Recovering a Lead Acid battery after it has been deeply discharged

[OriginalBigAl]

IDK if I ever bored you with the story of my 2002 Octavia TDi estate. It was when I was first ill and not driving and it was off the road for months. I decided to sell it, but the thing wouldn't start.

It was Winter and snowy. The battery was sub 2V and my CTEK MXS 5.0 wouldn't start a charge on it. I dug around in the booklet and found it needed to be above 2V before the charger would kick in.

So I got out a hairdryer and warmed the battery up for about 20 minutes in the hope of breathing life into it.

As soon as it read 2.1 or 2.2V, I switched the charger on and, hey presto, it started charging.

I set it to a de-sulphation cycle which took an absolute age, but when it was done, the battery was good to go.
It held the charge even when standing for a couple of weeks after and started every day.

It always helps to warm them up a bit , would the hairdryer be a perm...anent solution? .