The boring scientific bit!

Most car/truck batteries will/should have an open circuit voltage of 12.6 volts. If your battery discharges over a period of time, which can happen with a simple parasitic draw (such as a on board CPU, Alarms etc) or possibly leaving an interior light on, any of these will cause the battery to discharge.

When a battery is fully charged it has a specific gravity of 1260 (this is the measurement of sulfuric acid) this measurement can be checked with a hydrometer, when the battery discharges the sulfuric acid goes through a chemical reaction and becomes more like water and would measure a specific gravity of 1000.

If water freezes at 0 degrees C and your battery was completely discharged, then it is fair to say that your battery froze solid like an ice cube.

Once this happens, the battery is 99% unrecoverable. Your trickle charger would be useless on the battery.

What you should do:

When you replace your battery, you should have your charging system checked out. We automatically carry out the alternator test but not all garages do and some do not have the correct equipment to accurately test alternators. It’s not just a case of plugging a volt meter onto the battery, the alternator and battery are matched and the mechanic needs to determine the AMPS per hour of the battery and alternator and be sure the alternator is able to reach the correct figures.

In the future, if you plan to leave the vehicle longer than 4 weeks, you should disconnect the negative cable from your battery. This will eliminate any patristic draw down from the car alarm etc. Better still, invest in a battery condition trickle charger.