Starter battery discharged - how to check?

[SaylorMade]

Went to the boat today, to go sailing.
Unfortunately my starter-battery was discharged. I know why - I forgot to turn off the VHF last sunday and it is hooked to the starter battery (for some reason, but that is not what this about).
It was not entirely dead, the VHF still had dim lights in it, but the starter couldn't rotate. A voltmeter on the battery gave a reading of 10.5 volts

I put on a charger, and the LED's showed that it went into "Repair mode" but only for 10-15 minutes, then resumed to normal charging.
I will leave it on for the next couple of days (8 A charger, 60 A battery) and expect that it will be recharged.

Now to the question, how much has this deep discharge harmed the battery, and is there a way to check that?
I don't know the age of the battery, but it has performed excellent, and holds the charge very well.

I am just wondering if there is a way to find out if it should be replaced after this incident?

[barnakiel]

If the battery is old and important, replace.

You can use a load tester. Ask your nearest car garage they will have one.

b.