First indication was when we get a vehicle where the charge monitor went from yellow to half to 3/3 then to full very quickly. It then discharge quickly to yellow with the tortoise low power indicator showing. This quick flickering in charge level is not usual. We always suspected the Nimh battery.
Our recondition process now results in a good working battery - we therefore suspected the computer. Replacing the faulty computer with another fixed the problem. Out of more than 50 batteries reconditioned to date we have encountered about 5.
We think that this could be the result of diode degradation over time. If this is so then all battery computer will have a limited life!! Perhaps someone can shed more light on this.