Cordless Drills and Batteries

So I have this Bosch PSR 1440 cordless drill that I bought a few years ago.
I've never been a great believer in these cordless tools, but my younger brother Craig was always bragging about how useful his was.
Although I never used it on a daily basis, I must say that it's been a great tool.
For the last eight months I have not used it at all and when I started some DIY projects, I was distressed to find that the battery held hardly any charge.
Eight 3.5mm x 60mm into MDF and the battery is dead.

Searching for a battery, shows me nothing in South Africa, but I can get them from UK for £30+ plus postage and VAT when it lands here. For equivalent of about £40 I can go to Makro and get a new drill.

So I write Craig an email and mention it to him. Craig suggests I google "freezing drill batteries". I found one or two articles/forum topics but as usual they are either off topic, or venture off topic really fast, before delivering the "good stuff".

So I take the battery, place it in a ziplock plastic bag and left it in the freezer for 24 hours. After the freeze I immediately placed it in the charger and left it there overnight.

All I can say is that the drill is much better.
I have not done a comparative test with the same screws but I did fourty eight 3.5mm x 30mm wood screws into plywood before the battery showed any signs of weakening.
Although I cannot prove it, it seems the battery is holding even better on subsequent charges.

Ultimately this has turned a very frustrating situation into a more managable one and hopefully extends the life of my drill for a few more months.