As always read your owners manual and follow all the Manufacturers directions.

    ("Dead" means it can't turn the chuck / operate the tool or light up a flashlight)
    We have found that the common misbelieve that “a battery should be run dead” is the single worst thing that you can do to a battery (it is the same with lead/acid batteries and some Lithium-Ion).  AS SOON AS YOU NOTICE A POWER LOSS, THE BATTERY IS "DISCHARGED" AND SHOULD BE RECHARGED IMMEDIATELY.
  2. Please read rule # 1 again – it is that important.   New battery packs should be “charged fully” before you use your tool for the first time.  New battery packs will reach full loading capacity only after 4-5 charges.
  3. A NiCd or NiMH battery without even being used will lose its charge at a rate of about 1% per day.  Because of this when a battery has been run and will be then stored for some time, it is best to recharge before putting away.  For instance if you put a discharged battery “back into the case” and forget to recharge it for a couple weeks, or longer, it will probably be COMPLETELY DEAD by then.  Battery packs that are not in use regularly (not used for several weeks at a time) should be recharged at regular intervals (We suggest recharging every 1 or 2 months even without use)  
  4. Without going into great detail, when a DEAD battery is recharged, a few or more of the cells inside of it can “FLIP” in polarity.  This results in a “fully charged” battery that has a shorter run time and less power, or worse, a battery that “won’t take any charge”.  This is because those “FLIPPED” cells are fighting the cells charged with the correct polarity much like putting 3 cells into a flashlight in one direction and 1 cell backward – it won’t run long but it does run...dimly and only for a short while.  The Multi-bay Charger by Milwaukee Power Tools has been able to fix the majority of Milwaukee NiCd batteries that show these symptoms and/or won’t charge in standard, single battery chargers.
  5. Temperature also GREATLY affects battery performance.  Makita states in the owner’s manual of its 6932FDWDE impact driver   “(1.)  Do not charge a battery cartridge when temperature is BELOW 50°F or ABOVE 104°F.”  Milwaukee’s Multi-bay charger manual states it will sense battery temperature and will charge the battery..... “between 41°F and 113°F for NiCd, between 41°F and 95°F for NiMH.  When the battery temperature is outside of this range, charging will occur at a slower rate (taking up to 16 hours) to prevent damage to battery. .... the (Multi-bay) charger will automatically adjust to give the most rapid charge that is safe for the temperature. It has been our experience that repeated charging of a battery on a cold day will cause condensation inside the battery that corrodes the terminals, and can possibly freeze & break the circuit.  Signs of this occurring appear the same as water damage – a white film around the contacts.  If the temperature is below 50°F we suggest using electric tools, or for very small jobs, using the batteries that you have only charged once during that day and allowing them to warm overnight before charging them again.   
  6. The cells of a battery are soldered in series.  If a battery sustains a severe drop, or freezes, it can break any of several solder points between its cells.  The most common sign of this is a battery that won’t even cause the charger to start charging or “light up”.

* Chargers:  The most common problems we have found with chargers is improper voltage supply and improperly wired outlets.  Lightning strikes or even power surges over 120v will blow a fuse or worse inside most chargers – regardless of the brand.  Even inside of our store at Fairbury Fastener we have recorded up to 127volts for periods over 10 minutes coming out of a standard outlet.  In general rural areas seem to be the most susceptible to these types of problems.  We sell testers for under $30 that will check wiring and voltage issues.  It is best to check your wiring and voltage to find out if this is a problem before plugging in your charger.  As always follow your owners manual instructions.