# MH-C808M / C801D vs. C800S



## Al (Apr 6, 2007)

What is the "official" consensus?

C808M / C801D charging Hi or low at 2.0A or 1.0A vs. the C800S which halves these charging rates?

I know there are thread(s) with extensive analyses that deal with these MAHA chargers, but I thot it would be nice to start a "Readers Digest" thread.


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## Power Me Up (Apr 6, 2007)

*Re: MH-C801M / C801D vs. C801S*

I'm guessing that you're actually meaning the C808M, C801D and the C800S? AFAIK, there is no such thing as a Maha C801M or C801S...

Personally, I've got a couple of the C800S chargers, and I use them on the slow (soft) charge mode normally. I'm generally not in a hurry for my cells to be charged so I'd prefer to be gentler on them...


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## SilverFox (Apr 6, 2007)

*Re: MH-C801M / C801D vs. C801S*

Hello Al,

I prefer to charge at 2 amps...

Tom


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## Al (Apr 6, 2007)

*Re: MH-C801M / C801D vs. C801S*



Power Me Up said:


> I'm guessing that you're actually meaning the C808M, C801D and the C800S? AFAIK, there is no such thing as a Maha C801M or C801S...
> 
> Personally, I've got a couple of the C800S chargers, and I use them on the slow (soft) charge mode normally. I'm generally not in a hurry for my cells to be charged so I'd prefer to be gentler on them...



Good guessing ... changes implemented in original post ... early morning ... yawn-n-n-n ...


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## Brody (Apr 7, 2007)

While I do charge using the soft option on AAA or AA cells, even on the default charge rate, the batteries dont get hot with the C808m. One of the main reasons I got the Maha C808m charger was to allow me to charge C or D cell nimh cells. If you don't need to charge C or D cells, then the C801D or the C800S would be just fine. The C808M is quite a bit larger than the C801D or the C800S due to it's ability to charge C or D cells. If you want to see a size comparison, trying checking the review at www.digitaldingus.com/reviews/maha/mhc808m/index.php


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## Al (Apr 7, 2007)

So given the average, let's say, capacity of newer AA nimh cells of 2350mah (Eneloops: 2000 / Sanyo 2700) these chargers run a range of about .8c to .2c - higher or lower depending on the cells being charged.

Lacking the exteme flexibility of the MH-C9000 but having 8 slots, I'm feeling a C808M or C801D would be the way to go for someone interested in the MAHA 800 series chargers because both can charge newer AA cells at around the 1c rate which seems to be recommended by the expert(s) ... Thoughts?


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## bp044 (Apr 7, 2007)

Al said:


> So given the average, let's say, capacity of newer AA nimh cells of 2350mah (Eneloops: 2000 / Sanyo 2700) these chargers run a range of about .8c to .2c - higher or lower depending on the cells being charged.
> 
> Lacking the exteme flexibility of the MH-C9000 but having 8 slots, I'm feeling a C808M or C801D would be the way to go for someone interested in the MAHA 800 series chargers because both can charge newer AA cells at around the 1c rate which seems to be recommended by the expert(s) ... Thoughts?


 I intend to use eneloops exclusively. Are you saying the 800S which has a maximum charge rate of 1000mA would not be good for eneloop AA's ? I had always assumed the slower charge rate prolongs life of the cells


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## bp044 (Apr 7, 2007)

Al sorry I messed up your post


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## Al (Apr 7, 2007)

bp044 said:


> I intend to use eneloops exclusively. Are you saying the 800S which has a maximum charge rate of 1000mA would not be good for eneloop AA's ? I had always assumed the slower charge rate prolongs life of the cells



I dunno ... seems like a wide variety of opinions of what constitutes proper charge rate ...


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## bp044 (Apr 7, 2007)

Al said:


> I dunno ... seems like a wide variety of opinions of what constitutes proper charge rate ...


 There is a wide body of knowledge in CPF. Surely someone must know the best charge rate for Eneloop AA's .the first factor is prolonging cell life, quick charging NOT a factor


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## SilverFox (Apr 7, 2007)

Hello Bp,

According to the Eneloop specification sheet the recommended charging rate is 2000 mA for the AA cells and 800 mA for the AAA cells.

Tom


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## bp044 (Apr 7, 2007)

SilverFox said:


> Hello Bp,
> 
> According to the Eneloop specification sheet the recommended charging rate is 2000 mA for the AA cells and 800 mA for the AAA cells.
> 
> Tom


Hello Tom Thanks for doing the research I should have done I may sound paranoid. Is it possible that the manufacturer is not as interested as I am in prolonging cell life ?


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## SilverFox (Apr 8, 2007)

Hello Bp,

Let's pause for a minute and play with some numbers...

I have shown that a 2000 mAh cell can last at least 150 cycles when it is charged using a 15 minute charger. There is no reason the Eneloop cells wouldn't behave similarly. So, let's say that an Eneloop cell will give us a minimum of 150 cycles.

Let's go on to say that Eneloop cells cost $4.50 each.

Finally, let's say that you use your battery powered devices a lot and will be going through a full discharge almost every week.

Taking the cost of the cell ($4.50) and dividing it by its minimum life cycle (150 cycles) we come up with a cost of $0.03 per charge.

For ease of calculation, let's round the number of charges per year to 50.

This means that your cells, using the 15 minute charger to charge them, will last for 3 years, and the annual cost for the cells will be $1.50 per cell.

Now if you use a 1 hour charge and charge at 2 amps, or a 2 hour charge and charge at 1 amp, your cycle life should be more than 150 cycles. This means that your cost would be less.

Unfortunately, there is little experimental data that tells if there is an improvement in cycle life when you charge at slower rates. That is the reason that you never get an answer to your questions of what happens when you charge at slower rates. However, I am aware of the IEC cycle testing procedures. 

In the accelerated IEC cycle testing, the cell is charged at 1C and discharged at 1C. Every 50 cycles, the cell gets a 0.1C 16 hour charge. Cells are supposed to last a minimum of 500 cycles this way.

If the cells actually go for 500 cycles, your cost drops a lot. That works out to around $0.45 per cell per year, and you should get 10 years of life from them.

There you have it. The worst case is using the 15 minute charger and only getting 150 cycles from your cells. This will cost you $1.50 per cell per year.

The best case has you charging at 2 amps and your cells lasting over 500 cycles. In this case your cost is around $0.45 per cell per year.

If you are in a hurry and want your cells to charge up fast, you have to ask yourself if you can afford the $1.50 per cell per year. If you have more time, you can go with the 1C charge rate and hope for 500 or more cycles.

Now if you are interested in reducing the $0.45 per cell per year cost, I am not sure how much you can shave off. Let's suppose that you spend a year studying charger specifications and doing research on the most productive charging methods. I don't think you would be able to save $0.10 per cell per year, but if you did, would it be worth all the effort?

I can live with $1.50 per cell per year. If my cells last longer, that's great. 

I should also point out that this cost does add up. Right now, I have 30 Eneloop cells in use. I am not going through a charge/discharge cycle every week, but it is more like a charge/discharge cycle every month. This brings my cost (assuming only 150 cycles from my cells) to $0.36 per cell per year. I have 30 cells, so my annual cost will run $10.80. This is less than $1.00 per month, and that is within my budget.

Perhaps this little exercise will help you figure out what you can afford, and what direction you want to take.

Tom


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## bp044 (Apr 8, 2007)

*Re:SilverFox Re: MH-C808M / C801D vs. C800S*

Hello, Tom,
Thanks for the perfecty detailed explanation in Post # 12. 
I have the Duracell CEFCEF 15NC 15 minute charger. I don't know the charger rate but it must be quite high.
Thanks to your great info my plan is this:

Use the Duracell when I need 4 cells in a rush. I will buy the C800S to use at its maximum of 1000 mA. When I need 8 cells, no rush.
Would switching between the two chargers be detrimental to the cells?

Would the maximum of 1000mA charge rate of the C 800S be okay or should I buy the C801D with its 2000 rate? I really need 8 cells most of the time.


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## SilverFox (Apr 8, 2007)

Hello Bp,

You should have no problems at all switching between chargers. The C800S will do a great job with the Eneloop cells.

Tom


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## LiteTheWay (Apr 8, 2007)

Once again great info from Silverfox. I've ordered my C9000 thanks to his advice and also plan to follow it with charging rates.


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## Niconical (Feb 5, 2009)

Hhm, old thread, not sure if this will get a reply, but I'll give it a try, better than a new thread for 1 question. 

So, I have a Lacrosse BC700 and a Maha C9000 and couldn't quite make up my mind on a second Maha. 

I've finally decided on the C801D. 

I'm sure most of you know it, but just in case, it's this one. 

My question is this. Has anything changed? This thread and other info I found on it is quite old, but the charger does still seem to be a current model, so I just wanted to check that it is still a recommended charger or if there is something else that has replaced it that I missed. 

Thank you


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## Niconical (Feb 6, 2009)

:bump:...anyone?


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## Mr Happy (Feb 6, 2009)

Well, there is also the C800S of course, compared here.

And if you ever might want to charge C or D cells there is the C808M.

And then there are chargers from other manufacturers, like perhaps this one: http://www.batteryjunction.com/8800.html


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## Bones (Feb 6, 2009)

Niconical said:


> ...anyone?



I think the C801D is a good choice.

The one minor issue I would have with it over the C801S is that its default charge rate is 1C. Since I much prefer to charge at .5C, it would mean always having to remember to select the soft charge.

Conversely, it's always good to have the option of fast charging when you've inadvertently used up your supply of pre-charged cells.

Another advantage the 801D has over the 801S is its serious power supply, which should easily last a lifetime:

http://www.cpfmarketplace.com ... post2246314
.


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## josean (Feb 7, 2009)

I have the C800S since about 4 months.

It is an excelent charger. I only have AA/AAA, so I do not need a charger for C or D size.

The charger does a great work with old and aged batteries. I have been able to recover some batteries that were almost useless with my previous charger (a cheap timing charger).

I have about 40NiMH AA, 15NiMH AAA, 15 NiCd AA and this charger allows me to get the best of every battery. I have no LSD batteries so far, so I have no experience with eneloops or similar.

Regarding LSD batteries, I am just considering to buy 8 NiMH AA GP-Recyko+ according to the recomendations and good experience of a relative.


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## Empath (Mar 21, 2009)

There is a feature, or lack thereof, with the C800S that bugs me. The panel showing the icons doesn't light up with a backlight. Since it never has, I assume that's the way it's intended, unless mine is faulty.

I have to shine my flashlight on it to view the icons. I guess I can't complain about an opportunity to use a flahslight.


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## Black Rose (Mar 22, 2009)

My C800S is the same way.

I keep a fauxton on my charging stand so I can see the LED panel in low light conditions.


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## Empath (Mar 22, 2009)

Thanks Black Rose. I also have a C808M. I guess that made me think backlighting would be the same.


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## Russel (Mar 22, 2009)

SilverFox said:


> Hello Bp,
> 
> Let's pause for a minute and play with some numbers...



These days I've been keeping a MH-C9000 busy on the week ends doing break-in on all my eneloops. So, I've been using the MH-C808M (in addition to charging C and D cells) for charging AA and AAA cells while the C9000 is busy. Up to this point I have been using soft mode, 1000ma for AA cells, figuring that .5C was within the recommended .5 to 1C charging range and that being at the low end would be better for the health of the cells. After reading your post I have to laugh at myself for not wanting to charge at the full 1C rate thinking that it would help prolong the life of the cells. Thank you for taking the time to share your insights. Clearly, charging at 1C instead of .5C isn't going to make enough difference to Eneloop cells to worry about. From now on I will confidently be charging Eneloops in the MH-C808M at the default rate of 2000ma.


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## GarageBoy (Mar 22, 2009)

Wow, you guys actually need a light to see the LCD?
Mines working great, totally replaced my Energizer 15 min charger. 1Hr I can live with and plus, I can leave my non Eneloops in there


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## DavidD (May 18, 2011)

I am looking to get the new Fenix Tk41 which takes 8 AA cells, and so am looking at these three chargers: 808M, 801D & 800S. I don't currently have nor need C's & D's, so I am mainly looking between the 801D and the 800S.

I am a little confused about the charge rates on the 800S for AAA's. MAHA's site seems to indicate that AAA cells are charged at the same rate as AA cells (1A~ and thus need to be charged 'soft' for 500ma), while Thomas Distributing's site indicates that AAA cells are charged at 700ma 'fast' and 350ma 'soft'.

In the instances that I am not charging 8AA's at the same time, but a mix of AA's and AAA's:

re 800S, I would 'fast' AA's (1A) and 'soft' AAA's (500ma) - which prohibits charging both at the same time.

re 801D, I COULD 'fast' AA's (2A) and 'fast' AAA (700ma) OR...
I COULD 'soft' AA's (1A) and 'soft' AAA's (350ma) thus allowing charging of both at the same time.

So, how does the 800S charge AAA cells? If it doesn't have a reduced charge rate for AAA's, I probably will have to get the more expensive 801D. Any other thoughts on any of these three - since they have all been out for a while now, would be appreciated.

I hope all this made sense.

David


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## Chongker (May 18, 2011)

I personally use a C808M as I do have C and D cells, but I suspect some of the basic principles will be similar across all the chargers? The contact point for AAAs is seperate, so the charger detects that the cell is small using this method to set an appropriate charge current, which is as you said, 700mA fast and 350mA slow iirc. Sorry I can't tell you about the other two.


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## snakyjake (Dec 23, 2011)

I've been giving this a lot of thought between C801D versus C800S. I have thoughts to share.

1) The C801S is $25 cheaper than C801D. So I would figure that into the amortized cost. 
2) I have no problems waiting 2 hours for a complete charge (@ 1000mA).
3) I have backup batteries.
4) If my battery is dead, and I have no backup, waiting 1 hour at fast charge isn't going to help me either.
5) The presumption is charging AA batteries at 1000 mA extends the life and capacity versus 2000 mA; charging 0.1C is the manufacturer's recommendation. But perhaps the new Eneloops have lower internal resistance and can take higher amperage without lifespan loss??

Summary: If the quest is save money and maximize battery capacity life, the C800S is the recommendation. It only cost you 1 extra hour of charge time. If you can't wait 2 hours and don't have backups, but can wait 1 hour, then C801S would be the choice.

It is really too bad Maha doesn't have a charger defaulted to 1000 mA, with the option of a 2000 mA fast charge. It seems to me this would be the correct and logical design. So why am I thinking about this and not Maha, or the other manufactures?

Jake


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## 45/70 (Dec 23, 2011)

snakyjake said:


> ......charging 0.1C is the manufacturer's recommendation. But perhaps the new Eneloops have lower internal resistance and can take higher amperage without lifespan loss??



Hi Jake. I don't know where you saw Sanyo recommends a 0.1C charge rate. Last I knew they recommend a 1C rate. Of course you can charge cells at whatever rate you desire, as long as you do not exceed the maximum recommended rate.

My eneloops (1st generation) don't state this on the side of the cell, but many cells state something like "standard charge xxxmA for 16 hrs". This refers to the "IEC standard" by which the capacity of the cell was determined. Following this "standard", cells are charged at a 0.1C rate for 16hrs, rested for one hour, and then discharged at a 0.2C discharge rate to determine the capacity of the cell. The 0.1C "standard" charge isn't necessarily a recommended rate, it's just how the cell's capacity was determined.

Dave


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## snakyjake (Dec 23, 2011)

45/70 said:


> Hi Jake. I don't know where you saw Sanyo recommends a 0.1C charge rate. Last I knew they recommend a 1C rate.



Not Sanyo specific recommendation, but general recommendation. I may be wrong about this, as I just regurgitate what I read. I thought I read and understood correctly that .1C is a slow charge, and 1C is the fast charge. For a 2000 mAh battery: 0.1C = 200 mA, 1C = 2000 mA. Therefore 200 mA is the ideal; 1000 mA more ideal than 2000 mA.


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## 45/70 (Dec 23, 2011)

In the past anyway, it was generally accepted that NiMh cells should be charged at a medium to fast rate. This also applied to NiCd cells, but they are more tolerant of slow charging, being able to accept overcharge better, without being damaged.

One of the reasons behind faster charge rates being preferred over very slow rates, is due to the fact that "smart" chargers often depend on either a -dV termination, delta T, or in many cases both. At slower charge rates this doesn't work very well, as the "signal" is suppressed due to the low charge rate, and often termination of charge is missed, thus damaging the cell(s).

As I said, there's really nothing wrong with charging at any rate that you want, provided a proper and accurate means of charge termination is provided and the maximum charge rate is not exceeded. Actually, at a 0.1C rate, there is likely no damage to either chemistry of cell, as this is the same rate as is used when "forming" nickel based cells. The problem of missed termination when using smart chargers occurs when the charge rate is ~0.3C, or lower. It is at these slow charge rates where many smart chargers will miss termination of charge due to weak signals.

The point I was trying to make in my last post, is that many interpret the IEC standard charge rate as being the standard rate at which to charge cells. It is, but only if you are attempting to determine the capacity of the cell. There are many other charge rates that are acceptable, if you just want to charge your cells, however.

Dave


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## snakyjake (Dec 23, 2011)

I'm reading some more, and think I'm understanding the charge rate a bit more, or at least trying. So here's some "guessing":

I don't quite understand why the charge rate changes with capacity. The only reason I can think of is that high capacity batteries have lower internal resistance, therefore can accept a higher charge rate without generating increased temperature.

It appears the objective of the charge rate (i.e. 1C) is the relationship between the internal resistance and temperature. Amperage contributes to temperature. It is the high temperature that causes decreased life cycle, not the amperage measure. Therefore the logic would be to focus on temperature, not amperage/charge rate. 

If this is true, it would be a better design to measure temperature for the optimum charge rate. An additional attribute for charger evaluation would be to include battery temperature.

Jake


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## SilverFox (Dec 24, 2011)

Hello Jake,

Remember that in addition to internal resistance there is a chemical reaction going on inside the cell. As the chemical reaction reaches completion at full charge, heat is generated. The rate of heat produced is related to the charge rate.

Many chargers offer temperature termination. They just happen to cost more. With temperature termination there is always the question of where and how to accurately and reliably measure the cells temperature, and what, if any, correction factor is needed to translate surface temperature to internal cell temperature. Also, a comparative to ambient temperature is needed to allow for charging at various temperatures.

The main problem with temperature termination of a charge is that different cells, and different ages of cells, have different internal resistance. As a cell ages its internal resistance increases. This means that the cells temperature will be different at the same charge rate when the cell is new versus when the cell has been used for awhile.

Another way to do this is to track changes in the cells internal resistance during charging. As a cell heats up, its internal resistance lowers. The Schulze line of chargers uses this method to adjust charge rate and to terminate the charge. It seems to be more reliable and repeatable than simple temperature change monitoring. 

I will also add that if you want to build your own charger there is information available on the materials needed and how others have approached using cell temperature as a charging termination signal.

Tom


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## snakyjake (Dec 24, 2011)

Thanks Silverfox. I categorized charging and termination in different categories, so I agree with you on temperature termination (whether or not the cells reach full charge or not).


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## Wrend (Dec 26, 2011)

The following is from the Eneloop FAQ.



> *Can I use a "Quick Charger" to charge an eneloop battery?
> *Though it is possible to charge an eneloop battery in a "Quick Charger", it is not recommended. We recommend charging eneloop batteries in a NiMh charger that is 2 hours or more. Charging eneloop batteries in a "Quick Charger" can reduce the overall life of the battery...



Since charging time isn't an issue for me, I choose to follow this recommendation and charge my Eneloops at 0.5C/h.


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## Wrend (Dec 26, 2011)

snakyjake said:


> ...I don't quite understand why the charge rate changes with capacity...



Cell capacity is (more or less) proportional to the amount of the electrochemically reactive material within it. Larger sized cells of the same chemistry type will typically have higher capacities.

As far as the charge rate goes, you can think of it as a charge rate per volume. So in a way, charging a AA Eneloop cell at 1A (1000mA) is roughly the same rate as charging a AAA cell at 400mA. In this sense the rate doesn't charge.

In general NiMH batteries shouldn't be parallel charged, but Li-ion type cells for hobby use often are. If you charge two paralleled LiPo cells at 2A, each individual cell is charged at 1A. The charge rate per amount of available electrochemically reactive material is the same when charging one cell at 1A and two paralleled cells at 2A. Basically, the current is split between the two cells when charged in parallel.

On the other hand, charging two cells in series at 1A is the same as charging one cell at 1A. The difference is that charging the two cells in series requires a higher voltage to push the current into the cells at that rate. Charging the cells in series pushes the current into all of the cells together instead of splitting it up. In order for the current to go through one cell it must also go through the other cells to get there (effectively).

These characteristics correspond with why the capacity of a pack of cells in parallel increases with the amount of cells in parallel but the pack's voltage stays the same regardless of how many cells are in parallel, and why the voltage of a pack of cells in series increases with the amount of cells in series but the pack's capacity stays the same regardless of how many cells are in series. (This assumes all the cells are at the same level of charged capacity as each other to begin with; that is, fully charged, half charged, or whatnot, and that they're the same kind of cells as each other.)


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## gigahertz (Dec 27, 2011)

Quick question on the C800S.

I am wondering what kind of output does the AC wall adapter of the C800S puts out.

What I am trying to see is if it is a simple two contact 12V output to the charger and if it is then I can just make a cig. adapter so I can use the charger in my camping truck.

Thanks~!


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