EEVblog #397 - Turnigy Accucel 6 Charger Teardown

[EEVblog]

Inside the Turnigy Accucel 6 Lithium Ion/Polymer/Iron Phosphate 6A Battery Charger.
And a look at the JBC CD-2BB series soldering iron:
http://www.amazon.com/gp/product/B008LZ30Y4/ref=as_li_ss_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B008LZ30Y4&linkCode=as2&tag=ee04-20

Schematic: http://www.rcgroups.com/forums/showthread.php?t=1362933
MOSFETs:
MT8103A http://www.mtsemi.com/_control/upload_file/MT8103A.pdf
FDS6680 http://www.fairchildsemi.com/ds/FD/FDS6680.pdf




Dave.

[DeepThought]

Man, I'm still blown away by that soldering iron. Dear Santa Claus, I was a very nice boy this year...

Dave you mention some firmware hacks. What is done there and where can I find out more? Do you have some pointers for me?
I don't need a new charger per se, but I'm pretty fed up with the menu and software on my current one. Something more flexible would be great. Certainly worth the investment of some 20 quid.
I especially like to have a nicer LiPo charging method for deep discharged batteries. My current one just says "Go away, I'm not touching this. It's dead."
Get them working again with the NiMh constant current (I think) mode easily, just have to watch the temperature and go low on the amps. Drives me nuts.

[baoshi]

Fantastic video    especially love the schematic analysis part. Frankly I was not expecting the charger to be so well constructed.
A silly question: the dummy load part is directly driven by PWM without any filtering. Is it the best way to discharge a battery? And what's the purpose of measuring back the discharging current from DA1:1 if the mcu is already controlling the current? A safety measure?

Bob

[Skippy]

I really liked this video.

Silly question: Laptops have multicell batteries in them, right? Do laptops contain all of this multicell balancing gubbins? You don't get these big mosfets in laptops that regulate the charging, do you?

[robrenz]

That JBC is $16.00 cheaper if you go direct to the Janel website   

Dave, if you get a cut from that Amazon link please delete this post.

[Plecharts]

Silly question: Laptops have multicell batteries in them, right? Do laptops contain all of this multicell balancing gubbins? You don't get these big mosfets in laptops that regulate the charging, do you?

I have a feeling that most laptops use NiCd battery packs, or at least those I have seen did. You probably don't need to balance NiCd packs, or it does not make that big difference as it does in lithium batteries, where unbalanced pack can lead to big fire easily. Forget it, NiCd and LiIon can look the same...

Dave, what about making it not only regulated load, but also a power supply? I know it probably isn't really precise enough to be a competitor to some more advanced supplies, but it could be a pretty nice power supply for beginners. The unit I have even has auto turn-off on low voltage, so you can even connect it to a battery and make a portable one

[lewis]

Regarding desoldering:

Dave, get yourself once of these mate, they're awesome: http://www.rapidonline.com/Tools-Equipment/Xytronic-LF-6000-Lead-free-Desolder-Hot-Air-Station-77411

or one of these if you're feeling flush: http://uk.farnell.com/pace/8007-0479/soldering-system-mbt-301-td-100/dp/1279346?Ntt=mbt301

We use them both and they're indespensible for repair work!

For those that haven't seen them, it's a soldering iron with a hole up the middle. You heat up the pad on the PCB, press a button, and an electric pump sucks all the solder out of the joint into a collection tube in the iron's handle. No more manual solder suckers, no more soldering braid, no more pulling out plated-through holes, and they are fantastic for double sided and multi-layer boards. Think of it as a miniature heated vacuum cleaner. Expensive, but once you've used one you'll never ever be without it.

[Skippy]

Silly question: Laptops have multicell batteries in them, right? Do laptops contain all of this multicell balancing gubbins? You don't get these big mosfets in laptops that regulate the charging, do you?

I have a feeling that most laptops use NiCd battery packs, or at least those I have seen did. You probably don't need to balance NiCd packs, or it does not make that big difference as it does in lithium batteries, where unbalanced pack can lead to big fire easily.

Dave, what about making it not only regulated load, but also a power supply? I know it probably isn't really precise enough to be a competitor to some more advanced supplies, but it could be a pretty nice power supply for beginners. The unit I have even has auto turn-off on low voltage, so you can even connect it to a battery and make a portable one

I'm pretty certain that laptops use Li ion or Lipo batteries.

[Things]

Hi Dave, funnily enough I ripped apart this chargers bigger brother about 10 minutes before I saw your video!

I'm trying to reverse engineering the cell monitoring circuitry to use in my own projects, but I'm having a bit of trouble understanding how they're doing it.

If you look down near the MUX, you'll see that the BATT- is actually going through a divider into the MUX ... what would be the purpose of this? It seem as if BATT- is never directly connected to ground in the circuit.

Reason I ask is I need to be able to monitor 6 cells individually in my project, but the uC that'll be doing the monitoring will also be powered by the same batteries. I'm worried that the circuit is designed to have the "ground" and BATT- isolated to prevent large voltages on the uC pins.

Could you or someone else possibly explain what's going on here? Would that circuit be suitable when the uC doing the reading is powered off the same battery? Maybe through an isolated DC/DC converter?

Cheers,
Dan

[Plecharts]

I'm pretty certain that laptops use Li ion or Lipo batteries.

Oh well, forgot that LiIon sometimes look like NiCd cells.

[nitro2k01]

I really liked this video.

Silly question: Laptops have multicell batteries in them, right? Do laptops contain all of this multicell balancing gubbins? You don't get these big mosfets in laptops that regulate the charging, do you?

As far as I'm aware, most laptop batteries charge the cells in series, but I've seen sense lines going from the individual cell terminals. Presumably they are used for protection circuitry that prevents charging in under/overvolt condition for individual cells. Perhaps these lines could also be used for balancing.

I have a feeling that most laptops use NiCd battery packs, or at least those I have seen did. You probably don't need to balance NiCd packs, or it does not make that big difference as it does in lithium batteries, where unbalanced pack can lead to big fire easily.

Which decade are your laptops from? I actually own a Toshiba T2000SX vintage 386 laptop which does have a NiCd cell, but that's about the only time I've seen a NiCd in a laptop. I live i Europe. Maybe most laptops in the US (outside the scope or RoHS) are using NiCd cells and I just never knew, but I doubt it.

[T4P]

I have a feeling that most laptops use NiCd battery packs, or at least those I have seen did. You probably don't need to balance NiCd packs, or it does not make that big difference as it does in lithium batteries, where unbalanced pack can lead to big fire easily.

NiCD batteries in laptops ... what, 10 years ago?

I'm pretty certain that laptops use Li ion or Lipo batteries.

till today they are still using 18650s 3s2p arrangement with individual discharging leads at least for a 7.4V system with about 4AH, not sure about the larger packs but probably 6.2AH if they are not cheaping out and making the user pay a bomb for cheap chinese cells (The ones i have came out of a ACER laptop ala 2006, a single core AMD Turion 64 MT-40 Acer laptop that was smashed ... don't ask why)

I'm pretty certain that laptops use Li ion or Lipo batteries.

Oh well, forgot that LiIon sometimes look like NiCd cells.

That's a grevious mistake ...

[PuterGeek]

Those solder and rework stations are way too nice for my wallet! 

I bought an Aoyue solder station and separate rework system (refurbished 2702 was $40 less):
http://sra-solder.com/product.php/6363/22/aoyue_2900_lead_free_compatible_soldering_station
http://sra-solder.com/product.php/6681/1/aoyue_2702a_all_in_one_digital_hot_air_rework_station_110_volt

They worked pretty well in the engineering lab at my former employer. I bought them for my consulting/hobby use after I left. The desoldering tips will clog if you don't keep the filter damp and the desoldering trap springs rusted on the work one (now stainless steel).

I like the pistol grip Aoyue desoldering iron better than the straight Pace style. The combo use the same soldering iron tips (integral heaters) and are ready a few seconds after you switch them on.

There is also an all in one but the refurbished 2702 made the separates a little cheaper and adds a little flexiblity:
http://sra-solder.com/product.php/6936/1/aoyue_2703a_all_in_one_digital_hot_air_rework_station_110v

I'm not sure they would last in production use but they're fine for hobby or lab use. They definitely aren't JBC or Pace quality but both of them and some extra tips cost less than the JBC alone.

[PA0PBZ]

Do I understand correctly that the 'balancing act' works by discharging the cell(s) with the highest voltage and equalizing the cells that way? Looking at the schematic I don't see how it could charge individual cells this way.

[Matje]

Regarding desoldering:

Dave, get yourself once of these mate, they're awesome: http://www.rapidonline.com/Tools-Equipment/Xytronic-LF-6000-Lead-free-Desolder-Hot-Air-Station-77411

Whoa, they shure are gouging you over there in Britain...

This side of the channel the price for one of these http://www.rapidonline.com/Tools-Equipment/Xytronic-LF-8800-Solder-and-Desolder-Station-123560 is about the same as for the LF-6000 above - in Euros actually, not GBP.

[lewis]

Regarding desoldering:

Dave, get yourself once of these mate, they're awesome: http://www.rapidonline.com/Tools-Equipment/Xytronic-LF-6000-Lead-free-Desolder-Hot-Air-Station-77411

Whoa, they shure are gouging you over there in Britain...

This side of the channel the price for one of these http://www.rapidonline.com/Tools-Equipment/Xytronic-LF-8800-Solder-and-Desolder-Station-123560 is about the same as for the LF-6000 above - in Euros actually, not GBP.

Yep, sounds about right! Good old Britannia....

[JonnyBoats]

Dave,

This is another excellent video.

If you re-visit this charger in a future video I hope you show us how you deal with the lifted pads that you indicated could be fixed.

[Monkeh]

I have a feeling that most laptops use NiCd battery packs

Laptops haven't used nicads since about 1980.

[ecat]

Do I understand correctly that the 'balancing act' works by discharging the cell(s) with the highest voltage and equalizing the cells that way? Looking at the schematic I don't see how it could charge individual cells this way.

That's my understanding, and yes the cells are charged in series.

Since the maximum discharge current (1A?) is less then the max charge current (6A depending upon the attached power supply),  I guess the cycle is:
Charge on, discharge off
Wait until at least 1 cell is is fully charged
Charge off, discharge on
Wait until all fully charged cells <= highest voltage of uncharged cells
... repeat until all balanced and charged?

Balanced charge is just one option. Quick charge ignores the individual cell voltages (?).

I thought the really neat thing about this charger was the ability to calibrate it to within 10mV. Then I bought one, then I bought a Solartron 7150+ and discovered the charger was only 10mV over straight out the box  YMMV of course.

[PA0PBZ]

I think that the maximum discharge for a singe cell would be something like 200 mA (6 120 ohm resistors, ~4 volts).

[EEVblog]

That JBC is $16.00 cheaper if you go direct to the Janel website   
Dave, if you get a cut from that Amazon link please delete this post.

I do get a cut, but I don't care where people buy it from. If you can get it cheaper somewhere else then I encourage that.

Dave.

[EEVblog]

Regarding desoldering:
Dave, get yourself once of these mate, they're awesome: http://www.rapidonline.com/Tools-Equipment/Xytronic-LF-6000-Lead-free-Desolder-Hot-Air-Station-77411

or one of these if you're feeling flush: http://uk.farnell.com/pace/8007-0479/soldering-system-mbt-301-td-100/dp/1279346?Ntt=mbt301

We use them both and they're indespensible for repair work!

Yes, we've always had proper through hole desoldering guns at work (usually the Hakko ones). Never have done enough repair at home to warrant one for myself.

Dave.

[ecat]

Regarding desoldering:

Dave, get yourself once of these mate, they're awesome: http://www.rapidonline.com/Tools-Equipment/Xytronic-LF-6000-Lead-free-Desolder-Hot-Air-Station-77411

Whoa, they shure are gouging you over there in Britain...

This side of the channel the price for one of these http://www.rapidonline.com/Tools-Equipment/Xytronic-LF-8800-Solder-and-Desolder-Station-123560 is about the same as for the LF-6000 above - in Euros actually, not GBP.

Yep, sounds about right! Good old Britannia....

I'm sure most UK peeps here know this but for any others: If you can find cheaper within the EU then buy it. No import duties, no extra taxes, just a few extra days for delivery. Want to make sure the company you are buying from? Just ask/google around.

UK pricing is often a joke and the situation has to change or many companies will be out of business. Dave mentioned HobbyKing which makes for a perfect example: Earlier this  year I was looking for a LiPo pack and charger, looked locally, looked at UK mail order, looked at UK ebay. I remembered HobbyKing and found they had just opened a UK warehouse, the prices were incredible but no stock . I waited a week, looked again and bought the Accucel 6 charger + the Nano version of the battery Dave shows for around half the average UK price.

Half price! And not on any special sale and shipped from within the UK. No wonder they were out of stock.

[ttp]

Have one of them for couple of years and it's great, does all my batteries for RC and power tools.

There is hardware mod for it to get serial out to temperature sensor connector, there is a software (forgot the name now) that reads the data from the charger and plots charge/discharge characteristics. I have links at home but I'm travelling now, something to get you started - http://www.rcgroups.com/forums/showthread.php?t=1046318.

[DMX512]

Dave, what about making it not only regulated load, but also a power supply? I know it probably isn't really precise enough to be a competitor to some more advanced supplies, but it could be a pretty nice power supply for beginners. The unit I have even has auto turn-off on low voltage, so you can even connect it to a battery and make a portable one

I had the same idea. I have been wanting to hack my iMAX B6 (basically same as the Accucel 6) into an adjustable power supply, but I haven't got the experience. Sure the output may not be very clean, but it would be a great high current, portable power supply that could be powered from your car (when in the field). I guess it would be similar to Dave's uSupply but with ?0-25V, 0-6A, 50W max output.

If Dave is going to hack the Accucel 6 it into a regulated load, then also try to hack it into an adjustable power supply. Why not put its DC-DC converter to use?