Test/Review of Analyzing Charger Powerex MH-C9000

[Derek Dean]

Yes, Tapis, that's exactly what I've done (cut a small piece of cardboard to cover the lit panel), but it really would have been a nice touch to either have the screen go off after 20 seconds, or have a switch to turn it off manually. In any case, a minor issue for such a fine charger.

 

[MidnightDistortions]

Yeah that's a good idea and it is a minor issue. The charger is still well designed.

 

[racinjason]

I certainly like mine. Backlight isn't too bad. I've had mine for 2-3 years, never a problem.

 

[racinjason]

It's a great charger. Never any problems.

 

[SubLGT]

I had some connection issues with the AAA contacts so I took the unit apart and "adjusted" the contacts to eliminate the problem. After that I have had no problems unless the AAA cell has shrink wrap that wraps over the bottom radius of the cell.

My chargers are some of the first ones built. I don't know if this has changed with newer versions.

Tom

I also had connection problems with AAA batteries from my early production C9000, and finally disassembled the charger and reshaped the negative contacts to contact the battery closer to the center of the battery base. I also bent the positive contacts for the AA batteries, because I was beginning to experience occasional problems with AA batteries not making full contact when they were inserted.

 

[SubLGT]

Yes, Tapis, that's exactly what I've done (cut a small piece of cardboard to cover the lit panel), but it really would have been a nice touch to either have the screen go off after 20 seconds, or have a switch to turn it off manually. In any case, a minor issue for such a fine charger.

Cardboard? Tsk tsk. I'm sure you could find something much more interesting in one of your Lee or Rosco filter swatch books.

 

[Derek Dean]

Cardboard? Tsk tsk. I'm sure you could find something much more interesting in one of your Lee or Rosco filter swatch books.

Now why didn't I think of that? It turns out a LEE Filter Swatch fits perfectly over the LCD, and a deep blue one is actually quite lovely. Thanks for the suggestion, SubLGT!

 

[mauricio]

Great review, thanks!!!:twothumbs

 

[jonnyfgroove]

However if you don't have the time to get through all your cells , you can use the ICV feature at startup ( It takes less than 15 seconds ) .
That funktion tells you how much internal resistance the individual cell has. The value is between 1.4-2.10. The higher the value the higher internal resistance.

I've had this charger for years and I never realized it had this function.Thanks for the info.

And Thanks to HKJ for all his amazing reviews! :rock:

 

[Grijon]

Excellent review, thank you HKJ! I have one of these on the way!

 

[MidnightDistortions]

Nice review.

Can you comment on the AAA charging slots?

The AAA slots on my C9000 are extremely flaky. Any slight bump or movement of the charger causes random slots to go out as if no battery were present. I have to physical move the battery slightly to get it to register again with the charger acting as if I inserted a fresh battery.

The AA slots work flawlessly on mine save for the magic of SLOT 1.

I had some connection issues with the AAA contacts so I took the unit apart and "adjusted" the contacts to eliminate the problem. After that I have had no problems unless the AAA cell has shrink wrap that wraps over the bottom radius of the cell.

My chargers are some of the first ones built. I don't know if this has changed with newer versions.

Tom

I had this problem at first when i was testing my AAA Eneloop Pros. I remedied this by pushing the negative end on a slant holding that part of the battery in place while pressing down on the positive end. If you see the negative terminal pushed in and the little 2 indents in the middle of the positive terminal it should be in there correctly.

Now i seem to have the problem with some AAA batteries where the charger seems to detect the battery, start it's process and then reboots as if i took the cell out and put it back in again, what could be causing this? I know the battery is inserted correctly.

 

[SilverFox]

Hello MidnightDistortions,

There are 2 main causes. One is that the cell is losing contact. The other is that the cell is crap.

Tom

 

[MidnightDistortions]

Hello MidnightDistortions,

There are 2 main causes. One is that the cell is losing contact. The other is that the cell is crap.

Tom

Thanks, pretty sure along with the cells being crap (though i think they need to be properly broken in) i also checked the length of them with another cell and they are slightly shorter. They'll only discharge properly at 100mA but take forever to charge at 200mA, so i was attempting to try break-in or cycle them a bit to see if they could be optimized. Guess i'll have to resort to using a dumb charger to see if they can be helped at all.

 

[WDG]

...Now i seem to have the problem with some AAA batteries where the charger seems to detect the battery, start it's process and then reboots as if i took the cell out and put it back in again...

I've seen this when the cell's internal resistance gets high enough. FWIW, at this point, my old C.Crane chargers usually reject them, also. I recycle them or use only on dumb-chargers, from then on.

BTW, AAAs usually seem to go first, in my experience. IIRC, they tend to already have higher internal resistance when new than AAs.

 

[MidnightDistortions]

I've seen this when the cell's internal resistance gets high enough. FWIW, at this point, my old C.Crane chargers usually reject them, also. I recycle them or use only on dumb-chargers, from then on.

BTW, AAAs usually seem to go first, in my experience. IIRC, they tend to already have higher internal resistance when new than AAs.

Hmmm, never noticed the difference between AA/AAA cell resistance. The only problem i have with these cells (some no name brand that was included in some walkies) is they haven't been used much. They seem to work fine in my keyboard and has normal HSD behavior but they don't seem to handle my AAA Minimag unless i leave the light running for a few minutes, they seem to start kicking in a bit better.. still a bit dim but bright enough to put out a couple of lumens. One thing that these smart chargers don't do is repeat discharge as these batteries have that phenomenon where if the batteries get too discharged, take off the load for an hour or so and they work again for awhile. But the key is to keep using the batteries or cycle them when needed. It's a good reason to date the last time the batteries were refreshed so you can do the process again even if they are not used.

 

[L_D_Allan]

Thanks for the excellent review. I recall attempting to read it when I was considering the MH-C9000, but most of it was "over my head".

Now that I have had the charger for a month or so, I wonder if my model is newer than the one you reviewed. Perhaps it has newer firmware? I didn't observe if anyone else during this thread reported this. If so, my apologies.

[EDIT] Wrong.

The reason I mention this is that the default for CHARGE is now 500 rather than 1000.

[EDIT]: Wrong. My error. I had been using the C9000 to pre-discharge prior to BREAK-IN, related to another OP. I got the default DISCHARGE rate (500 ma) and default CHARGE rate (1000 mA0 mixed up.

I am a CPF newbie, so perhaps the default is different for different batteries. That doesn't seem to be the case, because with every AA and every AAA I've put in the MH-C9000, it has wanted to use a default CHARGE of 500.

I don't know if other things have changed. Maha may have some kind of "change log". I wonder if there is a way to "flash" the firmware, like you can with many devices. That seems unlikely, as there isn't any provision for USB or flash card.

The MH-C9000 is part way thru a BREAK-IN, so I can't check the firmware version until later. Do you recall the firmware in your test device? Or is it in the review and I didn't notice it? Is the firmware version something that shows up when it powers up?

 

[L_D_Allan]

I don't know if other things have changed. Maha may have some kind of "change log".

I re-read the review, and did notice some other non-trivial differences

• Internal resistance is reported ... there is an unexplained voltage not mentioned in their "user manual".
• I asked about that in an early post of mine to CPF. IIRC, the reply was "internal resistance" (which this newbie doesn't comprehend)
  http://www.candlepowerforums.com/vb...out-quot-mystery-voltage-quot-with-Maha-C9000
• [EDIT] I did find mention of HIGH mid-way in the review. Some or all of my comments in this post may not apply. Sorry.
• That voltage seems to only show up once for healthy batteries, near the start.
• It may sometimes show up only for the first battery, sometimes for each battery.
• I think the intended use might be to put one battery at a time in a slot, and observe what the internal resistance is, and proceed accordingly.
• The value seems to be the basis for reporting HIGH as a very strong hint to try to Recover the battery and/or discard.
• I had some old, abused AA's and AAA's. Their internal resistance would be well over 2.0 v. That value would show up, and then HIGH shown.
• I was never able to RECOVER any of the batteries for which HIGH was reported. Perhaps someone with more battery experience could?
• I ended up disposing of all those with HIGH. I've got a lot to learn to get the most out of my battery inventory.
• The charger seemed to "freeze" if any of the batteries had a HIGH value.
• IIRC, you couldn't even use the SLOT button to move to another battery with 2 or more were loaded.
• I did a Google search on "maha MH-C9000 firmware" and got a number of "hits", but they weren't particularly current.
• I used "Contact Us" to MahaEnergy.com with several questions.
  • latest firmware version?
  • change log?
  • update firmware possible for older chargers?
  • please confirm new feature of internal resistance and HIGH
  • also that default charge rate has changed from 1000 to 500
  • should have suggested that they update the user manual

 

[Power Me Up]

I wonder if there is a way to "flash" the firmware, like you can with many devices. That seems unlikely, as there isn't any provision for USB or flash card.

The MH-C9000 is part way thru a BREAK-IN, so I can't check the firmware version until later. Do you recall the firmware in your test device? Or is it in the review and I didn't notice it? Is the firmware version something that shows up when it powers up?

Unless they've changed the design, you can't update the firmware on the C9000 - last time I looked into it, Maha was using a one time programmable controller (i.e. once programmed, the firmware can't be changed)

If you take a look at the bottom of the charger, you should be able to find a sticker with a code on it - report back the code and that will give us an idea on how new it is.

 

[HKJ]

• Internal resistance is reported ... there is an unexplained voltage not mentioned in their "user manual".

Resistance is in ohm, the voltage show is probably the voltage measured during the initial current pulse, this do give an idea about the internal resistance.

 

[L_D_Allan]

If you take a look at the bottom of the charger, you should be able to find a sticker with a code on it - report back the code and that will give us an idea on how new it is.

ONODA ... is that different from what other owners have? Is it different from the review unit?