A strange one.
As the weather is improving - it's time to dig out the toys - both my Porsche and Seven live on CTEK trickle chargers, and whilst in HK, they have been in this state on and off for a number of years. All good and no issues.
Last week I tried to start the Porsche - just got clicking and warning messages - checked battery - holding 10v or so. Did a deep charge from the NOCO charger - back to 13.8v, but fell away immediately I tried to start the car. Got a new battery from Halfords (off the shelf, and rigged a temp supply whilst changing to keep memories etc). Car started ok, and is fine now. Checked the details - battery was the original, and at 11 years old I didn't mind having to change it. Car is now out of warranty, so didn't go down the Porsche OEM battery route as this would have been 4-500 pounds.
Yesterday, in preparation to go to the Midlands meet - I tried to start the Seven, exactly the same issue - battery at around 9.8v, and recovered via a deep charge, but wouldn't start the car and fell back immediately.
The cars were on trickle from two different CTEK chargers, a Polar 5.3, and a standard 5.3. Both for a number of months - the seven had not been started since last October.
The Seven Banner battery is around 6 years old, and the second one, the first having lasted over 10 years.
Is this just age (the batteries - not me) - or are the CTEK tricklers cooking the batteries here?