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

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claudem

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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.
 

Maxx_Power

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It is usually more than just 2 wires that carry the power. The pins for the battery carries with it information about the battery, and some casual exchanges of data from the computer to the battery on the SM Bus.

To get this to work, you will need a battery with a working circuitry inside, discard the internal cells, FIND A WAY TO FOOL THE BATTERY CONTROLLER (hard part, you MAY have to resort to installing some regulators outputting 3.7V and wire that to each cell's wire that goes to the controller), since the cells inside the battery are individually balanced for newer designs (see the 2nd link by ratedk), and wire the cells to a jack, probably mounted to the battery casing pointing out the backside.

ALTHOUGH, the usually easier way is to open the laptop up and see if the power board is replaceable...
 

weaselman

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Your going to hit a snag there, because belive it or not it`s not as simple as you think supplying the 12v, can I make a suggestion to you here.
Crack the battery open since it is dead anyway. in there you will be able to work out where the Plus and minus need to go solder the wires to there from the power supply.
If you look you will see a small circuit board. So wire the + - from the battery, unsolder them. Then solder the + - of the the power adapter feed to that. Tape the board with electrician tape avoiding shorting obviously.

Why am I telling you, well because that little board sends information of the status of the battery, data. If it is good, safe to use.
So if the laptop does not see it, then it may just say no way if you did it the other way as you were intending to do ok, just a heads up and yes it works.
 
Hi :)

I own a laptop repair company... you are replacing a 19/20 volt charger with a 15 volt charger... that will be fun... ever heard of OHMS LAW... I think you need to Google and understand it...

Also even if you do manage this... you ARE going to get a LOT of nag messages about incorrect charger/battery both on Boot and in Windows...

Is it REALLY worth the effort....just get it fixed properly by any decent lappy repair company...

All the best Brett :)
 

nukemaster

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Brett, I think you miss-understand the OP
They are talking about hacking the BATTERY to take the voltage(or just soldering right to the proper pins) and pass it.

The laptop gets more to from the DC jack to allow it to perform all the needed conversions and cover any losses(should be quit minimal).

Also you know most DC-DC converters do have a range they will operate in.

I would still recommend a PROPER fix, but if you have nothing to loose(its this or trash), very carefully hack that battery to bits :) do NOT ever push power into the batter cells as they WILL burst.

This is kind of like taking an old portable cd player that has a 4.5 volt charger and instead soldering a 3 volt adapter onto the 2 x AA batter connector inside the battery compartment of it and NEVER running it on batteries again(and clearly never running it off its old DC in jack).
 

Maxx_Power

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To the OP:

I thought just occurred to me. You didn't mention if the power circuitry problem is physical or electrical. If the jack is not making good contact anymore, the best repair is to unsolder the jack and replace the jack.

If the problem is electrical, the DC-DC regulation circuitry inside the laptop is shared between the 15V battery and the 19V DC input. Since both voltages needs to be stepped down to 5V for the onboard electronics, if the DC-DC converter doesn't work anymore, then the battery method LIKELY won't work either.

You used the words "Inner Converter" which confuses me a bit...
 

nukemaster

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I am willing to bet the changer(in the laptop not the power brick it self) is the problem. The OP says that a second changed battery would run the system.

Yeah, if it was just the plug, those are straight forward enough to re-solder. If it has been like that for a while, some arc damage may have been done(so a bit of cleanup would be in order).
 

claudem

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Thank you so very much for this very useful information.
I'll take some time to look into it and then post here how it turned out.
These links are very much appreciated! :)



What you wrote make sense, given the way smart batteries operate. If it boils down to having to go through all that you have described, then it would be unfeasible, as I don't have on my hand all the time or be willing to go through all the effort required.



These inspirons are very peculiar as to the AC adapter they accept. I didn't give out too many details in my initial post so as to make my questions more easily followed. My reason for wanting to do what I described in my initial post is based on two facts: 1) I don't have an original Dell AC adapter for this laptop and have already gone through two replacement ones (the first one simply got fried after a few minutes of the computer functioning properly with it, with battery inserted....it simply expired, and it was a proper 20V 4.5A 90W replacement charger designed for this family of laptops. The second one, simply was not accepted by the system as a suitable one, even though it had the same specs as the first one and is also designed for this family of Dell laptops, though a different brand than the first one. These laptops are very finicky as to the power supply they accept. And 2) I will not be using a working battery in this laptop...so I thought it would be great if I could find a way to bypass the charging system and supply the current directly at the battery port.
To answer more specifically your question, though, I have no idea as to what to solder on the Motherboard/Daughter Board to fix the problem, which you are pointing to.



I know what you are referring to. If it is this simple, I could do it easily... however, after reading what was written by Maxx_Power (see above), I am no longer so sure. Do you think it would still work this way, that a direct connection like you describe would fool the battery? I hope so, because this would be exactly the simple solution I am looking for.



This could work, OR it may not. For instance, I took this laptop to a friend's repair shop yesterday, and after a few unsuccessful trials he plugged into it some (obscure) (non-dell) replacement AC adapter, and the computer worked fine with it and a dead battery in. I have several of the 15V 4.5A AC adapter I mentioned with the exact same output as a fully charged battery, and if I could make this concept work.....I have access to a couple more Inspiron 8200s with seemingly the same problem as this one that I could get to work this way and so extend their useful life.



Actually, I'm not thinking of replacing the 20V adapter with a 15V one. 15V is the voltage supplied by a fully charged battery, and I was thinking of using that to make the system think a fully charged battery is inserted in the bay.



Exactly, nukemaster, you got it. Certainly, the battery cells will have to be taken out of the way or they will, as you say, burst. I wish this can be done, am just a little concerned about what was written earlier by Maxx_Power.



Nope, it's not a matter of the AC adapter jack not making good contact. As I described earlier, one AC adapter was "fried", a second one had the power light of the laptop go on but it was not accepted as a proper charger, and finally another one worked fine (but I cannot have that one as my friend from the shop needs it for his work). These laptops are just finicky as to the power supplies they accept, and even more so as they get older, for some reason. A fully charged battery powers this laptop just fine.



So should I go ahead and disassemble the battery, get rid of its cells and connect the +/- DC from the 15V DC charger as described in the link provided by ratedk in the first reply and see what happens? The points provided by Maxx_Power in his first post, however, have me concerned a bit... The battery is dead anyway and if this doesn't work, the laptop will probably be disassembled for parts and be retired for good.
 

nukemaster

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Sure, you are at a point of nothing else to do aside from replacing the onboard charger, chances are its a part of the board and not too easy to replace.

Be careful with the cells as li-ion is known to not like any kind of crushing/cutting/excessive shock.

If you leave any other hardware in the battery in place(and ensure nothing is shorted out as your new power supply will not like that), with some luck, you may be able to get it to work.
 

Maxx_Power

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I think, based on what you said about the power adapters, it seems like your power jack's center pin(s) is/are making intermittent contact. Some AC-DC adapters have a tip/tips that is/are slightly narrower (due to tolerances in manufacturing), so they may work with your laptop when you have a power jack contact issue.

IF this is the case, you need to solder a new jack (not very expensive) to replace the old one. I'm suggesting based on your symptoms, and the fact that this is the most COMMON reason, especially on Dell-HP machines, for why the power inlet has intermittent connectivity but battery runs fine.

I know you didn't ask for what the problem is, but just as a thought, before you try something much more difficult.

These power jacks are offered in TONS of places on the web, for example here:

http://www.powerjackshop.com/Dell/Dell-Inspiron-8200.html for $6.55. It looks like this:

pp13276.JPG
, not sure if yours looks like that.
 
So should I go ahead and disassemble the battery, get rid of its cells and connect the +/- DC from the 15V DC charger as described in the link provided by ratedk in the first reply and see what happens? The points provided by Maxx_Power in his first post, however, have me concerned a bit... The battery is dead anyway and if this doesn't work, the laptop will probably be disassembled for parts and be retired for good.

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.
 

claudem

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No, unfortunately these dell laptops have the notorious three-hole charger plug, like this:
http://www.level8technology.com/catalog/ac-dl05.jpg

EDIT: I'm sorry, you were right, that's the laptop's AC adapter jack.
I've already gone ahead with disassembling the battery and am ready to go ahead with the project. I would like to show you guys some pictures of the gutted out battery first, though, to get some feedback.
If the problem was intermittent contact between plug and jack, then why would one charger consistently light the power led? (it had an output of 3.18A, while this computer will not start unless it gets the full 4.5A, this is a well known fact talked about in many forums.) The charger that expired was probably defective in the first place, one of those cheap ones imported from China. As I said it is well known that the 8200 series is very finicky about adapters. The other charger, the one from my friend's shop, would consistently start the computer. And we tried a few times. I don't think it is a matter of intermittent contact and honestly don't feel like throwing away 6 bucks + shipping costs and waste any additional time on this one. Just my thoughts. I have a possible solution and would like to go ahead and give it a try. And I like the idea of making it work out this way, if successful.. :) Just my thoughts. Thanks however for providing the link and your suggestion.

EDIT2: Should the DC-adapter-output-to-battery approach not work, I could test your suggestion by bypassing the AC adapter jack and connecting the 20V 4.5A 90W output directly to the wires that connect to the jack. I already know the way to make this connection. The problem is, I don't have a proper charger for this machine, now that the Chinese one I had bought for it has expired. So I would have to re-order a new AC adapter for the laptop, and a good quality one would be $30-40. Don't feel like ordering another Chinese-made. Now maybe you see why I'm trying to make this solution work. This is an older PC I don't feel like throwing too much money into.
 
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