I own a small renovation (remodelling) company and we use Hitachi drills exclusively and have never had a battery go on us.
I found a company here in Canada that supplies batteries for almost anything and I have bought replacements for Makitas and DeWalt that have died and the price is quite good.
Try googling replacement batteries and see what you find.
If all else fails e me and I will look into from this end.
Peter
