Getting terrible battery life with an M4 Macbook pro.

I've been working on an 80,000 page book in MS Word and using a browser for research.

I also use Word for books and articles, and must often have a browser open for my research. I've found that what you see is most likely due to your browser or the web pages you have open.

I can run Word alone for a long time on battery, even on a geriatric Macbook Pro I use for travel. It has an 11 year old battery. Once I open certain web pages to fact-check, I can hear the single fan spool up in reaction to internal heating and see the charge level icon start to drop. I close the web page and all is normal again..

Chrome is probably the most resource-greedy of all the browsers:

but I can see demand go up on a site-by-site basis even in Safari. If you cannot live without Chrome, it's time to plug in.

I just did a test. With only your question open in Safari, discussions.apple.com was using about 5% energy per Activity Monitor. Then I opened the OWC site (eshop.macsales.com) where I shop a lot. When I reached an individual OWC product page, look what happened:

Impressive, and my CPU temps rose by 10°C within minutes of opening that page

I ran into similar situations when looking at election night result pages. All in Safari.

So before worrying about your Mac's battery, do what has already been wisely recommended: let Activity Monitor reveal any guilty parties.

View energy consumption in Activity Monitor on Mac - Apple Support

Maybe, maybe not. Apple's "up to 24 hour" claim is predicated on specific conditions, none of which involve using Microsoft's bloatware, or any browser other than Safari. Literally every other browser will consume more energy.

If you want suggestions post a picture of Activity Monitor.

If your Mac battery runs out of charge quickly - Apple Support but that document is very cursory. Activity Monitor gets into detail.

Have you divided that 80,000 words into multiple chapters? If not, moving 80,00 words in an out of memory to change a single word is VERY hard work for any computer.

MS Word has essentially always been able to work on chapters of a coherent larger work (including maintaining flat page numbers and index entries.)

Also what is the date of your most recent backup, and by what method?

A very large document as one file will cause Word to bring the ENTIRE document into RAM memory, which quickly fills and then splits out onto Virtual Memory on the disk. This I/O involved is not well indicated as taxing in the Energy pane, but MAY show in the memory pane as a large over-commitment of existing real RAM and a buildup of SWAP space used.

It is great that you are doing frequent backups -- we have heard sad stores of writers who worked for years on a eject, only to have it disappear in an instant due to hardware malfunction.I strongly suggest you look in the manual or help for tips on breaking your document into chapters.

You should look at Word documentation on chapter-books. You get MUCH speedier daily editing, and do not give up anything. You can have coherent page numbers staring at page one, and a renumber operation will simply read through the linked files, render each and computer the appropriate page numbers again. Forward and backward references (see page 56) continue to work fine. index and table of contents entries continue to work fine.

As a chapter book, your daily edits are quick and easy, and the longer time is only when you re-number or re-index instead of every change you make.