Received my new Maha MH-C9000

[DiverDn]

After reading a lot of threads on batteries, chargers and testers, I bought the Maha MH-C9000 and four, four packs of AA eneloops.

Like I mentioned I have read a ton of information from here and Battery University and I am starting to understand some of it, but not everything I throw against the wall is sticking. So I unpacked the new charger and thought I would try to learn how to use it on old batteries before I put the eneloops in it and do something to mess them up.

I dug out some old (8-10 years) Powerex 1700 mAh batteries and did a refresh cycle on them. Here is what they ended up at:

#1 1085 mAh 1.39v
#2 1405 mAh 1.43v
#3 1242 mAh 1.41v
#4 did not do anything

I am now running them through a Break-In cycle to see what happens.

Again I am sorry about asking questions that I am sure I read the answer too several times, but it did not stick with me for some reason.

• Why did the charge end at a higher voltage than the 1.2v listed on the battery?
• During the Break-In cycle the charger is displaying a mAh rating of around 400 and a mA rating. What does this mean and what is the difference between the two?

That is all for now, thanks for being understanding of my lack of knowledge.
John

 

[Niconical]

Q1, voltage:
Nimh are listed as 1.2v, but they actually have a resting voltage (when fully charged) of up to around 1.48v. The 1.2v refers to the voltage when it is under load, in use.

Q2, Break-in display:
When you do the break in you set each slot to the expected capacity of the battery, in this case, 1700mah for each of the old Powerex. The break in cycle does a charge for 16 hours at 1/10th of that (written as 0.1C, or for those batts, 170ma), then a discharge at 1/5th of that (0.2C, for those batts 340ma), then a full charge again at 0.1C. The Display will cycle between values for each slot, so the ma shoud read 170 on the charges, 340 on the discharge. The mah reading will be cumulative, how much has so far been put in or taken out. The only number that really matters is the capacity discharged when that is complete.

 

[45/70]

In addition to the excellent answers Niconical responded with, I'll point out that when you measure the voltage of a NiMH or NiCd cell that has been sitting at rest for a few minutes, and the voltage is 1.20 Volt or below, the cell is "dead" for all practical purposes, and should be recharged.

While measuring NiMH and NiCd voltage is not a reliable means to determine a cell's capacity, usually, a cell that has some amount of usable charge left in it, will read a voltage of 1.30 Volts or above.

Dave

 

[TakeTheActive]

...I bought the Maha MH-C9000 and four, four packs of AA eneloops...

...I am starting to understand some of it, but not everything I throw against the wall is sticking...

CLICK on my Green Sig Line LINK and read the articles in the first section. Those were my 'Newbie' questions from when I began visiting the CPF 'Batteries Included' Forum at least once daily around Thanksgiving 2008.

...I dug out some old (8-10 years) Powerex 1700 mAh batteries and did a refresh cycle on them Here is what they ended up at:

1. What was the Charge Rate setting?
2. What was the Discharge Rate setting?

Folks that post "I did a REFRESH...", "I CYCLEd my cells 10 times...", "I did a BREAK-IN..." aren't giving the 'Full Picture'.

...
#1 1085 mAh 1.39v
#2 1405 mAh 1.43v
#3 1242 mAh 1.41v
#4 did not do anything

Those are what one of our Guru Moderators would call *CRAP* cells (well, #2 @ 82% is ALMOST there).

In my Sig Line LINKs, read about Cell Recovery. You can 'experiment' with those Powerex cells.

What's their C9000 Impedance Check Voltage?

 

[DiverDn]

CLICK on my Green Sig Line LINK and read the articles in the first section. Those were my 'Newbie' questions from when I began visiting the CPF 'Batteries Included' Forum at least once daily around Thanksgiving 2008.

I have read most of them and that is the point I was trying to make, I understand part of it, but most of it does not sink in. I guess I will need to read it again.

1. What was the Charge Rate setting?
2. What was the Discharge Rate setting?

Folks that post "I did a REFRESH...", "I CYCLEd my cells 10 times...", "I did a BREAK-IN..." aren't giving the 'Full Picture'.

Charge rate was set at 500
discharge rate was also set at 500

Those are what one of our Guru Moderators would call *CRAP* cells (well, #2 @ 82% is ALMOST there).

That was the main reason that I started with these cells. It doesn't matter if they are toasted.

In my Sig Line LINKs, read about Cell Recovery. You can 'experiment' with those Powerex cells.

What's their C9000 Impedance Check Voltage? Huh! I must have slept through that part of the lesson.