Maha MH C808M Charger

Sub_Umbra

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I recently purchased about a dozen of the powerex 11,000 mah D cell and proceed to condition 8 of them in the 808. after 5 days. the 808 seems to get stuck at the discharge cycle with 1 bar blinking on all slots without going into the final charging cycle. The 808 seems to be overwhelm by the capacity of the D cell :thinking: and their algorithm get mixed-up because of the time needed to discharge those D-cells????:poke:

Paging SilverFox or William Chueh:popcorn:
The 808 is a quirky charger. I'd just stop the discharge and recharge the cells and try another conditioning cycle after the cells have a couple of cycles on them. Also, a UPS with a filtered power supply may reduce some of the 808's eratic behavior in some locations. For a charger often touted as 'Professional' it seems somewhat intolerant of dirty AC and it goes into amnesia if it loses power for even a half second. Either of these faults would seem to pretty much rule it out for professional use in most Third World countries -- and at least a few First World cities like New Orleans. :D
 
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Turbo DV8

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...the 808 seems to get stuck at the discharge cycle with 1 bar blinking on all slots without going into the final charging cycle.

I wonder if this response by William Chueh in the C9000 FAQ thread, is applicable to the 808?

We've come across a lot of AAA batteries (well-known and off brand, new and old) that have DC resistances exceeding 0.3 ohm. Their open circuit voltage, measured between discharge pulses, actually never reach the cutoff and the discharge continues until the MOSFET is unable to draw current (due to insufficient differential voltage). The under-load voltage will already be 0.8V but the open circuit voltage will still be above the discharge cutoff.As a result, the discharge never ends!

I take this to mean that if the 808 measures the open circuit voltage between discharge pulses (unlike the C9000), that the 808 could also fail to terminate discharge.
 

Swedpat

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I recently purchased the Maha MH C808M charger. LARGE charger in comparison to my former AA chargers...

Great to charge all batteries I need from AAA to D in the same charger. The first charging was 8 12000mAh D batteries. They were fully charged at ca 4,5 hours. 8 AA were then charged at less than 1,5 hours, didn't notice exactly.

Regards, Patric
 

Flea Bag

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I recently purchased about a dozen of the powerex 11,000 mah D cell and proceed to condition 8 of them in the 808. after 5 days. the 808 seems to get stuck at the discharge cycle with 1 bar blinking on all slots without going into the final charging cycle. The 808 seems to be overwhelm by the capacity of the D cell :thinking: and their algorithm get mixed-up because of the time needed to discharge those D-cells????:poke:

Paging SilverFox or William Chueh:popcorn:

I think I have the same brand and capacity D cells as you though I only use 4 at a time. My 808M seems to do okay with them and other types or sizes of NiMH but sometimes, it 'crashes' during the discharge phase of conditioning. The 808M seems much more reliable for charging than for discharging.

As mentioned somewhere earlier in this thread, the 808M is particularly sensitive to 'crashes' during the discharge cycle. This seems true for all sizes and capacities of my batteries (Sanyo AAA, AA & Powerex D). For example, if you twist the batteries in their charging slot, knock the charger accidentally or are a bit rough with inserting new cells while other cells are still discharging, then the charger has a higher chance of crashing and staying in the discharge phase indefinitely. This could be related to what another member said about the 808M being sensitive to power disruptions.
 

ptolemy

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I just picked this one up. I wanted to be able to charge all my bateries in One, so it'll replace bc-900 and some other I have.

Doing my first reconditioning right now. One thing I am missing is the ability to actual capasity of the batteries.

Seems like after it charges it fully, discharges, recharges it would be simple to keep an eye on it?

That's one thing I am missing and I find it important, for with so many different non-branded batteries coming from the asian market via EBay sellers are fraction of the price, It would be nice to find the studs and the duds :)

Cheers!

p.s is there a charger that does aa/aaa/c/d's and can to soft charge/discharge/analyze capacity (primarly c and d's cause I have eneloops aa/aaa and chances are they are exact mah as they say)?
 
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Geogecko

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Just ordered one of these. I asked Maha about a year or so ago, if they planned on making a AAA, AA, C, & D version of the C9000, and never got a response. I asked the same question a week or two ago, and never got a response either.

They will probably come out with one tomorrow, which is when I expect my C808M to show up. I'm excited to be able to charge C's now, as many of my daughter's and son's toys use them, and at $5 a 4 pack, it is getting rather expensive to buy batteries after batteries.

So, it still seems like people like this charger, from what I can tell. There were some early reports of some people having some heat problems, but I haven't seen any recently. Hopefully, this will be a good charger for many years to come.
 

servaas

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Just ordered one of these. I asked Maha about a year or so ago, if they planned on making a AAA, AA, C, & D version of the C9000, and never got a response.
I asked our account manager about this last year also, and MAHA do not have an intention to develop an 8 cell version of the 9000.

The tooling and development costs of a new product are very high, and selling 100,000+ of such a charger may take 10+ years, so it would take too long to recover the investment.

Being able to analyze more than 4 AA batteries can be achieved with a second MH-C9000. Sales of C and D batteries are a small % of AA volumes, so adding analyzer functionality to the MH-C808M would be catering to a niche within a niche, so I don't see that being developed either.
 

Geogecko

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I can see where you are coming from. I should have clarified where I was coming from, I guess. I meant just a 4 cell version of the C9000, that could also charge C and D cell batteries. Seems like the only cost would be in packaging, for a new mold for the plastic housing. The electronics seem to be there to support C and D charging (the C9000 supports up to 20,000mAh capacity, if I read correctly), so I would think the only changes electrically, may be a firmware revision.

That being said, since they already have an 8 cell charger without this funcionallity, it would cut into it's sales. Granted, not everyone is a battery junkie, so if they just priced it right (higher than the C808M), then only those interested in the added capabilities would buy it.

The low quantity of the larger cell useage probably also explains why Sayno does not make the Eneloop in anything other than AAA or AA.

I guess we just have to live with the C808M for larger cells.
 

Turbo DV8

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I meant just a 4 cell version of the C9000, that could also charge C and D cell batteries... I guess we just have to live with the C808M for larger cells.

Which is sort of too bad, because at $10-$13 a pop for a NiMH D cell, it would seem most crucial to monitor and match those cells compared to a $2.50-$3.50 NiMH AA cell. I think they have marked up the price of the 808 so unreasonably high, and the C9000 not too far below it, that they have sort of locked themselves out of any prospect of finding a spot in their line up between the two where even a 4D cell "C9000" could be profitable. Mention was made that the market for D-cell chargers was relatively small, but likewise the market for 8-cell chargers is relatively small also, yet Maha makes one. So, what's Maha to do? Invest the $$$ to make a 4-cell AAA-AA-C-D "C9000" and instantly obsolete the AAA-AA C9000, just to attract a relatively few C & D users? Or make a C-D only C9000 and, as was mentioned, sell to a niche within a niche? It's not that there isn't a market for a 4-cell AAA-AA-C-D analyzer, I think it's just that they can't find any way to massage it into their charger line up and be profitable.

Someone mentioned that a 4 D-cell C9000 would require a huge power supply, because if it were to charge in the purportedly desireable range of 0.5C range, the power supply would have to be able to deliver 20-24 amps. Double that for an 8-cell version. Yet the 808 charges 8 D-cells at only about 1/6C, yet terminates just fine. So, their 4 D-cell C9000 could charge at a very comfortable 1/3C with the same power supply, and over 0.5C for C-cells. I would think the bigger problem of making a D-cell analyzer would be in dissipating the heat generated by discharging 4 D-cells at the discharge currents which "niche users" might be requiring. Discharging, say, four 12 Ah D-cells at 0.5C would equate to about 30 watts of heat dissipation. At the very least, this would require a large area (bulky charger) and enough ventilation openings to rival a block of Swiss cheese. More realistically, it would require the use of active cooling. Oh well, I am just musing. Dreaming of such a D-cell analyzer is still free, and available today!
 

Geogecko

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Wow, this thing is gigantic! I guess I should have figured that out with 8 D cells piled in this thing. Unfortunately, these low discharges come precharged, so I haven't used the thing yet...

That said, what I mentioned about them having the electronics done isn't quite true. They would have to at least spin the board, in order to get the contacts at the right spacings...

I enjoyed the previous post, it had a lot of good arguments.

I'm hoping that the C cells will terminate fine on soft charging. For me, 4.5 hours is fine for charging, although from what ppl have said, even at the higher rate, things seem to remain fairly cool...
 

Turbo DV8

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Unfortunately, these low discharges come precharged, so I haven't used the thing yet...

I would say, "Go for it!" From what I've read, "precharged" doesn't mean they are fully charged at the factory. Then add to that the normal discharge (albeit LSD) since manufacture, and the cells could be down to less than 1.3 volts, so the 808 shouldn't have any problem terminating on that. Or, a discharge-charge couldn't at all hurt a new cell that has been sitting unused for a spell, so this could be the perfect time to try out that refresh function. Keep in mind that with 8 cells, the total time to refresh could be up to 3 or 4 days for D-cells, depending on charge rate selected. Even at 2 amps, the new C-cells should stay pretty cool on the 808. Just avoid doing anything like soft charge (1A) into a 12 Ah D-cell with a cooling fan over it. I ran into termination problems with active cooling with soft charge. I've since learned active cooling is completely uneccesary with the 808 at any rate with any size cell. Active cooling was a bad habit I carried over from using my BC-900! I have since stopped using active cooling with the BC-900 unless charging at 1 amp or higher, as the cooling also prevents reliable termination. Now I have enough BC-900's that I can charge just a pair in each, just in the outer slots for good ventilation. The 808 has plenty of cell spacing for good cooling. Your 808 will get warmer in the right-side bays, so if I am charging fewer than 8 cells, I start from the left and fill rightward to avoid the warmer area on the right. I mean, I have to be anal about something on the 808, right?:rolleyes:
 

Geogecko

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Ah, you were correct. I loaded her up with 8 C cells, and they are currently soft charging, and the bottom bar is the only one lit up right now...

Guess the crib aquarium will be coming in for a sooner than expected battery change. Oh, well. So far, there is no detectable change in battery temperature, but it's only been 15 minutes. I got my C9000 also charging some AA batteries.

The other thing I am impressed with, are the contacts on these two chargers. They are very well built, compared with the normal spring type of contacts on most chargers. I think this is what helps keep the temperature down while charging, by reducing the resistance of the connections with the batteries.

I think the price of the C808M is a little on the steep side, but I'm over all happy with it so far.
 

Turbo DV8

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Oh, well. So far, there is no detectable change in battery temperature, but it's only been 15 minutes.

Temps only rise appreciably very near the end of charge, although the older and more tired out the cell, the warmer overall it will become. Don't panic if the cells don't at first appear to terminate reliably on soft charge. I've read that it can sometimes take a couple cycles for some cells to provide reliable negative change in voltage at end of charge to trigger reliable termination.
 

regor_nono

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Hi. I just got my c808m this week. Actually, I got 2, the first one was a dud, the last 3 bays keep flashing done even if I put healthy cells in them. So I returned it for a refund. I got my second one from another merchant. This one's really great. I'm refreshing my cells now for 3 days.

I had some termination problems though, with new AAAs. But I'm sure it's the soft-charge on a 1000 mAH cell. The soft charge for AAA is 350mA, as I've read previously on this same thread. So that will make 0.35C, not suitable for termination.

I'm waiting for another 2 months to make more money to buy the C9000. Can't wait!

Thanks for the great posts on battery chargers. They all helped me to decide which charger to get. Especially to Silverfox, almost all info I know about rechargeables I got from him.

Thanks! :thumbsup:
 

Turbo DV8

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The soft charge for AAA is 350mA, as I've read previously on this same thread.

Thanks for reminding me of that! Some of my ROV Hybrids won't terminate at 200 mA on my BC-900, and I don't like the higher 550 mA of the Duracell Mobile charger for AAA cells. I'll try the 808 on my AAA's at 350 mA and see how it works out.
 

Sub_Umbra

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Thanks for reminding me of that! Some of my ROV Hybrids won't terminate at 200 mA on my BC-900, and I don't like the higher 550 mA of the Duracell Mobile charger for AAA cells. I'll try the 808 on my AAA's at 350 mA and see how it works out.
As clunky as it sounds, if you want to guarantee that your Maha C808M is charging at the gentler, "soft" setting you'll have have to take the extraordinary step of running it through a UPS.

The Maha C808M doesn't like even the briefest half second dip in power and goes directly into amnesia at the slightest power interruption, reverting to back to it's default 'hard charge' setting no matter how you programmed it to charge your cells.

This weakness could have been avoided with the addition of a cheap, mechanical Mode Switch or even just a few cents worth of flash memory, either of which would hold the user's choice over a power blink. They have not only not fixed this -- they have continued to design, manufacture and sell newer chargers with the very same weakness for years.
 

regor_nono

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As clunky as it sounds, if you want to guarantee that your Maha C808M is charging at the gentler, "soft" setting you'll have have to take the extraordinary step of running it through a UPS.

Yes, I'm also thinking of hooking up chargers to a UPS. Right now, I only have my charger hooked up to an automatic voltage regulator, as well as my other sensitive electronics (LCD TV, PS3, etc.), hoping it will be at least a temporary fix.
 

GMan4911

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Anybody try making an adapter to allow charging telephone battery packs? The terminals on the battery pack are on the back and are the pressure type. If I take it apart, I destroy the battery. The handset has two metal tabs at the base which I can attach alligator clips to. The problem is on the mh-c808m charger - the negative terminals extend out enough that I can attach an alligator clip to but I can't do the same with the positive terminals. I figure an adapter about the size of a D cell with metal tabs at the ends that extend out so that I can attach alligator clips would work.

Anybody seen anything like that? Good idea? Bad idea?
 
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