You need to find the pilot cell. It will be near the positive or negative terminal. One of the bus ties (long lead connectors between cells) will have data stamped onto it. Depending on the brand it will be easy to read or in some strange code only the manufacturer knows. A good battery manufacturer should make the information available on its website. Do the voltage checks mentioned above and determine the battery's age.
Warning! I don't know very many people who take the battery seriously or have the experience or knowledge (even at battery places). If you find someone who knows about batteries, keep in touch with this person. Get a second opinion on all battery repairs or service.
The Crown brand tolerates battery problems very well so you shouldn't have to do much more research or testing.
Understand that most batteries have a life of about 3 years, I don"t care about the design,etc. Nobody takes proper care of their batteries, very few know how.
Try to have a new battery within a year and get the battery manual for the brand you have (should be able to download off the website).

True ,I just gave a quick down and dirty way.I always tie my meter to overhead to test.But the fact of buying a lift from a company who repairs lifts that cant check a battery?
Scares me.

I never recommend "drive and deadhead at same time", since that requires looking and focusing in 2 different places at the same time, and the fact the chopper panel is controlling the drive function, and fly-back current is far stronger in the drive circuit. Just dead heading the hydraulics is far safer (especially to suggest for a non tech, or someone who might buy a battery forklift without being sure how to check the battery) and far more accurate.
Now if the unit has chopper hydraulics, then you need an amp meter and hydraulic pressure gauge to be sure how much load you are putting on the battery...

(The seller is a forklift repair shop in town, but they didn't seem to know how to test the battery. )

And that dont scare you?Make sure battery is charged and cooled for 8 hrs run truck for 10 to 15 min.Check main voltage then under load shouldn't be much of a drop.Load IE drive and dead head hyd at same time.

Here is the requested info.

Serial Number: 1A124725
Model Number: 30RCTT
Sales Customer Name:
Date Completed: 10/16/1992
Date Installed: 11/03/1992
Date Inactive:
Date Used: 02/02/2007

most crowns have the date stamped on the mast
in US format month-day-year

Thanks! How does one check out the battery? (The seller is a forklift repair shop in town, but they didn't seem to know how to test the battery. )

It is a 1992 machine. If you are looking at buying it you may want to have the battery checked out. A replacement battery is probably in the area of $3500 to $4000.