Tutorial: Laptop Battery Pack 18650 Extraction

[xzel87]

So I've been feeling confident lately in regards to my handling of 18650 laptop pull cells. All the cells I've pulled and recovered so far are working very well for their applications

So started to fulfill my curiosities in recovering less than 2.5V cells. My colleague gave me a 2006 laptop pack 2 days ago, took me an hour opening it, it was the toughest battery pack I had to open and I had to literally rip it apart (not the seams, had to rip the plastic casing) to get to the batteries, which turned out to be green bluish Samsung 18650-22B cells.

They all tested 0.01V :shakehead, I proceeded to place them in the bin.

The day after that, I happened to read the thread "how not to repair li-ion cells" where the guy uses a knife and cuts himself :green:. His batteries measured 0 volt and he jump started them with a 12v car battery, which was stupid and there were even sparks.

Unfortunately that made me curious, and the fact that my MC2 has this so called 0V activation so.... what the heck I decided to try it , took out the batteries from the bin and charged one of it...with the usb volt/amp detector I can see that the charger started to charge the battery with 60mah...after about 1 minute of that I took it off the charger and measured voltage was at 1.76, however the voltage was falling by 0.01 every few seconds or so. Popped it back in the charger and now I think it's been an hour plus, and the meter shows that it is being charged at 0.5A, it doesn't feel warm at all. I just checked the voltage a minute ago and it was up to 3.89V

Any input guys?

 

[CuriousOne]

Allow charge to finish, remove from charger, record the voltage. Put it aside, check voltage in 24 hours. If it dropped less than 10mv (0.01v) than batteries are fine.

I had no personal experience in recovering Samsung SDI cells that went below 2V, but I have large experience of such activity with Sanyo and Sony cells. Sanyos usually are dead after - even if recovered, self discharge is high, and capacity is much lower than it was before. Contrary, Sony cells are just fine and show no problems after recovery.

 

[SilverFox]

Hello Xzel87,

The reason we don't recommend trying to recover cells with low voltage has to do with safety. The potential for having damage occur inside the cell increases the longer it is at a low voltage. This is a chemistry reaction issue.

It is always fun to experiment but make sure you assess the dangers involved and take precautions to protect against them.

Tom

 

[zipplet]

Hi Xzel87!

Please do take the advice given by SilverFox. I linked to the video because of how shocking it was and I simply could not believe what the guy was doing. Some kind people have replied to his video and told him he shouldn't be doing that. Look at some of the disaster threads in the "Close calls" sub forum. There are legitimate dangers involved when doing this kind of thing. I'd say it's OK to mess around with reviving cells if they are NiMH or lead-acid, but I would leave lithium cells alone.

Kind regards,
Michael

 

[xzel87]

Appreciate the warning guys. But rest assured that I know of the risks involved in charging those cells that's why I have it charging in a metal container on tile floors with my multimeter (has additional function as a temperature probe) hooked up to it to monitor temperature. So far so good. Have one set charged up and left sitting to check voltage retention after a week. Probably junk cells but just for curiosity's sake I want to know.

 

[audio8]

Hi guys, relative newbie here, hope I'm posting in the right thread (this is the closest topic to my question).

I recently purchased a bunch (6 to be exact) unused Li-Ion battery packs made for some high-end ($5k+) professional portable test equipment. I bought them for the 18650's they are made of - it was a great deal as I got 6 4S3P packs (=72 pieces of Panasonic CGR18650CG's) for $30 on the 'bay. Before starting to extract the individual 18650's I decided what the heck, let's see how good the packs are as they are. It turned out that they have very high quality (based on TI chips) battery management PCBs with balancers, a multitude of protections and two thermal sensors per pack. They are very well built. So I decided to keep some of them in their original setup, as 14.8V 4S3P packs.

Since they were all shut off by the protection circuits when I received them (they were brand new but sat in storage for about 2 years), I checked the voltages directly at the battery terminals, bypassing the protection circuits, and they all measured 8-9V (2.0-2.25V per battery), so I knew they should be salvageable. I successfully "revived" and charged the packs with a 4S charger, and they all charge and work fine.

The only thing I wasn't able to figure out is the connections on the pack - the manufacturer purpose-built these packs for their equipment and doesn't publish any specs on the battery packs. I tried google to find a comparable battery management board, to no avail.

The battery management boards are branded "Galaxy" and there is a model number (I guess) "4L" on them. it is built around the TI BQ29330 and 20Z70 chips. My confusion is about the external connections. The pack has a connector with 4 wires: the usual P+ and P- are red and black. But there is also a green wire marked "D" on the PCB and a white one marked "C". From what I learned from googling this is that "C" may be a separate charging connection, I haven't found anything about "D".

I charged the packs using the P+ and P- connections, and this worked fine.

What is confusing for me is that when the packs are fully charged, I get 11.8V between P+ and "C" and also between P+ and "D" (it is the expected 16.6 - 16.8 between P+ and P-).

So here is what I don't know:

1. Is "C" a charging connection? If so, why do I get a voltage reading (at all) on it, and why about 5 V lower than the P+/P- terminals?
2. If "C" is indeed a charging connection, can I cause any damage by charging the pack through the P+ / P- connections, as it is implemented on other battery management PCBs?
3. What is the "D" connection?

Any input would be appreciated - thanks!

 

[CuriousOne]

"C" stands for "center" - equipment needs them for some purposes.
"D" usually stands for "data" - battery gives device info about it's serial, capacity, etc.

These batteries come from Broadcast grade cameras, aren't they?

 

[audio8]

"C" stands for "center" - equipment needs them for some purposes.
"D" usually stands for "data" - battery gives device info about it's serial, capacity, etc.

These batteries come from Broadcast grade cameras, aren't they?

Thanks CuriousOne - the packs are made for Sunrise Telecom STT-1505A ("Scaleable Test Tookit" - basically a rugged "suitcase" computer with a bunch of different test modules for networks, etc.). http://www.itm-group.com/datenblaetter/Sunrise/stt.pdf

Do you mean that "Center" would be a lower voltage connection tapped from the "middle" between series packs?

If the "D" connection is for data, why does it have 11+ Volts on it? I would expect data connections to have 0 volts until there is some communication, at which point the logical state change would cause it to oscillate between low (0V) and high (5V) doesn't it? Or, am I missing something?

Thanks!

 

[CuriousOne]

My info is based on personal experience of importing video camera chargers and batteries from China. Some came with older firmware, so it was necessary to update firmware, otherwise newer cameras would say that battery is not genuine.

In your case, if you post photos of PCB, a lot of questions will be answered imediately and with better precision.

 

[audio8]

My info is based on personal experience of importing video camera chargers and batteries from China. Some came with older firmware, so it was necessary to update firmware, otherwise newer cameras would say that battery is not genuine.

In your case, if you post photos of PCB, a lot of questions will be answered imediately and with better precision.

Thanks - good point. Here are some photos:

The battery pack:

Here's what's inside:

A close up of the PCB:

 

[ginbot86]

The C and D pins are used to communicate with the bq20z70 fuel gauge on the PCB, and both of them should be near zero volts with respect to P-.

The chipset on the PCB makes this battery pack a "smart battery" - one that has built-in intelligence to keep tabs on the battery's capacity, voltage, temperature, etc. There is this program called PackProbe that lets an Arduino microcontroller read out the information from smart batteries (mostly laptop batteries but any Smart Battery System (SBS) compliant battery can be read out). (link here: http://powercartel.com/projects/packprobe/ )

P+ and P- are the normal connections that you'll use to the battery pack.

 

[audio8]

The C and D pins are used to communicate with the bq20z70 fuel gauge on the PCB, and both of them should be near zero volts with respect to P-.

The chipset on the PCB makes this battery pack a "smart battery" - one that has built-in intelligence to keep tabs on the battery's capacity, voltage, temperature, etc. There is this program called PackProbe that lets an Arduino microcontroller read out the information from smart batteries (mostly laptop batteries but any Smart Battery System (SBS) compliant battery can be read out). (link here: http://powercartel.com/projects/packprobe/ )

P+ and P- are the normal connections that you'll use to the battery pack.

Thanks a lot - great info. Yes, the C and D connections read 0 if I measure against P-. The arduino software looks great - unfortunately, while I'm using raspberry pi's for a project, i don't have any arduinos around... But since that's optional, I'm fine with this info for now and may try the arduino software later.

Just to confirm: so both charging and discharging the battery would be trough the P+ / P- connections - did I get that right?

And one last question: is it okay to charge and use (to power connected equipment) a smart battery pack like this at the same time? I.e. if I am using the pack to power a gadget and the battery gets low, can I just connect a Li-Ion charger and keep using the equipment powered by the battery with the charger connected?

 

[ginbot86]

Thanks a lot - great info. Yes, the C and D connections read 0 if I measure against P-. The arduino software looks great - unfortunately, while I'm using raspberry pi's for a project, i don't have any arduinos around... But since that's optional, I'm fine with this info for now and may try the arduino software later.

Just to confirm: so both charging and discharging the battery would be trough the P+ / P- connections - did I get that right?

And one last question: is it okay to charge and use (to power connected equipment) a smart battery pack like this at the same time? I.e. if I am using the pack to power a gadget and the battery gets low, can I just connect a Li-Ion charger and keep using the equipment powered by the battery with the charger connected?

Yes, charging and discharging is done through the P+/P- connections.

As for simultaneous charge and discharge, it is fine to an extent. Any current drawn from the battery while charging can affect the charge time and, if the charger has a timer, could cause charging to terminate before the battery is full.

 

[audio8]

Yes, charging and discharging is done through the P+/P- connections.

As for simultaneous charge and discharge, it is fine to an extent. Any current drawn from the battery while charging can affect the charge time and, if the charger has a timer, could cause charging to terminate before the battery is full.

Great, thanks a lot for the info!

 

[RolandK]

hi,

i`m doing battery extraction from dead laptop packs for a while now and i wrote down the data for every cell.

from that i have made some statistics to show the typical condition of such cells. apparently, more than half of all cells are in pretty good shape and have more than 80% of their original capacity.

the cells were measured with Opus BT-3100 V2.1 charger.
all battery packs were "ready for trash", i.e. they had been sorted out to be put into the recycling box.

does anybody know if there are other statistics like these around?

regards
roland

 

[CuriousOne]

It had been confirmed (by several servicemans) that for example, Samsung made battery packs for laptops, will cut off output after 300 cycles of charge-discharge, no matter how bad or good cells really are. Actually, serviceman reset the counter in these batteries to prolong their life.

 

[RolandK]

Actually, serviceman reset the counter in these batteries to prolong their life.

there is a professional tool for this at http://be2works.com/

 

[varons666]

Hi Guys,

Hoping your'll can help me out as i cant understand this....
so ima NOOB, i have opened a samsung laptop battery and extracted 6 (Red, looks like sanyo) cells, when extracted test voltage on pack was 10.8v (battery says 11.1v) and tested mah was +-17500 (17.5ah), so from that these cells should be around 3.7v 3000mah each, cells where connected in series and parallel and this is the part that gets me, pack it wired, (3 x 2 cells in parallel, and those 3 sets are connected in series) which is fine to get the voltage but how does the mah add up? it should be 10.8v at 6000mah so how is the mah increasing in series?

then 2nd prob, i disconnected the series connections so now i have 3 sets of 2 cells in parallel, 1 set measures 3.65v at +-6000mah but when i connect another set to it (4 cells in parallel) the mah should be 12000mah but its not, mah only increases by 200mah and i have tested all 3 set individually and they test fine with just 2 cell in parallel.

please help if you can

 

[xzel87]

test individual batteries, what you're doing you're not getting accurate voltage reading and mah reading.

 

[varons666]

test individual batteries, what you're doing you're not getting accurate voltage reading and mah reading.

Ok so i took your advise and disconnected the 2 cells, 1 cell measures 3.6v at 6600mah, in parallel the mah is not doubling but i connected the silent cells in series and i get 7v at 12000mah