Thanks for the replies guys... appreciate it.
I am not using a voltage regulator as such, but instead, a boost-buck DC-DC converter, and their main power source is a switchmode regulated adapter. The boost-buck is great because even if I connect a big'ish load to the supply rail (causing a voltage drop), it does not affect the output voltage of the boost-buck at all
Whereas in my experience, an adjustable voltage regulator caused issues with the voltage connecting to the battery - but I don't realy want to get into that as it's past tense now.
In fact, I am planning on having 2 of these modules - one for 14.5V boost charge (when required), and one for 13.6V float charging (each with their own resistor and diode in series with their outputs. I will have a relay switching between the 2 modules, controlled by a micro-controller, which will also perform other tasks. For over-voltage protection for the battery, I will attach a crowbar circuit to intentionally blow a fuse located at the boost-buck inputs (the battery will have its own fuse as well).
MrAl: I like your suggestion with the different resistor values, but I think I will stick to just 1 resistor (per module) due to limitations with space that I will have on my PCB.
Another question!!!!! Once the battery gets full and it's time to switch to Float, is it ok to immediately supply the battery with the 13.6V (from 14.5V) - the other module - , or should I let the battery's voltage fall naturally a bit first, THEN apply the float voltage?