Rather than paying close on £5 each for replacement batteries, wouldn't it be simpler and much cheaper to replace the dry cells in the old AD28 packaging with three alkaline cells?
All you would need is a couple of AA cell holders as a one-off investment - and, of course, you will be enable to ensure that they are correctly wired! - then fill them with AA alkaline cells from Poundland which will cost you the grand sum of £1 for six.
I don't know how the capacity of an alkaline AA compares with one of the original zinc carbon cells but even if you have to replace them twice as often, you are still getting two AD28 replacements for £1!
EDIT: Ah, I see Jeffrey has had the same idea!
All you would need is a couple of AA cell holders as a one-off investment - and, of course, you will be enable to ensure that they are correctly wired! - then fill them with AA alkaline cells from Poundland which will cost you the grand sum of £1 for six.
I don't know how the capacity of an alkaline AA compares with one of the original zinc carbon cells but even if you have to replace them twice as often, you are still getting two AD28 replacements for £1!
EDIT: Ah, I see Jeffrey has had the same idea!
