I learned something new about the C9000 today

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?

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

lctorana said:

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

Click to expand...

or duracell 2650, about 4 days

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.

Mr Happy said:

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?

Click to expand...

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.

Click to expand...

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

viorel00 said:

or duracell 2650, about 4 days

Click to expand...

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

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.

Mr Happy said:

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...

Click to expand...

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!

distrbd said:

...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:

Click to expand...

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!

TakeTheActive said:

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

Click to expand...

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

davidefromitaly said:

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

Click to expand...

Must be LSD versions
Norm

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

Black Rose said:

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

Click to expand...

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.

Norm said:

Must be LSD versions
Norm

Click to expand...

nope... they are standard 2650 nimh

tested with a RC charger/discharger

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.