When you first get your battery:
Run your rechargeable battery through at least 3 full charge/discharge cycles before putting it into ordinary service. This will help obtain maximum capacity of the battery.
Storing your battery:
Store your Hitachi cordless drill battery in a cool dry place. Do not leave your battery exposed to direct sunlight or temperatures below 30 degrees F and above 100 degrees F. Always discharge NiCd, NiMH and Li-Ion batteries before storing; and fully charge lead acid batteries before storing.
Charging your battery:
Rechargeable batteries will perform better when trickle charged. Rapid or Fast charging can be used with NiCd, NiMH and Li-IOn batteries, but you must be sure that your charger can handle the cell chemistry involved. Please consult your charger manufacturer’s user guide for these specifications.
To calculate charge time for your battery, use the following equations:
Slow charger: (Cell capacity in mAh / Charging rate in mA) x 1.4 = Time in hours
Fast charger: (Cell capacity in mAh / Cahrging rate in mA) x 1.5 = Time in hours
For example if you have a 1700mAh battery and a charger charging at 700mA, you will need to charge the battery for approximately 3 1/2 hours.
Exercising your NiCd or NiMH battery:
Battery life will improve when you exercise your battery. To exercise a rechargeable NiCd or NiMH battery, first discharge the battery to 1 volt per cell (or until your equipment complains of “low battery”). (NiCd and NiMH batteries consist of 1.2 volts per cell – i.e. a 4.8 volt battery contains 4 cells). Finally, charge your battery with a trickle charge until fully charged. When fully charged a NiCd battery will show approximately 1.35 volts per cell, and a NiMH Dewalt cordless drill batteries will show about 1.39 volts per cell.
NOTES on Battery Chemistries:
Nickel-Cadmium rechargeable batteries are very durable and reliable. You may slow or fast charge most NiCd’s, but some manufacturers make different types of cells specifically for rapid charging or specifically for slow charging. NiCd battery performance is improved dramatically by interspersing discharge pulses between charge pulses. This is known as “burp” or “reverse load” charging. This method of charging allows the battery to more efficiently degass while charging.
NiCd batteries should not be left in a charger for more than 30 hours. Also, NiCd batteries should not be subjected to shallow discharge (i.e. using the battery for a short period of time, then recharging). This type of use may result in crystalline formation inside the battery which will diminish performance. This is known as the “memory effect”.
Nickel-Metal Hydride rechargeable batteries are the next level up from NiCd. They offer up to 40% more run time per volume than NiCd. They are also more environmentally friendly. The biggest advantage of NiMH over NiCd is their ability to accept a charge at any time without suffering from the “memory effect”. The memory effect does exist in NiMH, but the extent is a fraction of that in NiCd. The best way to charge NiMH batteries is either with the “burp” charging described above, or with a Delta V terminating charger. Before charging your NiMH battery, check with the charger manufacturer to make sure their charger can handle NIMH.
Li+ and Lithium Polymer
Lithium Ion and Lithium Polymer are the latest technologies in rechargeable batteries for portable equipment. They have the highest energy density among commercial batteries; twice that of NiCd. They also have a very low self-discharge rate.
Lithium based rechargeable Makita drill batteries are the most expensive batteries available commercially. Disposal of lithium based batteries may cause some concern since any moisture which may creep into the cell after corrosion could present danger of explosion.