I'm working outside from time to time, and my cord extender doesn't have a ground pin. What should I know about the effects of using a laptop without an outlet that has ground?
If you use a device without the earthing pin connected to earth, nothing much will happen to the laptop in everyday use however, if a live cable (through a fault) touches a metal part of your laptop / power supply the current could potentially earth through the user (you) causing an electric shock.
The earth is a safety feature that if an electric current inadvertently needs (due to a fault) will cause a circuit breaker to cut the electricity immediately. The circuit breaker will not reset if this route to earth is still present.
As those who wrote before me have attested to, in most cases you will be fine. The ground is for safety reasons.
For example, I was having issues with my Dell laptop including overheating of the power supply. I read that sometimes the ground is used as a factor for the power supply to support fluctuating demands of the laptop. When I switched back to a grounded outlet the problems stopped.
Therefore, I conclude, that whoever authored the article stating the ground wire for that laptop must be used or it can cause problems, was correct. It was news to me.
In most cases, you'll be fine. You may even find that the earth pin on your power adaptor is a plastic fake in any case; even if metal it may or may not be connected to anything.
Earthing is only going to be useful if something goes wrong inside the transformer block, and this is quite unlikely. Just follow the usual precautions for electronics outside: don't bury anything or get anything wet.