it do the impedance test and switch to the normal C/10 break-in charge.

That's something new I didn't know the C9000 would do.

Now I wonder how long batteries have to be sitting on the shelf before the voltage gets down to zero?

Sanyo MQH02 4AA/2AAA charger
I just bought 3 of these chargers, bundled with 2500mAh rechargeables.
Price was 10€/charger, these were sold with discount because the cells were ~3 years old.
Model number was MQH02-E-4-2500.
Batteries have manufacturing date 05 06 1G, 2005 june.
Cell voltages were 0.908 - 0.917.
Charger manufacturing date J H 0, 2005 august 30.

I guess it depends a lot what batteries are left in the shelf...

 

[davidefromitaly]

or duracell 2650, about 4 days

sorry but my duracell 2650 after 30 days still retain around 60% of the charge. maybe you have damaged cells

 

[distrbd]

Mr Happy Thank you for sharing what you just found out,I enjoy reading all your post and find them interesting and informative.

As a matter of fact I had 3 AA batteries which did not charge on C-9000(it kept displaying HIGH)but remembered in one of your posts you mentioned in a case like this it's a good idea to charge these cells in their own charger they came with first, then discharge/charge in C-9000.

Well I did exactly that and was pleasantly surprise to see them being revived in my c-9000 so now thanks to you I have 3 extra batteries which were almost considered crap.:thumbsup:
Keep it coming.
Ken.

 

[TakeTheActive]

I came across some NiMH batteries that had been in storage for so long that they read 0 mV on a voltmeter...


...What I found was the C9000 didn't try to start charging them right away. Instead it tickled them with a C/20 charge current until the voltage went up. Only then did it do the impedance test and switch to the normal C/10 break-in charge...

IIRC, in the 2 or 3 times this has hapened to me, it's consistently been 125mA, not C/20. A case where the Maha assists the La Crosse in return for the La Crosse assisting the Maha:

• When a cell's Voltage is too low for the BC-900 to accept it (i.e. 'Null'), 'warm it up' in the C9000.
  .
• When a cell's Internal Resistance is too high for the C9000 to accept it (i.e. 'HIGH'), 'warm it up' in the BC-900.

Owning BOTH is beneficial!

 

[TakeTheActive]

...As a matter of fact I had 3 AA batteries which did not charge on C-9000 (it kept displaying HIGH) but remembered in one of your posts you mentioned in a case like this it's a good idea to charge these cells in their own charger they came with first, then discharge/charge in C-9000.

Well I did exactly that and was pleasantly surprise to see them being revived in my c-9000 so now thanks to you I have 3 extra batteries which were almost considered crap.:thumbsup:

Don't get too excited!

IME, those cells are STILL *CRAP* - you just 'tricked' the C9000 into accepting them by 'warming them up', thus lowering their Internal Resistance, thus allowing them to pass the 'C9000 Impedance Check'. I'd guess that their COLD 'C9000 Impedance Check Voltage' is somewhere around 2.20VDC and their Capacity @ 0.2C is LE 80%.

• Measuring Maha MH-C9000 Impedance Check Voltage
  .
• Interpreting Maha MH-C9000 Impedance Check Voltage

Please report back!

 

[Mr Happy]

IIRC, in the 2 or 3 times this has hapened to me, it's consistently been 125mA, not C/20.

That's interesting. In this case the entered capacity was 2500 mA, so C/20 is 125 mA. Coincidence? First post updated.

 

[Norm]

sorry but my duracell 2650 after 30 days still retain around 60% of the charge. maybe you have damaged cells

Must be LSD versions
Norm

 

[Black Rose]

I wonder if I could use this discovery to help condition my NiCd cells that have been abused all summer in solar lights.

 

[Mr Happy]

I wonder if I could use this discovery to help condition my NiCd cells that have been abused all summer in solar lights.

It might not help a lot. It seemed like the C9000 switched over to proper charging as soon as the voltage got above 0.1.

 

[davidefromitaly]

Must be LSD versions
Norm

nope... they are standard 2650 nimh

tested with a RC charger/discharger

 

[slappomatt]

I'm pretty sure they where being sarcastic. I have those same Duracell 2650's and they work fine. but they do loose charge over time.