Latitude AC Adapter Issue

thank  you for the help fellow users - my latitude CPxH500GT suddenly wouldn't power on - i should have gone to the message board first as the suggestion to power on without the adapter worked - it took a few tries but then when i connected the adapter after it was on, it SEEMS to be charging - what a mess - can one buy a charger so that if this problem persists i can go with battery only? 

I have had the problem with the power supply just cutting out to a Latitude C840. I unplug it for about 30 seconds and plug it back in and it will work for a few days and happen again. The problem started when I began using the docking device.
I have contacted Dell service so we'll see what they say.

This is definately an issue!!!  We have a brand new Dell Latitude C840, and the AC adaptor "randomly" shuts off power exactly the way folks here are describing. This is extremely frustrating as I am on the road with no recourse to address this.

I do not believe it is temperature related either. I experimented by maintaining a cool temperature on the adapter and it exhibited identical random shutdown behavior.

Additional observations: Once it turns off, it never turns back on "randomly". You have to re-apply AC power (maybe multiple times) to get it to come back on.

I don't think it is software problem.

I suspect a design flaw in the AC Adaptor hardware. Potentially an expensive fix for Dell to admit.

Any advice is appreciated.

 

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@bseib wrote:

Any advice is appreciated.

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The next time it happens,  run the system diagnostics and test your battery/charging system.  It is possible that you have a minor short in the battery charging circuit inside your notebook causing the system to draw too much current from the adapter.  If this happens,  the adapter will shut-down to prevent damaging your notebook.  Running the diagnostics might show someting (or it might not) but you can't tell if you don't try...

I just purchased a 90 watt power supply and put it on the laptop that was having problems and it charged the battery immediately.  So I am thinking that it is the power supply that is causing the problems.  I guess what I don't understand is why did Dell send the 70 Watt power supply with the computer.

I strongly believe this is design issue.  Here are my excruiating details:

(1) Latitude C840 and 90W AC adapter (to date have tried 3 adapters all with same results)

(2) I can charge a FULLY discharged battery with no problems, ONLY IF COMPUTER OFF

(3) I can run computer forever, under full load (DVD, Floppy, Display on Full intensity), ONLY IF BATTERY FULLY CHARGED

(4) Battery holds charge for weeks, runs for two hours, charges in 20-30 minutes. Does not act like bad battery.

(5) BUT, if battery is partially discharged (doesn't matter whether 10% or 90%) AND computer is on (even if no DVD, floppy),

        AC Adapter will shutdown (i.e. green LED on adapter goes out).

(6) Used to get warm, so I suspected thermal shutdown.  But sometimes happens in minutes, so now I'm suspecting

        an over-current shutdown.  By design these adapters include protection circuits such as these to protect them.

        They are usually "reset", by unpugging A/C for 10 to 30 seconds.

(7) If I "reset" A/C adapter, its starts charging again, but then shuts down in a couple minutes.

(8) Now here's the good part.  If I shut off computer, reset A/C adapter, and just charge battery, I am successful.

     This works even if AC adapter is hot.

(9)  Remember these are 90W rated output adapters, so if they output 90W to the laptop, the AC adapter will

      dissipate about 30W due to inefficieny of the internal circuits (assumes adapter is 75% efficient).  You will notice

      20 - 30 watts of heat coming from a small box.

(10) Bottom line is tha the laptop requires X amount of current and charging the battery requires Y amount of current. I

      suspect that the C840 with the P4 and all its other "powerful" features, combine where X+Y is greater than

      the AC adapter can handle which causes either thermal or over-current shutdown.

(11) I would like to see Dell run some tests to confirm or deny this.  Or even publish the current draw requirements

     for the laptop running and for the battery charging....

 

All,

As I stated previously, if you have a problem, where the light on the AC adapter goes out, and especially if the AC adapter has already been replaced, then please contact Technical Support so that the system can be serviced.  It is my understanding that the motherboard must be replaced.

I don't have the problem with the AC adapter (the light stays on) but I have an interesting problem with the power management system; I've recently moved abroad into mainland Europe from the UK and from the moment I started using the foreign power supplies (both French and German) the computer would randomly power itself off when connected to the mains.  I thought this may be a motherboard problem, but it seems to work fine with batteries.  Also, if the computer was left to warm up a bit, the computer would be OK on AC power.

However, recently the problem has been getting worse and now it does it too with batteries albeit nowhere to the same extent with AC power.  Once the computer has been started up on batteries (after a struggle it is fine) it works fine...until I l plug it into the mains when it kicks up a fuss again.  Now the AC power ís just totally unstable, and lasts two minutes maximum whether it has warmed up or not.  This is looking to me to be a fault in the power management software in the BIOS as I am seeing posts left right and centre about this on the forums.

I don't think it is a problem with Windows, Linux, NetWare or whatever OS you may be using, as sometimes the system will power itself off at POST before the hard drive has been touched.  I suspect that it may be a BIOS problem and as such I will attempt to degrade the BIOS and also reformat the hard drive at some point.  My suspicion is that anti-surge technology is to blame here and in the vast majority of everyone's cases.  I also noticed a couple of things in particular.

* The more hardware I plug into the computer, the quicker it powers off.

* An overfragmented, error-ridden hard drive such as mine takes more power (not significantly so)

* Changing the screen brightness level at the BIOS settings screen to minimum also helps to minimise the auto-power off.

Hope this helps and hope someone can help me!

I have a Latitude C400 with the same problem, of which the motherboard has been changed two times the last month, (first time for a faulty NIC. but AC problem already occured as I understood), We also have another C400 that works fine, and I swapped AC adapter and battery to find the cause of the problem, but everything works fine whit that system.

Last swap was only two days ago, and this morning the AC adapter goes off as soon it is plugged into the system. Funny thing is that the AC adapter works stable with the same system with the battery removed.

Due to the comparison I made I think can safely say the ac adapter and battery are fine, The motherboard has already been replaced, I understood that the charger circuits are on the motherboard.so what could cause the problem???

 

 

 

had the same thing-  it WAS the motherboard- how do i know-because i replaced every other part ont the frigging thing....it finally tok motherboard replacent to fix the problem.  Call dell and have them replace MB

Well, they replace mobo two times already, problem only got worse.Now I can't have battery installed and AC power on at same time. Dell told me they do not know the solution and offered to take the thing back in exchange for a D400. Good service!!