I am using the original power adapter with the Dell Inspiron 6400 laptop and now when it boots up I get the following error message.

The AC power adapter type cannot be determined. You system will operate slower and the battery will not charge.

Please connect a Dell 65 W AC adapter or higher for best system operation. To resolve this issue, try to reseat the power adapter."

I don't have another power supply or laptop to try.

Is there a way to test the power supply, or whatever the computer uses to determine the power supply size?

  • what is the exact error message? "“Dell AC power adapter type cannot be determined” or "The AC power adapter wattage and type cannot be determined. The battery may not charge…Please connect a DELL 64W AC Adapter or greater for best system performance. To resolve this issue, try to reseat the power adapter."
    – Molly7244
    Feb 3, 2010 at 0:37
  • @Molly I have edited the question to include the exact message Feb 3, 2010 at 1:00
  • 2
    the issue is discussed here (i cannot vouch for the solution, hence i post this as a comment rather than an answer). but it's worth reading: laptops-battery.co.uk/blog/…
    – Molly7244
    Feb 3, 2010 at 1:01
  • 1
    I had a similar problem with a Vostro notebook recently, and the "press the cable (coming from adapter) towards the adapter" trick got rid of the error message (sometimes, not always).
    – Molly7244
    Feb 3, 2010 at 1:07
  • 2
    bottom line: it's a "design flaw" to "encourage" their customers to buy a replacement. :)
    – Molly7244
    Feb 3, 2010 at 1:20

5 Answers 5


Having just paid over £100 to have the the power board inside my daughter's Inspiron replaced and had the explanation confirmed by the Dell engineer, here is what happens:

The power connector consists of 3 pins, 2 are power and earth, the 3rd is a signal line to identify the PSU as a compatible (Dell) unit. If the Laptop does not get the signal, it does not allow the PSU to charge the battery, it will, however, allow it to power the laptop. The fault is a common one and happens because the plug sits so proud from the side of the laptop that it constantly gets knocked and causes the connector on the power board to fail, most commonly open circuiting the signal line.

To clarify, the power board on some Inspiron models is a separate unit to the motherboard and has the power socket mounted directly on it.

  • 2
    For more information on that circuit and how it appears to work in the power brick: laptop-junction.com/toast/content/… Aug 6, 2012 at 3:59
  • You are right, but it's not always the pin's fault, it can be also something than burned at the motherboard level. (also quoted from a technician).
    – Quidam
    May 8, 2020 at 2:59

As the message is happening outside Windows, it something going wrong at the BIOS level. I.e. a hardware failure of some variety. A loose connection, cable or a faulty chip on the motherboard. You can go into your BIOS (F2 during POST) and check the status of your AC adapter there too if you are curious. It will most likely be under the Battery Info subheading, under System.

If your laptop is still under warranty with Dell, give them a call. If you do not have a spare AC adapter that you can borrow from a friend or work colleague, I see no reason why they would not send a replacement out to you. Batteries are not covered under warranty so great, but AC adapters definitely are.

If the replacement AC adapter from your friend or from Dell also fails to work, it would indicate to me that there is a fault on the motherboard. Again, Dell should be able to replace this under warranty. If out of warranty, they should still at least be able to offer the part at a cost to you. Given the cost of the replacement part from memory, it will probably be cheaper to buy a new laptop or just live with it.


To answer your question about the power supply size, look on the power brick label for "output". It should say something like this:

DC 19.5V(19,5V) 4.62A(4,62A)

That means it provides 19.5 Volts with a maximum allowed Amperage draw of 4.62 Amps. Going back to basic electrical theory, we know that you multiply Amps by Volts to get Wattage.

So doing the Math, we get the following:

19.5Volts x 4.62Amps = 90.09Watts

So plug in your own adapter's numbers to figure out your maximum wattage. You can generally use an adapter with a higher wattage than you need, but rarely can you use one that is lower.

To reiterate the other answers, you'll need to contact Dell support for assistance with this. without equipment to swap, you'll have to get Dell to fix it for you.


Had the same problem. What it was for me was the centre pin in the charging cable was broken off. This pin charges the battery(11 volts) and the outer part(shell) keeps the laptop running(19 volts) but does not charge the battery.


Same problem here, so I've made some searches.

The answers given here are totally correct, but not complete.

The consequences of this problem:

  • The system is dramatically slowed down, (of course, even if you remove the warning message in the BIOS settings).

  • If the problem comes from your charger, the risk is that you will be unable to power on your computer sooner or later.

The reason why the system is slowed down is given in their error message:
The performance will adapt to your system...
meaning: As they don't know which kind of charger you use, to be safe, they will downngrade the processor speed (underclocked), to prevent things maybe like fire, exploding battery, apocalypse, I don't know.

First, a common misconception:
- It had no link with the battery itself. If a battery is not "recognized", it shows another kind of message saying something like "no battery", or in the same style.
So, replacing the battery do nothing, it's a different problem.

And it can have at least 4 or 5 totally different causes:

  • The central pin of the plug (S.M.A.R.T system), not aligned with the hole on the laptop socket. As mentioned in the answers here, this central pin is here to make the charger "recognized" by the BIOS. It's to prevent power supply that is not adapted, too weak or too strong, and can cause damages to the battery (or worse).

And if it's not aligned, it can be because it twisted, so to solve it, some people had good results with a tweezer. Some by twisting the wire. Or buying a new (genuine) charger.
Be warned that sometimes it solve the problem for a limited time, and after a while, the message and the system slow down come back.

It can also be a dirt in this place, try to clean or to blow on it.


  • The charger is not genuine. As with S.M.A.R.T technology, the charger (and probably battery) have to be genuine (OEM). If the charger is not genuine, the pin is not made with the same technology than the genuine one. It's automatically detected.

  • It can also be on the computer side, the socket connector of the computer being damaged, in such a way that buying a new charger doesn't solve the problem.

You can test wether it's on the computer side or on the charger side by using another (genuine) charger with the computer, to see if it solves the problem (some electronics & computing shops can let you try their for free probably), or try your charger on a different (DELL) computer.

In this case, you have to buy a new (genuine) power socket remplacement for your computer (source)

  • It can also be an electronic component of the motherboard that is burnt. In this case, replacing the socket or the charger won't do anything, of course.

  • It can be an error of communication between the motherboard and the charger, some people managed to fix this error by resetting the battery (sensor)

Steps here: https://www.ncconsumer.org/news-articles-eg/resetting-a-dell-laptop-battery-in-five-quick-steps.html

 1. Completely power down the laptop and remove the cord from the

 2. Flip the laptop over.

 3. Push on the battery release button or buttons to release the battery
    form the computer and remove the battery.

 4. Power on the computer without the battery, allowing it to boot

 5. Completely power the computer down and remove the cord once again.

 6. Reinstall the battery, plug in the power adapter and re-boot the

This solve the communication between the charger and the BIOS.

  • Some people reported this problem after a BIOS update. If it's true, it goes in the category "bad communication between charger and BIOS/motherboard". It doesn't seem the most common, the plug problems seem really more common, but you can always try to downgrade or upgrade the BIOS (wisely, without bricking your system).

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