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 '10 at 0:37
  • @Molly I have edited the question to include the exact message – Move More Comments Link To Top Feb 3 '10 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 '10 at 1:01
  • 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 '10 at 1:07
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    bottom line: it's a "design flaw" to "encourage" their customers to buy a replacement. :) – Molly7244 Feb 3 '10 at 1:20

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.


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.

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