3 Days to Say Havdalah (Klal 8 Siman 22) Hilchos Shabbos - S0238

We are continuing in siman 22, where the Chayei Adam discusses making havdalah later in the week. The Chayei Adam wrote that one can make havdalah until Tuesday at shkia, but one would not recite the brachos of ner and besamim. Today, the Chayei Adam will explain the reason.

The Chayei Adam writes that the purpose of the bracha on the besamim on Motzei Shabbos is for the neshama yeseirah (a dimension added to our neshama over Shabbos). In relation to Shabbos, the pasuk says va’yinafash, and the Gemara learns is it an acronym for vai avda nefesh, woe is to [the person] who loses their neshama yeseirah on Motzei Shabbos. Therefore, Chazal instituted that we make a bracha on besamim, because they have the ability to comfort the nefesh. Smell is a more delicate, metaphysical pleasure which is not as physical and ephemeral as food. Therefore, the neshama relates to it more than food. In order to help our neshama recover a little from the loss of the neshama yeseirah, we make a bracha on besamim.
However, this bracha is only relevant on Motzei Shabbos, at the point when the neshama yeseirah leaves us. Later in the week, it is no longer relevant, as the neshama has already “moved on”, so the bracha is not recited.

The bracha on the ner is also only recited on Motzei Shabbos. Chazal tell us that fire was created on Motzei Shabbos. After the first Shabbos ended, the special ohr created from the six days of creation was no longer effective, and it started getting dark. Hashem gave wisdom to Adam Harishon, and he took two rocks and knocked them together to create a spark. He was able to transfer the spark to tinder, and then created a fire. Since Motzei Shabbos is the time that fire was brought into the world, it is appropriate to thank Hashem for the benefit of having fire at the time it was created. Therefore, it is only relevant on Motzei Shabbos, so it is not recited later in the week.

The Chayei Adam moves into a scenario in which one plans to fast for three days and nights immediately after Shabbos, and what he should do regarding havdalah. Practically, this scenario is quite uncommon, but it can be more relevant in the case of a person who is in recovery from surgery where they are awake but unable to eat or drink. In these cases, the person could hear from someone else, or can make havdalah themselves and give the wine to someone else to drink it. The Chayei Adam suggests giving it to a child. 
The Mishnah Berurah points out that the latter option is not lechatchilla, and it is preferable to have someone else make havdalah and be motzi this person. However, the Chayei Adam appears to favor the second approach. The Piskei Mishnah Berurah points out that the Magen Avraham holds it is not appropriate, and we generally only rely on someone else drinking the wine when there is no one else who is able to recite havdalah themselves. If the other person can make the havdalah, he should do so.

Summary
One can make havdalah until Tuesday at shkia, but does not recite the brachos on besamim and ner.
If one is unable to drink the havdalah wine, it is preferable to have someone else be motzi them. If noone is able to be motzi them, the person who is unable to drink should make havdalah and someone else should drink the wine.