BM200 Charger information.

[Jinx]

@danaco

@Jeansy

@danaco

@Jeansy

How accurate is it at termination at various charge rates? What parameters terminate charge?

Hi Jeansy,
Full charge event is -dV like all NiMH chargers. There is a secondary 0dV condition that is checked as well. Depending on either one of those the full condition is set. The 0dV is a backup event, the -dV condition is primary for full charge termination.

I have never seen it miss the termination point on good quality cells, or any cells I tested for that matter. I have tested at all available rates from 200 to 1400 mA. Of course the concern is that at lower rates of charge it is harder for the charger to detect the -dV condition. This charger seems to be very good at determining that event. I suspect the addition of the 0dV algorithm backup may help with that. I have not gotten any reports from testers or customers about the charger missing charge termination. That does not mean it has not happened since not everyone would communicate that to me.

Hope that answered your question.

There are some other conditions that will terminate charge as well which are being added to the new model. They are backup events in case of defective cells or other abnormal conditions. However those are not in the current shipping charger. They will be in the new model. I should have some of those pre-production units for testing within the next week or two.

Thanks,

Thanks for the reply, so the charger doesn’t monitor dT or have a timer (say 16hrs) as back-up termination?

Not sure what you mean about monitor dT. If T is temperature then no, that is not a full charge termination event. However over temperature limit does suspend charging on the affected channels only, charging resumes with all parameters stored when temp below limits on the affected channel. All four channels monitored for temperature individually. dV (delta Voltage) is monitored for full charge event, both -dV and 0dV algorithms. No timer since charging a high capacity D cell could take quite a while. 20,000 mAh of charge is a terminating condition. I think that is everything but I will double check it. There may be a high V termination to catch high impedance cells but I am not sure if that is in the current version. I am working on the new unit and things are starting to run together in my head.

In the new model there will be other backups to better deal with defective cells and such. But they are not in the current shipping model and so I am not ready to discuss them as they may change before production.

Thanks,

Ok thanks for expanding, I hope you don’t think I’m being an ass asking all these questions, I’m genuinely interested and learning.

As for what I was referring to, I’ll allow Wikipedia to explain better than I can;

ΔT temperature charging method[edit source]
The ΔT temperature change method is similar in principle to the ΔV method. Because the charging voltage is nearly constant, constant-current charging delivers energy at a near-constant rate. When the cell is not fully charged, most of this energy is converted to chemical energy. However, when the cell reaches full charge, most of the charging energy is converted to heat. This increases the rate of change of battery temperature, which can be detected by a sensor such as a thermistor. Both Panasonic and Duracell suggest a maximum rate of temperature increase of 1 °C per minute. Using a temperature sensor also allows an absolute temperature cutoff, which Duracell suggests at 60 °C.[15]
With both the ΔT and the ΔV charging methods, both manufacturers recommend a further period of trickle charging to follow the initial rapid charge.

Do you also continue to trickle charge? Will the charger kick back in fully at a certain trigger point?

[danaco]

@Jeansy

@danaco

@Jeansy

@danaco

@Jeansy

How accurate is it at termination at various charge rates? What parameters terminate charge?

Hi Jeansy,
Full charge event is -dV like all NiMH chargers. There is a secondary 0dV condition that is checked as well. Depending on either one of those the full condition is set. The 0dV is a backup event, the -dV condition is primary for full charge termination.

I have never seen it miss the termination point on good quality cells, or any cells I tested for that matter. I have tested at all available rates from 200 to 1400 mA. Of course the concern is that at lower rates of charge it is harder for the charger to detect the -dV condition. This charger seems to be very good at determining that event. I suspect the addition of the 0dV algorithm backup may help with that. I have not gotten any reports from testers or customers about the charger missing charge termination. That does not mean it has not happened since not everyone would communicate that to me.

Hope that answered your question.

There are some other conditions that will terminate charge as well which are being added to the new model. They are backup events in case of defective cells or other abnormal conditions. However those are not in the current shipping charger. They will be in the new model. I should have some of those pre-production units for testing within the next week or two.

Thanks,

Thanks for the reply, so the charger doesn’t monitor dT or have a timer (say 16hrs) as back-up termination?

Not sure what you mean about monitor dT. If T is temperature then no, that is not a full charge termination event. However over temperature limit does suspend charging on the affected channels only, charging resumes with all parameters stored when temp below limits on the affected channel. All four channels monitored for temperature individually. dV (delta Voltage) is monitored for full charge event, both -dV and 0dV algorithms. No timer since charging a high capacity D cell could take quite a while. 20,000 mAh of charge is a terminating condition. I think that is everything but I will double check it. There may be a high V termination to catch high impedance cells but I am not sure if that is in the current version. I am working on the new unit and things are starting to run together in my head.

In the new model there will be other backups to better deal with defective cells and such. But they are not in the current shipping model and so I am not ready to discuss them as they may change before production.

Thanks,

Ok thanks for expanding, I hope you don’t think I’m being an ass asking all these questions, I’m genuinely interested and learning.

As for what I was referring to, I’ll allow Wikipedia to explain better than I can;

ΔT temperature charging method[edit source]
The ΔT temperature change method is similar in principle to the ΔV method. Because the charging voltage is nearly constant, constant-current charging delivers energy at a near-constant rate. When the cell is not fully charged, most of this energy is converted to chemical energy. However, when the cell reaches full charge, most of the charging energy is converted to heat. This increases the rate of change of battery temperature, which can be detected by a sensor such as a thermistor. Both Panasonic and Duracell suggest a maximum rate of temperature increase of 1 °C per minute. Using a temperature sensor also allows an absolute temperature cutoff, which Duracell suggests at 60 °C.[15]
With both the ΔT and the ΔV charging methods, both manufacturers recommend a further period of trickle charging to follow the initial rapid charge.

Do you also continue to trickle charge? Will the charger kick back in fully at a certain trigger point?

Oh no, the questions are why I am here in the forum.

Yes, now I understand. That is be a viable method of detecting full charge if the cells were isolated from other thermal sources. As they state little heat is generated by the battery until the cell reaches full charge, after that the charging energy is converted to heat. In it’s present form the BM200 is not capable of that full charge detection method due to thermal contamination from the charge circuits, as is the case with most low cost chargers. In the new model thermal isolation will be improved and there will be thermal measurements used but not the exact method stated above.

The charger is a constant current charger until full charge is detected then charge is terminated and maintenance trickle charge is applied.

I do not have the exact number handy but it is somewhere around 10 or 20 mA. I will get that number for you.

After full charge termination event and trickle charge applied the charger will not reset into any other mode without user intervention.

[Chloe]

In event of power failure during charge cycle, how does the charger behave? Does it have default charging settings?

What happens when you put in already charged cells? How long does it take to detect if they are fully charged and (presumably) enter trickle charge?

[danaco]

@Chloe

In event of power failure during charge cycle, how does the charger behave? Does it have default charging settings?

What happens when you put in already charged cells? How long does it take to detect if they are fully charged and (presumably) enter trickle charge?

In the event of a power failure the charger will default to charge mode at 200 mA upon power up.

Charging fully charged cells terminates usually within a few minutes after start of charge. However this depends on the cells being charged more than the charger. Poor cells with high internal resistance may take longer.

In answer to a previous question about trickle charge rate. The rate depends on the cells internal resistance. It is between approximately 5 - 20 mA. Trickle charge is accomplished by setting the PWM to minimum.

[danaco]

@HKJ

It is very interesting to see these pictures of chargers.

@kreisler

however Japcell, a Denmark company from the Skandinavias, licensed it and is redistributing it as BC4001 model.

japcell has placed its webserver in Denmark, but is not registered as a company in Denmark.

I see the Japcell charger. That is not the same charger even though they look the same. This BM200 has different charge circuits and firmware so that it can do cells up to 20 Ah. Comes with C&D adapters for charging and testing high capacity C & D cells. That is the old version that they had Opus print their name on for retail. It can only do cells up to 3000 mAh. Confusing yes. I will fix that shortly. Sorry to be adding to the confusion.

[Chloe]

Danaco, do you have any other chargers you can test (even lower current Ni-MH)? I started a thread recently about charging temps and your thermal imaging would be a great contribution there!

[danaco]

@Chloe

Danaco, do you have any other chargers you can test (even lower current Ni-MH)? I started a thread recently about charging temps and your thermal imaging would be a great contribution there!

Yes, I have lots of chargers. All the PowerEx chargers. Some Tenergy chargers. The La Crosse chargers. Tell me what you would like to see and I will take some thermals of it. I assume everyone is most interested in AA chargers??

[Chloe]

Hi Danaco, yes I think AA and AAA are the most popular Ni-MH sizes. Although hobby charger data would be nice I would prefer to focus on the kind with built-in charging bay (preferably using the internal power supply for fairness of comparison). Do you have any Nitecore/Jetbeam i4 intellicharger too?

[picrthis]

@Chloe

Hi Danaco, yes I think AA and AAA are the most popular Ni-MH sizes. Although hobby charger data would be nice I would prefer to focus on the kind with built-in charging bay (preferably using the internal power supply for fairness of comparison). Do you have any Nitecore/Jetbeam i4 intellicharger too?

@ Danaco………if you don’t have one let me know and I’ll ship one out to you.

[danaco]

@picrthis

@Chloe

Hi Danaco, yes I think AA and AAA are the most popular Ni-MH sizes. Although hobby charger data would be nice I would prefer to focus on the kind with built-in charging bay (preferably using the internal power supply for fairness of comparison). Do you have any Nitecore/Jetbeam i4 intellicharger too?

@ Danaco………if you don’t have one let me know and I’ll ship one out to you.

Nope, don’t have any of the Nitecore chargers. When I get it I will do a full thermal workup on it.
BTW picrthis I should have a charger to send to you for testing by Thursday.

I just started an AccuPower Accumanager 10 charger with 4 AA cells. I will post those thermal pics soon.

[picrthis]

@danaco

@picrthis

@Chloe

Hi Danaco, yes I think AA and AAA are the most popular Ni-MH sizes. Although hobby charger data would be nice I would prefer to focus on the kind with built-in charging bay (preferably using the internal power supply for fairness of comparison). Do you have any Nitecore/Jetbeam i4 intellicharger too?

@ Danaco………if you don’t have one let me know and I’ll ship one out to you.

Nope, don’t have any of the Nitecore chargers. When I get it I will do a full thermal workup on it.
BTW picrthis I should have a charger to send to you for testing by Thursday.

I just started an AccuPower Accumanager 10 charger with 4 AA cells. I will post those thermal pics soon.

OK, don’t waste your money on one because for AA they run too hot (my person opinion) I’ll get a new one out to you, I have more than I need, keep for your collection to compare against. :bigsmile:

PS: for 18650’s they are OK

[veer (vēer)]

Hehe, I like this thread :D!

[picrthis]

@Chloe

Hi Danaco, yes I think AA and AAA are the most popular Ni-MH sizes. Although hobby charger data would be nice I would prefer to focus on the kind with built-in charging bay (preferably using the internal power supply for fairness of comparison). Do you have any Nitecore/Jetbeam i4 intellicharger too?

Hi Chloe,

I had a very busy work week last week and I wasn’t able to ship the i4 out to Danaco until this morning in fact, but he should have it by Weds/Thur (8/28 or 8/29)

[Muskrut]

Danaco

I like your site and the way you explain the tech to a layman like me.

Some picture below. The charger is available on web site danaco.net and on ebay. It does use 12V input (2 Amps needed for maximum charge current) and can work with suitable car adapter for portable use or even with a solar panel in the field.

I have just bought a BM200 with the C and D adapter but the input is 12v 1.5 amps.
Is this an old model? I bought it from ebay. Item number 200952905605 its still listed as I write.

Should I return the BM200 and buy a Maha Powerex MH-C808M?

I normally just use AA’s and a few AAA’s but C and D’s poss in future.

And should I go for 2500mah eneloop xx or stick with the white 2000mah eneloop? Cos the white has a longer Lsd typically 75% after 5 years plus 1800 charges. Where as the eneloop xx may have a slightly higher mah, it only hold 85% after a year plus can only be charged 500 times.

Also is it true that these batteries have a lifespan of around 4 years regardless of use?

If you recommend I keep the BM200 then will the issue with thermals effect my batteries? or should I put a usb fan on the unit while charging?

Cost is not an issue with the recommendation you give.

Would be grateful for some guidance

Paul

[danaco]

Hi Paul,

Let me start with the BM200. I always accept returns. I asked that it be returned in the same state it was shipped.
The BM200 that you purchased has been modified for better thermal performance. It is on par with chargers like the BC-1000 when charging 4 cells at 1000 mA. Not that great actually. However if you charge 4 cells at or below 800 mA then you will see no issues and thermal performance is good. There are no issues with C and D cells either. Using a fan cures any of those thermal issues. You got the charger at a good price because I am selling out remaining stock. This charger is no longer being produced. It is on sale and will remain so until gone.

If you need to charge 8 C or D cells at once then the MH-C808M is a good choice. The reason for the BM200 is the ability to test C and D cells, the C808M can not do that.

As far as the eneloop batteries go. It depends on your application. If very long shelf life is important then stick with the eneloop white cells. If you need the higher capacity and good shelf life then the XX are the way to go. I will say the eneloop XX AA cells are just about the best all around that I have tested. High capacity, long shelf life, low internal resistance. They are just a bit pricey. I have seen no documentation about a 4 year limit on the cells. It is really the number of cycles that determine cell life. Unless they are over heated, then all bets are off.

Hope that helps,
Thanks,
Robert

[Muskrut]

@danaco

Hi Paul,

Let me start with the BM200. I always accept returns. I asked that it be returned in the same state it was shipped.
The BM200 that you purchased has been modified for better thermal performance. It is on par with chargers like the BC-1000 when charging 4 cells at 1000 mA. Not that great actually. However if you charge 4 cells at or below 800 mA then you will see no issues and thermal performance is good. There are no issues with C and D cells either. Using a fan cures any of those thermal issues. You got the charger at a good price because I am selling out remaining stock. This charger is no longer being produced. It is on sale and will remain so until gone.

If you need to charge 8 C or D cells at once then the MH-C808M is a good choice. The reason for the BM200 is the ability to test C and D cells, the C808M can not do that.

As far as the eneloop batteries go. It depends on your application. If very long shelf life is important then stick with the eneloop white cells. If you need the higher capacity and good shelf life then the XX are the way to go. I will say the eneloop XX AA cells are just about the best all around that I have tested. High capacity, long shelf life, low internal resistance. They are just a bit pricey. I have seen no documentation about a 4 year limit on the cells. It is really the number of cycles that determine cell life. Unless they are over heated, then all bets are off.

Hope that helps,
Thanks,
Robert

Thank you Robert

My apologies if I confused you.
I did not mean to imply that I bought the unit from yourself. It was bought from a vendor in China which is why I gave the ebay item number in my previous post.

Just wanted you to have a cursory look at the item and confirm whether I was sold an old model or the newer updated version.

What is the item number for your listing anyway?

[danaco]

@Muskrut

@danaco

Hi Paul,

Let me start with the BM200. I always accept returns. I asked that it be returned in the same state it was shipped.
The BM200 that you purchased has been modified for better thermal performance. It is on par with chargers like the BC-1000 when charging 4 cells at 1000 mA. Not that great actually. However if you charge 4 cells at or below 800 mA then you will see no issues and thermal performance is good. There are no issues with C and D cells either. Using a fan cures any of those thermal issues. You got the charger at a good price because I am selling out remaining stock. This charger is no longer being produced. It is on sale and will remain so until gone.

If you need to charge 8 C or D cells at once then the MH-C808M is a good choice. The reason for the BM200 is the ability to test C and D cells, the C808M can not do that.

As far as the eneloop batteries go. It depends on your application. If very long shelf life is important then stick with the eneloop white cells. If you need the higher capacity and good shelf life then the XX are the way to go. I will say the eneloop XX AA cells are just about the best all around that I have tested. High capacity, long shelf life, low internal resistance. They are just a bit pricey. I have seen no documentation about a 4 year limit on the cells. It is really the number of cycles that determine cell life. Unless they are over heated, then all bets are off.

Hope that helps,
Thanks,
Robert

Thank you Robert

My apologies if I confused you.
I did not mean to imply that I bought the unit from yourself. It was bought from a vendor in China which is why I gave the ebay item number in my previous post.

Just wanted you to have a cursory look at the item and confirm whether I was sold an old model or the newer updated version.

What is the item number for your listing anyway?

I see. Thanks for pointing that out. I took a look, I am not happy about that listing. I have no idea what version that charger is. My chargers are marked by internal identification. They are not supposed to be selling those C&D adapters to others either. So much for that. Have you tried any C&D cells to see if it handles the high capacity cells?? Sorry, I can not give you any guidance on that charger.

Here is the listing for my BM200. 231019038042
Like I said I am selling out stock and it is no longer produced. At least not for me.

Here is the listing for the new charger. Complete redesign even though they look the same. An extensive amount of development work went into this new charger for excellent thermal performance and functionality.
BT-C2000. item 331042777396

Thanks,
Robert

[ohaya]

Hi,

I don’t know if anyone noticed, but he dropped the price of the BM200 on Ebay to $29.47:

http://www.ebay.com/itm/231019038042?ssPageName=STRK:MEWNX:IT&\_trksid=p3984.m1439.l2649

2 hours left on it at this point, so I went ahead and bought one :)…

[danaco]

Take your time. I will keep them on sale until stock is gone. I expect they will last through the Christmas season. This is a great deal.
BM200 is no longer in production, at least not for me, can not say about the Chinese sellers that have popped up everywhere, that copy the text from my listings.

The new charger is shipping. Opus BT-C2000. Almost a complete redesign. It fixes any known issues plus many improvements. Thermal performance is very good. I believe it is a worthy charger.

Enjoy,
Robert

[danaco]

@kreisler

@danaco

The new charger is shipping. Opus BT-C2000. Almost a complete redesign. It fixes any known issues plus many improvements. Thermal performance is very good. I believe it is a worthy charger.

If you could arrange to send out a review sample to the community, we’d appreciate it. There is always a willing reviewer somewhere among us crowdies

Thanks Robert for everything you’ve been doing for the charger scene!

A charger has been sent for a published review. However it will probably take over a month for that to be finished. Until then I am happy to answer any questions. Perhaps I need to start a new thread for this charger?? Yes, me thinks so. I will try to get a new thread with charger information up by this weekend.

Thanks,
Robert