Which charger is suitable for my laptop?

@AvivC  that system ships with a 65W AC adapter for configurations that do NOT have a discrete (NVIDIA) graphics card, and a 90W adapter for configurations that do.  You can always play it safe by just getting a 90W adapter.  Even if your system doesn't need the extra power, it won't be damaged by the extra wattage (as long as it's a Dell adapter) and the system might actually be able to use the extra wattage to charge the battery a bit faster.

Welcome to the Dell Community  @AvivC 

Dell Latitude E6540 90 Watts:

https://www.parts-people.com/index.php?action=category&id=140&subid=453&refine=90+watt

The Most Trusted Source For Dell OEM Replacement Parts:

Best regards,

U2

EDIT: You can always check what any laptops power requirements are!!! "Watts" 

Look for the Volts and Amps on the bottom or under the battery.

V x A = W     Volts x Amps = Watts

Hi, thanks for replying.

I bought a 90W charger (non-Dell), and the screen shows a message saying I need a 130W charger.

So what do I need to get?

Thank you

Are you using a docking station?  If so, that would be why your system is saying you need a 130W adapter.  If you're not using a docking station, I haven't heard of a Latitude system that required 130W just to be used on its own, but if that's what the system is telling you, then I guess that's what you need.  I would be careful using non-Dell power supplies though.  If the system can't determine the wattage of the third-party adapter because it doesn't support Dell's proprietary identification mechanism, then the system will typically play it safe by drawing as little power as possible from the unknown adapter, in which case the battery likely won't charge and the system might significantly throttle its performance to reduce its power consumption.  And then there are of course potential quality issues with third-party adapters.  With systems that support being charged over USB-C it's another story, because those systems use the industry standard USB Power Delivery spec, so reputable third-party adapters work fine as long as they provide the necessary amount of wattage, but the E6540 doesn't have USB-C.

@AvivC 

Did you look on the bottom of the laptop for the "Power Requirement"??? "Under the battery"

I have an E6510 that says 19.5V  ~ 4.62A/6.7A  

19.5V x 4.62A = 90.09   (90 Watts)

19.5V x 6.7A = 130.67  (130 Watts)

What does yours say???

Regards,

U2

Hi!

I saw your post about discrete graphics needing more wattage.

Is that true only for charging the battery faster, or will my computer be limited if it only has 65W instead of 90W (and has discrete graphics card)?

Kind regards