Did I get missed terminations?

[e_dogg]

I just received my Maha C9000 yesterday and gave 4 of my discharged AA Durabrids a whirl in the "Refresh and Analyze" mode. I set it to 700mA charge (should I have left this at 1000mA?) and left the default 500mA discharge for each cell.

After a few hours, it was bedtime. Two of the cells were and the other 2 were still going. I had told my wife about the BC-900 meltdowns so she's paranoid about the C9000 and made me unplug it. I'm not sure if the 2 that were running should have terminated by then or if they still needed the charge.

Cell 1 - 2213, 1.45v - missed termination?
Cell 2 - 2057, 1.44v - terminated by itself
Cell 3 - 2210, 1.44v - missed termination?
Cell 4 - 1925, 1.46v - terminated by itself

Also, a quick question about the "C" designation to make sure I understand it right. My Durabrids & Duraloops are 2000mAh so 1C would be 2000mA and .5C would be 1000mA, correct?

I'm now running a set of AAA Durabrids through it at 500mA charge and 500mA discharge. I hope that's an acceptable rate...

Sorry for the noob-ish question. I'm a little overwhelmed by the information here and trying to wrap my brain around it all.

[shark_za]

You are correct on the charge rates so why not stick to them?

0.5C is suggested as the lowest to use so that 1000mA.

You are charging at 500mA (0.25C) and you could miss a termination signal.

The automatic 1000mA charge of the C9000 is pretty much the simplest way to charge cells.
Pop them in and do nothing else.

[Black Rose]

You are charging at 500mA (0.25C) and you could miss a termination signal.

He's using 500 mA on AAA cells, no problem there.

As for cells 1 and 3, after a couple of hours at 700 mA, I don't think they had sufficient time to complete the charge.
At 700 mA, they would need at least 3 hours to reach a point where they should terminate.

[e_dogg]

You are correct on the charge rates so why not stick to them?

0.5C is suggested as the lowest to use so that 1000mA.

You are charging at 500mA (0.25C) and you could miss a termination signal.

The automatic 1000mA charge of the C9000 is pretty much the simplest way to charge cells.
Pop them in and do nothing else.

I want to try matching my cells so I want to run a "refresh and analyze" on all of them to get them into pairs. I'm still learning about charge rates so I wanted to make sure that what I was doing sounded good. After matching them into pairs, I'll use the regular default "stick it in and charge" method for regular recharging.

He's using 500 mA on AAA cells, no problem there.

As for cells 1 and 3, after a couple of hours at 700 mA, I don't think they had sufficient time to complete the charge.
At 700 mA, they would need at least 3 hours to reach a point where they should terminate.

Thanks for the confirmation. I had a feeling that cells 1 and 3 just might not have had enough time to finish before unplugging them. But when I saw the mAh was ~200 (10%) over the rated mAh, I was a little concerned. It sounds like these could just be a couple of really good cells, then.

I'll start using the default 1000mA charge rate for my AAs and use 500mA for my AAAs.

[Mr Happy]

Most high quality cells will get above 1.47 V when charging. However, Rayovac Hybrids may be marginal in this regard and may only just reach 1.47 at the peak. If they do reach 1.47 V the C9000 will terminate the charge on max voltage very quickly. If they do not reach 1.47 V the C9000 will terminate on another criterion like minus delta-V, in which case it could take rather longer before they finish.

My guess is that your cells would eventually have terminated, but you didn't give them quite enough time.

[PeAK]

I
Thanks for the confirmation. I had a feeling that cells 1 and 3 just might not have had enough time to finish before unplugging them. But when I saw the mAh was ~200 (10%) over the rated mAh, I was a little concerned. It sounds like these could just be a couple of really good cells, then.

I'll start using the default 1000mA charge rate for my AAs and use 500mA for my AAAs.

The following is from the page 2 of the Maha manual:

Refresh & Analyze Mode

• First recharges the battery, rest for one hour, discharge, rest, then
recharges again. Charging and discharging rates are programmable.
• Reports the discharge capacity at the end of the cycle.
• Useful when the battery capacity needs to be determined. Also
useful for battery with degraded performance.
• Recommended once every ten cycles for NiMH batteries.

On page 4:

Note the charging capacity is usually higher than the actual capacity of the battery owing to some energy lost as heat.

Charging capacity cannot be used to judge the performance the battery. Instead, it can only be used to determine the progress of the charger. It is normal for this number to exceed the actual capacity by as much as 20-30%.

I gather the batteries that did not finish up were reporting the "charge capacity" to that point. The ones that finished were reporting the "discharge/actual capacity".

Note that although there are references to greater than 0.5C charge rates (i.e. 1000mA), the Maha's algorithim looks to see if the battery exceeds 1.47 volts and this allows charging at much lower rates where no negative delta-V signal might be generated (True of most batteries). If there is such a signal (below 1.47), then the Maha charger will stop charge. The only downside is that a top-up charge is required for an hour as 1.47 is somewhat conservative. So feel free to charge at 200mA with a C9000!

[jhellwig]

Cell 1 - 2213, 1.45v - missed termination?
Cell 2 - 2057, 1.44v - terminated by itself
Cell 3 - 2210, 1.44v - missed termination?
Cell 4 - 1925, 1.46v - terminated by itself

Cells 2 and 4 actually completed their refresh cycle and were displaying the mAh from the discharge portion of the cycle. 1 and 4 were probably still in the final charge portion of the refresh cycle. The mah you were seeing is what actually went into the cell and is no indication of a missed charge. More mAh goes into the cell to charge it than you can get out of the cell while using it.

If those cells got into the 2500mAh range on the charge cycle them I might worry about them having missed termination.

The c9000 stops charge based on -dv, temperature rise or a high enough voltage. It could miss the termination but will probably stop before anything bad happens due to the voltage being high.

[vali]

If you were reading the charged capacity and not the discharged one, then all is fine. Some of the energy that were put onto the cell is transformed in heat and for that reason you need more mAh to fully charge it. Of course, too much energy and you are overcharging the cell. About 10% over the nominal capacity should be fine as long as the battery were completely discharged. If you were reading something like 2600 mAh or so, then you were missing terminations and damaging your cells.

New cells or properly maintained will need a lower charge rate to develop a -dV strong enough to the C9000. We tend to stay in the safe zone and thats the reason why we recommend 0.5C at minimum (and even that is not enough in crap cells), because a missed termination is worse than charging at higher currents.

Oops: Peak beat me in replying speed. "About 10% over the nominal capacity" can be 20% as his post said (and the Maha docs).

[WDG]

If cells 1 & 3 were still charging when you noted those numbers, I'm guessing you were seeing the amount of charge put into them, rather than their capacity. This sometimes throws people off with the MH-C9000. The charge put in will always be larger than actual capacity. The display then switches to capacity after it's done.

If you're wanting to match the cells, I'd recommend that doing a break-in will give you more accurate capacity numbers on these cells than R&A. I'd encourage you to discharge first. I mostly use R&A for maintenance cycling and to check for possible problem cells.

[e_dogg]

Thanks for the info, everyone! This is starting to make more sense now. I've read the manual and various threads here and was still a little confused.

There are a whole bunch of Duraloops/Durabrids in line for R&A but they're still charged. I figure I'll R&A them as I use them rather than using the charger to discharge them.

I do have some 4-5 year old 2700 mAh Panasonic NiMH batteries that seem to still work ok. Not quite as good as my newer Duraloops/Durabrids but still acceptable. Would they benefit from a break-in cycle? Or would an R&A do the trick?

Also, are my wife's melt-down concerns warranted (I know, I shouldn't have told her about the BC-900 in the first place )? The manual says the break-in cycle takes something like 30 hours which means that the charger would have to run overnight and while I'm out of the house.

[Mr Happy]

For a very old cell in unknown condition I would go straight to a break-in cycle. However, 2700 mAh is likely to be optimistic for the true capacity, so I would set the break-in at 2500 mAh or even 2300 mAh perhaps.

I am not aware of any meltdown events with the C9000. The worst that might happen, in the very unlikely event of a missed termination at high charge rate, if the high temperature sensor did not cut in first, would be a fizzled cell.

If it bothers you, you could put the charger in the garage.

[e_dogg]

If it bothers you, you could put the charger in the garage.

Funny you mention that - my next door neighbor's house burned down and it started from the garage.

Granted the fire was started by kids siphoning gas with a vacuum, but still...

[PeAK]

For a very old cell in unknown condition I would go straight to a break-in cycle...

Could you not view a 'refresh and analyze" cycle as a poor man's break-in cycle...in addition it's faster. So some of the benefit of a break-in with the upside being less time on the charger.

[Mr Happy]

Could you not view a 'refresh and analyze" cycle as a poor man's break-in cycle...in addition it's faster. So some of the benefit of a break-in with the upside being less time on the charger.

You could, but from a few ad-hoc tests I have seen very little benefit from performing a R&A cycle on an under-performing cell. There is something about the break-in cycle that seems to get much better results.

[e_dogg]

I've finished discharging those Panasonics and am running an R&A on a set of Duraloops that just died on me.

I think I'll go ahead and try the break-in tomorrow morning on the Panasonics and hope it finishes before bedtime.

Man, this is a fun toy!

[Mr Happy]

I think I'll go ahead and try the break-in tomorrow morning on the Panasonics and hope it finishes before bedtime.

...before bedtime the following day

(It requires about 40 hours to complete a break-in cycle.)

[TakeTheActive]

I just received my Maha C9000 yesterday...

...I'm now running a set of AAA Durabrids through it at 500mA charge and 500mA discharge. I hope that's an acceptable rate...

I want to try matching my cells so I want to run a "refresh and analyze" on all of them to get them into pairs...

...I'll start using the default 1000mA charge rate for my AAs and use 500mA for my AAAs.

...If you're wanting to match the cells, I'd recommend that doing a break-in will give you more accurate capacity numbers on these cells than R&A. I'd encourage you to discharge first. I mostly use R&A for maintenance cycling and to check for possible problem cells.

For ALL of your cells, AA and AAA, unless you have a specific purpose in mind and need an advanced 'guesstimate' of runtime, I'd DISCHARGE @ 0.2C (or as close to it as possible) to get 'Standard' Capacity numbers that you can compare against. IMO, DISCHARGING @ 500mA for 800mAh AAAs is high. I'd use 200mA (closest to 160mA).

For CHARGING 800mAh AAAs, I'd start off with 400mA. Remember that regardless of the cell size or Capacity, both AAs and AAAs get TWO HOURS @ 100mA after the C9000 display shows 'Done'. Check the temperature of your AAAs (and AAs) @ 1.46VDC. They may like more current or they may like less.

Take a look at the results of Experiment #A3 in: Test for how well batteries suit your charger. CHARGING at a higher current (2000mAh AA @ 1500mA and 1800mA) caused the C9000 to terminate on Max Voltage sooner (i.e. UNDERcharged the cells), which then allowed the 100mA for 2 hours to 'gently' top them off. From what I've read here in the CPF 'Batteries Included' Archives, ~100-110°F (~38-43°C) is not damaging to your cells. Over 122°F (50°C) is where I begin to get concerned. And I only see that with my *CRAP* cells. UNDERcharging is always better than OVERcharging as far as TOTAL CYCLES are concerned.

There are SO MANY Pros and Cons to the different methods of maintaining your rechargeable cells that it's not really possible for anyone but you, with knowledge and experience, to decide which is best. Folks can give you 'generalizations' and/or what works for THEM, but, it's up to YOU to determine what works for YOU.

1. What device are your 'Matched Pairs' going to be used in?
   .
2. How much current does it draw?
   .
3. How often will the cells need to be recharged?

...If cells 1 & 3 were still charging when you noted those numbers, I'm guessing you were seeing the amount of charge put into them, rather than their capacity. This sometimes throws people off with the MH-C9000. The charge put in will always be larger than actual capacity. The display then switches to capacity after it's done...

IME, distinguishing between CHARGE Capacity and DISCHARGE Capacity is more of a challenge for (new) La Crosse owners. IIRC, several months ago, one La Crosse owner INSISTED that he was getting Capacities of ~3200mAh from his AAs (I don't recall if they were Eneloops; I 'think' they were ~2000mAh LSDs though) with a Charge Rate of 200mA.

[TakeTheActive]

Could you not view a 'refresh and analyze" cycle as a poor man's break-in cycle...

I once ran 10 R&A cycles on some 'not-so-vibrant-but-not-yet-*CRAP*' cells and the Capacity DECREASED after each cycle.

Slow 'Deep Discharge' followed by slow '0.1C for 16 Hours Charge' seems to work the best at getting the 'atrophied' chemicals back in the game.

[e_dogg]

...before bedtime the following day

(It requires about 40 hours to complete a break-in cycle.)

Doh! I guess I mis-remembered what the manual said...I thought it was like 16 hours but maybe that's just the trickle charge phase of it.

For ALL of your cells, AA and AAA, unless you have a specific purpose in mind and need an advanced 'guesstimate' of runtime, I'd DISCHARGE @ 0.2C (or as close to it as possible) to get 'Standard' Capacity numbers that you can compare against. IMO, DISCHARGING @ 500mA for 800mAh AAAs is high. I'd use 200mA (closest to 160mA).

For CHARGING 800mAh AAAs, I'd start off with 400mA. Remember that regardless of the cell size or Capacity, both AAs and AAAs get TWO HOURS @ 100mA after the C9000 display shows 'Done'. Check the temperature of your AAAs (and AAs) @ 1.46VDC. They may like more current or they may like less.

Thanks for the info, TTA. I'll reserve the 500mA discharge for AA cells and stick with 200mA for AAA cells.

Regarding temperature, the cells have felt warm, which is to be expected. I could try using my digital cooking thermometer to get an idea of actual temperature but figured that since they weren't hot, it shouldn't be a big deal. In fact, I think my cells get warmer in my Duracell Mobile Charger...

Take a look at the results of Experiment #A3 in: Test for how well batteries suit your charger. CHARGING at a higher current (2000mAh AA @ 1500mA and 1800mA) caused the C9000 to terminate on Max Voltage sooner (i.e. UNDERcharged the cells), which then allowed the 100mA for 2 hours to 'gently' top them off. From what I've read here in the CPF 'Batteries Included' Archives, ~100-110°F (~38-43°C) is not damaging to your cells. Over 122°F (50°C) is where I begin to get concerned. And I only see that with my *CRAP* cells. UNDERcharging is always better than OVERcharging as far as TOTAL CYCLES are concerned.

I think I've read all your experiments before but I'll give that one a closer read.

There are SO MANY Pros and Cons to the different methods of maintaining your rechargeable cells that it's not really possible for anyone but you, with knowledge and experience, to decide which is best. Folks can give you 'generalizations' and/or what works for THEM, but, it's up to YOU to determine what works for YOU.

1. What device are your 'Matched Pairs' going to be used in?
   .
2. How much current does it draw?
   .
3. How often will the cells need to be recharged?

You're tellin' me!!! There are so many pros and cons that it's enough to make a guy's head spin! (where's the Linda Blair smiley when you need it?)

To answer your questions, though, I'll primarily use them in a Panasonic digital camera, Romisen RC-N3, Jetbeam Jet-I Pro EX. And I have no idea how much current any of those items draw. I have a decent amount of cells to rotate through so they won't be discharged/charged all that frequently. Maybe once every couple of months...

I once ran 10 R&A cycles on some 'not-so-vibrant-but-not-yet-*CRAP*' cells and the Capacity DECREASED after each cycle.

Slow 'Deep Discharge' followed by slow '0.1C for 16 Hours Charge' seems to work the best at getting the 'atrophied' chemicals back in the game.

Excellent info...I'll be sure not to abuse the R&A feature as I don't want to prematurely kill my cells.

[WDG]

Doh! I guess I mis-remembered what the manual said...I thought it was like 16 hours but maybe that's just the trickle charge phase of it.

It actually does two 16 hour 0.1C charges, with a 0.2C discharge in between. You can tell your wife that there's no reason to worry, as the charge portions of Break-in are purely timed... no missed terminations possible.

[e_dogg]

It actually does two 16 hour 0.1C charges, with a 0.2C discharge in between. You can tell your wife that there's no reason to worry, as the charge portions of Break-in are purely timed... no missed terminations possible.

Thanks for the clarification. I actually let it run last night and just didn't say anything about it.

I also realized that on my first R&A run I confused "rest" with "done". So the cycle was actually not complete and the cells were just in a resting state between charge/discharge. Oh well, they're charged now so I'll just wait to use them a few times and then run them through a full R&A cycle.

[UserName]

It actually does two 16 hour 0.1C charges, with a 0.2C discharge in between.

Regarding that, is it necessary, or recommended, to start a break-in cycled with cells discharged? I've only done a few break-ins since getting my c9000 last week, and I wasn't sure. To err on the safe side, I ran a discharge cycled before starting the break-in, just because I wasn't sure it sounded like a good idea to start that 16hr .1C charge on an already full cell.

[TakeTheActive]

Regarding that, is it necessary, or recommended, to start a break-in cycled with cells discharged?

If you think it out, logically, charging a FULLY CHARGED cell for 16 more hours, even at 0.1C, isn't accomplishing much.

Sure, you'll 'mix up' some of the chemicals that didn't get 'exercised' when the previous higher current charge terminated (more than likely on Max Voltage). But, that will probably be completed in a few hours (WAG) and the remaining time will just be wasted generating unnecessary heat.

Since I have so many low current devices that run MONTHS between charges, I precede EVERY CHARGE with a DISCHARGE (just to 'mix up' / 'exercise' the chemicals 'at the bottom of the jar' / 'stuck in the corners').

[e_dogg]

Regarding that, is it necessary, or recommended, to start a break-in cycled with cells discharged? I've only done a few break-ins since getting my c9000 last week, and I wasn't sure. To err on the safe side, I ran a discharge cycled before starting the break-in, just because I wasn't sure it sounded like a good idea to start that 16hr .1C charge on an already full cell.

I think the manual recommends doing a break-in cycle on a discharged battery...or I read that here...I've read so much C9000 info the last few days my brain is full.

[WDG]

Regarding that, is it necessary, or recommended, to start a break-in cycled with cells discharged?

I figure it's most likely more safe to discharge first, so that's what I do.