You can never have too many PetSafe batteries on hand. PetSafe collar batteries have pretty good lifespans but when they start to lose their charge they leave your dog unprotected as a collar with a low battery may not always be able to activate when it receives the signal from your fence.

Once you realize you're out of spare batteries, you won't be able to safely put your dogs out until you get a replacement. Avoid taking the chance by stocking up on the appropriate PetSafe battery for your collar so you never have a gap in fence function.