A battery that is nearly finished will pass a voltage test at noon and fail at dawn, when it is coldest and its charge is lowest. But the same symptom comes from a corroded earth strap, a tired starter, or something on the car drawing current all night.
We load-test the battery, measure the alternator output, and then measure the parasitic draw with the car locked and asleep. That last number is the one most people never check, and it is why batteries get replaced twice.
How we tell: Worse after the car has stood two days than after one.
In this order
The same three steps as every car that comes through the door: the check, then the quote, then your old parts.
JMD 2,500comes off the bill
Battery load-tested, alternator output and draw measured cold.
0JMD 60,000120,000
Whatever comes off your car is bagged with your registration on it and handed to you when you collect. It is the simplest proof that the part we charged you for was the part we changed.