MH-C9000 Break in eneloops 2300mAh?!

[Ohmic]

For the first time I have used the 'break in' feature on my MH C9000.

This was done with 4 AA eneloop cells of recent manufacture and which have not seen heavy use yet.

I set the cell capacity to 2000mAh on the charger and proceeded with the break in.

I took the cells out of the charger when 2300mAh (approximately) had been put into the cells. Voltage was 1.49V. The charger indicated that the 'charge' process was still continuing, no cell displayed 'done' yet.

Cells were only very slightly warm to the touch. Barely above room temp.

To me this seemed concerning, hence my decision to end the process.

What are people's thoughts on this? Did the charger make an error or did something go wrong?

Have these cells been over-chargered? I thought the charger would terminate at 1.47V, In this mode it does not seem so.

 

[Mr Happy]

On a break-in the cell is supposed to be charged at 0.1C for 16 hours, so in the case of Eneloops the C9000 is supposed to put 2000 x 1.6 = 3200 mAh of charge into the cell. As it happens the C9000 has a quirk and it only puts 2880 mAh into the cell, but this is probably close enough to make no difference.

People usually talk about overcharging as a bad thing, but paradoxically, when conditioning NiMH batteries overcharging them in this way is a good thing.

Every rule has its exceptions, and this is one of them.

 

[TorchBoy]

The Eneloops weren't fully charged. For a Break-In the charger uses a 0.1C charge for 16 hours. This puts a nominal 1.6 times the capacity into the cells. In practice it's more like 1.44 times the capacity because the thing has a 90% duty cycle. It keeps charging for the 16 hours without checking for the normal termination signals like stopping at 1.47 V.

Edit: Ha ha, I type slower than Mr Happy.

 

[Niconical]

Put in the 4 batts, select break in, enter 2000 mah for each slot, come back in 39 hours.

The only number that matters is the one at the end, after 39 hours, everything else is just the C9000 getting on with it.

 

[Ohmic]

Thanks very much for the replies:twothumbs

Next time I will simply leave the cells to complete the break in.

Because this is the first time I have run it, I decided to be over-cautious.

Can't see this feature being used too much in all honesty anyway

 

[brted]

My understanding is that the charge rate is so low that it doesn't hurt the battery to be overcharged in a break-in cycle. Although I always discharge the battery before doing a break-in, supposedly it safe to do it even if it already has charge left in it.

 

[45/70]

As brted pointed out, a lot of people discharge the cells before running a "Break-In". I do this as well.

The advantage to discharging the cells first, is that by adding one fairly simple step (although it does add a bit to the total time) you are accomplishing two maintenance items.

The "Break-In" is useful, as it redistributes the chemicals more evenly throughout the cell, usually providing better performance. A slow discharge before doing the "Break-In" helps to break down crystalline anomalies within the cells internal structure. This can help performance by allowing the cell to deliver higher voltage under load. The slow discharge is particularly helpful with non LSD cells, but can be beneficial to LSD cells as well.

Any NiMH (or NiCd) cell that is used infrequently, or perhaps been in storage for a while, will benefit from both of these procedures. With cells that are charged and discharged regularly, the advantages are somewhat less, however even these cell's performance can be improved some, if run through at least a "Break-In" once, or twice a year. If cells are frequently "topped off" rather than nearly fully discharged on a regular basis, I've seen better performance doing a slow discharge, followed by the normally recommended "break-In" cycle every 25-30 cycles.

Dave

 

[TakeTheActive]

...Can't see this feature being used too much in all honesty anyway

Why? :thinking:

 

[Russel]

Charging NiMH cells at higher charge rates is more efficienct.

In other words, if you charge 2300mAh cells at 1C or 2.3A it will take aproximately 1.1 hours to charge, or 110% of the capacity. If you charge the same 2300mAh cells at C/10 or 230mAh it will take about 15 hours to charge the cells or 150% of the capacity because the charge efficiency is lower at lower charge rates.

I have learned that for normal charging .5C to 1C is the best charge rate for NiMH AA and AAA cells. When you first charge the cells, or if the cells have been unused for over a year, then it is recommended to perform a forming charge. A forming charge is .1C for about 14 to 16 hours. The Maha MH-C9000 "Break-in" mode is a 16 hour forming charge. Charging NiMH cells at a low rate for essentially a long time occasionally, helps to keep the cells vibrant. The C-9000 manual recommends a break-in charge every 30 cycles. I would add that it is a good idea to perform a discharge to .9 volts per cell then a forming (break-in) charge when the cells are new and just taken out of the package. Then once a year or every 30 cycles, whichever comes first. Charging at a conventional .5 to 1C for the normal everyday charging.

One other aspect of the .1C 14 to 16 hour charge is dealing with battery packs. If you are charging a permanent pack of four cells, for example, you need to be carefull of a couple of things.

First, you want to be especially carefull not to discharge the pack lower that .9 volts per cell, in the case of a 4 cell NiMH pack, 3.6V for the pack. The reason for this is that if the cells voltage aren't in balance and you discharge the pack too low, you can "reverse charge" the lowest cell, which is distructive. (The lowest cell can reach 0 volts before the other cells and actually begin charging in reverse.)

The other thing to be carefull of is heat and overcharging the highest cell in a pack. So, the normal method of charging a multi-cell NiMH pack is the .1C charge for 14 to 16 hours. It will bring all the cells up to full charge and if one or more of the cells has more of a charge to begin with the lower charged cells will catch up by the time the 14 to 16 hours are up. Overcharging at .1C isn't harmfull for NiMH cells as long as the charge time is limited to 16 hours, and charging at a low rate reduces the amount of heat generated. A battery pack usually can't dissipate heat as fast as individual cells.

 

[TakeTheActive]

I HATE PACKS!

Charging NiMH cells at higher charge rates is more efficienct.

In other words, if you charge 2300mAh cells at 1C or 2.3A it will take aproximately 1.1 hours to charge, or 110% of the capacity. If you charge the same 2300mAh cells at C/10 or 230mAh it will take about 15 hours to charge the cells or 150% of the capacity because the charge efficiency is lower at lower charge rates...

Although I agree that the OP's choice in title is somewhat confusing, I believe that the major concern / question here is "Why did my 2000mAh Eneloops take in over 2300mAh during a 2000mA BREAK-IN?"

(Newbie with lack of understanding of rechargeable battery theory.)

...One other aspect of the .1C 14 to 16 hour charge is dealing with battery packs. If you are charging a permanent pack of four cells, for example, you need to be carefull of a couple of things.

First, you want to be especially carefull not to discharge the pack lower that .9 volts per cell, in the case of a 4 cell NiMH pack, 3.6V for the pack. The reason for this is that if the cells voltage aren't in balance and you discharge the pack too low, you can "reverse charge" the lowest cell, which is distructive. (The lowest cell can reach 0 volts before the other cells and actually begin charging in reverse.)...

I HATE PACKS!

That said, IMO, 0.9VDC per cell is too low - you could have 1.2+1.2+1.2+0.0=3.6VDC. The more I read at CPF, the more I tend to favor 1.1VDC per cell ('maybe' 1.0 now-and-then). Thus, 4.4VDC will allow for 1.2+1.2+1.2+0.8=4.4VDC (not bad at all for Cell #4),while 1.2+1.2+1.2+0.4=4.0VDC is bad, but not ZERO or REVERSE.

 

[Russel]

Re: I HATE PACKS!

...That said, IMO, 0.9VDC per cell is too low - you could have 1.2+1.2+1.2+0.0=3.6VDC. The more I read at CPF, the more I tend to favor 1.1VDC per cell ('maybe' 1.0 now-and-then). Thus, 4.4VDC will allow for 1.2+1.2+1.2+0.8=4.4VDC (not bad at all for Cell #4),while 1.2+1.2+1.2+0.4=4.0VDC is bad, but not ZERO or REVERSE.

Good point!

If the pack has been properly cared for and charged at .1C for 14 to 16 hours (cells balanced) and isn't displaying any signs of major degradation (low voltage or high voltage drop under a load), discharge to .9V per cell should be OK. But, that is a lot of ifs...

 

[TorchBoy]

Why? :thinking:

I believe he was referring to his own use of the feature.

 

[was.lost.but.now.found]

Re: I HATE PACKS!

Although I agree that the OP's choice in title is somewhat confusing, I believe that the major concern / question here is "Why did my 2000mAh Eneloops take in over 2300mAh during a 2000mA BREAK-IN?"

(Newbie with lack of understanding of rechargeable battery theory.)


I HATE PACKS!

That said, IMO, 0.9VDC per cell is too low - you could have 1.2+1.2+1.2+0.0=3.6VDC. The more I read at CPF, the more I tend to favor 1.1VDC per cell ('maybe' 1.0 now-and-then). Thus, 4.4VDC will allow for 1.2+1.2+1.2+0.8=4.4VDC (not bad at all for Cell #4),while 1.2+1.2+1.2+0.4=4.0VDC is bad, but not ZERO or REVERSE.

Thankfully, we're only discussing killing cells and not detonating pipe bombs.

 

[Ohmic]

I believe he was referring to his own use of the feature.

Correct.

I regularly charge/discharge my cells and they seem to be performing beautifully without being 'broken in'. I used the feature out of curiosity.

The main disadvantage is the large amount of time it takes to perform break in.

Despite this, I have still learned a great deal about the break-in process because of the information people have posted in this thread, so here's a big thanks again:thumbsup:

 

[cckw]

Why? :thinking:

TakeTheActive is sometimes covert in spreading wisdom. It is like he only wants to educate thinkers. Click the links in his sig line and read on.

Since I'm nicer then TTA I'll spoon feed you a little. the break-in mode is a 2 day process, it is a series of charge-discharge, that acts kinda like stretching a balloon with your hands a few times before blowing it up. Or to look at it another way, and this is what you are missing, it is something like defragmenting your hard drive. Should be done every now and then. Those who never do it don't know they are the cause of future problems.

Oh, and the apparent overcharge is part of that process. It is how much it stuffed in on that leg of the process, you don't have that in usable juice just because it shows on the display.

 

[TakeTheActive]

I believe he was referring to his own use of the feature.

You're re-stating the obvious because...? :thinking:

Thankfully, we're only discussing killing cells and not detonating pipe bombs.

I don't understand how your reply, in ANY which way or manner, relates to this thread.

Sarcasm is not appreciated.

Correct.

I regularly charge/discharge my cells and they seem to be performing beautifully without being 'broken in'. I used the feature out of curiosity...

It's like (back in the OLD days!) you bought a car and SPECIFICALLY ordered the air-conditioning option, but you prefer to drive with the windows open (or in a convertible with the top down).

BREAK-IN is one of the 'highly prized' (NOT AVAILABLE on many other chargers) features of the C9000. If you don't 'value it', perhaps you could have saved some money and purchased a different charger.

cckw stated it rather well (re: 'Thinkers').

To expand:

1. I *LOVE* to share my knowledge with others. :twothumbs
   (i.e. I *LOVE* to GOOGLE! I use GOOGLE a LOT!! When I explain things, my wife says I go into TOO MUCH DETAIL!!!)
   .
2. I *HATE* to repeat things.
   (i.e. If I do something once, I really dislike doing the IDENTICAL thing again. Like if you just spent an hour composing a reply and then LOST IT! Re-composing that reply is just about impossible for me - i.e. no interest.)
   .
3. I *HATE* to waste things.
   (i.e. *CRAP* cells, old pencils, 'scrap' lumber, analog NTSC devices, HDD space on forums...)
   .
4. I *DISLIKE* lazy, self-centered folks.
   (i.e. I used to reply 'SEARCH' to those who 'POST without even reading the STICKYs / FAQs', but now I just quietly 'move along'... )
   .
5. Yada, Yada, Yada - who cares... :tired:

TakeTheActive is sometimes covert in spreading wisdom. It is like he only wants to educate thinkers. Click the links in his sig line and read on...

So true!

Show me the SLIGHTEST bit of initiative and I'll devote HOURS to helping you understand something - just look at the LENGTH and COMPLEXITY of my posts.

Maybe more 'Indirect' (#2) than 'Covert' though... :thinking:

If every Newbie read *ALL* of my Sig Line LINKs, I wonder how many Newbie questions would be re-posted...

(Well, that was certainly fun! I got to re-visit my OVER-formatted style (too much BOLD / COLOR / SMILIES / etc... - Back to the program now...)

 

[Ohmic]

It's like (back in the OLD days!) you bought a car and SPECIFICALLY ordered the air-conditioning option, but you prefer to drive with the windows open (or in a convertible with the top down).

BREAK-IN is one of the 'highly prized' (NOT AVAILABLE on many other chargers) features of the C9000. If you don't 'value it', perhaps you could have saved some money and purchased a different charger.

The break-in feature was not a significant factor in choosing this charger. It's always there if I decide to use it though, which is good, but there are other features I valued much higher, which thankfully the C9000 offers,

they are;

Good build quality
Reputable and proven product support and customer satisfaction
Ability to display parameters such as Cell voltage, current, capacity, etc

I understand your point TTA, I will search harder before starting a new thread topic.

 

[TorchBoy]

Sarcasm is not appreciated.

You are now referring to your own disappreciation of that feature.

... just look at the LENGTH and COMPLEXITY of my posts.

Including highly developed (although probably unnecessary) use of colour - which I actually only realised because of the post you so disapproved of. :thumbsup:

 

[jimbo231]

Sorry to bring up an old thread but new eneloops are partially charged so I was wondering if the break in is .1C charge out of the pack or is that after I discharge the cell first?

 

[Shadowww]

It seems to be general consensus that discharging cells before break-in is better for them (and yields 50-100mAh more after first break-in).