Bosch Kl 1208 User 39-s Manual -

The KL 1208 uses a simple LED system to communicate the charging status: : Power is on and the unit is active. Yellow LED (Blinking) : Charging is in progress.

: The battery may be faulty and should be professionally tested. Bosch Kl 1208 User 39-s Manual

The working lamp on the unit will light up if the battery has a charge. The KL 1208 uses a simple LED system

: Battery acid is highly corrosive. If it contacts skin or eyes, rinse immediately with large amounts of water for 15 minutes and consult a doctor. The working lamp on the unit will light

Most keypads allow for manual panic triggers:

: It is normal for the charger to become quite warm or hot during the initial phase of charging a deeply discharged battery.

See detailed listing and parts references for the KL 1208 on diagram of the indicator lights Are you trying to charge a specific type of battery (AGM, Gel, or Standard)? like clamps or cables? 1208 and 2404 Manual A4 - Electronic Power Systems