Picked up an apparently unused 75Ah car battery today for £20. I've charged it fully from the panel and it's going to sit overnight on the headlight bulb, so should still be going tomorrow morning 40Ah later (a 60% depth of discharge cycle). Hope it really is OK and I've not been spun some story - apparently it was bought for this lady's son's Audi TT which she was looking after while he travelled but wouldn't start, she lifted the bonnet and found a battery shaped hole so assumed someone had nicked the battery and that was why it wouldn't start. So she bought this one, only to find out from her son that the battery was in the boot... It looks clean, was sitting at 12.8V and came in packaging dated January this year so fingers crossed...