Instruct: Classify the given review into positive or negative sentiment.
Query: Does what it's supposed to

Attached first to dead battery on Mazda Miata - it sits much of the winter. Instructions say it will most likely not revive a completely dead battery, and it did not. Jumped the battery from another vehicle and drove it around the block a few times. Attached Tender and it brought the battery back to full charge overnight. Then attached it to lawn tractor and it brought it back the next night. Will use for boat batteries next. May buy a second.