Bests & Worsts Reviews from Amazon

There is an intelligent circuit board inside the pack that needs to be powered, and it draws its power from the very cells it is monitoring. The basic design flaw is that the circuit is wired to be powered by only one of the many cells in the pack. The board draws a constant although small current from that single cell. If the battery is not used for a few weeks then that cell will deep discharge causing a weak link in the bank of cells, the pack then fails in the charger. Makita has programmed the circuitry so that if you try to charge the battery 3 times in this state, it will permanently disable it. Normal behavior is to think "why is it not charging, let me try again". If more than 1 year old, it is out of warranty. Makita should step up, redesign the battery, and offer on their website to replace any batteries which have not been abused with the new design. I would not buy any more Makita tools powered by this battery.