Whats normal voltage drop from a 4amp load? (210ah)

wopachop wrote:
I have two brand new 6v from costco. I pulled 20amp hours out of them a week ago and then fully charged with an automotive battery tender.

Today i put a 3.8a load on them and voltage is down at 12.15v after a few minutes.

I am not convinced the batteries are fully charged. Did the charger hold 14.7+ volts until amps charging was less than one amp?
Have you verified full charge with a hydrometer?
Did you let them rest unconnected 48 hours and observe 12.7+ volts?