Projecta DC20 Instruction Manual page 10

Q. Why does the 'FULLY CHARGED' LED come on straight away?
A. There are three possible reasons why the 'FULLY CHARGED' LED may come on straight away.
1. The battery is fully charged.
2. The battery has taken a surface charge.
3. The battery has a faulty cell.
Q. What is Surface Charge?
A. Batteries unused or left flat for some time build up a resistance to being recharged. When the
charger is first connected, these batteries will take a surface charge, and the 'FULLY CHARGED'
LED will illuminate within a short period of time. The battery however is not fully charged. The
charger is voltage sensitive and cannot differentiate between a surface charge and a fully
charged battery. After a few hours the battery may start to accept some charge but most
batteries with this condition will not recover.
Q. What is a Faulty Cell?
A. 12 Volt batteries contain 6 cells and one faulty cell is enough to ruin your battery. If after twelve
hours of charging your battery is still flat, you should test the cells using a hydrometer. If one
reading is lower than the rest it indicates a faulty cell. It is pointless to continue charging; the
battery needs replacing.
Q. Why is there no output at the charger's terminals?
A. The charger incorporates short circuit protection that makes it much safer to use. For this reason
the charger will only output power when properly connected to a battery. To check if the charger
is functioning, follow the instructions to connect and operate the charger as normal on a flat
battery. While the battery is charging measure the battery voltage with a volt or multi-meter.
Charging can be confirmed if the voltage is increasing (within the voltage parameters set out in
the specifications).
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