Cordless power tool battery and charger maintenance and care

Shop for Batteries and Chargers
The wrong charger and battery can cause an explosion Always use the recommended battery with your charger and cordless power tool. An incompatible battery can cause serious damage to the tool, charger or battery and could even result in an explosion.
Electrolyte of nickel battery needs redistributing before use. Before the first use of a NiCd battery it will need to be primed by charging and discharging it to redistribute electrolyte and ensure all the cells are at the same level of charge (see  How to prime a nickel-based cordless power tool battery).

Care during battery use

Don't use batteries and chargers and power tools when there are flammable substances in the workplace. Avoid using cordless power tools in dusty conditions if you can; fitting and removing a battery from a power tool can ignite dust. Similarly, never use a power tool when there are flammable gases in the air.
If the batteries get hot they need to be cooled down or thrown away. If your nickel-based battery becomes hot during use, stop using it until it cools down again. If your Li-ion battery gets hot, it has been damaged and you will need to replace it.
Wonkee Donkee says: When you are taking the temperature of the battery, remember that it will be hotter in the cells because they are surrounded by insulation.
Change the battery when you notice a reduction in power to the cordless power tool. Recharge the battery when you notice a reduction in performance of your power tool. To continue working with the cordless power tool after this point can damage the tool.
Batteries shouldn't really be discharged by running them down in the cordless power tool. Li-ion batteries should never be discharged by running it down in the tool after the performance has decreased, like you might if you were priming a nickel-based battery. Over-discharging a Li-ion battery will damage it permanently.
Release trigger to turn off tool and reset battery. Many Li-ion batteries will cut out if they are being overloaded, overheated or over-discharged. If this happens to you, turn the cordless power tool off and then start it again. This resets the battery. If it cuts out again it means it needs charging or cooling down before you can continue using it.
Try not to drop your battery as it can damage it, particularly Li-Ion batteries. If your battery or charger gets a big knock it is advisable to get it serviced before continuin to use it as it may be damaged. NiCd batteries are the least susceptible to being dropped but Li-ion batteries are fragile.
Try not to use batteries in extreme temperatures. Try not to use your battery when it is below 0 degrees Celsius (such as outside in winter) or above 40 degrees Celsius (such as in a hot building in summer) as extreme temperatures can permanently damage the battery.
You need to use a voltage converter that will convert the voltage of the electricity, not just pass the power, for an american charger. Check the charger’s label to ensure it is suitable to use on UK mains power. If you have an American charger then it is probably designed for an electrical input of 120V and 60Hz rather than the UK household standard of 230V and 50Hz. Using a plug converter will not prevent the voltage from damaging the charger. You will need a converter to convert the voltage from the mains to 120V and 60Hz.
Multimeters can be used when diagnosing problems with a battery by measuring the voltage and capacity. There are a couple of tools that can be useful when looking after your cordless power tool batteries. Multimeters are devices that combine a voltmeter (a device to measure the voltage of a battery) and an ammeter (a device to measure how much electrical current is running through a circuit). They are useful when fixing a damaged battery or when you are priming your nickel-based battery (see How to prime a nickel-based cordless power tool battery).
Infrared thermometers are good for testing the battery temperature to avoid overheating it. Infrared thermometers use a laser to detect the temperature of an object. They are great if you want to accurately measure the temperature of a battery when it is in use or being charged. Remember that the cells will be hotter than the reading due to the foam padding insulating them.

Care during charging

Unplug the charger of a cordless power tool battery between uses Unplug the charger between uses to prevent any accidental short circuits.
Don't let power lead of charger get trodden on or pulled badly. Don’t let the charger cable get tangled or trodden on as that can damage it. Especially if you are holding a tool like an angle grinder. It could be very dangerous
Trickle charge the cordless power tool battery for no longer than 24 hours Avoid overcharging nickel-based batteries, particularly NiMH batteries. The battery can be left in the charger for up to 24 hours on trickle charge but any longer and it is best to remove it for storage or use.
Electrolyte vented out of battery and formed white crystals Nickel-based batteries have resealable valves on each cell to avoid explosion due to build-up in pressure during overcharging. The valves open to release the pressure causing electrolyte to seep out. Although they reseal, the amount of electrolyte is reduced which means the cell won’t work as well as it did.
Undercharging is a lot safer than overcharging a battery. Overcharging is a lot worse than undercharging so if you don’t think the charger is working properly, remove the battery early.
Try not to use chargers in extreme temperatures. It is best to charge batteries in a temperature between 4 and 29 degrees Celsius.