Maybe this is where we're getting hung up. What exactly do you mean by your battery acceptance? During bulk you should be at constant current, and the voltage rises towards the set acceptance voltage. Then, it shifts into acceptance mode, and charges at constant voltage 'til the current drops to about 2% of C(20). Right?
Perhaps there is confusion about the word
acceptance. BTW, I seem to recall that the 3 phases of charging (or stages) are bulk, absorption and float, not bulk, acceptance, and float.
Edit: I read the Link 2000 R manual, and it does say "acceptance." Most likely where you got that.
Battery acceptance is the ability of the bank to absorb current, and is not a phase or stage of charging. That's all. The fuller a battery is, the less current it can and will take, regardless of what phase or stage of charging one may be experiencing.
If you have a small bank compared to your charging
SOURCE (so we can dispense with typing 'charger or alternator' from now on
), the bulk phase would be expected to be very short, because one is providing a LOT of current with a rapidly rising voltage. One will reach the voltage setpoint rather quickly, and, as you correctly stated, the current will begin to decline. That current reduction is due solely to battery acceptance. At any given pressure, i.e., voltage, the flow, i.e., current, will decline.
The regulator is NOT telling your charging source to reduce the current. The battery acceptance is "pushing back", if you will, against whatever current could be available IF the voltage hadn't stopped rising.
[EDIT: Your F10 function is a safety device and does not affect this discussion about battery acceptance. This is because you have the AO shunt, which most other popular, i.e., Balmar, external regulators do not have, a shunt. Its end result is identical to the functions used by Balmar called amp or belt manager.]
Once the voltage setpoint is reached, it's the battery acceptance that controls the current that can be absorbed.
See, that's why English sucks for engineering stuff!!!
Acceptance, absorption, accept, absorb, phases, stages...yadayada
Anyway, even with my house bank which is twice the size of yours, but with my 75A shorepower charger, I see this all the time when I come back from a day long day sail. The bulk phase simply doesn't take very long. In the over two deacdes since I have had this system, I have never had any issues with overcharging during bulk, because it simply doesn't last that long. You may choose to go back to re-read what I've said now with perhaps a better understanding of why I said what I did.
I don't know how familiar you have gotten with your Link. First, have you read my "Gotcha Algorithm" article? If not, I'll send you a link to it, helped to develop it thanks to Rich Stidger and Donalex, both on this very forum. It's important. Second, I have attached a little known but important document that I "captured" shortly after I bought my boat and my Link 2000. The info in it is NOT in either the Link 2000 or 2000-R manuals. Hope you don't ever need it, but I have, twice so far in 20 years, once just last month. Hope it helps if you need it.