Dell is known to not have good batteries but contrary to their tarnished reputation, they actually are pretty good in some of their models. They have a 10 hour in between charge in many of them. The 8th genration Intel has a very good battery life. The 2-in-1 Latitude 7390, however, is not getting good reviews for its power source.
There are ways that the battery life can be extended. Dell is good about coaching on how to do such things. The night light option can be turned off and it will save power. All in all, there are Dell laptops that have great battery lives and some that practically have none at all so it is imperative to read the reviews of each different make and model in order to determine if a particular one does have a good battery...or not.
Reportedly, yes, Dell laptops do have a good battery life. In two recent experiments, Dell came top of battery life trials. One of these trials was done by Laptop Mag who stated the Dell XPS 15 lasted a solid 11 hours and 53 minutes.
Consumer Reports placed a Dell fifth saying the large screen Inspiron - which size allows for juggling spreadsheets and screening videos gave 9.25 hours per charge,