Connecting an AC adapter directly to Dell Inspiron 8200's battery jack

[claudem]

I have an old Dell Inspiron 8200 which is in good working condition except for the laptop's (inner) converter that is responsible for using the power supplied by the laptop's AC adapter, using it to both charge the battery and to power the computer while the battery is in. This is a known issue with this laptop model that has caused problems to a lot of people once these laptops start getting old.

Aside from the laptop's original AC adapter (with an output of DC20V 4.5A), I also happen to own another high quality AC adapter (from another laptop long gone), which happens to have the exact output as this laptop's battery, that is, DC15V 4.5A.

Now, what I would like to do is to bypass the faulty laptop's (inner) converter (that is, the problematic circuitry inside the laptop), get rid of the laptop's battery (which does not work anyway), and connect my quality DC15V 4.5 AC adapter (which as I said provides the exact same output as a fully charged battery for this laptop) directly to the battery jack inside the laptop.
Basically, this way, the laptop will "think" that a fully charged battery is in. I've tested it with another working battery from the repair shop, and the laptop works perfectly fine with the power supplied by a battery inserted in the battery jack.

However, I am not sure to which two out of the six or seven battery jack connectors (of the battery jack inside the laptop) I need to solder the + and - output wires from the DC15V 4.5A AC adapter (actually, I will not solder the output wires from the adapter directly to the battery jack, but will make it unpluggable, for convenience/safety reasons).

Could someone who exactly understands what I'm talking about here please provide some directions in this regard? All I need to know is which (two) battery jack wires I need to connect the DC15V 4.5A adapter output to. Thanks.

 

[claudem]

That looks like the jack linked by Maxx_Power.

Yes, you are correct, that's my jack then. My bad

Anyway, I've disassembled the battery pack. It is a Dell Battery Module, Rechargeable Li-on Battery, type 66Whr, Capacity 66Whr, Rating: 14.8V 4460 mAh. It consists of 8 battery cells, 4 groups of 2, each two in parallel and the four groups in series which achieves the battery rating above. Cells are Sony Fukushima STG US 18650GR. I've taken 8 pictures showing the details and the connections, but don't seem to find a way to post them here. How do I go about posting the pictures I've taken? Advice?

There are one red wire and one black wire which emerge from the battery pack and go into the battery circuit, which I assume to be the positive and negative to which I should attach the output from the AC to DC adapter. I would like to post the pictures first, though, to see what you guys think and receive any suggestions you may have before going ahead with the deed.

 

[claudem]

If you disassemble the battery make a diagram of how everything is connected. Cells , circuits, and the rest and post it in your answer. That way I will determine how you should replace the cells with the psu you have.

I've disassembled the battery and taken a few pictures. I think I've located the the two wires I need to attach the PSU to, but would like some feedback before I go ahead. Does tomshardware allow pictures uploading, or should I place them elsewhere and link to them?

 

[nukemaster]

in general, you just upload to a host like dropbox/imageshack ect

You can embed with BB code IMG tags

 

[jarotech]

You can replace each group of cell with a resistance of 100K ohms, connect the positive (+) to the terminal 1 and negative (-) to the terminal 7. We'll see if the four resistors will replace the cells.

 

[claudem]

You can replace each group of cell with a resistance of 100K ohms, connect the positive (+) to the terminal 1 and negative (-) to the terminal 7. We'll see if the four resistors will replace the cells.

It doesn't seem very easy to do what you suggest *at this point*. Unfortunately, your directions to replace each battery group with a 100K ohm resistor came after my disassembling the battery and all those connections that were in there between the cells have now been destroyed in the process. I didn't know I was supposed to replace each battery group with a resistor, in which case I would have preserved them. Sorry. Perhaps I can reconstruct the connections by looking at the pictures.
From the pictures it can be seen that there are two short wires (red and black ones) that from the battery groups go to the circuit board of the smart battery. I assume those to be the DC14.8V 4460mAh from a fully charged battery. The path to the actual jack terminals is solidly enclosed and not easily accessible without breaking up something. So the DC output from the 15V 4A charger, I think, should probably go to those two wires in order to simulate the presence of a battery in the bay. As it can be seen, there are three longer wires (one yellow and two white ones) that go from the smart battery circuit board to the middle and to the back of the battery groups. I assume those to have to do with the recharging regulator, SMB clock, data, etc. Plus there is a sensor located near the middle of the battery groups (the black one, not sure if it can be seen in the pictures) which goes to the circuit board, which I assume to be the temperature sensor.

Please take a look at the pictures and let me know what you think.

 

[claudem]

Unfortunately, I can see that somehow the pictures are now less clear after uploading than they are on my computer.... Hope they can still be useful, though.

 

[claudem]

UPDATE: I went ahead and soldered the DC15V 4A output to red wire (+) and black wire (-) - the wires attached to the smart battery circuit board, then turned the power on. I then measured with a voltmeter. As expected, there was DC15V at red/black wire connections, however no current whatsoever at battery terminal.
I think it's much more complex than what it appears to be and that the smart battery system checks that cells be present and that there be a handshake between all components *before* allowing power to the terminal. The smart battery is like a small computer system, independent, within the laptop system.
The following is some very interesting reading for those who want to learn more about the SMB bus and its implications:
http/media.blackhat.com/bh-us-11/Miller/BH_US_11_Miller_Battery_Firmware_Public_WP.pdf
What I'll try next (I have nothing to lose a this point) is I'll get rid of the circuit board within the smart battery and all other connections and then apply the DC current from 15V 4A adapter directly to battery terminals 1 and 7 as suggested. I have a very important question, though, which I'd much appreciate to have answered before I go ahead with it:

"You can replace each group of cell with a resistance of 100K ohms, connect the positive (+) to the terminal 1 and negative (-) to the terminal 7. We'll see if the four resistors will replace the cells."

Would you please refer to the pictures above and let me know which one is in your opinion terminal 1(+)? Is it the one near the outside edge of the battery or is it the innermost one? Many thanks.

EDIT: Is terminal 1 (positive +) A or B in the picture below?

 

[jarotech]

Li-Ion Battery Pinout

1 - bat voltage
2 - smbclk
3 - smbdat
4 - ground use in laptop for battery presence connected to 7
5 - syspress
6 - nc
7 - ground

From your picture I don't really know if A or B is the positive. But what you said about the handshake between the battery and laptop is true.

 

[claudem]

So, is there a way to find out which one is the + positive and which one is the ground? The battery is a Dell Battery Module, Rechargeable Li-on Battery, Type 66Whr, Capacity 66Whr, Rating: 14.8V = 4460mAh

it reads:

Made in Japan
2-171-008-12

and there is a sticker on it reading:

JP-02U265-48330-2CS-3FDH
REV. A02

If anyone knows how to learn more about the wiring of this battery, please post here and please let me know. I'm interested in knowing, concerning terminals 1 and 7 , which one is the positive + and which one is the ground. Thanks.

 

[ratedk]

Look for connections on the battery's board, near the pins, that share a common conductor, that is most likely the ground

 

[claudem]

I found out from a reliable source that the correct terminal numbering for this specific battery (Dell Battery Module Type 66Whr) is this:



1 gnd
2
3
4 gnd
5 data
6 clk
7 +

So, having gotten rid of everything inside the battery shell except for the terminal, and connecting the DC15V 4A transformer ground to 1 and 4 and positive to 7, and inserting the battery shell thus powered into battery bay, I finally attempted to start laptop. Pressing on the power button, the battery led lights up intermittently for a while (intermittent green light on, as if battery is being charged), then, after about 20 seconds of that, led goes steady orange (meaning battery is not sufficiently charged) and the computer shuts off (as it would with an insufficiently charged battery in bay and no AC adapter connected).

I think the laptop's SMB system is getting highly confused because while it is getting proper values from battery terminals 1, 4 and 7, it receives no expected values from 5 and 6....since there is nothing attached to 5 and 6. If only there were a way to put to sleep the laptop's SMB mechanism seeking handshake with smart battery data, this setup would work out perfectly well.......

EDIT: Question: Could it be that it simply needs more amperage? It has also just occurred to me that perhaps power management could be possibly turned off in the BIOS....but I have no idea if it would affect this behavior (problem is that I cannot access the BIOS unless the computer turns on). Do you have any ideas or suggestions you would like to contribute along the lines of getting the computer to work this way? Thanks.

 

[jarotech]

I don't know what is your source, but the terminals 5 and 6 are not connected to your laptop. The SMB is seeking information with terminals 2 and 3. If you made a graph of your connections when you removed the battery, it will be easier to connect the resistors in place of the cells.

 

[claudem]

I don't know what is your source, but the terminals 5 and 6 are not connected to your laptop. The SMB is seeking information with terminals 2 and 3. If you made a graph of your connections when you removed the battery, it will be easier to connect the resistors in place of the cells.

Unfortunately, as I have already said earlier, I can no longer access that information as the battery was gutted out before my reading your suggestion that I attach resistors in the place of the cell groups. All I have now as reference is the pictures I posted, and you can see those too. I have no other way to make a graph of those connections at this point.
However, the info you posted earlier, with terminal 1 being the positive and 7 being the negative is incorrect for this battery (Dell Type 66Whr), which is demonstrated by the fact that connecting positive to 7 and negative to 1 as I did I get an initial response from the charging system which would be impossible if those polarities were inverted. Where did you get your information from?

Is there a way to find a diagram of the connections for this specific battery online? It should definitely be available somewhere, and then we could try the resistor thing. If anyone knows where to find this type of information specific to the Dell Type 66Whr battery, would you please post it here? Thanks.

 

[nukemaster]

@jarotech

Since I have NEVER tried to hack a laptop battery into a power supply, I have a question. Are you using the resistors to create a voltage divider(well a bunch of them) so that the chip sees a voltage for each cell? or does the chip look for resistance from the cells them self

Do you do lots of electrical work?

 

[claudem]

I've just modified this thread's title to reflect that we are talking specifically about the Dell Inspiron 8200 laptop and its battery module.

 

[jarotech]

@jarotech

Since I have NEVER tried to hack a laptop battery into a power supply, I have a question. Are you using the resistors to create a voltage divider(well a bunch of them) so that the chip sees a voltage for each cell? or does the chip look for resistance from the cells them self

Do you do lots of electrical work?

Yes I use the resistors to create a voltage divider to simulate the cells, Claudem said five wires are connected to the cells, red positive, black negative, two white and a yellow wire, that means each group of cells are connected to the circuit inside the casing of the battery. But if the circuit check also for the current from the cells, then the value of the resistors are not good. I have to start some place because I never did that before.

I am an electronics technician and I work in electronics since 1976.

 

[nukemaster]

I was guessing that. I do not do too much electrical, but play a bit.

 

[claudem]

UPDATE: My friend from the repair shop ended up giving me the AC adapter (the one that worked) for free...
I've been using it yesterday and today, and the laptop works just fine. I no longer have a working battery, so I have
no way of telling if the laptop would be charging the battery if there were one. Just as I guessed, it was not a problem
with the AC adapter jack in the laptop. I had read in several forums that this laptop family is very finicky about
the AC adapter they will recognize as suitable. The one that works flawlessly is rated at 20V, 4.5A, 90W.
Thanks guys for all your feedback. It was an enjoyable experimenting in what might have worked. It would have
been nice to see if jarotech's resistor approach would have worked, given that this is a smart battery system with
the laptop trying to establish a recognizable handshake with the circuits in the battery: that would have been quite
an achievement and an excellent learning experience. However, I'm now past that and enjoying my inspiron 8200,
from which I'm writing this post. Thank you all again!

 

[nukemaster]

Well, I have a pile of 100k's kicking around so if I ever have a laptop battery fail. I will try this just to see what it does(assuming I have a working adapter or other stable voltage source and have not used the resistors by then)

 

[Maxx_Power]

UPDATE: My friend from the repair shop ended up giving me the AC adapter (the one that worked) for free...
I've been using it yesterday and today, and the laptop works just fine. I no longer have a working battery, so I have
no way of telling if the laptop would be charging the battery if there were one. Just as I guessed, it was not a problem
with the AC adapter jack in the laptop. I had read in several forums that this laptop family is very finicky about
the AC adapter they will recognize as suitable. The one that works flawlessly is rated at 20V, 4.5A, 90W.
Thanks guys for all your feedback. It was an enjoyable experimenting in what might have worked. It would have
been nice to see if jarotech's resistor approach would have worked, given that this is a smart battery system with
the laptop trying to establish a recognizable handshake with the circuits in the battery: that would have been quite
an achievement and an excellent learning experience. However, I'm now past that and enjoying my inspiron 8200,
from which I'm writing this post. Thank you all again!

Sounds like a good fix!