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5-3-8. Safety device
The Model UC 24YJ is equipped with a safety device that stops charging (and extinguishes the lamp) if any of the
following troubles occurs.
The electrolyte adheres to the thermistor built in the battery. The battery temperature cannot be detected
correctly in this case.
The relay in the charger is at the end of its service life.
How to check whether it is a failure of the battery or the charger
If the lamp goes off, disconnect the power cord plug from the receptacle first. Wait 3 to 5 minutes then connect
the power cord plug to the receptacle again.
In the case of , the lamp lights and the charger operates normally.
In the case of , the lamp does not light and the charger is at the end of its service life.
5-4. Batteries
5-4-1. Types and characteristics of batteries
Two types of batteries are available for electric power tools, Ni-Cd batteries and Ni-MH batteries. The
characteristics of the Ni-Cd batteries and the Ni-MH batteries are described in the table below.
1
2
1
2
Item
Capacity
Relationship between discharging
capacity and temperature
Self-heating during charging
Impact on the environment
Characteristics
Ni-MH batteries have higher capacity than Ni-Cd batteries.
See Fig. 15.
Ni-MH batteries have higher self-heating value than Ni-Cd batteries.
Ni-Cd batteries give impact on the environment as they include a
harmful substance (cadmium).
Ni-MH batteries are environmentally friendly as they do not include any
harmful substance.
Fig. 15 Relationship between battery temperature and capacity
Battery temperature
Battery temperature
Capacity
Capacity
Ni-Cd batteries
Ni-MH batteries
(*) If a Ni-MH battery is used (discharged) when the battery temperature is 0˚C or less, the battery
performance is extremely low at first but it becomes normal near the end of the operation because the
battery is warmed up. When the battery temperature is -10˚C or less and the capacity is 0, warm up the
battery by charging.
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Summary of Contents for UC 24YJ
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