Difference between "I have told You" and "I t

What is the exact diffrenece between "I have told you" and "I told you" and
"I had told you"

The time....

There's usually little difference between I've told you and I told you in daily spoken language...I've told you is just a little bit more linked to a present event...
I'd told...is the past of the past (past perfect)...

Could be used in a narrative: After he'd fallen into the water he remembered that I had told him not to climb that tree...