Maha MH-C9000 SUPPORT / FAQ - continuation

[Mr Happy]

I maybe misunderstood the best way of prolonging the life of the cells. Having 8 and cycling them means they have probably had only about 60 cycles or so each (if that) but yes, they are probably approaching 2 years old.

This is generally fine, but the higher capacity cells like the 2700 mAh ones will sustain fewer cycles before they wear out. The only way to squeeze the higher capacity into those cells is to make the parts thinner, smaller and more fragile so that more can fit into the same volume. A rule of thumb is that 2700 mAh cells will tend to wear out after less than 100 cycles, whereas 2000 mAh cells might last for 200 cycles or more. The latest Eneloops are advertised to last for 1500 cycles, but those are special marketing department cycles and should not be taken as an indication of what you will actually achieve. It will however be way more than 60.

[iamasmith]

Thanks again!

Anybody know for sure about that 'ramp up' feature I mentioned?

[Mr Happy]

Anybody know for sure about that 'ramp up' feature I mentioned?

Applying carefully timed high current pulses before charging is not a generally recognized way to revive or recondition NiMH batteries. There was a possible reason for doing it to NiCd batteries but that reason does not apply to NiMH.

[iamasmith]

Picked one up today from Maplins and put the first batch of 4 on to Refresh and Analyse. It immediately showed up High on one so that has been discarded and we'll see what happens with the others. Nice unit!

[iamasmith]

One more question, sorry , when doing the Refresh and Analyse (which I note goes through steps Charge, Rest, Discharge, Rest Charge) as suggested from 1 to 3 times when attempting to rescue batteries is it recommended to intersperse the Refresh and Analyse stages with a Discharge stage in between or simply repeat them?

I assume the charger will on the 2nd and 3rd runs just check and top off then go into rest and then discharge, rest and charge so no harm done but I wanted to check that this was the way it was intended to be used.

Also, I'm assuming that if Break in is used on a cell then one should use Discharge before doing this (unless brand new and not pre charged)?

[Mr Happy]

One more question, sorry , when doing the Refresh and Analyse (which I note goes through steps Charge, Rest, Discharge, Rest Charge) as suggested from 1 to 3 times when attempting to rescue batteries is it recommended to intersperse the Refresh and Analyse stages with a Discharge stage in between or simply repeat them?

I assume the charger will on the 2nd and 3rd runs just check and top off then go into rest and then discharge, rest and charge so no harm done but I wanted to check that this was the way it was intended to be used.

Also, I'm assuming that if Break in is used on a cell then one should use Discharge before doing this (unless brand new and not pre charged)?

With Refresh and Analyze the idea is to repeat until there is no further improvement. So if you do a Discharge after the Refresh has finished you can compare that reading to what the R&A reported. If the new discharge reading has increased it might be worth doing another R&A, otherwise not. If you have any plans on storing the cell rather than using it immediately, then discharging it is also a good idea, since traditional NiMH cells (not the new low self-discharge variety) last better if they are stored in a discharged state and cycled every six months or so.

As for the Break-In question, opinions vary. Many of us like to do a discharge first, but in theory it shouldn't make a lot of difference either way.

Also, when you run a Break-In you should set the capacity to what was measured by Refresh and Analyze, rather than the number printed on the cell.

[iamasmith]

..
Also, when you run a Break-In you should set the capacity to what was measured by Refresh and Analyze, rather than the number printed on the cell.

Thanks again, that sounds like it might be important but wasn't obvious from anything I read about the charger. I'm not really sure why you would lower the Break-In mAh setting, it doesn't seem obvious if you are trying to reactivate a cells full capacity and in any case Maha say that Break-In will attempt to slowly deliver 1.6 times the value entered for Break-In anyway.

Sorry for all the newbie questions btw

[Mr Happy]

Thanks again, that sounds like it might be important but wasn't obvious from anything I read about the charger. I'm not really sure why you would lower the Break-In mAh setting, it doesn't seem obvious if you are trying to reactivate a cells full capacity and in any case Maha say that Break-In will attempt to slowly deliver 1.6 times the value entered for Break-In anyway.

You are right, it is not obvious. However, the Break-In cycle applies a measured and deliberate overcharge to the cell, which relies on the recycle reactions inside the cell being able to absorb and throw away the excess charge. If a cell happens to be somewhat worn out, then the ability to dissipate excess charge may be worn out as well. Therefore it is best to start gentle, and increase the charge rate if the cell can handle it. If the first Break-In cycle on the cell gives a higher capacity, then by all means use that capacity for the next Break-In.

[iamasmith]

2 out of the 5 so far tried (one showed High and was discarded immediately) seem OKish at about 83% capacity, they are doing their second R&A right now.

The other 2 that are in the charger are doing discharge capacity readings of 1880mAh and 1788mAh (remember these started out as 2700mAh cells)

Do you think it's worth trying to run a break in on these or just dump them? (I did pick up some Eneloops today also btw as a replacement)

Interestingly (and I think shockingly) the output current on the charger I HAD been using that came with these Uniross cells was a full 2.7A.... no wonder it charged them quick.. this could explain why they haven't survived all that long - that's going in the bin.

[uk_caver]

The other 2 that are in the charger are doing discharge capacity readings of 1880mAh and 1788mAh (remember these started out as 2700mAh cells)

Remember they started out as claimed 2700mAh cells, which doesn't necessarily mean they ever got anywhere near 2700mAh.
If you're getting 1800/1900mAh now, that might still be ~80% of actual original capacity.

[iamasmith]

Well, I have had success with 4 of the 8 original Uniross Performance 2700s and they have a good 80% of the capacity.

I've also got 4 Eneloop 1500s that have been through the process.

Finally, to see if it is viable I have taken the 3 very poorly performing Uniross 2700s which were down to about 1900mAh and having discharged them they are on a break in set to 1900mAh. 190mA for 16 hours is still 3040mAh, but at a bit more of a conservative rate so it will be interesting to see what happens.

Anybody really managed to recover cells performing so badly with this unit?

Cheers for the advice folks,

Andy

[Mikl1984]

Maha name: MHS-CO1202000SS

Real Model: HAS02412U-AS produced by WEIHAI POWER ELECTRONICS CO LTD

I found this via UL database: E306708
http://database.ul.com/cgi-bin/XYV/t...439&sequence=1

[gopajti]

Hi, this is the newest firmware -> 0K0AA?

[Mikl1984]

It's just production batch
Your's made Jan 2011

[jalyst]

If you want to test your high frequency hearing you can do it here. However, there is a VERY HIGH possibility that your soundcard won't support anything beyond 20 Khz and some don't go even beyond 15 Khz. There is good possibility that new MH-C9000 has very high frequency charge sound in a range of 17 Khz to 20 Khz so its silent to majority of users.

LOL, I wonder if dogs would be freaked-out by the noise?

[Flashaholic_71]

newbie.

[jylam]

I did a search to see if anyone else have this problem but cannot find anything...

I have 4 AAA Duraloops (800mAh, MIJ) that I used in the office for my wireless mouse (a pair at a time). They are charged with the older generation Duracell CEF14 charger whenever my mouse runs out of power and I use the 4 cells in pairs in rotation. I don't think they were charged/discharged for more than 50 to 60 cycles.

Recently, I found the batteries lasting less and less time. I decided to take them home to my MH-C9000 to refresh them. However, when I put them into the MH-C9000 and set to any of the charge cycle (charge, refresh, cycle or break-in), the charger would reset as soon as the cycle starts (the display turn dark and then light up again waiting for input as if I pulled out and reinsert the battery). This happens across all the slots and on all 4 AAAs. Only the discharge cycle would work but it shows "done" almost immediately for all 4 cells.

Two of the AAA's shows open voltage of 1.38V and the other two shows 1.19V with my voltmeter, if that helps.

Hoping it is not a charger problem, I tried some other AA and AAA Duraloops at home and I don't observe the same problem. The C9000 would go on with a charge cycle.

So... is it safe to say that the problem is NOT with my Maha charger? Also, is it time to toss the 4 AAAs from the office or is there other ways to "revive" them?

Thanks in advance for your help.

[Mr Happy]

Hi jylam,

When the C9000 does this it means the batteries have such a high internal resistance that the charger resets and will not try to charge them. This is an observed feature of the C9000, although it is only seen with batteries that are in very bad shape. You can tell from that that the problem lies with the batteries. Probably the CEF14 charger has ruined them by repeated overcharging. You do need to get some new batteries, but you should also charge them with a better battery charger. For a good life with AAA cells you should preferably find a charger that uses 500 mA on AAA cells and has smart termination. Your C9000 would seem to fit the bill. I recommend you charge your new batteries on the C9000 and dispose of the CEF14.

[Wrend]

Just got done reading both threads over the last few days in my spare time.

Do I get a cookie?

Glad to know all the quirks the C9000 has/had and to know mine is up to date and working as it should. Thanks for all of your contributions!

Looks like it'll do a good job of keeping my Eneloops healthy. Only slight reservation I had was thinking that it might overcharge the AAAs a little with the 2 hour 100mA top off charge. But, now it looks like that probably isn't the case? Has anyone compared a break in test followed by a second discharge, then normal charge (allowing for the top off charge to complete), and then another discharge to compare capacities? Haven't gotten around to it myself yet. I've been busy going through my new cells, breaking them in to test them and get them ready for service.

Before I got the C9000, I would individual charge, or series charge depleted cells in groups or packs of 2, 4, 5, 6, and 8 at a 0.1C/h rate for about 14 hours (which seemed to be long enough to charge and balance them). If they only made an 8 cell MH-C9000... Guss I'll probably end up picking up another one on my next order of cells (still need a few more so that I have enough on reserve).

The 1000mAh (0.5C/h) default charge rate is nice for AA Eneloops, but I wouldn't want to accidentally charge some older AAAs at that rate after a short power outage, if it can be avoided. Has anyone worked out a way to prevent this from happening? Basically, I'd like something similar to a fuse, only the opposite, that would trip when the power goes out, and that I'd manually have to reset after the power comes back on. I've shopped around a little and can't seem to find anything like this. I might end up building something if I can't find what I'm looking for, and for the fun of it. This time of year there are a lot of storms that go through the area, and I'm going to be breaking in cells for another month and a half at least.

[uk_caver]

Has anyone worked out a way to prevent this from happening? Basically, I'd like something similar to a fuse, only the opposite, that would trip when the power goes out, and that I'd manually have to reset after the power comes back on. I've shopped around a little and can't seem to find anything like this.

At least some plug-in RCDs (GFIs) disconnect on supply removal and have to be manually primed before passing power again.

[45/70]

Just got done reading both threads over the last few days in my spare time.

Do I get a cookie?

Yes, or you should anyway! I say this because if everyone did read through threads completely, before asking questions, they would often find that their question had already been answered previously. On the other hand, I can understand being reluctant to read through threads that are as extensive as this one, and quite a few others.

Only slight reservation I had was thinking that it might overcharge the AAAs a little with the 2 hour 100mA top off charge. But, now it looks like that probably isn't the case?

Many have come to the conclusion that the AAA eneloops are robust enough that they can absorb this slight overcharge. I myself try to pull the cells soon after "DONE", if I can. This way there is no doubt that any possible damage to the cells due to overcharging, will be avoided. That's just me though. I figure the slight tradeoff in lower obtained capacity vs. potentially longer cell life is worth it. If I forget and the cells do end up going through the 2 hour "top off", I don't sweat it, as I said, many think these cells can handle it.

One thing to consider, pound for pound, AAA cells compared to AA cells are at a disadvantage, due to their diminutive size. Regardless of the chemistry of the cells, the AA version is always going to last longer. It's a case where "bigger is better" when it comes to battery cells. When miniaturization is involved, there is frequently a bit of a tradeoff, take a laptop vs. a desktop computer for example. Anyway, I figure if I can help the AAA eneloops out a bit, I'll give it a shot.

The 1000mAh (0.5C/h) default charge rate is nice for AA Eneloops, but I wouldn't want to accidentally charge some older AAAs at that rate after a short power outage, if it can be avoided. Has anyone worked out a way to prevent this from happening?

I simply run all of my chargers through a UPS, as I do my cordless phone. This won't help if the power is out for a really long time, but avoids most problems. The power consumed by the C9000 is minimal, so it works out for me most of the time.

I live in a rural area where the power company definitely puts us on the "back burner". The power goes out here on average once per day. Usually it's just a "blip", in which case a UPS has no problem backing up the charger(s). Once in a while, as happened just last week, a T-storm came through and the power was out for 6 hours. In this situation the UPS may not cover the situation, but I'm well aware that the power went out in such instances, and can take the necessary steps required to rectify the situation.

Dave

[Wrend]

Thanks for the recommendations, guys.

It turns out that I actually have a nice 12V relay hanging around collecting dust anyway. I can hook that up with a momentary switch and use one of the relayed lines to power the relay itself and one of the other lines to power the charger. I'd have to put it in line after the wall wart AC adapter though, and it would only be good for one of the chargers.

So something like a GFI would work better still since I could use it for more than one charger. Unfortunately, I can't seem to find one locally here in the home improvement, big box, or other stores that will do.

A UPS might work too. Since the chargers run off of 12VDC, I might just get a deep cycle 120AH Pb battery to run them off of which is being maintained while the power is on. I'd need to find a nice maintenance/float charger for that though. That might be the way to go since I can use the Pb in some other applications too. I'm getting more into amateur radio and would like to have portable power off the grid in case of an emergency. As well as powering my other 12V portable chargers that I use for my RC batteries.

But, that's getting a little more expensive and isn't really a quick fix like I was hoping for.

Any troubles with powering the C9000 off of Pbs?

Cheers.

[Russel]

[...]Any troubles with powering the C9000 off of Pbs?[...]

I routinely operate my MH-C9000 off of a 12V car battery while it is being charged with a solar panel. The voltage varies from 12.5V to 14.2V without any detrimental effects to the charger.

[Wrend]

Good deal. Think I'll go that route then.

In the mean time I think I'll make something using that relay. Now to hunt down that project box with the momentary switch on it. Think I have a double color LED that I'll use to know the status of the relay at a glance.

Should be a fun afternoon project. I'll have to wait 'til around 00:30 tonight for the charger to be done with its current break in before I put some deans plugs in line on the AC adapter, though. I'll want to do that eventually anyway for connecting the charger to the Pb bus.

Happy charging.

-Mick

Oh, also, I'll report back with those AAA capacity comparisons I was talking about to see how fully the top off charge charges them, and whether or not I think it's worth worrying about them being over charged. As it is, it is pretty close to a 0.1C/h rate anyway.

[tallyram]

Sorry if this has already been covered.

My C9000 always stops charging slot 1 first. I have 24 eneloops and no matter which ones I'm charging slot 1 peaks first with around 100mah less than the others. Is this normal for this charger?

[Wrend]

Not that I know of. The ports on mine do seem to vary just a little from each other consistently, but it seems to be close to about 1% to 2% capacity.

Maybe the calibration of that port is a little off. If you're concerned about it, it might be worth it to send it in to be serviced or replaced.

[tallyram]

This C9000 is a replacement. I sent my original back for the same issue! Just had another batch of eneloops come off and slot 1 read about 100mah lower and stopped the charge 6 minutes sooner. I really don't want to pay shipping for another return. It seems like a nice charger, but how did I just happen to get 2 with the same problem? Wondering if this is just bad QC???? Going to email maha.

[Wrend]

Here are those AAA Eneloop test results on new cells. All were initially discharged at 100mA.

Break In (800mAh) Discharge 1: Cell 1 (808mAh), Cell 2 (821mAh), Cell 3 (809mAh), Cell 4 (816mAh); Average (813.5mAh)

100mA Discharge 1: Cell 1 (829mAh), Cell 2 (835mAh), Cell 3 (829mAh), Cell 4 (834mAh); Average (831.5mAh)

All cells were then charged at 0.5C/h (400mA) and allowed to "top off" charge for 2 hours, "trickle" charge for 1 hour, and then disconnected to rest for 1 hour.

100mA Discharge 2: Cell 1 (806mAh), Cell 2 (822mAh), Cell 3 (811mAh), Cell 4 (814mAh); Average (813.5mAh)

Break In (800mAh) Discharge 2: Cell 1 (809mAh), Cell 2 (818mAh), Cell 3 (809mAh), Cell 4 (817mAh); Average (813.25mAh)

Though it's far from proving anything conclusively, based on these numbers, I don't think allowing the Eneloop AAAs to go through the Top Off charge is significantly overcharging them. Also, keep in mind that the 100mA discharge capacity tests should have allowed for somewhat more capacity to discharge from the cells than the Break In 160mA discharge test results.

Though the MH-C9000 does not appear to be overcharging these cells with the Top Off charge, it may still be marginally beneficial for maximum battery cycle life to not top off charge these cells.

What I'm actually concerned a little more about now is the heat build up from the charger behind cells 2 and 3. I may install a thin metal strip along the flat area behind where the cells are placed and bend it down along the sides and a little behind the charger to help even out and radiate this heat away.

[ltcdata]

Hello everyone!
After 1 month of reading EVERYTHING i could about chargers, mostly here, a post from taketheactive on fatwallet, etc, i've finally decided on the maha MH-C9000 over the LaCrosse 9009.
I think the only things that i hate but i have to live with of the maha are the impossibility to set the four banks to the same setting at once, and only being able to see the status of 1 cell at the same time (the 4 displays in the 9009 could be perfect on the maha!).
But the lowest voltage of the trickle charge of the maha, the ability to better fine tune the charging of each cell (i have Sanyos 2700's, Eneloops, AA, AAA's, etc), the refresh functions, etc.. i think the maha is a better charger than the LaCrosse. Being me a technical guy i will buy it. I use the nimh batteries for Nikon flashes and flashlights mostly.
I live in argentina, so i expect 1 month minimum of delivery time.
I will post again when i receive it

[Swedpat]

Yesterday I received the MH-C9000 charger. I understand it's a great charger, but what advanced! I try to read the description but am not sure I get it.
Any basic tip for Eneloop AAA/AA and 2500-2700mAh common batteries, about charging/discharging current? It is programmable but what is best? I know that lower current is better for the battery life, but too low isn't good either... What's the difference between the "C"-rates and mAh value? In this case I really feel me as a newbie and a dummy...