14.5 V is only going to be possible if the battery is completely flat; as the SoC rises the voltage will drop. A fully charged battery will only take 13.2 V as it reduces to trickle charge. Claimed being the operative word. You will only get a measurable improvement if the old battery was severely compromised by dead or shorted cell. Otherwise any improvement will be negligible by replacing what is an old, but functioning, battery.
