I do not believe when Jesus said 'Before Abraham was born, I am.', that he was referring to be YHWH of the OT, my reasons for this is as follows.
That firstly the term "ego eimi" (I am) wasn't the term used for the name of YHWH in the OT, the term for YHWH's name was "ego eimi ho on" which roughly means "I am the existence". No doubt the term "Before Abraham was, I am," is certainly appropriate. The Greek literally says, "Before Abraham comes to be I am," or "Before Abraham came to be, I am." However claiming the "ego eimi" was in regards to YHWH is another thing.
Another point to why I don't believe Jesus was refereeing to YHWH is because of all the other usages of the term 'ego eimi/ I am'. The term "I am" gets used a ton of times in the NT, however for one to wave his magic stick and simply pick and choose when the term means YHWH and when it doesn't is wrong.
Here are some example of times the term "ego eimi is used but does mean YHWH simply for the reason that the trinitrian doesn't want it to. At Luke 22:33, when Peter said to Jesus, "I am prepared to go to prison with you and to death," should we assume that by his usage of 'ego eimi' he was saying "YHWH is prepared to go to prison with you and to death?". Again, if we simply assumed the words ego eimi were to be understood as the divine name, when John the Baptist used the words ego eimi saying, "I am not the Christ" should we wave our magic stick and say John the Baptist said, "Yahweh is not the Christ"? Of course not! In all these instances there's no reason to believe so, the same can be found with Jesus usage of ego eimi, there's nothing in the text to say or even imply that when he said 'ego eimi/I am' that it meant YHWH, the only thing that does suggest it is a already pre-conceived idea that Jesus is God.
Jesus used the term elsewhere in John where it is quite clear he did not intend to use a divine name. For example, the Samaritian woman said to Jesus, "I know that the Christ is coming" and Jesus responded to her, "I am who speaks to you." It should be obvious to anyone that Jesus uses the words ego eimi not for the purposes of claiming to be YHWH but to let her know he is the Christ who she just mentioned.
Some people also claim that the fact that the Jews picked up stones to kill Jesus proves that the term was used to show that he was YHWH, however looking again at the other instances Jesus use of the word its clear this is also false. During this very same dialogue with the Jews in John chapter 8, Jesus used the term ego eimi several times before he used it at verse 8:58 (8:12,16,18,23,24,28). And through all these many utterances of ego eimi by Jesus, none of these Jews at any time ever supposed Jesus was referring to the divine name YHWH. For example, when Jesus said, "Unless you believe that I am you wil die in your sins," the Jews did not respond by supposing Jesus was claiming to be YHWH. Instead, they did just the opposite by responding, "Who are you?"The thought that Jesus was using a divine name never even crossed their mind. And again At John 8:24-25, rather than recognizing the words ego eimi to be a direct reference to their God's divine name, the Jews had absolutely no idea who Jesus was claiming to be. But Trinitarians expect people to believe the claim that when Jesus used the same term at 8:58, the Jews immediately recognized, and necessarily would have recognized, ego eimi to be a reference to the divine name of their God.
Again the only reason why Jesus usage of "I am" (ego eimi) in John 8:58 was in reference to YHWH (according to the trinitrian) is because a trinitrian who already believes Jesus is God picks up his magic wand, waves it, and says that they want it to mean YHWH. There's simply not one shred of evidence to suggest it.