How to use correctly apostrophe after noun?

[hmp_khauff]

Please let me know if these examples are correct.

James' car is very fast. (Is it correct to use apostrophe after the noun if the word is a proper name that ends in "s"?
Mary and my apartment was sold yesterday. (Is it correct not to use apostrophe after my?
Customer laptop computer's battery discharges very quickly. (Is it correct to use apostrophe on the penultimate noun?)

Thanks in advance.

[Barb_D]

Please let me know if these examples are correct.

James' car is very fast. (Is it correct to use apostrophe after the noun if the word is a proper name that ends in "s"?

Some people write James', as you have. Others, including me, write James's. Both are correct. Just be consistent.

Mary and my apartment was sold yesterday. (Is it correct not to use apostrophe after my?

Don't every write "my's." It's not a word. This means the apartment belonged jointly to you and Mary.

Customer laptop computer's battery discharges very quickly. (Is it correct to use apostrophe on the penultimate noun?)
The customer's [THIS one needs an apostrophe] laptop battery...

Thanks in advance.

.

[BobSmith]

Customer laptop computer's battery discharges very quickly. (Is it correct to use apostrophe on the penultimate noun?)
The customer's [THIS one needs an apostrophe] laptop battery...

[not a teacher]

I hope Barb_D doesn't mind me expounding on this last one.

The reason why “customer” gets the apostrophe and why “computer” does not, as you have guessed (good guess, BTW!), is because “laptop computer” and “computer battery” are both relatively common phrases in spoken English. That makes them less likely to be subject to the possessive. There are a lot of common phrases that aren’t “words” yet, like “car engine” or “TV show” or “guitar case”. Each of these could be found, in one situation or another, in the possessive or not.

If phrases aren’t common, you might string them together, like:

The plane’s cockpit’s dashboard’s surface was damaged.

I’ve often typed “my boss’s boss’s boss” which signifies the person in charge 3 levels up from me. As soon as there is a common phrase, you can skip the possessive:

The plane’s cockpit’s computer battery’s surface was damaged.

Granted that’s a contrived example (and any native speaker would rework it), hopefully it shows my point. So, back to the original... in a pinch, you could string them all together:

Customer’s laptop’s computer’s battery discharges...

and while strange, it isn’t really “wrong”, and it’s much better sounding (to a native speaker) than “Customer laptop computer's battery discharges”.