I believe suppliers used to store batteries dry and only add acid at the point of sale. I don't know if this still happens.

Lead-acid batteries self-discharge by around 5% a month - slower at low temperatures and faster in warmer weather. Once discharged below about 10.5V then sulfation sets in and the battery is damaged if left in this state.

I think the OP has the wrong thinking on batteries.

2 cars each require a battery - agreed.

Batteries are 6/7 years old - buy 2 sets of good quality (& long jump) leads

Flat battery - a neighbour, friend, taxi driver etc etc could volunteer I am sure and good jump leads will get you started.

Stand-by emergency battery & a brand new spare? Wasted money IMHO and a pain to remember to charge and where will the car(s) be when the battery fails and the "new battery" is on the garage floor?

A new battery can last well over 6/7 years, my Mazda Xedos battery lasted over 12 years! The brand new Yuasa spare battery in the garage is more likely to fail from age & neglect (sulfation) than a batteries in his 2 cars if used regularly with a decent run every week or so.

i only have 1 battery not 2 a new Yuasa delivered to my front door within 48 hrs for £58.99 a distress purchase from Halfords 1 mile away lists the same battery as starting at £100 without delivery. I have a very compact capacitor type jump starter that lives in the boot of the 107 unless the 108 is going to be left at an airport etc. There are also jump leads left in the boot of both cars from yesteryear. My new battery will be fitted to the 107 rather than be left for years then that battery will be left on a conditioner.

I would never just turn up at a neighbours house and expect them to jump start my car. If any of my neighbours wanted me to jump start one of their neglected cars from mine because they couldn't be bothered to buy a jump starter or battery charger. it would not be happening. They could use my Sealey jump starter or Noco charger no problem but they would not be compromising the electrical integrity of my cars.

My garage is not cold or damp and the battery is on a wooden shelf not the floor.

So how long would a supplier leave a sealed for life battery sitting in a warehouse before getting rid of it?

Where did my post say that I had 2 spare batteries and kept my new battery on the floor as opposed to a shelf?

Edited by Lrac on 17/08/2021 at 08:53